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NASA's Astrobiology Announcememnt

the media lost interest, but the scientific discussion continues.
there were many (legitimate) concerns from scientists all-over, than an official response by the NASA scientist to some of these critiiques and here is a rebuttal of that response.

very interesting debate (kinda technical for the uninitiated), and a couple of the control they are asking are very legit (others criticisms are just speculations). also overall very easy experiment to perform now, so we should know the definitive answer in a few months.
stay tuned. :)
 
More breaking news: http://journalofcosmology.com/Abiogenesis123.html
From the paper:
4. No arsenic involvement in formation of high energy bonds

But there is even more direct biochemical evidence that makes impossible for arsenic to play the role of a stable component of a nucleic acid backbone in an aqueous environment. Arsenic is a poison, and this has been known for millenia. Beside involvement in oxido-reduction reactions (which can be used both to evolve arsenite into its more innocuous form arsenate, and to recover energy), arsenic can indeed replace phosphorus in many phosphorolytic reactions and even form carbohydrate arsenates that are similar to their phosphate analogs (Lagunas & Sols, 1968). However this is limited to exchange reactions that cannot lead to stable and useful compounds.

It is also possible to begin to construct compounds along the line predicted to exist if phosphorus could replace arsenic, for example by constructing an arsenical analog of adenosine diphosphate (an essential pre-requisite if the if the claims published by Science were true). While difficult, a synthesis in which the phosphono-oxy group of ADP was replaced by the arsenomethyl group (arsenate itself was far too unstable at this position, requiring replacement of the bridging oxygen by a methylene group) was achieved by Dixon and colleagues. The product was unable to compete for ADP in any of its standard substrates (Webster et al. 1978). A further demonstration puts the final nail in the coffin: the arsonomethyl analogue of AMP can be used as a substrate for adenylate kinase. It permits transfer of a phospho group from ATP, but like all anhydrides of arsonic acids breaks down immediately, transforming the enzyme into an ATPase (Adams et al. 1984). The situation would be even worse if the hypothetical arsenical analog of ATP could have existed.
Click to expand...
 
it will take some time before we know.
unlikely it is all wrong, but certainly there are accumulating doubts aboyt at least some parts.

first of all the experiments need to be repeated by others, then some of the various controls proposed by the critics needs to be performed and the new results analyzed.

the paper you quoted is not a proper rebuttal. it is more of a commentary with some argument drawn from other papers. I don't know that journal, so i am not sure how reputable it is, or if it is peer-reviewed itself.

in any case,the instability of the arsenic compounds in vitro was already known, what the authors of the science papers seemed to suggest was that the bacteria had evolved a way to deal with it and stabilize it (possibly involving salt, lipids and those vacuoles).

as i mentioned in earlier, the control experiment are pretty straightforward so soon enough the current debate based on theory and speculation will leave the floor to the new data, and then we will know what is going on really.
 
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