Arquivo da tag: Genética

How Genetics Is Changing Our Understanding of ‘Race’ (New York Times)

Credit: Angie Wang

In 1942, the anthropologist Ashley Montagu published “Man’s Most Dangerous Myth: The Fallacy of Race,” an influential book that argued that race is a social concept with no genetic basis. A classic example often cited is the inconsistent definition of “black.” In the United States, historically, a person is “black” if he has any sub-Saharan African ancestry; in Brazil, a person is not “black” if he is known to have any European ancestry. If “black” refers to different people in different contexts, how can there be any genetic basis to it?

Beginning in 1972, genetic findings began to be incorporated into this argument. That year, the geneticist Richard Lewontin published an important study of variation in protein types in blood. He grouped the human populations he analyzed into seven “races” — West Eurasians, Africans, East Asians, South Asians, Native Americans, Oceanians and Australians — and found that around 85 percent of variation in the protein types could be accounted for by variation within populations and “races,” and only 15 percent by variation across them. To the extent that there was variation among humans, he concluded, most of it was because of “differences between individuals.”

In this way, a consensus was established that among human populations there are no differences large enough to support the concept of “biological race.” Instead, it was argued, race is a “social construct,” a way of categorizing people that changes over time and across countries.

It is true that race is a social construct. It is also true, as Dr. Lewontin wrote, that human populations “are remarkably similar to each other” from a genetic point of view. 

But over the years this consensus has morphed, seemingly without questioning, into an orthodoxy. The orthodoxy maintains that the average genetic differences among people grouped according to today’s racial terms are so trivial when it comes to any meaningful biological traits that those differences can be ignored.

The orthodoxy goes further, holding that we should be anxious about any research into genetic differences among populations. The concern is that such research, no matter how well-intentioned, is located on a slippery slope that leads to the kinds of pseudoscientific arguments about biological difference that were used in the past to try to justify the slave trade, the eugenics movement and the Nazis’ murder of six million Jews.

I have deep sympathy for the concern that genetic discoveries could be misused to justify racism. But as a geneticist I also know that it is simply no longer possible to ignore average genetic differences among “races.”

Groundbreaking advances in DNA sequencing technology have been made over the last two decades. These advances enable us to measure with exquisite accuracy what fraction of an individual’s genetic ancestry traces back to, say, West Africa 500 years ago — before the mixing in the Americas of the West African and European gene pools that were almost completely isolated for the last 70,000 years. With the help of these tools, we are learning that while race may be a social construct, differences in genetic ancestry that happen to correlate to many of today’s racial constructs are real.

Recent genetic studies have demonstrated differences across populations not just in the genetic determinants of simple traits such as skin color, but also in more complex traits like bodily dimensions and susceptibility to diseases. For example, we now know that genetic factors help explain why northern Europeans are taller on average than southern Europeans, why multiple sclerosis is more common in European-Americans than in African-Americans, and why the reverse is true for end-stage kidney disease.

I am worried that well-meaning people who deny the possibility of substantial biological differences among human populations are digging themselves into an indefensible position, one that will not survive the onslaught of science. I am also worried that whatever discoveries are made — and we truly have no idea yet what they will be — will be cited as “scientific proof” that racist prejudices and agendas have been correct all along, and that those well-meaning people will not understand the science well enough to push back against these claims.

This is why it is important, even urgent, that we develop a candid and scientifically up-to-date way of discussing any such differences, instead of sticking our heads in the sand and being caught unprepared when they are found.

To get a sense of what modern genetic research into average biological differences across populations looks like, consider an example from my own work. Beginning around 2003, I began exploring whether the population mixture that has occurred in the last few hundred years in the Americas could be leveraged to find risk factors for prostate cancer, a disease that occurs 1.7 times more often in self-identified African-Americans than in self-identified European-Americans. This disparity had not been possible to explain based on dietary and environmental differences, suggesting that genetic factors might play a role.

Self-identified African-Americans turn out to derive, on average, about 80 percent of their genetic ancestry from enslaved Africans brought to America between the 16th and 19th centuries. My colleagues and I searched, in 1,597 African-American men with prostate cancer, for locations in the genome where the fraction of genes contributed by West African ancestors was larger than it was elsewhere in the genome. In 2006, we found exactly what we were looking for: a location in the genome with about 2.8 percent more African ancestry than the average.

When we looked in more detail, we found that this region contained at least seven independent risk factors for prostate cancer, all more common in West Africans. Our findings could fully account for the higher rate of prostate cancer in African-Americans than in European-Americans. We could conclude this because African-Americans who happen to have entirely European ancestry in this small section of their genomes had about the same risk for prostate cancer as random Europeans.

Did this research rely on terms like “African-American” and “European-American” that are socially constructed, and did it label segments of the genome as being probably “West African” or “European” in origin? Yes. Did this research identify real risk factors for disease that differ in frequency across those populations, leading to discoveries with the potential to improve health and save lives? Yes.

While most people will agree that finding a genetic explanation for an elevated rate of disease is important, they often draw the line there. Finding genetic influences on a propensity for disease is one thing, they argue, but looking for such influences on behavior and cognition is another.

But whether we like it or not, that line has already been crossed. A recent study led by the economist Daniel Benjamin compiled information on the number of years of education from more than 400,000 people, almost all of whom were of European ancestry. After controlling for differences in socioeconomic background, he and his colleagues identified 74 genetic variations that are over-represented in genes known to be important in neurological development, each of which is incontrovertibly more common in Europeans with more years of education than in Europeans with fewer years of education.

It is not yet clear how these genetic variations operate. A follow-up study of Icelanders led by the geneticist Augustine Kong showed that these genetic variations also nudge people who carry them to delay having children. So these variations may be explaining longer times at school by affecting a behavior that has nothing to do with intelligence.

This study has been joined by others finding genetic predictors of behavior. One of these, led by the geneticist Danielle Posthuma, studied more than 70,000 people and found genetic variations in more than 20 genes that were predictive of performance on intelligence tests.

Is performance on an intelligence test or the number of years of school a person attends shaped by the way a person is brought up? Of course. But does it measure something having to do with some aspect of behavior or cognition? Almost certainly. And since all traits influenced by genetics are expected to differ across populations (because the frequencies of genetic variations are rarely exactly the same across populations), the genetic influences on behavior and cognition will differ across populations, too.

You will sometimes hear that any biological differences among populations are likely to be small, because humans have diverged too recently from common ancestors for substantial differences to have arisen under the pressure of natural selection. This is not true. The ancestors of East Asians, Europeans, West Africans and Australians were, until recently, almost completely isolated from one another for 40,000 years or longer, which is more than sufficient time for the forces of evolution to work. Indeed, the study led by Dr. Kong showed that in Iceland, there has been measurable genetic selection against the genetic variations that predict more years of education in that population just within the last century.

To understand why it is so dangerous for geneticists and anthropologists to simply repeat the old consensus about human population differences, consider what kinds of voices are filling the void that our silence is creating. Nicholas Wade, a longtime science journalist for The New York Times, rightly notes in his 2014 book, “A Troublesome Inheritance: Genes, Race and Human History,” that modern research is challenging our thinking about the nature of human population differences. But he goes on to make the unfounded and irresponsible claim that this research is suggesting that genetic factors explain traditional stereotypes.

One of Mr. Wade’s key sources, for example, is the anthropologist Henry Harpending, who has asserted that people of sub-Saharan African ancestry have no propensity to work when they don’t have to because, he claims, they did not go through the type of natural selection for hard work in the last thousands of years that some Eurasians did. There is simply no scientific evidence to support this statement. Indeed, as 139 geneticists (including myself) pointed out in a letter to The New York Times about Mr. Wade’s book, there is no genetic evidence to back up any of the racist stereotypes he promotes.

Another high-profile example is James Watson, the scientist who in 1953 co-discovered the structure of DNA, and who was forced to retire as head of the Cold Spring Harbor Laboratories in 2007 after he stated in an interview — without any scientific evidence — that research has suggested that genetic factors contribute to lower intelligence in Africans than in Europeans.

At a meeting a few years later, Dr. Watson said to me and my fellow geneticist Beth Shapiro something to the effect of “When are you guys going to figure out why it is that you Jews are so much smarter than everyone else?” He asserted that Jews were high achievers because of genetic advantages conferred by thousands of years of natural selection to be scholars, and that East Asian students tended to be conformist because of selection for conformity in ancient Chinese society. (Contacted recently, Dr. Watson denied having made these statements, maintaining that they do not represent his views; Dr. Shapiro said that her recollection matched mine.)

What makes Dr. Watson’s and Mr. Wade’s statements so insidious is that they start with the accurate observation that many academics are implausibly denying the possibility of average genetic differences among human populations, and then end with a claim — backed by no evidence — that they know what those differences are and that they correspond to racist stereotypes. They use the reluctance of the academic community to openly discuss these fraught issues to provide rhetorical cover for hateful ideas and old racist canards.

This is why knowledgeable scientists must speak out. If we abstain from laying out a rational framework for discussing differences among populations, we risk losing the trust of the public and we actively contribute to the distrust of expertise that is now so prevalent. We leave a vacuum that gets filled by pseudoscience, an outcome that is far worse than anything we could achieve by talking openly.

If scientists can be confident of anything, it is that whatever we currently believe about the genetic nature of differences among populations is most likely wrong. For example, my laboratory discovered in 2016, based on our sequencing of ancient human genomes, that “whites” are not derived from a population that existed from time immemorial, as some people believe. Instead, “whites” represent a mixture of four ancient populations that lived 10,000 years ago and were each as different from one another as Europeans and East Asians are today.

So how should we prepare for the likelihood that in the coming years, genetic studies will show that many traits are influenced by genetic variations, and that these traits will differ on average across human populations? It will be impossible — indeed, anti-scientific, foolish and absurd — to deny those differences.

For me, a natural response to the challenge is to learn from the example of the biological differences that exist between males and females. The differences between the sexes are far more profound than those that exist among human populations, reflecting more than 100 million years of evolution and adaptation. Males and females differ by huge tracts of genetic material — a Y chromosome that males have and that females don’t, and a second X chromosome that females have and males don’t.

Most everyone accepts that the biological differences between males and females are profound. In addition to anatomical differences, men and women exhibit average differences in size and physical strength. (There are also average differences in temperament and behavior, though there are important unresolved questions about the extent to which these differences are influenced by social expectations and upbringing.)

How do we accommodate the biological differences between men and women? I think the answer is obvious: We should both recognize that genetic differences between males and females exist and we should accord each sex the same freedoms and opportunities regardless of those differences.

It is clear from the inequities that persist between women and men in our society that fulfilling these aspirations in practice is a challenge. Yet conceptually it is straightforward. And if this is the case with men and women, then it is surely the case with whatever differences we may find among human populations, the great majority of which will be far less profound.

An abiding challenge for our civilization is to treat each human being as an individual and to empower all people, regardless of what hand they are dealt from the deck of life. Compared with the enormous differences that exist among individuals, differences among populations are on average many times smaller, so it should be only a modest challenge to accommodate a reality in which the average genetic contributions to human traits differ.

It is important to face whatever science will reveal without prejudging the outcome and with the confidence that we can be mature enough to handle any findings. Arguing that no substantial differences among human populations are possible will only invite the racist misuse of genetics that we wish to avoid.

David Reich is a professor of genetics at Harvard and the author of the forthcoming book “Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past,” from which this article is adapted.

Interdisciplinary approach yields new insights into human evolution (Vanderbilt University)

PUBLIC RELEASE: 

Vanderbilt biologist Nicole Creanza Nicole Creanza takes interdisciplinary approach to human evolution as guest editor of Royal Society journal

The evolution of human biology should be considered part and parcel with the evolution of humanity itself, proposes Nicole Creanza, assistant professor of biological sciences. She is the guest editor of a new themed issue of the Philosophical Transactions of the Royal Society B, the oldest scientific journal in the world, that focuses on an interdisciplinary approach to human evolution.

Stanford professor Marc Feldman and Stanford postdoc Oren Kolodny collaborated with Creanza on the special issue.

“Within the blink of an eye on a geological timescale, humans advanced from using basic stone tools to examining the rocks on Mars; however, our exact evolutionary path and the relative importance of genetic and cultural evolution remain a mystery,” said Creanza, who specializes in the application of computational and theoretical approaches to human and cultural evolution, particularly language development. “Our cultural capacities-to create new ideas, to communicate and learn from one another, and to form vast social networks-together make us uniquely human, but the origins, the mechanisms, and the evolutionary impact of these capacities remain unknown.”

The special issue brings together researchers in biology, anthropology, archaeology, economics, psychology, computer science and more to explore the cultural forces affecting human evolution from a wider perspective than is usually taken.

“Researchers have begun to recognize that understanding non-genetic inheritance, including culture, ecology, the microbiome, and regulation of gene expression, is fundamental to fully comprehending evolution,” said Creanza. “It is essential to understand the dynamics of cultural inheritance at different temporal and spatial scales, to uncover the underlying mechanisms that drive these dynamics, and to shed light on their implications for our current theory of evolution as well as for our interpretation and predictions regarding human behavior.”

In addition to an essay discussing the need for an interdisciplinary approach to human evolution, Creanza included an interdisciplinary study of her own, examining the origins of English’s contribution to Sranan, a creole that emerged in Suriname following an influx of indentured servants from England in the 17th century.

Creanza, along with linguists Andre Sherriah and Hubert Devonish of the University of the West Indes and psychologist Ewart Thomas from Stanford, sought to determine the geographic origins of the English speakers whose regional dialects formed the backbone of Sranan. Their work combined linguistic, historical and genetic approaches to determine that the English speakers who influenced Sranan the most originated largely from two counties on opposite sides of southern England: Bristol, in the west, and Essex, in the east.

“Thus, analyzing the features of modern-day languages might give us new information about events in human history that left few other traces,” Creanza said.

New Research Shocks Scientists: Human Emotion Physically Shapes Reality! (IUV)

BY  /   SUNDAY, 12 MARCH 2017

published on Life Coach Code, on February 26, 2017

Three different studies, done by different teams of scientists proved something really extraordinary. But when a new research connected these 3 discoveries, something shocking was realized, something hiding in plain sight.

Human emotion literally shapes the world around us. Not just our perception of the world, but reality itself.

Emotions-Physically-Shape-Reality

In the first experiment, human DNA, isolated in a sealed container, was placed near a test subject. Scientists gave the donor emotional stimulus and fascinatingly enough, the emotions affected their DNA in the other room.

In the presence of negative emotions the DNA tightened. In the presence of positive emotions the coils of the DNA relaxed.

The scientists concluded that “Human emotion produces effects which defy conventional laws of physics.”

Emotions-Have-An-Effect-On-Reality

In the second, similar but unrelated experiment, different group of scientists extracted Leukocytes (white blood cells) from donors and placed into chambers so they could measure electrical changes.

In this experiment, the donor was placed in one room and subjected to “emotional stimulation” consisting of video clips, which generated different emotions in the donor.

The DNA was placed in a different room in the same building. Both the donor and his DNA were monitored and as the donor exhibited emotional peaks or valleys (measured by electrical responses), the DNA exhibited the IDENTICAL RESPONSES AT THE EXACT SAME TIME.

DNA-Responds-To-Our-Emotions

There was no lag time, no transmission time. The DNA peaks and valleys EXACTLY MATCHED the peaks and valleys of the donor in time.

The scientists wanted to see how far away they could separate the donor from his DNA and still get this effect. They stopped testing after they separated the DNA and the donor by 50 miles and STILL had the SAME result. No lag time; no transmission time.

