Arquivo da tag: Biotecnologias

‘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.


To Bring Back the Extinct (Edge)

A Conversation with Ryan Phelan [8.28.12]

 One of the fundamental questions here is, is extinction a good thing? Is it “nature’s way?” And if it’s nature’s way, who in the world says anyone should go about changing nature’s way? If something was meant to go extinct, then who are we to screw around with it and bring it back? I don’t think it’s really nature’s way. I think that the extinction that we’ve seen since man is 99.9 percent caused by man.

RYAN PHELAN is the Executive Director of Revive and Restore, a project within The Long Now Foundation, with a mission to provide deep ecological enrichment through extinct species revival.

[ ED. NOTE: The following conversation took place at the seventh annual Science Foo Camp (SciFoo), hosted by Nature, Digital Science, O’Reilly Media, and Google, August 3 – 5, 2012, at the Googleplex in Mountain View, California. Special thanks to Philip Campbell of Nature, Timo Hannay of Digital Science, Tim O’Reilly of O’Reilly Media (“Foo” stands for “friends of O’Reilly”), and Chris DiBona and Cat Allman of Google. —JB ]


[RYAN PHELAN:] The big question that I’m asking right now is: If we could bring back an extinct species, should we? Could we? Should we? How does it benefit society? How does it advance the science? And the truth is, we’re just at the beginning of trying to figure all this out. I got inspired really thinking about this through my involvement with George Church, and I’ve been on the periphery of an organization that he started called The Personal Genome Project. Over the last seven years I’ve been working primarily in personalized medicine, keeping my eye on the application of genomic medicine in different areas, and the growth of genomics and the shockingly drop in the sequencing price, and the cost of sequencing, and what that means to all different areas of science.

One thing led to another and we started talking with George about what it would mean if we could actually apply this towards the de-extinction of species. It turns out, of course, that in George’s lab he’s pioneering in all these methods. Right now, George’s approach of basically editing the genome starts to make the concept of bringing something back really plausible.


There are right now probably three different methods that are being used to contemplate bringing back species. The most traditional is what they refer to as back breeding, and we see that going on right now with the ancient cattle called aurochs. Basically, what they do is they start by taking the strains of cattle that are closest to the ancient aurochs and try to breed back in much the way they do with plant biology and hybridization.

The other area that is being done is in cloning, and the best example of that is with the Spanish Pyrenean ibex (a wild mountain goat). They actually were able to get some cellular matter from the last remaining ibex to clone. The Spanish scientists that did all that work feel that that cloning is completely viable. The truth is that when they did that ibex, it only lasted seven minutes, because of a particular lung frailty. That’s quite common in cloning anything. That is just something that cloning technology has to deal with, so he feels really confident if he had funding he could clone an extinct species now without a problem, and solve the lung issue.

The third concept is the one that we’re focused on right now: genome editing that George Church is pioneering. The way it would work (and again, I’m not the scientist here, George is better to explain it) the idea would be to take the most closely related extant living species and actually compare it genomically with the extinct species, and basically gene by gene match it, and edit it accordingly.

The species of choice right now that we’re looking at helping, aiding, and abetting, is the passenger pigeon, and the passenger pigeon, as you may know, is an iconic bird that had flocks in the billions just over a hundred years ago. A hundred and fifty years ago the passenger pigeon darkened the sky when it would pass. They say that these flocks were so thick in the sky that when they passed it could take a mile for a flock of birds to go by. They would darken the sky. It’s an amazing concept. We don’t have anything like that today. When that happened, it went from being the most prolific bird, and in just 30 years to being extinct. Why does that matter? Well, it matters for a lot of reasons. What was going on ecologically there? What did that bird bring to that whole eastern deciduous forest? God knows, it had a tremendous impact. I think we’re just now trying to figure out what would that impact might be like today if you were to reintroduce it.

The idea with the passenger pigeon is to take a closely related relative, which is the and-tailed pigeon, and sequence that genome. We’re sequencing that right now at Harvard, with an intern that we’re helping to fund, named Ben Novak. Right now we’re in the process of doing that work, and then they will basically edit the band-tail genome until the band-tail walks, and talks, and flies like a passenger pigeon. That’s how resurgence will occur.

We’re using the term “resurgence” because as you can imagine, there’s a lot of controversy over if you could bring back an extinct species, is it invasive? Would it become an invasive species? And is this a bad thing?

We’re in the process of starting a new organization. It’s called Revive and Restore. If we were to say it has a mission, it’s to help rethink extinction, to basically bring back extinct species if it’s the right thing to do. We’re contemplating the ethics involved in all this. This fall we’ll have a conference that we’re sponsoring in Washington DC, and I think it’s going to be thrilling. We’re bringing in 25 to 35 the scientists from all over the world that are actually doing extinction work— from the Korean team that’s working on the wooly mammoth, to the New Zealand and Australian teams that are de-extincting some species yet to be identified. They’re calling it the Lazarus Project. We don’t really know what it is. It could be the Moa. There are different theories about what it is. But, hopefully, in the fall we’ll learn more about that.

