Arsenic-based life.. what changes?

[baric]

Here is an "official" response from the team about the questions and criticisms of their research:
http://www.universetoday.com/81783/s...to-criticisms/

I certainly do not have the expertise to evaluate their responses, but I would certainly like to hear the opinion of those who do have such expertise.

[Procyan]

I am a average joe smoe biochemist and never dreamed I would disagree with any NASA team. I loved the Mckay study and never saw anything wrong with the technique or the conclusion. But this latest thing is not correct and the response adds nothing to the material already presented.

For example, when they say that the DNA contained BOUND arsenic or was ASSOCIATED with As, I'm just waiting for the other shoe to drop. The critical thing is was it covalently bonded in a functional way or adsorbed and co-migrating with the sample. They argue that the cleaning was sufficient to ensure that it was incorporated. I refer to my earlier comments and those of others on this...this needs to be repeated using stringent cleaning and also next to proper controls.

When pressed on stability issues, Iron Lisa said that the proposed As molecules were different from those shown to be unstable. That is true, the Arseno-diester bonds that would be in the DNA construct are links to deoxyribose. The studies on stability involved alkyl (saturated carbon chains) which are less electron withdrawing that oxygen rich sugars. But that is secondary in this case. The primary determinate of stability is the size of the arsenic atom relative to phosphate. Its valence shell (where the elections that react are located) is further from the nucleus and therefore more weakly bound. It is easier for them to react with say a water molecule, substituting the OH portion for the alcohol group of sugar.

Look, there is a good science case to look into this further and it most certainly is being investigated by others. I'm not concerned about NASAs image being damaged because it will all come out in the wash, and people will already have formed their opinions. Just like the faked moon landings, if you are disposed to believe the negative then you will see this in that vein. Others here have correctly observed that this is science 'working". My personal hope is that this bug does have an unique biochemistry and we get to open an new chapter of study.

[Hernalt]

Q&A: 'Science' Journal Official Talks Arsenic-Based Life: "A recent announcement of the discovery of arsenic-based life on Earth was preceded by intense media speculation about possible implications for the search for extraterrestrial life. Now the journal Science is looking to keep the discussion grounded in a more Earthly reality."

[kzb]

It looks from the responses on here that the kind of sinking feeling I got when I saw this being reported on UK TV was justified...here is someone else with some pithy comments on this:

http://www.starshipreckless.com/blog/?p=3668

[Hernalt]

NASA to Announce New Discovery by Hubble Space Telescope

Clearly, Hubble has discovered arsenic based life.

[Swift]

Two new studies do not reproduce the arsenic-life paper
From R&D Magazine on-line

It was a provocative finding: strange bacteria in a California lake that thrived on something completely unexpected—arsenic. What it suggested is that life, a very different kind of life, could possibly exist on some other planet.

The research, published by a leading scientific journal in 2010, led to overheated speculation about how life might exist elsewhere—and quickly some dissent about the original finding.

On Sunday, that same journal, Science, released two papers that rip apart the original research. They "clearly show" that the bacteria can't use arsenic as the researchers claimed, said an accompanying statement from the journal.

...

For both new papers, scientists did their own tests of the bacteria. One team, led by Rosemary Redfield of the University of British Columbia in Vancouver, Canada, reports that arsenic does not contribute to the bacteria's growth. Maybe the original results came from some sort of undetected contaminant in the arsenic the researchers used, they suggest.

The other paper, from Swiss researchers, finds the bacteria to be highly resistant to the poisonous effects of arsenic but still dependent on phosphorus to grow. They concluded that in the original experiment, trace contamination with phosphorous may have let the bacteria grow.