The DNA and the donor had the same identical responses in time. The conclusion was that the donor and the DNA can communicate beyond space and time.

The third experiment proved something pretty shocking!

Scientists observed the effect of DNA on our physical world.

Light photons, which make up the world around us, were observed inside a vacuum. Their natural locations were completely random.

Human DNA was then inserted into the vacuum. Shockingly the photons were no longer acting random. They precisely followed the geometry of the DNA.

Light-Photons-Followed-The-Geometry-DNA

Scientists who were studying this, described the photons behaving “surprisingly and counter-intuitively”. They went on to say that “We are forced to accept the possibility of some new field of energy!”

They concluded that human DNA literally shape the behavior of light photons that make up the world around us!

So when a new research was done, and all of these 3 scientific claims were connected together, scientists were shocked.

They came to a stunning realization that if our emotions affect our DNA and our DNA shapes the world around us, than our emotions physically change the world around us.

Scientists-Make-A-Claim-That-Human-Emotion-Defy-The-Conventional-Laws-Of-Physics-And-Reality

And not just that, we are connected to our DNA beyond space and time.

We create our reality by choosing it with our feelings.

Science has already proven some pretty MINDBLOWING facts about The Universe we live in. All we have to do is connect the dots.

Sources:
– https://www.youtube.com/watch?v=pq1q58wTolk;
– Science Alert;
– Heart Math;
– Above Top Secret;
– http://www.bibliotecapleyades.net/mistic/esp_greggbraden_11.htm;

O peso através das gerações (Pesquisa Fapesp)

Entre ratos, efeitos do consumo excessivo ou da falta de comida podem ser transmitidos para filhos e netos 

REINALDO JOSÉ LOPES | ED. 252 | FEVEREIRO 2017

Experimentos com ratos feitos por pesquisadores de universidades de São Paulo reforçam a ideia de que o excesso de peso pode ser um fenômeno que transcende gerações – e não apenas porque os filhos tendem a herdar dos pais genes que favorecem o acúmulo de energia e os tornam predispostos à obesidade ou porque vivem em um ambiente com disponibilidade excessiva de comida. Alterações na oferta de alimento para as fêmeas um pouco antes ou durante a gravidez parecem aumentar, por mecanismos ainda pouco compreendidos, a probabilidade de que tenham filhos e até netos com sobrepeso.

Em uma série de testes, a bióloga Maria Martha Bernardi e sua equipe na Universidade Paulista (Unip) alimentaram algumas ratas no início da vida reprodutiva e outras já grávidas com uma dieta bastante calórica e aguardaram para ver o que acontecia com a primeira geração de filhotes e também com os filhos desses filhotes. Tanto os roedores que nasceram de mães superalimentadas quanto os da geração seguinte apresentaram mais predisposição a desenvolver sobrepeso.

A tendência de ganho excessivo de peso ocorreu mesmo quando os filhos e os netos dessas ratas foram alimentados apenas com a dieta padrão de laboratório. Segundo Martha, esses resultados indicam que o período em que o feto está se desenvolvendo no útero é crucial para definir a regulação do metabolismo do animal e, ao menos, o da geração seguinte.

Se essas mudanças aparecessem apenas na primeira geração, o mais natural seria imaginar que alterações hormonais provocadas pela dieta materna teriam afetado os filhotes. Como o efeito avança até a segunda geração, os pesquisadores suspeitam que a propensão a ganhar peso seja mantida por mecanismos epigenéticos: alterações no padrão de ativação e desligamento dos genes provocadas por fatores ambientais, como a dieta, e transmitidas às gerações seguintes. Essas mudanças no perfil de acionamento dos genes não alteram diretamente a sequência de “letras químicas” do DNA, apesar de serem herdadas através das gerações. Embora o grupo de Martha não tenha analisado o padrão de atividade dos genes, dados obtidos por cientistas mundo afora indicam que mudanças no perfil de ativação gênica sem alteração na sequência de DNA podem acontecer tanto em animais quanto em seres humanos.

Dieta que engorda
Curiosamente, não foi só a superalimentação materna durante a gestação que parece ter mexido com o perfil de ativação de seus genes e deixado filhos e netos com tendência a engordar. Em um dos experimentos, realizado em parceria com pesquisadores das universidades de São Paulo (USP), Federal do ABC (UFABC) e Santo Amaro (Unisa), 12 fêmeas de ratos receberam 40% menos comida do que o considerado normal para as roedoras prenhes, enquanto oito ratas do grupo de controle foram alimentadas com a dieta habitual de laboratório.

As fêmeas que passaram fome durante a gestação ganharam menos da metade do peso das ratas que puderam comer à vontade. Os filhotes das mães submetidas à restrição alimentar nasceram menores e continuaram mais magros durante algum tempo, ainda que recebessem a mesma quantidade de comida que os filhos das ratas que não passaram fome. Só na idade adulta a diferença desapareceu e os dois grupos de roedores alcançaram peso semelhante, embora os filhos das ratas famintas apresentassem uma proporção maior de gordura corporal – em especial, de uma forma de gordura que se acumula entre os órgãos (gordura visceral), associada a maior risco de problemas cardiovasculares.

A diferença mais importante surgiu na segunda geração. Os netos de ratas que haviam comido pouco enquanto estavam prenhes nasceram menores, mas, depois de adultos, eram um pouco (de 10% a 15%) mais pesados que os netos das ratas alimentadas normalmente. Eles tinham mais gordura visceral e também sinais de inflamação no cérebro. Esse ganho extra de peso ocorreu mesmo com as fêmeas da primeira geração, portanto, mães desses animais, tendo sido alimentadas normalmente. É como se a privação de alimento experimentada pelas ratas da geração inicial provocasse uma reprogramação metabólica duradoura em seus descendentes, afirmam os pesquisadores em artigo publicado em maio de 2016 na revista Reproduction, Fertility and Development.

O trabalho da equipe paulista, nesse ponto, confirma pesquisas anteriores que já haviam encontrado uma associação entre episódios de fome na gravidez e o nascimento de filhos com propensão ao aumento de peso e aos problemas de saúde a ele associados. Embora não tenham identificado o mecanismo específico por trás desse efeito, Martha Bernardi e sua equipe suspeitam que compostos produzidos pelo organismo das mães da geração inicial, parcialmente privadas de comida na gestação, ativem genes que favorecem o rápido ganho de peso no filhote. Assim, os sinais químicos emitidos pelo corpo materno funcionariam como um alerta de que o ambiente é de escassez e que é preciso usar com máxima eficiência os recursos alimentares disponíveis. Essa sinalização recebida pelo organismo do filhote poderia fazer toda a diferença, representando a chance de crescer e sobreviver em um ambiente com privação de alimento. “Mas também pode levar à obesidade, caso a oferta de alimentos volte a se normalizar depois que ele nasce”, explica Martha.

Estudos realizados nas décadas anteriores mostraram uma situação muito parecida com a descrita acima entre os descendentes das mulheres que ficaram grávidas durante o chamado Hongerwinter (inverno da fome, em holandês), quando os exércitos nazistas que recuavam na Holanda diante do avanço dos Aliados cortaram boa parte do transporte de suprimentos para o país entre o fim de 1944 e o começo de 1945, no final da Segunda Grande Guerra. Tanto os filhos quanto os netos das sobreviventes do Hongerwinter apresentavam taxas de obesidade e problemas metabólicos acima do esperado para a população geral.

Inflamação no cérebro
Em outro estudo, Martha e seus colegas forneceram alimentação hipercalórica – uma mistura de ração padrão mais um suplemento líquido rico em diferentes tipos de gordura – para 10 ratas logo após o desmame, enquanto outro grupo de fêmeas recebeu a alimentação normal e serviu de controle. Conforme o esperado, as ratas submetidas à dieta hipercalórica quando bebês ficaram acima do peso, ainda que não obesas, ao chegar à puberdade. Efeitos semelhantes foram observados em suas filhas: eram ratas que, quando adultas, apresentaram sobrepeso e alterações metabólicas, como o acúmulo de gordura visceral, embora tenham sido tratadas apenas com uma dieta balanceada durante toda a vida. Também publicado na Reproduction, Fertility and Development, esse trabalho e outros estudos do grupo indicam que o sobrepeso foi o desencadeador de processos inflamatórios que afetaram o cérebro da mãe e da prole, de forma aparentemente duradoura.

Se parece estranho imaginar que o excesso de peso pode levar a uma inflamação cerebral, é preciso lembrar que as células de gordura não são meros depósitos de calorias. Os adipócitos, como são chamados, produzem uma grande variedade de substâncias, entre as quais moléculas desencadeadoras de inflamações, que chegam à corrente sanguínea e, a partir dela, ao hipotálamo, região do cérebro associada, entre outras funções, ao controle da fome.

Trabalhos do grupo da Unip ainda não publicados indicam ainda que essa inflamação pode atingir outras áreas cerebrais dos roedores. A hipótese dos pesquisadores é de que o processo inflamatório no órgão esteja ligado à reprogramação do organismo transmitida da mãe para os filhotes, incluindo aí alterações no controle do apetite que podem se manter durante a vida adulta.

Para Alicia Kowaltowski, pesquisadora do Instituto de Química da USP que estuda a relação entre a dieta e os mecanismos de produção de energia das células, é bastante forte a possibilidade de que a tendência ao sobrepeso e à obesidade seja passada de uma geração para outra por meios que não envolvem a herança de genes favorecedores do ganho de peso. “A questão é saber quais são os mecanismos que estão por trás desses fenômenos”, conta a pesquisadora.

Entre tais mecanismos, um candidato que tem ganhado força são as transformações epigenéticas. O prefixo grego epi significa superior, e na palavra epigenética, cunhada nos anos 1940 pelo embriologista inglês Conrad Waddington, designa a área da biologia que estuda as modificações químicas motivadas pelo ambiente que levam à ativação ou inativação dos genes e alteram o funcionamento do organismo. Uma das modificações químicas mais comuns e simples sofrida pelos genes é a chamada metilação. Nela, um grupo metila, formado por um átomo de carbono e três de hidrogênio (CH3), acopla-se a um trecho de DNA, impedindo que ele seja lido pelo maquinário da célula. O resultado é o silenciamento daquela região. Estudos com dezenas de espécies de animais, plantas e fungos já mostraram que o perfil de metilação pode ser transmitido de uma geração para outra e afetar as características da prole.

Influência paterna
O papel das mães no sobrepeso dos filhos parece cada vez mais sólido. E quanto ao papel do pai? “Há alguns indícios de que a influência paterna também pode ocorrer, mas eles são menos claros”, diz Martha Bernardi. Por um lado, faz sentido que influências epigenéticas possam ser transmitidas pelo lado paterno – assim como outras células do organismo, os espermatozoides podem ser afetados por alterações no padrão de ativação dos genes produzidas por influência do ambiente. Se tais mudanças não forem totalmente eliminadas após o encontro entre as células sexuais masculinas e os óvulos, o novo indivíduo gerado pela fecundação poderia carregar parte da memória epigenética de seu pai.

Um estudo de 2015, feito por uma equipe da Universidade de Copenhague, na Dinamarca, e liderado por Romain Barrès, mostrou que esse cenário é plausível ao estudar os espermatozoides de 16 homens obesos e outros 10 com peso normal. No caso dos voluntários obesos, os padrões epigenéticos, como os de metilação, concentravam-se em genes ligados ao desenvolvimento do sistema nervoso, em especial os que são importantes para o controle do apetite (e, portanto, do peso), o que não ocorria com os homens magros.

Barrès e seus colegas fizeram outra comparação sugestiva entre as marcações epigenéticas dos espermatozoides dos obesos antes da cirurgia de redução de estômago e as desses mesmos participantes após a operação. Resultado: depois da cirurgia, o padrão epigenético das células lembrava o de homens com peso normal.

“O mais importante a respeito dessas descobertas é sugerir que tais modificações podem ocorrer em células germinativas, ou seja, os óvulos e espermatozoides, e ser transmitidas para gerações seguintes”, diz o médico Licio Augusto Velloso, professor da Faculdade de Ciências Médicas da Universidade Estadual de Campinas (FCM-Unicamp), que estuda os mecanismos celulares e moleculares ligados à origem da obesidade e do diabetes. “Os estudos epigenéticos avançaram muito na última década e se espera que, num futuro não muito distante, o mapeamento de fatores ambientais e de seu impacto em diferentes aspectos da epigenética nos ajude a prevenir doenças importantes”, afirma Velloso.

Enxergar o excesso de peso pelo prisma epigenético pode trazer mais uma peça relevante para o quebra-cabeça da epidemia global de obesidade e de doenças metabólicas ligadas a ela. Historicamente associado à saúde e à fartura, o excesso de peso se tornou um problema de grandes proporções primeiro nos países ricos, mas hoje é cada vez mais comum em países mais pobres – a começar pelo Brasil, onde quase 60% da população adulta está acima do peso considerado saudável, conforme dados do Instituto Brasileiro de Geografia e Estatística (IBGE). Muitos países em desenvolvimento passaram rapidamente de um contexto em que a desnutrição era um problema grave para outro em que a obesidade é muito mais preocupante.

Artigos científicos
JOAQUIM, A. O. et al. Maternal food restriction in rats of the F0 generation increases retroperitoneal fat, the number and size of adipocytes and induces periventricular astrogliosis in female F1 and male F2 generationsReproduction, Fertility and Development. 31 mai. 2016.
JOAQUIM, A. O. et alTransgenerational effects of a hypercaloric dietReproduction, Fertility and Development. 25 ago. 2015.

What Did Neanderthals Leave to Modern Humans? Some Surprises (New York Times)

Geneticists tell us that somewhere between 1 and 5 percent of the genome of modern Europeans and Asians consists of DNA inherited from Neanderthals, our prehistoric cousins.

At Vanderbilt University, John Anthony Capra, an evolutionary genomics professor, has been combining high-powered computation and a medical records databank to learn what a Neanderthal heritage — even a fractional one — might mean for people today.

We spoke for two hours when Dr. Capra, 35, recently passed through New York City. An edited and condensed version of the conversation follows.

Q. Let’s begin with an indiscreet question. How did contemporary people come to have Neanderthal DNA on their genomes?

A. We hypothesize that roughly 50,000 years ago, when the ancestors of modern humans migrated out of Africa and into Eurasia, they encountered Neanderthals. Matings must have occurred then. And later.

One reason we deduce this is because the descendants of those who remained in Africa — present day Africans — don’t have Neanderthal DNA.

What does that mean for people who have it? 

At my lab, we’ve been doing genetic testing on the blood samples of 28,000 patients at Vanderbilt and eight other medical centers across the country. Computers help us pinpoint where on the human genome this Neanderthal DNA is, and we run that against information from the patients’ anonymized medical records. We’re looking for associations.

What we’ve been finding is that Neanderthal DNA has a subtle influence on risk for disease. It affects our immune system and how we respond to different immune challenges. It affects our skin. You’re slightly more prone to a condition where you can get scaly lesions after extreme sun exposure. There’s an increased risk for blood clots and tobacco addiction.

To our surprise, it appears that some Neanderthal DNA can increase the risk for depression; however, there are other Neanderthal bits that decrease the risk. Roughly 1 to 2 percent of one’s risk for depression is determined by Neanderthal DNA. It all depends on where on the genome it’s located.

Was there ever an upside to having Neanderthal DNA?

It probably helped our ancestors survive in prehistoric Europe. When humans migrated into Eurasia, they encountered unfamiliar hazards and pathogens. By mating with Neanderthals, they gave their offspring needed defenses and immunities.