We’ll be talking with these scientists about the different technologies that they’re deploying, of which this genome hybridization technique that George is doing is going to be one and I’m sure there are others. We’ll be talking about the ethics of re-wilding. It’s one thing to actually bring back a species in the lab. It’s another to actually release it into the wild. And so we’ll be talking to scientists that are working in captive breeding, like the San Diego Zoo, with the California ondor. We’ll be talking with the frozen zoos that are doing this kind of banking of genetic material, and trying to figure out what kind of ethical framework we could create, so that when these scientists actually start to succeed in these fields we can somehow socialize this in the public discourse.

What I fear, quite honestly, is backlash that we’ve seen around genetically modified foods, that these organisms will be deemed genetically modified, which, of course, they are. This is genome engineering, and there may be way too much of a concern over what happens when they go into the wild.

One of the fundamental questions here is, is extinction a good thing? Is it “nature’s way”? And if it’s nature’s way, who in the world says anyone should go about changing nature’s way? If something was meant to go extinct, then who are we to screw around with it and bring it back? I don’t think it’s really nature’s way. I think that the extinction that we’ve seen since man is 99.9 percent caused by man.

I’m going to just take the passenger pigeon as an example, not because it’s my favorite bird, but because it’s so iconic. If we are the ones that are responsible for blasting it out of the sky, do we have a little bit of responsibility to think about bringing it back now that we have science that can easily allow for it? I say “easily,” but in the scheme of things, it’s still going to be a lot of heavy lifting to help make this happen.

What does all this mean to the average citizen? A good example of a reintroduction of a species is the peregrine falcon. The peregrine falcon had actually gone extinct as a species in the East. For many of us bird lovers, we love the peregrine falcon. We love seeing that bird fly and soar like it does. But, it was really only through captive breeding and a reintroduction of a sub-species from the Rocky Mountain area that we even have a peregrine now flourishing on the East Coast. Where the peregrine falcon really wants to nest is on bridges or on the sides of skyscrapers, and that bird is now evolving into a bird that is better adapted for working in an urban environment.

What’s going to happen is, even if we were to have a passenger pigeon, they’re not going to be in the flocks of the billions any more. Their impact with agriculture will be lessened, because of an obvious reduction in size. The truth is, if anything happened with that bird, we know it’s a tremendous game bird that people loved, and probably people would be shooting it for good meat, good game.

One question is: If you could actually bring back anything, would you bring back the California grizzly bear? A species that could eat people? Well, we recently were at the California Academy of Sciences, up front and personal with “Monarch”, the last California grizzly, a beautiful specimen there, and we were joking, and not really joking, saying, “Well, what if you could genome edit the California grizzly so that it didn’t like the taste of people?” That would be kind of interesting! Big megafauna, good for the land, but take the fear of it out for people. The truth is all of this could someday be possible.

Some people have said to us, “Well, are you one click away from “Jurassic Park” here?” The truth is, we’re not. “Jurassic Park” was a good movie, if that, but the science is not there at all today, and the reason for that is that we don’t have a close relative of the dinosaurs. We just don’t have it. The only reason that this concept of bringing back an extinct species works right now is if you can take those genomes and actually edit them based on either a close living relative, or you’ve got viable cell tissue, and we don’t have that. So right now that one is not a worry. But could it be someday? Sure.

The concept of Revive and Restore is an idea that might well blossom on the West Coast, here in Silicon Valley, but the truth is that the pressures that I think all these scientists who are working in de-extinction worldwide will feel will be around this whole question of: Who are you to play God and bring back an extinct species? Who are you to introduce something that could be “invasive”? Whether it’s in academia or it’s being done in industry, I think the science is going to be challenged around this really intriguing issue. That’s why I think an organization like Revive and Restore can actually help with the public discourse.

Somebody has to responsibly help the industry and academia think through these heady issues, and I think we’re going to start that dialogue this fall. But in the absence of it, what we’re going to see is the, “Oh, my God, we’re cloning this dangerous species again,” or we’re doing something horrific with our chicken to avoid the Avian flu. These things are going to happen.

Everyone wants to bring up the Neanderthals, and interestingly enough, anyone who’s working around the Neanderthal genome is reluctant to participate in our fall workshop, because they last thing they want is to be criticized or implicated in bringing back a Neanderthal. It’s just verboten.

I’ve been dealing with this whole genetic exceptionalism now for almost a decade with personalized medicine. There has always been a hypersensitivity to anything genetic and I’m looking forward to when we get over that.

The most interesting part of all this is going to be where the science goes, what we learn from doing this. It’s not going to be necessarily about bringing back something. It’s going to be about what we learn.

