Yup

NASA has discovered a new life form, a bacteria called GFAJ-1 that is unlike anything currently living in planet Earth. It's capable of using arsenic to build its DNA, RNA, proteins, and cell membranes.

As implicações disto são imensas

Klawfive, talvez queiras pensar em fazer um mestrado nisto :p

isto é photoshop, pá! Tudo falso

(03-12-2010, 01:58)FoxRS Wrote: isto é photoshop, pá! Tudo falso

Nem mais!
Reparem neste pormenor:



Deixaram um bocado do que estava por baixo e aquele u ficou com uma perna maior! Que trabalho de amador.

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um updatezito:

http://astropt.org/blog/2010/12/02/nasa-...more-42037

[youtube]http://www.youtube.com/watch?v=WVuhBt03z8g[/youtube]

[youtube]http://www.youtube.com/watch?v=kiWlhNDMDHQ[/youtube]

[youtube]http://www.youtube.com/watch?v=tevWzkVrk2s[/youtube]

Pessoalmente comeco a nao dar a mi'nima importancia aos "grandes" anu'ncios que a NASA faz. O ano passado foi "grande" anu'ncio de que descobriram planetas (fora do sistema solar), desta vez e' isto... Isto e' do mais chato que ha'.

A tentativa de chamar a isto vida nao terrestre ou alieni'gena e' irritante e mostra que estes tipos so' estao interessados na publicidade e glo'ria imediata.

(03-12-2010, 12:01)Cobaia Wrote:

Isso sem o alt text não é a mesma coisa. A piada é que serviram arsénico aos repórteres.

Não sou biólogo, mas sigo uns na net (pelo Planet Atheism) , e pelo que percebi a importância disto é do tipo: tanto quanto se sabia, a vida tinha de ser baseada em X, porque todas as formas conhecidas o eram; este caso é diferente, logo mostra que afinal a vida pode também ser baseada em Y. Obriga um pouco a alterar-se certas definições e pressupostos. Claro que o interesse é para biólogos, e não para a população em geral -- não estamos prestes a ser dominados por formas de vida baseadas em arsénico.

Mas, sim, estava toda a gente à espera de vida extraterrestre ou coisa parecida.

(04-12-2010, 10:48)Dehumanizer Wrote: Não sou biólogo, mas sigo uns na net (pelo Planet Atheism) , e pelo que percebi a importância disto é do tipo: tanto quanto se sabia, a vida tinha de ser baseada em X, porque todas as formas conhecidas o eram; este caso é diferente, logo mostra que afinal a vida pode também ser baseada em Y. Obriga um pouco a alterar-se certas definições e pressupostos. Claro que o interesse é para biólogos, e não para a população em geral -- não estamos prestes a ser dominados por formas de vida baseadas em arsénico.

[quote='Dehumanizer' pid='14384' dateline='1291459689']
Mas, sim, estava toda a gente à espera de vida extraterrestre ou coisa parecida.

Hum!? Nao. Ningue'm estava 'a espera disso. Bom... Talvez meia du'zia de idiotas.

http://davidbrin.blogspot.com/2010/11/wh...other.html Wrote:Planned participants are:
- Mary Voytek, director, Astrobiology Program, NASA HQ
- Felisa Wolfe-Simon, NASA astrobio research fellow, U.S. Geol. Survey
- Pamela Conrad, astrobiologist, Goddard Space Flight Center
- Steven Benner, Foundation for Applied Molecular Evolution
- James Elser, professor, Arizona State University

Pause and consider. There are no exoplanetary astronomers. None. If there were new spectroscopic data about -- say -- exoplanetary atmosphere composition, wouldn't there be an expert in that field?

Hence -- and judging from the types of expertise represented -- I would hazard to guess it may have to do with fresh discoveries in prebiotic and biotic chemistry. (One of the panel members has forecast imminent shortages of easily-mined free phosphorus on Earth.

Acho que preciso de elaborar um bocado o que disse e o que penso sobre isto... Cá vai.