That trait for blood clotting helped wounds close up quickly. In the modern world, however, this trait means greater risk for stroke and pregnancy complications. What helped us then doesn’t necessarily now.

Did you say earlier that Neanderthal DNA increases susceptibility to nicotine addiction?

Yes. Neanderthal DNA can mean you’re more likely to get hooked on nicotine, even though there were no tobacco plants in archaic Europe.

We think this might be because there’s a bit of Neanderthal DNA right next to a human gene that’s a neurotransmitter implicated in a generalized risk for addiction. In this case and probably others, we think the Neanderthal bits on the genome may serve as switches that turn human genes on or off.

Aside from the Neanderthals, do we know if our ancestors mated with other hominids?

We think they did. Sometimes when we’re examining genomes, we can see the genetic afterimages of hominids who haven’t even been identified yet.

A few years ago, the Swedish geneticist Svante Paabo received an unusual fossilized bone fragment from Siberia. He extracted the DNA, sequenced it and realized it was neither human nor Neanderthal. What Paabo found was a previously unknown hominid he named Denisovan, after the cave where it had been discovered. It turned out that Denisovan DNA can be found on the genomes of modern Southeast Asians and New Guineans.

Have you long been interested in genetics?

Growing up, I was very interested in history, but I also loved computers. I ended up majoring in computer science at college and going to graduate school in it; however, during my first year in graduate school, I realized I wasn’t very motivated by the problems that computer scientists worked on.

Fortunately, around that time — the early 2000s — it was becoming clear that people with computational skills could have a big impact in biology and genetics. The human genome had just been mapped. What an accomplishment! We now had the code to what makes you, you, and me, me. I wanted to be part of that kind of work.

So I switched over to biology. And it was there that I heard about a new field where you used computation and genetics research to look back in time — evolutionary genomics.

There may be no written records from prehistory, but genomes are a living record. If we can find ways to read them, we can discover things we couldn’t know any other way.

Not long ago, the two top editors of The New England Journal of Medicine published an editorial questioning “data sharing,” a common practice where scientists recycle raw data other researchers have collected for their own studies. They labeled some of the recycling researchers, “data parasites.” How did you feel when you read that?

I was upset. The data sets we used were not originally collected to specifically study Neanderthal DNA in modern humans. Thousands of patients at Vanderbilt consented to have their blood and their medical records deposited in a “biobank” to find genetic diseases.

Three years ago, when I set up my lab at Vanderbilt, I saw the potential of the biobank for studying both genetic diseases and human evolution. I wrote special computer programs so that we could mine existing data for these purposes.

That’s not being a “parasite.” That’s moving knowledge forward. I suspect that most of the patients who contributed their information are pleased to see it used in a wider way.

What has been the response to your Neanderthal research since you published it last year in the journal Science?

Some of it’s very touching. People are interested in learning about where they came from. Some of it is a little silly. “I have a lot of hair on my legs — is that from Neanderthals?”

But I received racist inquiries, too. I got calls from all over the world from people who thought that since Africans didn’t interbreed with Neanderthals, this somehow justified their ideas of white superiority.

It was illogical. Actually, Neanderthal DNA is mostly bad for us — though that didn’t bother them.

As you do your studies, do you ever wonder about what the lives of the Neanderthals were like?

It’s hard not to. Genetics has taught us a tremendous amount about that, and there’s a lot of evidence that they were much more human than apelike.

They’ve gotten a bad rap. We tend to think of them as dumb and brutish. There’s no reason to believe that. Maybe those of us of European heritage should be thinking, “Let’s improve their standing in the popular imagination. They’re our ancestors, too.’”

Cultural differences may leave their mark on DNA (Science Daily)

Date:
January 10, 2017
Source:
University of California – San Francisco
Summary:
Signatures of ethnicity in the genome appear to reflect an ethnic group’s shared culture and environment, rather than their common genetic ancestry, report scientists. Epigenetic signatures distinguishing Mexican and Puerto Rican children in this study cannot be explained by genetic ancestry alone, the researchers say.

The researchers identified several hundred differences in methylation associated with either Mexican or Puerto Rican ethnicity, but discovered that only three-quarters of the epigenetic difference between the two ethnic subgroups could be accounted for by differences in the children’s genetic ancestry. Credit: © DigitalGenetics / Fotolia

A UC San Francisco-led study has identified signatures of ethnicity in the genome that appear to reflect an ethnic group’s shared culture and environment, rather than their common genetic ancestry.

The study examined DNA methylation — an “annotation” of DNA that alters gene expression without changing the genomic sequence itself — in a group of diverse Latino children. Methylation is one type of “epigenetic mark” that previous research has shown can be either inherited or altered by life experience. The researchers identified several hundred differences in methylation associated with either Mexican or Puerto Rican ethnicity, but discovered that only three-quarters of the epigenetic difference between the two ethnic subgroups could be accounted for by differences in the children’s genetic ancestry. The rest of the epigenetic differences, the authors suggest, may reflect a biological stamp made by the different experiences, practices, and environmental exposures distinct to the two ethnic subgroups.

The discovery could help scientists understand how social, cultural, and environmental factors interact with genetics to create differences in health outcomes between different ethnic populations, the authors say, and provides a counterpoint to long-standing efforts in the biomedical research community to replace imprecise racial and ethnic categorization with genetic tests to determine ancestry.

“These data suggest that the interplay between race and ethnicity as social constructs and genetic ancestry as a biological construct is more complex than we had realized,” said Noah Zaitlen, PhD, a UCSF assistant professor of medicine and co-senior author on the new study. “In a medical context both elements may provide valuable information.”

The research — published January 3, 2017 in the online journal eLife — was led by Joshua Galanter, MD, MAS, formerly an assistant professor of medicine, of bioengineering and therapeutic sciences, and of epidemiology and biostatistics at UCSF, who is now a scientist at Genentech. The research was jointly supervised by Zaitlen and co-senior author Esteban Burchard, MD, MPH, a professor of bioengineering and therapeutic sciences and of medicine in UCSF’s schools of Pharmacy and Medicine and the Harry Wm. and Diana V. Hind Distinguished Professorship in Pharmaceutical Sciences II at UCSF.

“This is a big advancement of our understanding of race and ethnicity,” Burchard said. “There’s this whole debate about whether race is fundamentally genetic or is just a social construct. To our knowledge this is the first time anyone has attempted to quantify the molecular signature of the non-genetic components of race and ethnicity. It demonstrates in a whole new way that race combines both genetics and environment.”

Teasing apart roles of genetics, environment in ethnic differences in disease

Researchers and clinicians have known for many years that different racial and ethnic populations get diseases at different rates, respond differently to medications, and show very different results on standard clinical tests: “For a whole range of medical tests, whether your physician is told that your lab result is normal or abnormal depends entirely on the race/ethnicity box that you tick on an intake form,” Zaitlen said.

It’s tempting to assume that such health disparities between races and ethnicities all stem from inherited genetic differences, but that’s not necessarily the case. Different racial and ethnic groups also eat different diets, live in neighborhoods with more or less pollution, experience different levels of poverty, and are more or less likely to smoke tobacco, all of which could also impact their health outcomes.

“A lot of our research involves trying to tease apart how much of health differences between populations are genetic and how much are environmental,” Zaitlen said.

The researchers turned to epigenetics to search for answers to these questions because these molecular annotations of the genetic code have a unique position between genetic ancestry and environmental influence. Unlike the rest of the genome, which is only inherited from an individual’s parents (with random mutations here and there), methylation and other epigenetic annotations can be modified based on experience. These modifications influence when and where particular genes are expressed and appear to have significant impacts on disease risk, suggesting explanations for how environmental factors such as maternal smoking during pregnancy can influence a child’s risk of later health problems.

Epigenetic signatures of ethnicity could be biomarkers for shared cultural experiences

In the new study, the team examined methylation signatures in 573 children of self-identified Mexican or Puerto-Rican identity drawn from the GALA II study, a cohort previously developed by Burchard to study environmental and genetic components of asthma risk in Latino children. They identified 916 methylation sites that varied with ethnic identity, but found that only 520 of these differences could be completely explained by genetic ancestry — 109 could be partially explained by ancestry, while 205 could not be explained by ancestry at all.

Overall, the researchers found that about 76 percent of the effect of ethnicity on DNA methylation could be accounted for by controlling for genetic ancestry, suggesting that nearly a quarter of the effect must be due to other, unknown factors. The researchers found that many of these additional methylation sites corresponded to sites that previous studies had shown to be sensitive to environmental and social factors such as maternal smoking, exposure to diesel exhaust, and psychosocial stress. This led the team to hypothesize that a large fraction of their newly disovered epigenetic markers of ethnicity likely reflect biological signatures of environmental, social, or cultural differences between ethnic subgroups.

“This suggests that using epigenetics as a biomarker could give you a lot of information about environmental exposures within particular populations that’s not captured by genetics,” Zaitlen said. “Our next step will be to understand how specific epigenetic signatures are linked to particular environmental exposures, and use those signals to understand patient risk.”

Scientists and clinicians have increasingly tried to move away from simplistic racial and ethnic categories in disease research, the authors say, and — with the rise of precision medicine — in clinical diagnosis and treatment as well. Studies by the Burchard group and others have found that using genetic ancestry rather than ethnic self-identification significantly improves diagnostic accuracy for certain diseases.

But the new data showing that a large fraction of epigenetic signatures of ethnicity reflect something other than ancestry suggests that abandoning the idea of race and ethnicity altogether could sacrifice a lot of valuable information about the drivers of differences in health and disease between different communities.

“Like a standard family history, ethnicity is association with disease for both genetic and environmental reasons,” Zaitlen said. “If your dad or mom had a heart attack, that tells doctors a lot about your risk for a heart attack. Part of that is genetic, but part of it is that your lifestyle is influenced heavily by your parents’ lifestyle. Your ethnic group is like a much bigger family — it’s partly a matter of genetics, but it also reflects the environment of your broader community.”


Journal Reference:

  1. Joshua M Galanter, Christopher R Gignoux, Sam S Oh, Dara Torgerson, Maria Pino-Yanes, Neeta Thakur, Celeste Eng, Donglei Hu, Scott Huntsman, Harold J Farber, Pedro C Avila, Emerita Brigino-Buenaventura, Michael A LeNoir, Kelly Meade, Denise Serebrisky, William Rodríguez-Cintrón, Rajesh Kumar, Jose R Rodríguez-Santana, Max A Seibold, Luisa N Borrell, Esteban G Burchard, Noah Zaitlen. Differential methylation between ethnic sub-groups reflects the effect of genetic ancestry and environmental exposureseLife, 2017; 6 DOI: 10.7554/eLife.20532

Cientistas propõem projeto para criar genoma humano sintético (O Globo)

O Globo, 02/06/2016

Imagem de reprodução de DNA de hélice quádrupla – Divulgação/Jean-Paul Rodriguez

WASHINGTON — Um grupo de cientistas propôs, nesta quinta-feira, um projeto ambicioso para criar um genoma humano sintético, que tornaria possível a criação de seres humanos sem a necessidade de pais biológicos. Esta possibilidade levanta polêmica sobre o quanto a vida humana pode ou deve ser manipulada.

O projeto, que surgiu em uma reunião de cientistas da Universidade Harvard, nos EUA, no mês passado, tem como objetivo desenvolver e testar o genoma sintético em células dentro de laboratório ao longo de dez anos. O genoma sintético humano envolve a utilização de produtos químicos para criar o DNA presente nos cromossomas humanos. A meta foi relatada na revista “Science” pelos 25 especialistas envolvidos.

Os cientistas propuseram lançar, ainda este ano, o que chamaram de Projeto de Escrita do Genoma Humano e afirmaram que iriam envolver o público nessa discussão, que incluiria questões éticas, legais e sociais.

Os especialistas esperam arrecadar US$ 100 milhões — o equivalente a R$ 361 milhões — em financiamento público e privado para lançar o projeto este ano. No entanto, eles consideram que os custos totais serão inferiores aos US$ 3 milhões utilizados no Projeto do Genoma Humano original, que mapeou pela primeira vez o DNA humano.

O novo projecto “incluirá a engenharia completa do genoma de linhas de células humanas e de outros organismos importantes para a agricultura e saúde pública, ou aqueles que interpretar as funções biológicas humanas”, escreveram na “Science” os 25 cientistas, liderados pelo geneticista Jef Boeke, do Centro Médico Langone, da Universidade de Nova York.

How the introduction of farming changed the human genome (Science Daily)

Study tracks gene changes during the introduction of farming in Europe

Date:
November 23, 2015
Source:
Harvard Medical School
Summary:
Genomic analysis of ancient human remains identifies specific genes that changed during and after the transition in Europe from hunting and gathering to farming about 8,500 years ago. Many of the genes are associated with height, immunity, lactose digestion, light skin pigmentation, blue eye color and celiac disease risk.

Ancient DNA can provide insight into when humans acquired the adaptations seen in our genomes today. Credit: Image courtesy of Harvard Medical School

The introduction of agriculture into Europe about 8,500 years ago changed the way people lived right down to their DNA.

Until recently, scientists could try to understand the way humans adapted genetically to changes that occurred thousands of years ago only by looking at DNA variation in today’s populations. But our modern genomes contain mere echoes of the past that can’t be connected to specific events.

Now, an international team reports in Nature that researchers can see how natural selection happened by analyzing ancient human DNA.

“It allows us to put a time and date on selection and to directly associate selection with specific environmental changes, in this case the development of agriculture and the expansion of the first farmers into Europe,” said Iain Mathieson, a research fellow in genetics at Harvard Medical School and first author of the study.

By taking advantage of better DNA extraction techniques and amassing what is to date the largest collection of genome-wide datasets from ancient human remains, the team was able to identify specific genes that changed during and after the transition from hunting and gathering to farming.

Many of the variants occurred on or near genes that have been associated with height, the ability to digest lactose in adulthood, fatty acid metabolism, vitamin D levels, light skin pigmentation and blue eye color. Two variants appear on genes that have been linked to higher risk of celiac disease but that may have been important in adapting to an early agricultural diet.

Other variants were located on immune-associated genes, which made sense because “the Neolithic period involved an increase in population density, with people living close to one another and to domesticated animals,” said Wolfgang Haak, one of three senior authors of the study, a research fellow at the University of Adelaide and group leader in molecular anthropology at the Max Planck Institute for the Science of Human History.

“Although that finding did not come fully as a surprise,” he added, “it was great to see the selection happening in ‘real time.'”

The work also supports the idea that Europe’s first farmers came from ancient Anatolia, in what is now Turkey, and fills in more details about how ancient groups mixed and migrated.

“It’s a great mystery how present-day populations got to be the way we are today, both in terms of how our ancestors moved around and intermingled and how populations developed the adaptations that help us survive a bit better in the different environments in which we live,” said co-senior author David Reich, professor of genetics at HMS. “Now that ancient DNA is available at the genome-wide scale and in large sample sizes, we have an extraordinary new instrument for studying these questions.”

“From an archaeological perspective, it’s quite amazing,” said co-senior author Ron Pinhasi, associate professor of archaeology at University College Dublin. “The Neolithic revolution is perhaps the most important transition in human prehistory. We now have proof that people did actually go from Anatolia into Europe and brought farming with them. For more than 40 years, people thought it was impossible to answer that question.”

“Second,” he continued, “we now have evidence that genetic selection occurred along with the changes in lifestyle and demography, and that selection continued to happen following the transition.”