Just like everything that we know that’s really innovative in science, you never know the unintended benefits or what the outcomes are going to be. Specifically, around the study of extinct species we’re going to probably learn what made them vulnerable to extinction. The implications for endangered species are tremendous. We don’t really know why things go extinct. We can surmise, but right now we could actually start to look at the genetic level, at what some of these contributory factors were, and I think that’s really exciting.


Jennifer Jacquet:  To the question of who is Ryan Phelan, or anybody else, to bring an extinct species back I would counter: who was anyone to make these animals extinct to begin with?  An estimated 869 species have gone officially and, so far, irreversibly extinct just since the 16th century, and 290 more species are considered critically endangered and possibly extinct — and in almost all cases the finger points to humans.  Many of these disappearances, like the Tasmanian tiger, the Great auk, and the Steller’s sea cow, were precipitated by a relatively small group that never asked their fellow earthlings, let alone future generations, if they wanted these animals gone forever.  Should the entire group have been queried, my guess is that its majority, certainly in the case of the large, delicate, and vegetarian Steller’s sea cow, would have answered in a resounding “No.”  (Admittedly the response might be different in the case of the saber-toothed cat, for instance, which went extinct not long after the invention of farming.)  To be in favor of human-induced extinction seems one of the pillars of myopia.

But what is a genome edited songbird brought back from extinction to do against the poachers in the Mediterranean?  What happens when the reconstituted baby Yangtze River dolphin (last seen in 2005) is released into still sullied Chinese waters?  We already have captive-bred tigers, but that hasn’t stopped the habitat fragmentation and human takeover that has led to fewer than 3500 wild tigers (there were 100,000 in 1900) today in India.  In other words, does this technical solution, which is elegant and scientifically interesting, as Phelan points out, distract from old boring problems?  Or does it necessitate more work on pollution, habitat loss, and human behavior because the species that would be the usual victims now have a shot at immortality?

Risco é coisa séria (JC)

JC e-mail 4364, de 14 de Outubro de 2011.

Artigo de Francisco G. Nóbrega enviado ao JC Email pelo autor.

A sociedade moderna está banhada em comunicação. Como “boa notícia não é notícia”, a lente psicológica humana registra sempre um cenário pior que a realidade. A percepção usual é que os riscos de todos os tipos aumentam dia a dia. A redução global da violência, por exemplo, é tema do livro recente do psicólogo da Universidade Harvard, Steven Pinker ( Ao arrepio do senso comum, ele demonstra, objetivamente, que estamos progredindo neste quesito.

Mas nossa mente não descança em sua aguda capacidade de detectar outras fontes de risco. Temos alguns campeões de audiência: energia nuclear para eletricidade, alimentos geneticamente modificados e aquecimento global catastrófico e antropogênico. O dano potencial das três ameaças mencionadas, objetivamente, não se concretizou de maneira alguma, embora a terceira ameaça deva se realizar no futuro, segundo seus defensores. As pessoas se encantam com o automóvel e seus acessórios, cada vez mais atraentes. Não se pensa em baní-lo, apesar de resultar em cerca de 40.000 mortos e inúmeros incapacitados cada ano, só no Brasil. David Ropeik, que pertence ao Centro Harvard para Análise de Risco, explica como facilmente se distorce o perigo real de situações. Quanto mais afastadas do senso comum (como radiação e plantas geneticamente modificadas), mais facilmente são manipuladas, por ignorância ou interesses outros, apavorando o cidadão comum. Ropeik explica como este medo sem sentido passa a ser um fator de estresse e um risco objetivo para a saúde das pessoas, devendo ser evitado.

Dentro desse universo, são justificadas as preocupações do Dr. Ferraz (“O feijão nosso de cada dia”, Jornal da Ciência, 6/10/2011). Ele é membro da CTNBio, atua na setorial vegetal/ambiental e sua área de concentração é em agroecologia, o que explica, pelo menos em parte, suas dúvidas. No entanto essas preocupações não têm a consistência sugerida pelo autor e a análise da CTNBio, que resultou na aprovação deste feijão, é confiável.

A comissão se pauta sempre pelas diretivas da legislação que são amplas, para dar conta de todas as possibilidades de risco para os consumidores e meio ambiente. No entanto o corpo técnico existe exatamente para atuar de maneira seletiva e consciente, examinando caso a caso. Os testes são examinadas com o rigor que a modificação introduzida na planta exige para plena segurança. Se as modificações são consideradas sem qualquer risco significativo, os testes são avaliados à luz deste fato.

