This column on the “arsenic bacteria” controversy brought on some good questions. The following was the also posed by biologists when the announcement of the so-called arsenic bacteria came out:
"What about the RNA?"
This is a great question. If these bugs were living with no phosphorus, they’d have to substitute in arsenic in the DNA and the RNA. So the researchers making the claim would have had to prove arsenic was in the RNA as well.
This question also brings out the difference between claims made by the paper and the press conference and press releases. In the scientific paper, the researchers were not clear how much arsenic actually got incorporated into the DNA.
The press materials implied there was no phosphorus at all in these bugs – they were the first known organisms to live without this essential element. At a NASA press conference the lead researcher also implied that all the phosphorus in the DNA was replaced by arsenic – how could it be otherwise if there was no phosphorus in the system?