Prying more from the past

Members of the current team and others have used ancient DNA in the past few years to learn about Neanderthals and the genes they passed to humans, identify ancestors of present-day Europeans, trace migrations into the Americas and probe the roots of Indo-European languages. Studying natural selection, however, remained out of reach because it required more ancient genomes than were available.

“In the past year, we’ve had a super-exponential rise in the number of ancient samples we can study on a genome scale,” said Reich, who is also an associate member of the Broad Institute of Harvard and MIT and a Howard Hughes Medical Investigator. “In September 2014, we had 10 individuals. In this study, we have 230.”

The DNA came from the remains of people who lived between 3,000 and 8,500 years ago at different sites across what is now Europe, Siberia and Turkey. That time span provided snapshots of genetic variation before, during and after the agricultural revolution in Europe.

Among the 230 ancient individuals were 83 who hadn’t been sequenced before, including the first 26 to be gathered from the eastern Mediterranean, where warm conditions usually cause DNA to degrade.

Members of the team used several technological advances to obtain and analyze the new genetic material. For example, they exploited a method pioneered by Pinhasi’s laboratory to extract DNA from a remarkably rich source: a portion of the dense, pyramid-shaped petrous bone that houses the internal auditory organs. In some cases, the bone yielded 700 times more human DNA than could be obtained from other bones, including teeth.

“That changed everything,” said Pinhasi. “Higher-quality DNA meant we could analyze many more positions on the genome, perform more complex tests and simulations, and start systematically studying allele frequency across populations.”

What made the cut

Although the authors caution that sample size remains the biggest limitation of the study, comparing the ancient genomes to one another and to those of present-day people of European ancestry revealed 12 positions on the genome where natural selection related to the introduction of farming in northern latitudes appears to have happened.

“Some of those specific traits have been studied before,” said Reich. “This work with ancient DNA enriches our understanding of those traits and when they appeared.”

Besides the adaptations that appear to be related to diet, pigmentation, immunity and height, the possible selective pressure on other variants was less clear.

“We can guess by looking at the function of the gene, but our power is limited,” said Mathieson. “It’s quite frustrating.”

It’s too early to tell whether some of the variants were themselves selected for or whether they hitched a ride with a nearby beneficial gene. The question pertains especially to variants that seem to be disadvantageous, like increased disease risk.

Being able to look at numerous positions across the genome also allowed the team to examine complex traits for the first time in ancient DNA.

“We can see the evolution of height across time,” said Mathieson.

Researchers had noticed that people from southern Europe tend to be shorter than those from northern Europe. The new study suggests that the height differential arises both from people in the north having more ancestry from Eurasian steppe populations, who seem to have been taller, and people in the south having more ancestry from Neolithic and Chalcolithic groups from the Iberian peninsula, who seem to have been shorter.

The team wasn’t able to draw conclusions about the other complex traits it investigated: body mass index, waist-hip ratio, type 2 diabetes, inflammatory bowel disease and lipid levels.

Reich, for one, hopes researchers will one day have thousands of ancient genomes to analyze. He would also like to see this type of study applied to non-European populations and even to other species.

“It will be interesting to study selection in domesticated animals and to see if there is coevolution between them and the people who were domesticating them,” said Mathieson.


Journal Reference:

  1. Iain Mathieson, Iosif Lazaridis, Nadin Rohland, Swapan Mallick, Nick Patterson, Songül Alpaslan Roodenberg, Eadaoin Harney, Kristin Stewardson, Daniel Fernandes, Mario Novak, Kendra Sirak, Cristina Gamba, Eppie R. Jones, Bastien Llamas, Stanislav Dryomov, Joseph Pickrell, Juan Luís Arsuaga, José María Bermúdez de Castro, Eudald Carbonell, Fokke Gerritsen, Aleksandr Khokhlov, Pavel Kuznetsov, Marina Lozano, Harald Meller, Oleg Mochalov, Vyacheslav Moiseyev, Manuel A. Rojo Guerra, Jacob Roodenberg, Josep Maria Vergès, Johannes Krause, Alan Cooper, Kurt W. Alt, Dorcas Brown, David Anthony, Carles Lalueza-Fox, Wolfgang Haak, Ron Pinhasi, David Reich. Genome-wide patterns of selection in 230 ancient EurasiansNature, 2015; DOI: 10.1038/nature16152

‘Na África, indaguei rei da minha etnia por que nos venderam como escravos’ (BBC Brasil)

14 janeiro 2016

Zulu Araújo | Foto: Divulgação

Image captionA convite de produtora, arquiteto fez exame genético e foi até Camarões para conhecer seus ancestrais

“Somos o único grupo populacional no Brasil que não sabe de onde vem”, queixa-se o arquiteto baiano Zulu Araújo, de 63 anos, em referência à população negra descendente dos 4,8 milhões de africanos escravizados recebidos pelo país entre os séculos 16 e 19.

Araújo foi um dos 150 brasileiros convidados pela produtora Cine Group para fazer um exame de DNA e identificar suas origens africanas.

Ele descobriu ser descendente do povo tikar, de Camarões, e, como parte da série televisiva Brasil: DNA África, visitou o local para conhecer a terra de seus antepassados.

“A viagem me completou enquanto cidadão”, diz Araújo. Leia, abaixo, seu depoimento à BBC Brasil:

“Sempre tive a consciência de que um dos maiores crimes contra a população negra não foi nem a tortura, nem a violência: foi retirar a possibilidade de que conhecêssemos nossas origens. Somos o único grupo populacional no Brasil que não sabe de onde vem.

Meu sobrenome, Mendes de Araújo, é português. Carrego o nome da família que escravizou meus ancestrais, pois o ‘de’ indica posse. Também carrego o nome de um povo africano, Zulu.

 

Momento em que o Zulu confronta o rei tikar sobre a venda de seus antepassados

Ganhei o apelido porque meus amigos me acharam parecido com um rei zulu retratado num documentário. Virou meu nome.

Nasci no Solar do Unhão, uma colônia de pescadores no centro de Salvador, local de desembarque e leilão de escravos até o final do século 19. Comecei a trabalhar clandestinamente aos 9 anos numa gráfica da Igreja Católica. Trabalhava de forma profana para produzir livros sagrados.

Bom aluno, consegui passar no vestibular para arquitetura. Éramos dois negros numa turma de 600 estudantes – isso numa cidade onde 85% da população tem origem africana. Salvador é uma das cidades mais racistas que eu conheço no mundo.

Ao participar do projeto Brasil: DNA África e descobrir que era do grupo étnico tikar, fiquei surpreso. Na Bahia, todos nós especulamos que temos ou origem angolana ou iorubá. Eu imaginava que era iorubano. Mas os exames de DNA mostram que vieram ao Brasil muito mais etnias do que sabemos.

Zulu Araújo | Foto: Divulgação

“Era como se eu estivesse no meu bairro, na Bahia, e ao mesmo tempo tivesse voltado 500 anos no tempo”, diz Zulu sobre chegada a Camarões

Zulu Araújo | Foto: Divulgação

Pergunta sobre escravidão a rei camaronense foi tratada como “assunto delicado” e foi respondida apenas no dia seguinte

Quando cheguei ao centro do reino tikar, a eletricidade tinha caído, e o pessoal usava candeeiros e faróis dos carros para a iluminação. Mais de 2 mil pessoas me aguardavam. O que senti naquele momento não dá para descrever, de tão chocante e singular.

As pessoas gritavam. Eu não entendia uma palavra do que diziam, mas entendia tudo. Era como se eu estivesse no meu bairro, na Bahia, e ao mesmo tempo tivesse voltado 500 anos no tempo.

O povão me encarava como uma novidade: eu era o primeiro brasileiro de origem tikar a pisar ali. Mas também fiquei chocado com a pobreza. As pessoas me faziam inúmeros pedidos nas ruas, de camisetas de futebol a ajuda para gravar um disco. Não por acaso, ali perto o grupo fundamentalista Boko Haram (originário da vizinha Nigéria) tem uma de suas bases e conta com grande apoio popular.

De manhã, fui me encontrar com o rei, um homem alto e forte de 56 anos, casado com 20 mulheres e pai de mais de 40 filhos. Ele se vestia como um muçulmano do deserto, com uma túnica com estamparias e tecidos belíssimos.

Depois do café da manhã, tive uma audiência com ele numa das salas do palácio. Ele estava emocionado e curioso, pois sabia que muitos do povo Tikar haviam ido para as Américas, mas não para o Brasil.

Fiz uma pergunta que me angustiava: perguntei por que eles tinham permitido ou participado da venda dos meus ancestrais para o Brasil. O tradutor conferiu duas vezes se eu queria mesmo fazer aquela pergunta e disse que o assunto era muito sensível. Eu insisti.

Ficou um silêncio total na sala. Então o rei cochichou no ouvido de um conselheiro, que me disse que ele pedia desculpas, mas que o assunto era muito delicado e só poderia me responder no dia seguinte. O tema da escravidão é um tabu no continente africano, porque é evidente que houve um conluio da elite africana com a europeia para que o processo durasse tanto tempo e alcançasse tanta gente.

No dia seguinte, o rei finalmente me respondeu. Ele pediu desculpas e disse que foi melhor terem nos vendido, caso contrário todos teríamos sido mortos. E disse que, por termos sobrevivido, nós, da diáspora, agora poderíamos ajudá-los. Disse ainda que me adotaria como seu primeiro filho, o que me daria o direito a regalias e o acesso a bens materiais.

Foi uma resposta política, mas acho que foi sincera. Sei que eles não imaginavam que a escravidão ganharia a dimensão que ganhou, nem que a Europa a transformaria no maior negócio de todos os tempos. Houve um momento em que os africanos perderam o controle.

Zulu Araújo | Foto: Divulgação

“Se qualquer pessoa me perguntar de onde sou, agora já sei responder. Só quem é negro pode entender a dimensão que isso possui.”

Um intelectual senegalês me disse que, enquanto não superarmos a escravidão, não teremos paz – nem os escravizados, nem os escravizadores. É a pura verdade. Não dá para tratar uma questão de 500 anos com um sentimento de ódio ou vingança.

A viagem me completou enquanto cidadão. Se qualquer pessoa me perguntar de onde sou, agora já sei responder. Só quem é negro pode entender a dimensão que isso possui.

Acho que os exames de DNA deveriam ser reconhecidos pelo governo, pelas instituições acadêmicas brasileiras como um caminho para que possamos refazer e recontar a história dos 52% dos brasileiros que têm raízes africanas. Só conhecendo nossas origens poderemos entender quem somos de verdade.”

Ancient viral molecules essential for human development (Science Daily)

Date: November 23, 2015

Source: Stanford University Medical Center

Summary: Genetic material from ancient viral infections is critical to human development, according to researchers.


Rendering of a virus among blood cells. Credit: © ysfylmz / Fotolia

Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.

They’ve identified several noncoding RNA molecules of viral origins that are necessary for a fertilized human egg to acquire the ability in early development to become all the cells and tissues of the body. Blocking the production of this RNA molecule stops development in its tracks, they found.

The discovery comes on the heels of a Stanford study earlier this year showing that early human embryos are packed full of what appear to be viral particles arising from similar left-behind genetic material.

“We’re starting to accumulate evidence that these viral sequences, which originally may have threatened the survival of our species, were co-opted by our genomes for their own benefit,” said Vittorio Sebastiano, PhD, an assistant professor of obstetrics and gynecology. “In this manner, they may even have contributed species-specific characteristics and fundamental cell processes, even in humans.”

Sebastiano is a co-lead and co-senior author of the study, which will be published online Nov. 23 in Nature Genetics. Postdoctoral scholar Jens Durruthy-Durruthy, PhD, is the other lead author. The other senior author of the paper is Renee Reijo Pera, PhD, a former professor of obstetrics and gynecology at Stanford who is now on the faculty of Montana State University.

Sebastiano and his colleagues were interested in learning how cells become pluripotent, or able to become any tissue in the body. A human egg becomes pluripotent after fertilization, for example. And scientists have learned how to induce other, fully developed human cells to become pluripotent by exposing them to proteins known to be present in the very early human embryo. But the nitty-gritty molecular details of this transformative process are not well understood in either case.

An ancient infection

The researchers knew that a type of RNA molecules called long-intergenic noncoding, or lincRNAs, have been implicated in many important biological processes, including the acquisition of pluripotency. These molecules are made from DNA in the genome, but they don’t go on to make proteins. Instead they function as RNA molecules to affect the expression of other genes.

Sebastiano and Durruthy-Durruthy used recently developed RNA sequencing techniques to examine which lincRNAs are highly expressed in human embryonic stem cells. Previously, this type of analysis was stymied by the fact that many of the molecules contain highly similar, very repetitive regions that are difficult to sequence accurately.

They identified more than 2,000 previously unknown RNA sequences, and found that 146 are specifically expressed in embryonic stem cells. They homed in on the 23 most highly expressed sequences, which they termed HPAT1-23, for further study. Thirteen of these, they found, were made up almost entirely of genetic material left behind after an eons-ago infection by a virus called HERV-H.

HERV-H is what’s known as a retrovirus. These viruses spread by inserting their genetic material into the genome of an infected cell. In this way, the virus can use the cell’s protein-making machinery to generate viral proteins for assembly into a new viral particle. That particle then goes on to infect other cells. If the infected cell is a sperm or an egg, the retroviral sequence can also be passed to future generations.

HIV is one common retrovirus that currently causes disease in humans. But our genomes are also littered with sequences left behind from long-ago retroviral infections. Unlike HIV, which can go on to infect new cells, these retroviral sequences are thought to be relatively inert; millions of years of evolution and accumulated mutations mean that few maintain the capacity to give instructions for functional proteins.

After identifying HPAT1-23 in embryonic stem cells, Sebastiano and his colleagues studied their expression in human blastocysts — the hollow clump of cells that arises from the egg in the first days after fertilization. They found that HPAT2, HPAT3 and HPAT5 were expressed only in the inner cell mass of the blastocyst, which becomes the developing fetus. Blocking their expression in one cell of a two-celled embryo stopped the affected cell from contributing to the embryo’s inner cell mass. Further studies showed that the expression of the three genes is also required for efficient reprogramming of adult cells into induced pluripotent stem cells.

Sequences found only in primates

“This is the first time that these virally derived RNA molecules have been shown to be directly involved with and necessary for vital steps of human development,” Sebastiano said. “What’s really interesting is that these sequences are found only in primates, raising the possibility that their function may have contributed to unique characteristics that distinguish humans from other animals.”

The researchers are continuing their studies of all the HPAT molecules. They’ve learned that HPAT-5 specifically affects pluripotency by interacting with and sequestering members of another family of RNAs involved in pluripotency called let-7.

“Previously retroviral elements were considered to be a class that all functioned in basically the same way,” said Durruthy-Durruthy. “Now we’re learning that they function as individual elements with very specific and important roles in our cells. It’s fascinating to imagine how, during the course of evolution, primates began to recycle these viral leftovers into something that’s beneficial and necessary to our development.”


Journal Reference:

  1. Jens Durruthy-Durruthy, Vittorio Sebastiano, Mark Wossidlo, Diana Cepeda, Jun Cui, Edward J Grow, Jonathan Davila, Moritz Mall, Wing H Wong, Joanna Wysocka, Kin Fai Au, Renee A Reijo Pera. The primate-specific noncoding RNA HPAT5 regulates pluripotency during human preimplantation development and nuclear reprogrammingNature Genetics, 2015; DOI: 10.1038/ng.3449

‘Não podemos brincar de Deus com as alterações no genoma humano’, alerta ONU (ONU)

Publicado em Atualizado em 07/10/2015

A modificação do código genético permite tratar doenças como o câncer, mas pode gerar mudanças hereditárias. UNESCO pede uma regulamentação clara sobre os procedimentos científicos e informação à população.