Testes com muitos animais, altamente confiáveis estatisticamente, seriam exigidos pela comissão na eventualidade de uma planta transgênica produzir, por exemplo, uma molécula pesticida não protéica que seria em tudo semelhante a uma droga produzida pela indústria farmacêutica. Isto poderá acontecer em certo momento, já que as plantas têm capacidade de produzir os mais variados pesticidas naturais para se defenderem na natureza. A substância seria absorvida no intestino e se disseminaria por órgãos e tecidos, possivelmente exercendo efeitos sistêmicos e localizados que exigem avaliação. Isso já aconteceu, sem querer, com uma batata produzida por melhoramento convencional nos EUA. Seu consumo levou a mal estar e foi recolhida apressadamente: portava altos níveis de glicoalcalóides tóxicos para o homem, o que explicava sua excelente resistência às pragas da cultura.

No caso do feijão Embrapa, nenhuma molécula não protéica nova é produzida e o pequeno RNA que interfere com a replicação do vírus, caso alguém venha a ingerir folhas e caules, será um entre centenas ou milhares de RNAs que ingerimos diariamente com qualquer produto vegetal. O RNA introduzido, no entanto, não foi detectado no grão do feijão cozido, usando técnicas extremamente poderosas.

As variações detectadas, se estatisticamente significativas (concentração de vitamina B2 ou cisteína por exemplo) não representam risco algum. A técnica clássica de cultura de tecidos, usada para gerar variedades de qualidade em horticultura e propagação de árvores, reconhecidamente resulta em variações naturais que introduzem certas modificações desejáveis e algumas indesejáveis, que o melhorista depois seleciona. É a variação somaclonal, que também afeta os clones geneticamente modificados na sua fase de seleção.

Portanto, é no mínimo ingênuo dizer que o feijão Embrapa 5.1 “deveria ser idêntico” a variedade de origem pois as manipulações necessárias para gerar o transgênico resultam em certas alterações que, se irrelevantes, são ignoradas e se deletérias são descartadas pelos cientistas. Se fizermos as mesmas análises, cujos resultados preocupam alguns, com as muitas variedades convencionais consumidas no país, as diferenças serão impressionantes e irrelevantes para a questão “segurança”.

Como já foi comentado anteriormente, não existe base factual (bioquímica ou genética) para imaginar que o feijão Embrapa apresente risco maior do que um feijão comum ou melhorado por mutagênese química ou física, que por sinal, não é supervisionado nutricional e molecularmente antes de sua comercialização. Sem base biológica, os testes tornam-se formalidades supérfluas e o ruído experimental, principalmente com amostras pequenas, quase inevitavelmente vai gerar resultados que são irrelavantes a menos que se amplie muito o número de animais (para amostras controle e transgênicas) além de ser prudente incluir animais alimentados com outros feijões convencionais para uma idéia realista do significado das variações detectadas. Imaginem o custo dessa busca “caça fantasma”, desencadeada simplesmente devido a uma aplicação pouco esclarecida do princípio da precaução. As preocupações sem base racional, levantadas a todo momento pelos que temem a tecnologia, se aplicariam com maior lógica aos produtos convencionais.

Caso isso aconteça, do dia para a noite estaria inviabilizada a produção agrícola do planeta. Por que não fazer estudos com Rhizobium e nodulação em todos os feijões comercializados? Por que não conduzir estudos nutricionais de longo prazo com os alimentos convencionais derivados de mutagênese? Qual a razão lógica que exclui essas preocupações com as plantas convencionais? Ou a razão seria metafísica? A alteração introduzida seria “contra a natureza”, algo como o pecado original, que, em muitas interpretações, consistiu apenas em comer o fruto da “árvore do conhecimento”? Recentemente 41 cientistas suecos da área vegetal lançaram um manifesto contra a sobre-regulação da genética moderna na Europa (reproduzido no blog GenPeace: Os autores observam que, fazendo um paralelo com as exigências para os produtos farmacêuticos, a “lógica da legislação atual sugere que apenas drogas produzidas por meio de engenharia genética deveriam ser avaliadas quando a efeitos indesejáveis”.

Instilar o medo com base em suposições não ajuda a proteger a população ou o meio ambiente. Marie Curie teria dito “Na vida nada deve ser temido. Mas tudo deve ser compreendido”. Considero irresponsável usar o “princípio da precaução” como alguns o fazem. Inclusive a OMS caiu nesta armadilha, classificando os telefones celulares no grupo 2B de risco para causar câncer. A radiação destes equipamentos é cerca de um milhão de vezes inferior à energia que pode produzir radicais livres e gerar dano ao DNA. A classe 2B inclui o risco de câncer relativo ao café, resíduos da queima de combustíveis fósseis e uso de dentadura…. O que a WHO manteve viva, irresponsavelmente, é a justificativa para a dúvida, que vai legitimar pesquisas caras e irrelevantes, cujo resultado será inconclusivo, como o mega estudo anterior. Incrivelmente mais perigoso é o uso do celular enquanto se dirige.

Francisco G. da Nóbrega é professor da Universidade de São Paulo (USP).