1- NASA
Já lá vai o tempo em que a NASA era a National Aeronautics and Space Administration; está cada vez mais longe da exploração espacial. Hoje em dia está a abandonar tudo o que diz respeito ao espaço; recentemente o presidente dos EUA cancelou mais um grande bocado do programa espacial da NASA; uma boa parte dos planos futuros inclui passar a usar os serviços de empresas para pôr equipamento em orbita; grande parte dos planos de utilização da estação espacial internacional foram abandonados.
Os mais recentes grandes anúncios feitos pela NASA têm sido uma desilusão; junto à lista anterior a "grande" descoberta feita pelo Mars Rover que nunca chegou a ser grande.
Não é que cada uma destas coisas seja má só por si mas mostram que o caminho da NASA vai ser sempre a descer.
Por outro lado há uma quantidade enorme de coisas em que a NASA está envolvida e que não precisa de estar. Por exemplo, o processamento de dados (sobretudo imagens) pode muito bem ser feito por entidades exteriores, até mesmo por amadores! Basta pensar na quantidade brutal de pessoas interessadas que regularmente estudam as imagens da NASA e na capacidade de processamento de dados que por aí há sem ser aproveitado.
Eu não sei exactamente o que é o trabalho "normal" de um astro-biólogo mas não me parece que seja andar a chafurdar num lago. Este trabalho que eles fizeram relacionado com ADN está perfeitamente ao nível das capacidades de qualquer universidade média (até várias em Portugal).

2- Esta "descoberta"
...Tem de ficar para amanhã.

NASA’s announcement last week that bacteria had been discovered that appeared to replace phosphorus with arsenic and thrive even in the most poisonous environments, has now come under fire from a number of scientists.

The findings reported last week, were that some bacteria (GFAJ-1) thrived when access to phosphate was removed and the bacteria were grown in a highly toxic culture rich is arsenate. The scientists suggested the bacteria thrived because they were able to replace phosphorus, which has always been thought vital to life, with arsenic, which is directly under it on the periodic table and has similar chemical properties. The researchers also suggested the bacteria were replacing phosphorus with arsenic within the bases that make up DNA.

These findings, if correct, would mean the scientists had found a new form of life on Earth, and it would also re-write the guide book on the essential requirements for life to exist elsewhere.

After the findings were published in Science, other scientists began immediately to express their doubts at the conclusions of the paper, with some even expressing the opinion the paper should not have been published at all.

One of the critics was Dr. Alex Bradley, from Harvard University, who blogged that there were a number of problems with the research. Firstly, if arsenic had replaced phosphorus in the DNA the molecule would have broken into fragments when the DNA was placed in water, since the arsenic would have hydrolyzed, and yet it did not. Secondly, the paper showed there was a small amount of phosphorus in the medium and Bradley argued that even though small, this could have been enough, since bacteria metabolism is extremely efficient.

Dr. Bradley also pointed out the bacteria live in Mono Lake, which is rich in arsenic but which also contains a higher concentration of phosphate than almost anywhere else on Earth, and this means there would be no selective pressure for a life based on arsenic to evolve.

Dr. Bradley also suggested a mass spectrum of the DNA sequences would have shown whether or not the nucleotides contained arsenic in place of phosphorus, but this was not done.

Another critic was University of British Columbia biologist Rosie Redfield, who reviewed the paper on her blog, and has more recently submitted a letter to the journal. Among her conclusions are that the paper “doesn't present ANY convincing evidence that arsenic has been incorporated into DNA (or any other biological molecule).” She also writes: “If this data was presented by a PhD student at their committee meeting, I'd send them back to the bench to do more cleanup and controls.”

Dr. Redfield also points out there was phosphate in the culture and that the authors did not calculate whether the amount of growth they saw in the arsenate-only medium could be supported by the phosphate present. She calculates on the blog that the growth of the bacteria is actually limited by the amount of phosphorus.

Another point made by Redfield is that the arsenic bacteria were “like plump little corn kernels” and contain granules, which are usually produced by bacteria when they have ample supplies of carbon and energy sources but there are shortages of other nutrients needed for growth.

The authors of the arsenic bacteria paper initially refused to be drawn into the arguments, saying the discussion should be confined to peer-reviewed journals, but one of the authors, Ronald Ormeland, did answer questions on the controversy after giving a lecture on the findings at NASA headquarters yesterday. He said the amount of phosphorus in the sample was too small to sustain growth, and a mass spectrum was not done because they did not have enough money, and wanted to get the result published quickly. He also pointed out that the bacteria are still there and other scientists could duplicate the work and carry out further experiments if they wished.