Foto: Flickr/ ynse

“Terapia genética poderia ser o divisor de águas na história da medicina e a alteração no genoma é sem dúvida um dos maiores empreendimentos da ciência em nome da humanidade”, afirmou a Organização das Nações Unidas para a Educação, a Ciência e a Cultura (UNESCO) sobre um relatório publicado pelo Comitê Internacional de Bioética (IBC) nesta segunda-feira (5).

O IBC acrescentou, no entanto, que intervenções no genoma humano deveriam ser autorizadas somente em casos preventivos, diagnósticos ou terapêuticos que não gerem alterações para os descendentes. O relatório destaca também a importância da regulamentação e informação clara aos consumidores.

O documento ressaltou os avanços na possibilidade de testes genéticos em casos de doenças hereditárias, por meio da terapia genética, o uso de células tronco embrionárias na pesquisa médica e uso de clones e alterações genéticas para fins medicinais. São citadas também novas técnicas que podem inserir, tirar e corrigir o DNA, podendo tratar ou curar o câncer e outras doenças. Porém, estas mesmas técnicas também possibilitam mudanças no DNA, como determinar a cor dos olhos de um bebê, por exemplo.

“O grande medo é que podemos estar tentando “brincar de Deus” com consequências imprevisíveis” e no final precipitando a nossa própria destruição”, alertou o antigo secretário-geral da ONU, Kofi Annan em 2004, quando perguntado qual seria a linha ética que determinaria o limite das alterações no genoma humano. Para responder a essa questão, os Estados-membros da UNESCO adotaram em 2005 a Declaração Universal sobre Bioética e Direitos Humanos que lida com os dilemas éticos levantados pelas rápidas mudanças na medicina, na ciência e tecnologia.

SBPC critica projeto sobre biodiversidade (Fapesp)

Texto aprovado na Câmara dos Deputados facilita o acesso ao patrimônio genético e conhecimentos associados, mas ignora os direitos das comunidades indígenas e tradicionais, diz presidente da entidade

BRUNO DE PIERRO | Edição Online 11:00 20 de fevereiro de 2015

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A Sociedade Brasileira para o Progresso da Ciência (SBPC), que representa 120 associações científicas, divulgou esta semana uma carta em que sugere modificações no projeto de lei sobre biodiversidade e recursos genéticos, aprovado na Câmara dos Deputados no dia 10 de fevereiro e que será agora apreciado pelo Senado. No documento, a entidade critica a prerrogativa do Estado de ignorar direitos de comunidades indígenas e tradicionais na repartição de benefícios resultantes do acesso ao conhecimento associado ao patrimônio genético. Prevista no Protocolo de Nagoya, assinado por 91 países – entre eles o Brasil – a repartição de benefícios envolve o compromisso de compensar financeiramente países e comunidades pelo uso de seus recursos genéticos e conhecimentos tradicionais. O protocolo foi aprovado pela 10aConferência das Partes em 2010, e ainda não foi ratificado pelo Congresso brasileiro.

Outro aspecto destacado na carta é que a repartição dos benefícios só será aplicada sobre a comercialização de produtos acabados, que chegarão ao mercado. “Isso fere o direito do povo e da comunidade de participar da tomada de decisão quanto à repartição de benefícios oriundos do acesso ao conhecimento tradicional associado”, escreve no documento Helena Nader, professora titular da Universidade Federal de São Paulo (Unifesp) e presidente da SBPC. Também é questionado um tópico da lei que permite a instituições estrangeiras acessarem a biodiversidade brasileira, para fins de pesquisa e desenvolvimento, sem precisar se associar a uma instituição nacional, como estabelece a legislação vigente. Na carta, a SBPC reconhece avanços no projeto aprovado, entre eles a retirada da necessidade de autorização prévia para a realização de pesquisas com recursos genéticos.

Em junho do ano passado, o governo federal enviou para o Congresso Nacional o PL 7.735, em caráter de urgência. O projeto simplifica o acesso e exploração do patrimônio genético em pesquisas com plantas e animais nativos e facilita a utilização de conhecimentos tradicionais e indígenas associados à biodiversidade. Um dos principais avanços da proposta é que o acesso aos recursos genéticos para fins de pesquisa e desenvolvimento tecnológico dependerá apenas de um cadastro eletrônico e não mais de uma solicitação a órgãos como o Conselho de Gestão do Patrimônio Genético (CGen), do Ministério do Meio Ambiente (MMA), e o Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). A medida atende a um pleito antigo da comunidade científica e de setores industriais, que nos últimos tempos levaram adiante seus estudos sem seguir a legislação à risca e foram multados.

No entanto, após a votação na Câmara, a comunidade científica, representada pela SBPC, criticou alguns pontos da lei. “O projeto de lei reconhece o direito de populações indígenas, comunidades tradicionais e pequenos agricultores de participar da tomada de decisões, mas isenta, em muitos casos, as empresas e pesquisadores da obrigação de repartir os benefícios, que é a compensação econômica do detentor do conhecimento tradicional associado à biodiversidade”, explica Helena Nader.

O projeto aprovado estabelece que o pagamento desses benefícios à comunidade que detém o conhecimento associado seja estabelecido em um Acordo de Repartição de Benefícios, no qual esteja a definição do montante negociado a título de repartição de benefícios. O usuário também deverá depositar no Fundo Nacional de Repartição de Benefícios (FNRB) 0,5% da receita líquida anual obtida por meio da exploração do material reprodutivo, como sementes ou sêmen, decorrentes do acesso ao conhecimento tradicional para beneficiar os codetentores do mesmo conhecimento.

Se a exploração envolver algum componente do patrimônio genético, a repartição monetária de benefícios será de 1% da receita líquida anual das vendas do produto acabado ou material reprodutivo, a ser depositada no FNRB. Há ainda a previsão de se estabelecer um acordo setorial, no qual a repartição de benefícios poderá ser reduzida até de 0,1% da receita líquida da comercialização do produto acabado ou material reprodutivo. É dada a possibilidade da repartição não ser feita em dinheiro, mas sim por transferência de tecnologia e outras formas de cooperação entre as partes envolvidas, como o intercâmbio de recursos humanos e materiais entre instituições nacionais e participação na pesquisa. Em algumas situações, no entanto, é impossível identificar a origem do conhecimento, que já está difundido na sociedade. Nesses casos, o pagamento de royalties será destinado ao FNRB, para, entre outras coisas, proteger a biodiversidade e os conhecimentos tradicionais.

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Contudo, diz Helena Nader, a lei exclui da obrigação de repartir benefícios os fabricantes de produtos intermediários e desenvolvedores de processos oriundos de acesso ao patrimônio genético ou ao conhecimento tradicional associado ao longo da cadeia produtiva. Também isenta micro e pequenas empresas do dever de dividir os benefícios com as comunidades tradicionais. “Não é justo, nem ético, definir quando se dará a repartição de benefícios oriunda do acesso a conhecimentos tradicionais associados, sem antes consultar os detentores de tais conhecimentos”, diz ela.

Para Vanderlan Bolzani, professora da Universidade Estadual Paulista (Unesp) e membro da coordenação do programa Biota-FAPESP, a nova legislação falha ao não exigir que a compensação econômica seja revertida em benefícios sociais para a comunidade local. “Muitas dessas populações vivem em situação precária e dependem unicamente do extrativismo como fonte de sobrevivência. Além do pagamento de royalties, são necessárias ações que promovam o desenvolvimento social e econômico dessas comunidades”, diz Vanderlan.

Entidades representantes das populações extrativistas e indígenas alegam que não foram convidadas para participar de reuniões com representantes do governo e da indústria. De acordo com o deputado federal Alceu Moreira (PMDB-RS), relator do projeto, as reuniões que antecederam a votação no Congresso contaram com a participação de membros da Fundação Nacional do Índio (Funai) e do Instituto Nacional de Colonização e Reforma Agrária (Incra), que segundo ele representam oficialmente os índios e outras comunidades tradicionais. “Não fizemos uma assembleia geral aberta por se tratar de um tema muito técnico”, disse Moreira.

Para o biólogo Braulio Ferreira de Souza Dias, secretário-executivo da Convenção sobre Diversidade Biológica (CDB) da Organização das Nações Unidas (ONU), o Congresso Nacional deveria aproveitar o debate em torno da nova lei e considerar a ratificação do Protocolo de Nagoya, em vigor desde outubro do ano passado. “Trata-se do principal instrumento internacional sobre acesso a recursos genéticos”, afirma Dias. Segundo ele, o projeto aprovado na Câmara fere o Protocolo de Nagoya no que se refere ao direito do país provedor de recursos genéticos e conhecimentos tradicionais de receber repartição dos benefícios. Isso porque, segundo um artigo do projeto aprovado na Câmara, a utilização do patrimônio genético de espécies introduzidas no país pela ação humana até a data de entrada em vigor da lei não estará sujeita à repartição de benefícios prevista em acordos internacionais dos quais o Brasil seja parte. “Isso poderá criar embaraços ao acesso a recursos genéticos e conhecimentos tradicionais de outros países necessários para o aprimoramento da agricultura brasileira, inclusive para promover sua adaptação às mudanças climáticas”, diz Dias.

Facilitação para estrangeiros
Hoje, para o pesquisador estrangeiro ou pessoa jurídica estrangeira vir ao Brasil realizar pesquisa que envolva coleta de dados, materiais, espécimes biológicas e minerais, peças integrantes da cultura nativa e cultura popular, o Ministério da Ciência, Tecnologia e Inovação (MCTI) deve autorizar, supervisionar a fiscalização e analisar os resultados obtidos. Somente são autorizadas as atividades em que haja a coparticipação de alguma instituição de pesquisa brasileira bem avaliada pelo CNPq. A nova proposta agora permite que entidades estrangeiras, não associadas a instituições nacionais, realizem pesquisa com a biodiversidade do país mediante uma autorização do CGen.

“Abriu-se a possibilidade da pessoa jurídica estrangeira ter autorização para acesso a componente do patrimônio genético do Brasil sem estar associada a uma instituição de ciência e tecnologia nacional, o que é preocupante”, diz Helena Nader. Isso, diz ela, pode ameaçar os interesses nacionais e colocar em risco o patrimônio brasileiro. Helena ressalta que, em outros países latino-americanos com biodiversidade muito rica, exige-se que instituições estrangeiras tenham vínculo com órgãos de pesquisa nacionais, de modo a proteger interesses do país provedor de recursos genéticos.  “Se proibirmos que instituições de outros países venham pesquisar aqui, perderemos a oportunidade de desenvolver ciência de qualidade no país”, argumenta o deputado Alceu Moreira. Helena Nader afirma que não se trata de proibir a vinda de estrangeiros. “Trata-se apenas de manter a instituição internacional comprometida com os interesses da pesquisa brasileira. É uma forma de cooperação científica em que os dois lados ganham”, diz ela.

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Avanços
O CGen atualmente é composto por 19 representantes de órgãos e de entidades da administração pública federal. A partir de 2003, passou a contar com representantes da sociedade na função de membros convidados permanentes, com direito a voz mas não a voto. A primeira versão do PL 7.735 não garantia a participação plena de representantes da sociedade civil.  Após negociações, o texto foi modificado e houve uma mudança na composição do CGen, com 60% de representantes do governo e 40% de membros da sociedade civil, entre eles representantes das comunidades indígenas e tradicionais, pesquisadores e agricultores tradicionais. “Esse foi um importante avanço obtido com a aprovação do projeto de lei. A comunidade científica e outros segmentos sociais demandam essa participação plena, com direito a voto, há muito tempo”, explica Helena Nader.

Outro avanço do projeto aprovado foi inserir em seu escopo os recursos genéticos para a alimentação e a agricultura. Antes, na proposta enviada pelo poder executivo, esses recursos estavam de fora e ficariam no âmbito da legislação antiga, de 2001. Segundo à nova proposta de lei, os royalties serão cobrados sobre a comercialização do material reprodutivo – a semente, por exemplo. Já a exploração econômica do produto acabado será isenta da compensação, com exceção das variedades cultivadas pelas comunidades tradicionais ou indígenas.

A não obrigação de se repartir os benefícios também vale para a pesquisa básica que, segundo Vanderlan Bolzani, se beneficiará da nova lei. “A ciência não acessa a biodiversidade apenas para dela retirar produtos. É importante estudar a estrutura molecular de plantas, por exemplo, para compreender como se desenvolve a vida em determinada região”, explica Vanderlan.  Segundo ela, a maioria dos cientistas que pesquisam a biodiversidade está hoje na ilegalidade. Nos últimos anos, as punições para quem não segue a legislação se tornaram mais severas. Dados do governo federal, divulgados pela Agência Câmara, mostram que as ações de um núcleo de combate ao acesso ilegal ao patrimônio genético, que atuou em 2010, resultaram em multas com valor total de aproximadamente R$ 220 milhões.

Um dos casos mais notórios ocorreu em novembro daquele ano, com a autuação, em R$ 21 milhões, da empresa de cosméticos Natura por uso da biodiversidade sem autorização. A empresa, que mantem parceria com universidades para pesquisas novas moléculas, não esperou os trâmites para liberar a permissão do chamado provedor (seja o governo ou uma comunidade tradicional ou indígena) e um contrato de repartição de benefícios. A Natura alegou que todos os seus produtos têm repartição de benefícios, mas reclamou que não poderia esperar dois anos por uma autorização de pesquisa do CGen (ver Pesquisa FAPESP nº 179).

Huge epigenomic map examines life’s impact on our genes (New Scientist)

18 February 2015 by Catherine Brahic

Magazine issue 3009.

THE nature versus nurture debate is getting a facelift this week, with the publication of a genetic map that promises to tell us which bits of us are set in stone by our DNA, and which bits we can affect by how we live our lives.

The new “epigenomic” map doesn’t just look at genes, but also the instructions that govern them. Compiled by a consortium of biologists and computer scientists, this information will allow doctors to pinpoint precisely which cells in the body are responsible for various diseases. It might also reveal how to adjust your lifestyle to counter a genetic predisposition to a particular disease.

“The epigenome is the additional information our cells have on top of genetic information,” says lead researcher Manolis Kellis of the Massachusetts Institute of Technology. It is made of chemical tags that are attached to DNA and its packaging. These tags act like genetic controllers, influencing whether a gene is switched on or off, and play an instrumental role in shaping our bodies and disease.

Researchers are still figuring out exactly how and when epigenetic tags are added to our DNA, but the process appears to depend on environmental cues. We inherit some tags from our parents, but what a mother eats during pregnancy, for instance, might also change her baby’s epigenome. Others tags relate to the environment we are exposed to as children and adults. “The epigenome sits in a very special place between nature and nurture,” says Kellis.

Each cell type in our body has a different epigenome – in fact, the DNA tags are the reason why our cells come in such different shapes and sizes despite having exactly the same DNA. So for its map, the Roadmap Epigenomics Consortium collected thousands of cells from different adult and embryonic tissues, and meticulously analysed all the tags.

So far, they have produced 127 epigenomes, each corresponding to a different cell type, from brain cells to skin cells. That’s a big advance on the 16 published in 2012 by the ENCODE project, which are included in the new map.

The consortium also cross-referenced these healthy epigenomes with previous data on the genetic components of dozens of diseases, including type 1 diabetes, Crohn’s disease, high blood pressure, inflammatory bowel disease and Alzheimer’s disease (see “Alzheimer’s epigenetics“).

The results, says Kellis, allow doctors to see what cell types are likely to be disrupted in people with these conditions. For instance, they suggest disruptions in the epigenome of the brain’s cingulate gyrus cells may play a role in attention deficit hyperactivity disorder (Nature, DOI: 10.1038/nature14248).

Richard Meehan of the University of Edinburgh, UK, says the work offers “incredibly valuable information which will be absorbed and debated for years to come”. He suggests that one day doctors will look at your epigenomes during routine health checks to suss out how the nature versus nurture battle is playing out inside your cells. These scans would reveal your genetic predisposition to certain conditions, and how your lifestyle is affecting those risks.

By adjusting your choices accordingly, you will be able to delay disease, or minimise its effects for as long as possible. “It’s not going to move any further forward the point at which your life ends, but make the years up to that point – years that are spent in physical decline – a whole lot better,” says Meehan.

“You see this on Star Trek,” he adds. “Nobody lives any longer but they just seem to be healthier up to the point where life, unfortunately, passes away.”

Alzheimer’s epigenetics

While you can’t change the genes you were born with, you might be able to alter your epigenome – and its influence on your health – through tinkering with your lifestyle.

Studying cells from people with Alzheimer’s and a mouse version of the disease highlights both immune cells and brain cells as key players. This finding supports other studies suggesting that an immune disorder is at least partially responsible for Alzheimer’s.

Manolis Kellis and his team at MIT (see main story) were able to identify both genetic and non-genetic effects. While the immune disruptions were coded in the cells’ genetics, the changes in the brain cells appeared to be influenced by environmental inputs like diet, education, physical activity and age, and are probably associated with epigenetic changes (Nature, DOI: 10.1038/nature14252).

“We have an interplay between genetics and epigenetics,” says Kellis. “You might not be able to do anything about the genetic but you might be able to do something about the epigenomic by – I don’t know – maybe reading more books.”

*   *   *

Cientistas publicam o primeiro atlas do epigenoma humano (O Globo)

Dados sobre processos que afetam células, responsáveis por sua diferenciação em 111 dos tecidos do corpo, podem ajudar na melhor compreensão de diversas doenças e no desenvolvimento de novos tratamentos para elas

POR CESAR BAIMA


No alvo: epigenoma abre caminho para novas abordagens no tratamento e cura de várias doenças
Foto: Alamy/Latinstock

No alvo: epigenoma abre caminho para novas abordagens no tratamento e cura de várias doenças – Alamy/Latinstock

RIO – Sequenciado completamente pela primeira vez há pouco mais de uma década, o genoma humano, com suas cerca de 3 bilhões de “letras”, guarda todas as informações necessárias para “construir” uma pessoa. Mas, apesar de quase todas nossas células terem o mesmo DNA, elas podem, e devem, ser muito diferentes umas das outras para que o corpo funcione bem. Afinal, os neurônios do cérebro cumprem trabalhos bem distintos do das células do músculo cardíaco, que por sua vez não poderiam fazer o que fazem as do fígado.

É a conhecida diferenciação celular, e para que isso aconteça é preciso controlar quais genes serão ativados e quais permanecerão dormentes nas células. E é aí que entra em cena o chamado epigenoma, nome dado ao conjunto de processos e reações químicas que regulam esta expressão genética. Ele teve seu primeiro atlas de ação em 111 tecidos que compõem o feto e o organismo humano publicado ontem na edição desta semana da revista “Nature”, junto com mais de 20 artigos neste e outros periódicos científicos abordando seus mecanismos e possíveis relações com doenças e condições como asma, câncer, problemas cardíacos e Alzheimer.

COMO PREENCHER UM ‘MAPA-MÚNDI’ EM BRANCO

Isso porque, mesmo não alterando diretamente o DNA, o epigenoma tem grande importância na maneira como nossas células funcionam e pode ser influenciado por fatores ambientais e hábitos individuais, como a poluição e o tabagismo. Em alguns casos, inclusive, sua atuação pode até mesmo ser hereditária, ajudando a responder o mistério do que é fruto da natureza e o que é resultado da criação — cuja resposta, muitas vezes, deverá ser “ambos”. Segundo os pesquisadores, é como se o genoma fosse um mapa-múndi em branco ao qual o estudo do epigenoma agora acrescenta os nomes dos países, estados e cidades, suas rodovias e ferrovias e a localização de portos e aeroportos, tornando-o muito mais útil.

— Hoje, podemos sequenciar o genoma humano de forma rápida e barata, mas interpretar este genoma ainda é um desafio — lembra Bing Ren, professor da Universidade da Califórnia em San Diego e coautor de diversos dos artigos relacionados ao projeto de mapeamento do epigenoma. — Estes 111 mapas de referência do epigenoma são essencialmente um livro de vocabulário que nos ajuda a decifrar cada segmento do DNA em células distintas e tipos de tecido. Estes mapas são como retratos do genoma humano em ação.

Diante disso, ainda durante o projeto — no qual o Instituto Nacional de Saúde dos EUA (NIH) investiu US$ 300 milhões desde 2006 numa colaboração de centenas de cientistas de dezenas de instituições espalhadas pelo mundo —, diversos pesquisadores começaram a buscar na interação entre genoma e epigenoma possíveis fatores que levam ao desenvolvimento de doenças, abrindo caminho para novas abordagens na busca de tratamentos ou cura.

— As células do fígado e do cérebro usam diferentes pedaços do DNA para produzir um repertório distinto de proteínas dependendo de como os marcadores epigenéticos foram introduzidos em cada célula durante o desenvolvimento embrionário — destaca Steven Jones, professor da Universidade Simon Fraser, no Canadá e outro dos participantes no projeto. — E estes marcadores podem mudar ao longo da vida em resposta a fatores ambientais. De fato, mudanças nos padrões epigenéticos originais de uma célula já foram associadas a diversas doenças humanas, incluindo câncer e Alzheimer.

Leia mais sobre esse assunto em  http://oglobo.globo.com/sociedade/ciencia/cientistas-publicam-primeiro-atlas-do-epigenoma-humano-15375408#ixzz3SDJ9Lxy7
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Epigenética na agricultura é tema de livro (Facesp)

11 de fevereiro de 2015

Por Diego Freire

Agência FAPESP – Pesquisadores da Universidade de São Paulo (USP) estão entre os autores e editores do livro Epigenetics in Plants of Agronomic Importance: Fundamentals and Applications, publicado pela editora Springer, que trata do controle da expressão gênica de plantas de interesse agronômico, como o tomate.

Um dos editores é Juan Armando Casas-Mollano, que conduz no Instituto de Química (IQ) a pesquisa “Caracterização funcional de uma recentemente identificada família de MUT9 kinases in Arabidopsis thaliana e cana-de-açúcar”, com apoio da FAPESP na modalidade Jovem Pesquisador, no âmbito do Programa FAPESP de Pesquisa em Bioenergia (BIOEN).

“O livro reúne informações sobre plantas além das chamadas plantas modelo, como a Arabidopsis, amplamente utilizada em todas as áreas da ciência por ter um genoma pequeno e um ciclo de vida rápido e por ser de fácil manipulação”, disse Casas-Mollano.

A epigenética é o estudo de qualquer transformação na expressão de genes que ocorre sem haver mudança na sequência do DNA. Essas alterações, de ordem química, podem ocorrer na molécula de DNA e em proteínas chamadas histonas, podendo ser herdadas na divisão celular. O fenômeno tem alto impacto na biologia do organismo e na definição de diferentes fenótipos, isto é, da sua morfologia, do seu desenvolvimento e de aspectos do comportamento.

“O livro tem informações detalhadas sobre os mecanismos epigenéticos em plantas de importância agronômica. Essas informações podem trazer contribuições para o desenvolvimento de técnicas de manipulação, inibição ou ativação e seleção de proteínas e vias metabólicas, permitindo criar plantas resistentes a patógenos e a estresse ambiental, além de aumentar a produtividade”, afirmou Casas-Mollano.

O pesquisador é coautor do capítulo Histone H3 Phosphorylation in Plants and Other Organisms, com Izabel Moraes, também do IQ. O capítulo revisa e discute avanços mais recentes no estudo de fosforilação de proteínas histonas em plantas.

A fosforilação é a adição de um grupo fosfato a uma proteína ou a outra molécula, sendo um dos principais elementos nos mecanismos de regulação das proteínas, associada ao silenciamento gênico.

“Trata-se de ‘desligar’ a expressão de um gene por meio de mecanismos que não estejam relacionados à modificação de sua sequência gênica. Dessa forma, um gene que está sendo expresso, ou ‘ligado’, naturalmente é ‘desligado’, conforme a necessidade, por meio da fosforilação”, explicou Moraes.

A pesquisadora investiga no IQ o papel de determinados genes no controle do tempo de floração das plantas, fundamental para o sucesso da sua propagação, no projeto de pós-doutorado Compreendendo o papel das kinases MUT9 na regulação do tempo de floração em Arabidopsis thaliana, realizado com apoio da FAPESP e orientação de Casas-Mollano.

O livro conta ainda com um capítulo de autoria do também pesquisador da USP Fabio Tebaldi Silveira Nogueira, da Escola Superior de Agricultura Luiz de Queiroz (Esalq), que trata da epigenética do tomate. Nogueira conduz em Piracicaba a pesquisa Análise funcional do papel de microRNAs no controle da arquitetura vegetativa e desenvolvimento de frutos, com apoio da FAPESP.

Epigenetics in Plants of Agronomic Importance: Fundamentals and Applications – Transcriptional Regulation and Chromatin Remodelling in Plants
Editores: Raul Alvarez-Venegas, Clelia de la Peña, Juan Armando Casas-Mollano
Lançamento: 2014
Preço: US$ 149
Páginas: 152

Mais informações: www.springer.com/life+sciences/plant+sciences/book/978-3-319-07970-7

Do viruses make us smarter? (Science Daily)

Date: January 12, 2015

Source: Lund University

Summary: Inherited viruses that are millions of years old play an important role in building up the complex networks that characterize the human brain, researchers say. They have found that retroviruses seem to play a central role in the basic functions of the brain, more specifically in the regulation of which genes are to be expressed, and when.

Retroviruses seem to play a central role in the basic functions of the brain, more specifically in the regulation of which genes are to be expressed, and when, researchers say. Credit: © Sergey Bogdanov / Fotolia

A new study from Lund University in Sweden indicates that inherited viruses that are millions of years old play an important role in building up the complex networks that characterise the human brain.

Researchers have long been aware that endogenous retroviruses constitute around five per cent of our DNA. For many years, they were considered junk DNA of no real use, a side-effect of our evolutionary journey.

In the current study, Johan Jakobsson and his colleagues show that retroviruses seem to play a central role in the basic functions of the brain, more specifically in the regulation of which genes are to be expressed, and when. The findings indicate that, over the course of evolution, the viruses took an increasingly firm hold on the steering wheel in our cellular machinery. The reason the viruses are activated specifically in the brain is probably due to the fact that tumours cannot form in nerve cells, unlike in other tissues.

“We have been able to observe that these viruses are activated specifically in the brain cells and have an important regulatory role. We believe that the role of retroviruses can contribute to explaining why brain cells in particular are so dynamic and multifaceted in their function. It may also be the case that the viruses’ more or less complex functions in various species can help us to understand why we are so different,” says Johan Jakobsson, head of the research team for molecular neurogenetics at Lund University.

The article, based on studies of neural stem cells, shows that these cells use a particular molecular mechanism to control the activation processes of the retroviruses. The findings provide us with a complex insight into the innermost workings of the most basal functions of the nerve cells. At the same time, the results open up potential for new research paths concerning brain diseases linked to genetic factors.

“I believe that this can lead to new, exciting studies on the diseases of the brain. Currently, when we look for genetic factors linked to various diseases, we usually look for the genes we are familiar with, which make up a mere two per cent of the genome. Now we are opening up the possibility of looking at a much larger part of the genetic material which was previously considered unimportant. The image of the brain becomes more complex, but the area in which to search for errors linked to diseases with a genetic component, such as neurodegenerative diseases, psychiatric illness and brain tumours, also increases.”


Journal Reference:

  1. Liana Fasching, Adamandia Kapopoulou, Rohit Sachdeva, Rebecca Petri, Marie E. Jönsson, Christian Männe, Priscilla Turelli, Patric Jern, Florence Cammas, Didier Trono, Johan Jakobsson. TRIM28 Represses Transcription of Endogenous Retroviruses in Neural Progenitor CellsCell Reports, 2015; 10 (1): 20 DOI: 10.1016/j.celrep.2014.12.004

Cientistas descobrem dois genes relacionados a crimes violentos (Zero Hora)

A característica estava presente em 10% dos 900 criminosos finlandeses analisados em estudo de instituto sueco

Mais um estudo científico conclui que a genética pode estar relacionada a crimes violentos. Desta vez, a partir da análise de quase 900 criminosos na Finlândia, pesquisadores descobriram dois genes que ampliaram em 13 vezes as chances de a pessoa ter comportamento violento repetidamente.

Veja a matéria completa em: http://zh.clicrbs.com.br/rs/noticias/planeta-ciencia/noticia/2014/10/cientistas-descobrem-dois-genes-relacionados-a-crimes-violentos-4630569.html

(Zero Hora)

How learning to talk is in the genes (Science Daily)

Date: September 16, 2014

Source: University of Bristol

Summary: Researchers have found evidence that genetic factors may contribute to the development of language during infancy. Scientists discovered a significant link between genetic changes near the ROBO2 gene and the number of words spoken by children in the early stages of language development.


Researchers have found evidence that genetic factors may contribute to the development of language during infancy. Credit: © witthaya / Fotolia

Researchers have found evidence that genetic factors may contribute to the development of language during infancy.

Scientists from the Medical Research Council (MRC) Integrative Epidemiology Unit at the University of Bristol worked with colleagues around the world to discover a significant link between genetic changes near the ROBO2 gene and the number of words spoken by children in the early stages of language development.

Children produce words at about 10 to 15 months of age and our range of vocabulary expands as we grow — from around 50 words at 15 to 18 months, 200 words at 18 to 30 months, 14,000 words at six-years-old and then over 50,000 words by the time we leave secondary school.

The researchers found the genetic link during the ages of 15 to 18 months when toddlers typically communicate with single words only before their linguistic skills advance to two-word combinations and more complex grammatical structures.

The results, published in Nature Communications today [16 Sept], shed further light on a specific genetic region on chromosome 3, which has been previously implicated in dyslexia and speech-related disorders.

The ROBO2 gene contains the instructions for making the ROBO2 protein. This protein directs chemicals in brain cells and other neuronal cell formations that may help infants to develop language but also to produce sounds.

The ROBO2 protein also closely interacts with other ROBO proteins that have previously been linked to problems with reading and the storage of speech sounds.

Dr Beate St Pourcain, who jointly led the research with Professor Davey Smith at the MRC Integrative Epidemiology Unit, said: “This research helps us to better understand the genetic factors which may be involved in the early language development in healthy children, particularly at a time when children speak with single words only, and strengthens the link between ROBO proteins and a variety of linguistic skills in humans.”

Dr Claire Haworth, one of the lead authors, based at the University of Warwick, commented: “In this study we found that results using DNA confirm those we get from twin studies about the importance of genetic influences for language development. This is good news as it means that current DNA-based investigations can be used to detect most of the genetic factors that contribute to these early language skills.”

The study was carried out by an international team of scientists from the EArly Genetics and Lifecourse Epidemiology Consortium (EAGLE) and involved data from over 10,000 children.

Journal Reference:
  1. Beate St Pourcain, Rolieke A.M. Cents, Andrew J.O. Whitehouse, Claire M.A. Haworth, Oliver S.P. Davis, Paul F. O’Reilly, Susan Roulstone, Yvonne Wren, Qi W. Ang, Fleur P. Velders, David M. Evans, John P. Kemp, Nicole M. Warrington, Laura Miller, Nicholas J. Timpson, Susan M. Ring, Frank C. Verhulst, Albert Hofman, Fernando Rivadeneira, Emma L. Meaburn, Thomas S. Price, Philip S. Dale, Demetris Pillas, Anneli Yliherva, Alina Rodriguez, Jean Golding, Vincent W.V. Jaddoe, Marjo-Riitta Jarvelin, Robert Plomin, Craig E. Pennell, Henning Tiemeier, George Davey Smith. Common variation near ROBO2 is associated with expressive vocabulary in infancy. Nature Communications, 2014; 5: 4831 DOI:10.1038/ncomms5831

The original Eskimos have no living descendants, say scientists (The Christian Science Monitor)

By Charles Choi, LiveScience Contributing Writer / August 28, 2014

Ancient human DNA is shedding light on the peopling of the Arctic region of the Americas, revealing that the first people there did not leave any genetic descendants in the New World, unlike previously thought.

The study’s researchers suggest the first group of people in the New World Arctic may have lived in near-isolation for more than 4,000 years because of a mindset that eschewed adopting new ideas. It remains a mystery why they ultimately died off, they added.

The first people in the Arctic of the Americas may have arrived about 6,000 years ago, crossing the Bering Strait from Siberia. The area was the last region of the New World that humans populated due to its harsh and frigid nature.

But the details of how the New World Arctic was peopled remain a mystery because the region’s vast size and remoteness make it difficult to conduct research there. For example, it was unclear whether the Inuit people living there today and the cultures that preceded them were genetically the same people, or independent groups.

The scientists analyzed DNA from bone, teeth and hair samples collected from the remains of 169 ancient humans from Arctic Siberia, Alaska, Canada and Greenland. They also sequenced the complete genomes of seven modern-day people from the region for comparison.

Previous research suggested people in the New World Arctic could be divided into two distinct groups — the Paleo-Eskimos, who showed up first, and the Neo-Eskimos, who got there nearly 4,000 years later. [In Photos: Life in the Arctic region of the Americas]

The early Paleo-Eskimo people include the Pre-Dorset and Saqqaq cultures, who mostly hunted reindeer and musk ox. When a particularly cold period began about 800 B.C., the Late Paleo-Eskimo people known as the Dorset culture emerged. The Dorset people had a more marine lifestyle, involving whaling and seal hunting. Their culture is divided into three phases, altogether lasting about 2,100 years.

“One may almost say kind of jokingly or informally that the Dorsets were the hobbits of the Eastern Arctic, a very strange and very conservative people that we are just now getting to know a little bit,” said study co-author William Fitzhugh, an anthropologist at the Smithsonian Institution’s National Museum of Natural History in Washington, D.C.

The Dorset culture ended sometime between 1150 and 1350 A.D., getting rapidly replaced after the sudden appearance of Neo-Eskimo whale-hunters known as the Thule culture. These newcomers from the Bering Strait region brought new technology from Asia, including complex weapons such as sinew-backed bows and more effective means of transportation such as dog sleds. The Thule “pioneered the hunting of large whales for the first time ever in, I guess, maybe anywhere in the world,” Fitzhugh said.

Modern Inuit cultures emerged from the Thule during the decline of whaling near the end of the period known as the Little Ice Age, which lasted from the 16th to 19th century. This ultimately led the Inuit to adopt the hunting of walruses at the edges of ice packs and the hunting of seals at their breathing holes.

Previous studies hinted that some modern Native Americans, such as the Athabascans in northwestern North America, might be descended from the Paleo-Eskimos. However, these findings now quash that idea. “The results of this paper have a bearing not just on the peopling of the Arctic, but also the peopling of the Americas,” lead study author Maanasa Raghavan, a molecular biologist at the University of Copenhagen’s National Museum of Natural History in Denmark, told Live Science.

The new findings suggest the Paleo-Eskimos apparently survived in near-isolation for more than 4,000 years. The arrival of Paleo-Eskimos into the Americas was its own independent migration event, with Paleo-Eskimos genetically distinct from both the Neo-Eskimos and modern Native Americans.

“I was actually surprised that we don’t find any evidence of mixture between Native Americans and Paleo-Eskimos,” said study co-author Eske Willerslev, an evolutionary geneticist also at the University of Copenhagen’s National Museum of Natural History. “In other studies, when we see people meeting each other, they might be fighting each other, but normally they actually also have sex with each other, but that doesn’t seem to really have been the case here. They must have been coexisting for thousands of years, so at least from a genetic point of view, the lack of mixture between those two groups was a bit surprising.”

The reason the Paleo-Eskimos may not have mixed with the Neo-Eskimos or the ancestors of modern Native Americans was “because they had such an entirely different mindset,” Fitzhugh said. “Their religions were completely different, their resources and their technologies were different. When you have people who are so close to nature as the Paleo-Eskimos had to be to survive, they had to be extremely careful about maintaining good relationships with the animals, and that meant not polluting the relationship by introducing new ideas, new rituals, new materials and so forth.”

The researchers did find evidence of gene flow between Paleo-Eskimos and Neo-Eskimos. However, this likely occurred before the groups migrated to the New World, back in Siberia, among the common ancestors of both lineages.  The new evidence suggests that in the American Arctic, the two groups largely stayed separate.

In addition, while differences in the artifacts and architecture of the Pre-Dorset and Dorset had led previous studies to suggest they had different ancestral populations, these new findings suggest the Early and Late Paleo-Eskimos did share a common ancestral group. “The pre-Dorset people, the Dorset ancestors, seemed to have morphed into Dorset culture,” Fitzhugh told Live Science.

One mystery these findings help solve is the origin of the Sadlermiut people, who survived until the beginning of the 20th century in the region near Canada’s Hudson Bay, until the last of them perished from a disease introduced by whalers. The Sadlermiut avoided interaction with everyone outside their own society, and according to their Inuit neighbors, the Sadlermiut spoke a strange dialect, were bad at skills the Inuit considered vital, such as constructing igloos and tending oil lamps, were unclean, and did not observe standard Inuit taboos, all of which suggested that the Sadlermiut were descended from Paleo-Eskimos instead of Neo-Eskimos.

However, these new findings revealed the Sadlermiut showed evidence of only Inuit ancestry. Their cultural differences from other Inuit may have been the result of their isolation.

It remains a mystery why the Dorset people ultimately died off. Previous studies suggested the Dorset were absorbed by the expanding Thule population — and the Thule did adopt Dorset harpoon types, soapstone lamps and pots, and snow houses. However, these new findings do not find evidence of interbreeding between the groups.

One possibility is that the rise of the Thule represented “an example of prehistoric genocide,” Fitzhugh said. “The lack of significant genetic mixing might make it appear so.” However, Thule legends of the Dorset “tell only of friendly relations with a race of gentle giants,” Fitzhugh added.

Another possibility is that diseases introduced by Vikings or the Thule may have triggered the collapse of the Dorset, Fitzhugh said. However, “if it’s disease, then you’d expect to find dead bodies of Dorset people in their houses, and that’s never been found,” Fitzhugh said. [Fierce Fighters: 7 Secrets of Viking Seamen]

To help solve this and other remaining mysteries about the peopling of the New World Arctic, the researchers plan to look at more ancient human remains in both the Americas and Asia. The scientists detailed their findings in the Aug. 29 issue of the journal Science.

 

US Scientists, Oil Giant Stole Indigenous Blood (Common Dreams)

Published on Wednesday, June 18, 2014 by Common Dreams

For years, scientists working with Maxus Energy took blood samples from hundreds of Amazonian tribal members

– Max Ocean, editorial intern

Members of the Ecuadorean indigenous group known as the Huaorani (Credit: Jean-François Renaud/cc/flickr)

U.S. scientists working together with oil company Maxus Energy took around 3,500 blood samples from the indigenous Amazonian tribe known as the Huaorani, Ecuador charged on Monday.

The Huaorani are known for a unique genetic makeup that makes them immune to certain diseases.

René Ramírez, the head of the Ecuadorian Ministry of Higher Education, Science and Technology, told Ecuador state TV on Monday that samples were taken from around 600 Huaorani, and that multiple pints of blood were taken from many members of the tribe. Ramírez said that it is not yet known whether the samples have resulted in any commercial gains, but that samples were sold for scientific research.

According to an initial investigation two years ago, “It was demonstrated that the Coriell Institute has in its stores samples (from the Huaorani) and that it sells genetic material from the Huaorani people.” Harvard University was among the purchasers. Specifically, the 2012 report found that since 1994, seven cell cultures and 36 blood samples were distributed to eight different countries.

In the same report the Huaorani said that scientists had tricked them into allowing their blood to be taken between 1990 and 1991; however, President Rafael Correa said that there is now evidence that samples were taken as far back as the 1970s “in complicity with the oil company operating in the area.”

The Huaorani allegedly agreed to give the blood samples because scientists lied to them about why the samples were being taken. They were told the samples were being taken for medical tests, but never received results.

According to the website Hispanically Speaking News, in his weekly radio address on Saturday, President Correa said that at least 31 research papers were written between 1989 and 2012 based on the blood samples obtained––all without the consent of the Huaorani or the royalty payments normally required.

The taking of the samples was illegal, as Ecuador’s constitution bans the use of scientific research including genetic material in violation of human rights.

According to AFP, when the allegations first emerged in 2012, the U.S. Embassy said it was not aware of the case, and they did not immediately issue a response after Ecuador brought the charges on Monday.

What gave us the advantage over extinct types of humans? (The Hebrew University of Jerusalem)

22-Apr-2014

Jerry Barach

The answer lies in changes in the way our genes work

Jerusalem, April 22, 2014 — In parallel with modern man (Homo sapiens), there were other, extinct types of humans with whom we lived side by side, such as Neanderthals and the recently discovered Denisovans of Siberia. Yet only Homo sapiens survived. What was it in our genetic makeup that gave us the advantage?

The truth is that little is known about our unique genetic makeup as distinguished from our archaic cousins, and how it contributed to the fact that we are the only species among them to survive. Even less is known about our unique epigenetic makeup, but it is exactly such epigenetic changes that may have shaped our own species.

While genetics deals with the DNA sequence itself and the heritable changes in the DNA (mutations), epigenetics deals with heritable traits that are not caused by mutations. Rather, chemical modifications to the DNA can efficiently turn genes on and off without changing the sequence. This epigenetic regulatory layer controls where, when and how genes are activated, and is believed to be behind many of the differences between human groups.

Indeed, many epigenetic changes distinguish us from the Neanderthal and the Denisovan, researchers at the Hebrew University of Jerusalem and Europe have now shown.

In an article just published in Science, Dr. Liran Carmel, Prof. Eran Meshorer and David Gokhman of the Alexander Silberman Institute of Life sciences at the Hebrew University, along with scientists from Germany and Spain, have reconstructed, for the first time, the epigenome of the Neanderthal and the Denisovan. Then, by comparing this ancient epigenome with that of modern humans, they identified genes whose activity had changed only in our own species during our most recent evolution.

Among those genetic pattern changes, many are expressed in brain development. Numerous changes were also observed in the immune and cardiovascular systems, whereas the digestive system remained relatively unchanged.

On the negative side, the researchers found that many of the genes whose activity is unique to modern humans are linked to diseases like Alzheimer’s disease, autism and schizophrenia, suggesting that these recent changes in our brain may underlie some of the psychiatric disorders that are so common in humans today.

By reconstructing how genes were regulated in the Neanderthal and the Denisovan, the researchers provide the first insight into the evolution of gene regulation along the human lineage and open a window to a new field that allows the studying of gene regulation in species that went extinct hundreds of thousands of years ago.

 

Genetic study tackles mystery of slow plant domestications (Science Daily)

Date: April 17, 2014

Source: Washington University in St. Louis

Summary: Did domesticating a plant typically take a few hundred or many thousands of years? Genetic studies often indicate that domestication traits have a fairly simple genetic basis, which should facilitate their rapid evolution under selection. On the other hand, recent archeological studies of crop domestication have suggested a relatively slow spread and fixation of domestication traits. A new article tries to resolve the discrepancy.

Closeup of a mature seedhead of foxtail millet. Like other domesticated cereals, foxtail millet has nonshattering spikes that retain their seeds during harvesting. Credit: © Ruud Morijn / Fotolia

“The Modern View of Domestication,” a special feature of TheProceedings of the National Academy of Sciences (PNAS) published April 29, raises a number of startling questions about a transition in our deep history that most of us take for granted. At the end of the last Ice Age, people in many spots around the globe shifted from hunting animals and gathering fruits and tubers to cultivating livestock and plants.

It seems so straightforward and yet the more scientists learn, the more complex the story becomes. Recently, geneticists and archeologists working on domestication compared notes and up popped a question of timing. Did domesticating a plant typically take a few hundred or many thousands of years?

Genetic studies often indicate that domestication traits have a fairly simple genetic basis, which should facilitate their rapid evolution under selection. On the other hand, recent archeological studies of crop domestication have suggested a relatively slow spread and fixation of domestication traits.

In this special issue of PNAS, Washington University in St. Louis biologist Ken Olsen, PhD, and colleagues ask whether complex genetic interactions might have slowed the rate at which early farmers were able to shape plant characteristics, thus reconciling the genetic and archeological findings.

Olsen, associate professor in the Department of Biology in Arts & Sciences, together with colleagues from Oklahoma State University and the University of Guelph in Ontario, Canada, conclude that these interactions are not a key factor in domesticated plants. The process of domestication, Olsen said, favored gene variants (alleles) that are relatively insensitive to background effects and highly responsive to selection.

But finding these alleles in the first place must have difficult, Olsen said. Only a subset of the genes in the wild population would have reliably produced a favored trait regardless of the crop variety into which they were bred and regardless of where that crop was grown. So the early stages of domestication might have been beset by setbacks and incomprehensible failures that might help explain the lag in the archeological record.

“What we are learning suggests there’s a whole lot of diversity out there in wild relatives of crop plants or even in landraces, varieties of plants and animals that are highly adapted to local conditions,” Olsen said, “that wasn’t tapped during the domestication process.”

“These plant populations could provide the diversity for continued breeding that is going to be very important as the world faces climatic change,” he said. “This is why it is important we understand the early stages of domestication.”

Two possible speed bumps

Many crops are distinguished from their wild ancestors with a suite of traits called the domestication syndrome. This includes seeds that remain attached to the plant for harvesting (a trait called nonshattering), reduced branching and robust growth of the central stem and bigger fruits, seeds or tubers.

Over the past 20 years, researchers have begun to identify the genes that control some of the most important domestication traits, no easy task in the days before rapid sequencing, because they had to start with plant traits and work back to unknown genes.

This work showed that many domestication traits were under the control of single genes. For example the gene teosinte branched1 (tb1) converts highly branched teosinte plants into single stalks of corn.

But the seeming importance of single genes could have been an artifact of the method used to identify domestication genes, which required the researcher to pick “candidate” genes and, perhaps, prematurely narrow the search, overlooking indirect genetic effects.

“Little is known about the underlying genetics of domestication,” Olsen said. “We decided to look at genetic mechanisms for modifying plant phenotypes that hadn’t been explored before, in part because not much data is available.”

The new work examines the possibility that two indirect effects — the influence of the genetic background on the expression of a gene (called epistasis) and the effects of the environment on the expression of genes — might have slowed the selection of plants with the desired traits.

Epistasis and environmental effects in domestication genes

By selecting animals for coat color, animal breeders may have stabilized certain epistatic and environmental interactions in companion animals (see photos at right). But when the plant scientists looked at comparable genetic mechanisms in domesticated plants, they found the reverse to be true. Farmers seem to have selected for plant variants that were insensitive to epistatic and environmental interactions.

Shattering in domesticated foxtail millet provides an example of insensitivity to epistasis. Branching in maize illustrates insensitivity to environmental effects.

Shattering in foxtail millet and its wild ancestor, green millet, is controlled by two stretches of DNA containing or linked to genes that underlie this trait, a major one called QTL 1 and a minor one called QTL2. In this as in other epistatic interactions, the effect of an allele at one location depends on the state of the allele at the other location. But when wild and domesticated plants are crossed, these “genetic background effects” are not symmetric.

Shattering in plants with a wild green-millet allele at the QTLI location depends on the allele at the QTL2 location. In contrast, shattering in plants with the foxtail-millet allele at QTL1 is unaffected by the allele at the QTL2 location.

In the limited number of examples at their disposal, the scientists found it to be generally true that that domesticated alleles were less sensitive to genetic background than wild alleles. The domestication genes, in other words, tended to be ones that would produce the same result even if they were introduced into a different crop variety.

Teosinte provides a good example of the sensitivity of gene expression to the environment. Teosinte is strongly affected by crowding. When a teosinte plant with a wild tb1 gene is repeatedly backcrossed with maize, it produces highly branched plants in uncrowded growing conditions but plants with smaller lateral branches when it is crowded.

Again, however, the effect is not symmetric. The domesticated trait is less sensitive to the environment than the wild trait; plants with the domesticated tb1 gene allele are unbranched whether or not they are crowded.

Unlike companion-animal breeders, early farmers seem to have selected domestication-gene alleles that are insensitive to genetic background and to the environment. This process would have been slow, unrewarding and difficult to understand, because the effects of gene variants on the plant weren’t stable. But once sensitive alleles had been replaced with robust ones, breeders would have been able to exert strong selection pressure on plant traits, shaping them much more easily than before, and the pace of domestication would have picked up.

No wonder the archeological record indicates there were false starts, failed efforts and long delays.

Revolução neandertal (Folha de S.Paulo)

JC e-mail 4907, de 07 de março de 2014

Svante Pääbo, cientista que liderou o mapeamento do genoma do homem de Neandertal, conta em livro sua descoberta que abalou a antropologia

A história de como os humanos deixaram a África e povoaram o resto do mundo tem hoje seu foco em pesquisas sobre o DNA, deixando os fósseis –matéria-prima indispensável da antropologia– meio fora dos holofotes. Há quem questione se essa mudança é benéfica, mas é difícil desvincular essa revolução acadêmica do nome de um cientista: Svante Pääbo.

Em novo livro, o geneticista sueco radicado na Alemanha conta como essa mudança de perspectiva se instalou. Para tal, narra a história de seu principal objetivo científico, o sequenciamento do genoma do homem de Neandertal, a última criatura do gênero Homo a pisar na Terra antes de o Homo sapiens tomar o planeta inteiro para si.

Pääbo é o sujeito magricela que aparece em uma fotografia estampada em vários jornais em 7 de maio de 2010 na qual está olhando para um crânio de neandertal. Naquele dia, quando o cientista publicou a primeira versão do genoma do hominídeo extinto, teorias de evolução humana baseadas apenas na interpretação do formato de fósseis começaram a ter de ser alteradas para acomodar algumas revelações.

Aquela que chamou mais a atenção, sem dúvida, foi a de que H. sapiens e H. neanderthalensis legaram ao planeta os frutos de uma inusitada história de amor. Pessoas de etnias europeias ainda carregam no DNA cerca de 3% de ancestralidade neandertal.

O genoma desse hominídeo e a descoberta subsequente de uma linhagem totalmente nova do gênero Homo –os denisovanos, descritos por Pääbo com base no DNA extraído de um único osso de dedo– mostraram que a saída da África foi um processo bem mais complexo.

Achar DNA em ossos com dezenas de milhares de anos, porém, não era (e não é) coisa trivial. Pääbo, que se descreve como um sujeito paranoico por limpeza (para evitar contaminar amostras), também exigia de si repetir seus experimentos inúmeras vezes, cada vez que obtinha um bom resultado. Não poupa, por isso, criticas às revistas “Science” e “Nature” por terem publicado estudos que considera de baixo padrão.

Com o modesto título “Neanderthal Man”, o livro conta muito mais do que a história do sequenciamento de um genoma. Pääbo começou sua carreira acadêmica patinando entre disciplinas tão distintas quanto egiptologia e bioquímica. Seu ponto de virada foi a extração de DNA de uma múmia egípcia, estudo que realizou escondido de seu orientador de doutorado, usando uma amostra cedida por um museu da Alemanha Oriental. (O curador que cedeu o pedaço de múmia foi depois abordado pela Stasi, a polícia comunista.)

Uma boa parte do livro é dedicada a tecnicalidades de extração de DNA, apesar de as histórias de negociações para obtenção de fósseis serem mais interessantes.

No meio dos trabalhos de sequenciamento do neandertal, Pääbo conta sobre o racha com seu colaborador Ed Rubin, do Laboratório Nacional Lawrence Berkeley, que passou a competir diretamente por amostras de fósseis.

Além de intriga, há também um bocado de romance para o que se espera de um livro de ciência. Abertamente bissexual, Pääbo não se intimida em contar a história de um triângulo amoroso que envolveu sua mulher e outro cientista de seu instituto.

Nada disso, porém, é narrado mais passionalmente do que a epopeia científica do genoma do neandertal, que mudou a noção sobre o que significa ser humano.

(Rafael Garcia/Folha de S.Paulo)
http://www1.folha.uol.com.br/fsp/cienciasaude/155225-revolucao-neandertal.shtml

A challenge to the genetic interpretation of biology (University of Eastern Finland)

19-Feb-2014

Keith Baverstock

A proposal for reformulating the foundations of biology, based on the 2nd law of thermodynamics and which is in sharp contrast to the prevailing genetic view, is published today in the Journal of the Royal Society Interface under the title “Genes without prominence: a reappraisal of the foundations of biology”. The authors, Arto Annila, Professor of physics at Helsinki University and Keith Baverstock, Docent and former professor at the University of Eastern Finland, assert that the prominent emphasis currently given to the gene in biology is based on a flawed interpretation of experimental genetics and should be replaced by more fundamental considerations of how the cell utilises energy. There are far-reaching implications, both in research and for the current strategy in many countries to develop personalised medicine based on genome-wide sequencing.

This shows the inactive linear peptide molecule with a sequence of amino acids derived from the gene coding sequence folds to a protein.

Is it in your genes?

By “it” we mean intelligence, sexual orientation, increased risk of cancer, stroke or heart attack, criminal behaviour, political preference and religious beliefs, etcetera. Genes have been implicated in influencing, wholly or partly, all these aspects of our lives by researchers. Genes cannot cause any of these features, although geneticists have found associations between specific genes and all of these features, many of which are entirely spurious and a few are fortuitous.

How can we be so sure?

When a gene, a string of bases on the DNA molecule, is deployed, it is first transcribed and then translated into a peptide – a string of amino acids. To give rise to biological properties it needs to “fold” into a protein.

This process consumes energy and is therefore governed by the 2nd law, but also by the environment in which the folding takes place. These two factors mean that there is no causal relationship between the original gene coding sequence and the biological activity of the protein.

Is there any empirical evidence to support this?

Yes, a Nordic study of twins conducted in 2000 showed there was no evidence that cancer was a “genetic” disease – that is – that genes play no role in the causation of cancer. A wider international study involving 50,000 identical twin pairs published in 2012, showed that this conclusion applied to other common disease as well. Since the sequencing of the human genome was completed in 2001 it has not proved possible to relate abnormal gene sequences to common diseases giving rise to the problem of the “missing heritability”.

What is the essence of the reformulation?

At the most fundamental level organisms are energy-consuming systems and the appropriate foundation in physics is that of complex dissipative systems. As energy flows in and out and within, the complex molecular system called the cell, fundamental physical considerations, dictated by the 2nd law of thermodynamics, demand that these flows, called actions, are maximally efficient (follow the path of least resistance) in space and time. Energy exchanges can give rise to new emergent properties that modify the actions and give rise to more new emergent properties and so on. The result is evolution from simpler to more complex and diverse organisms in both form and function, without the need to invoke genes. This model is supported by earlier computer simulations to create a virtual ecosystem by Mauno Rönkkö of the University of Eastern Finland.

What implications does this have in practice?

There are many, but two are urgent.

1) to assume that genes are unavoidable influences on our health and behaviour will distract attention from the real causes of disease, many of which arise from our environment;

2) the current strategy towards basing healthcare on genome-wide sequencing, so called “personalised healthcare”, will prove costly and ineffective.

What is personalised health care?

This is the idea that it will be possible to predict at birth, by determining the total DNA sequence (genome-wide sequence), health outcomes in the future and take preventive measures. Most European countries have research programmes in this and in the UK a pilot study with 100,000 participants is underway.

Modelo pode ajudar a prever como espécies da Mata Atlântica responderão às mudanças climáticas (Fapesp)

Pesquisadores do Brasil e dos EUA buscam compreensão dos processos evolutivos, geológicos, climáticos e genéticos por trás do padrão atual da biodiversidade (foto:Samuel Iavelberg)

11/02/2014

Por Karina Toledo

Agência FAPESP – Compreender os processos evolutivos, geológicos, climáticos e genéticos por trás da enorme biodiversidade e do padrão de distribuição de espécies da Mata Atlântica e, com base nesse conhecimento, criar modelos que permitam prever, por exemplo, como essas espécies vão reagir às mudanças no clima e no uso do solo.

Esse é o objetivo central de um projeto que reúne pesquisadores do Brasil e dos Estados Unidos no âmbito de um acordo de cooperação científica entre o Programa de Pesquisas em Caracterização, Conservação, Recuperação e Uso Sustentável da Biodiversidade do Estado de São Paulo (BIOTA-FAPESP) e o programa Dimensions of Biodiversity, da agência federal norte-americana de fomento à pesquisa National Science Foundation (NSF).

“Além de ajudar a prever o que poderá ocorrer no futuro com as espécies, os modelos ajudam a entender como está hoje distribuída a biodiversidade em áreas onde os cientistas não têm acesso. Como fazemos coletas por amostragem, seria impossível mapear todos os microambientes. Os modelos permitem extrapolar essas informações para áreas não amostradas e podem ser aplicados em qualquer tempo”, explicou Ana Carolina Carnaval, professora da The City University of New York, nos Estados Unidos, e coordenadora do projeto de pesquisa ao lado de Cristina Miyaki, do Instituto de Biociências da Universidade de São Paulo (IB-USP).

A proposta, segundo Carnaval, é promover a integração de pesquisadores de diversas áreas – como ecologia, geologia, biogeografia, genética, fisiologia, climatologia, taxonomia, paleologia, geomorfologia – e unir ciência básica e aplicada em benefício da conservação da Mata Atlântica.

O bioma é considerado um dos 34 hotspots mundiais, ou seja, uma das áreas prioritárias para a conservação por causa de sua enorme biodiversidade, do alto grau de endemismo de suas espécies (ocorrência apenas naquele local) e da grande ameaça de extinção resultante da intensa atividade antrópica na região.

A empreitada coordenada por Carnaval e por Miyaki teve início no segundo semestre de 2013. A rede de pesquisadores esteve reunida pela primeira vez para apresentar suas linhas de pesquisa e seus resultados preliminares na segunda-feira (10/02), durante o “Workshop Dimensions US-BIOTA São Paulo – A multidisciplinary framework for biodiversity prediction in the Brazilian Atlantic forest hotspot”.

“Convidamos alguns colaboradores além de pesquisadores envolvidos no projeto, pois queremos críticas e sugestões que permitam aperfeiçoar os trabalhos”, contou Miyaki. “Essa reunião é um marco para conseguirmos efetivar a integração entre as diversas áreas do projeto e criarmos uma linguagem única focada em compreender a Mata Atlântica e os processos que fazem esse bioma ser tão especial”, acrescentou.

Entre os mistérios que os cientistas tentarão desvendar estão a origem da incrível diversidade existente na Mata Atlântica, possivelmente fruto de conexões existentes há milhões de anos com outros biomas, entre eles a Floresta Amazônica. Outra questão fundamental é entender a importância do sistema de transporte de umidade na região hoje e no passado e como ele permite que a Mata Atlântica se comunique com outros sistemas florestais. Também está entre as metas do grupo investigar como a atividade tectônica influenciou o curso de rios e afetou o padrão de distribuição das espécies aquáticas.

Desafios do BIOTA

Durante a abertura do workshop, o presidente da FAPESP, Celso Lafer, realçou a importância de abordagens inovadoras e multidisciplinares voltadas para a proteção da biodiversidade da Mata Atlântica. Ressaltou ainda que a iniciativa está em consonância com os esforços de internacionalização realizados pela FAPESP nos últimos anos.

“Uma das grandes preocupações da FAPESP tem sido o processo de internacionalização, que basicamente está relacionado ao esforço de juntar pesquisadores de diversas áreas para avançar no conhecimento. Este programa de hoje está relacionado a aspirações dessa natureza e tenho certeza de que os resultados serão altamente relevantes”, afirmou Lafer.

Também durante a mesa de abertura, o diretor do IB-USP, Carlos Eduardo Falavigna da Rocha, afirmou que o programa BIOTA-FAPESP tem sido um exemplo para outros estados e outras fundações de apoio à pesquisa em âmbito federal e estadual.

Carlos Alfredo Joly, professor da Universidade Estadual de Campinas (Unicamp) e coordenador do BIOTA-FAPESP, apresentou um histórico das atividades realizadas pelo programa desde 1999, entre elas a elaboração de um mapa de áreas prioritárias para conservação que serviu de base para mais de 20 documentos legais estaduais – entre leis, decretos e resoluções.

Joly também falou sobre os desafios a serem vencidos até 2020, como empreender esforços de restauração e de reintrodução de espécies, ampliar o entendimento sobre ecossistemas terrestres e sobre os mecanismos que mantêm a biodiversidade no Estado e intensificar as atividades voltadas à educação ambiental.

Para 2014, Joly ressaltou dois desafios na área de conservação. “Estamos iniciando uma campanha para o tombamento da Serra da Mantiqueira. Já fizemos alguns artigos de jornais, estamos lançando um website específico e vamos trabalhar para conseguir tombar regiões acima de 800 metros, áreas apontadas como de extrema prioridade para conservação no atlas do BIOTA”, disse.

Outra meta para 2014, segundo Joly, é trabalhar para que o Brasil ratifique o protocolo de Nagoya – tratado internacional que dispõe sobre a repartição de benefícios do uso da biodiversidade – até outubro, quando ocorrerá a 12ª Conferência das Partes da Convenção sobre Diversidade Biológica.

“É fundamental que um país megadiverso, que tem todo o interesse de ter sua biodiversidade protegida por esse protocolo internacional, se torne signatário do protocolo antes dessa reunião”, afirmou Joly.