The latest paper shows that the “arsenic monster” GFAJ-1 goes to a huge amount of effort, “even more than other life”, to avoid arsenate, says Wolfgang Nitschke from the Mediterranean Institute of Microbiology in Marseilles, France, who co-authored a commentary questioning the conclusion that GFAJ-1 could replace phosphate with arsenate. “This shows clearly that life doesn’t like arsenate in cytoplasm,” he says.
Felisa Wolfe-Simon, lead author on the original Science paper and now at Lawrence Berkeley National Laboratory in Berkeley, California, says that the new paper “represents the kind of careful study that really helps the community”. However, she points out that this work “doesn’t necessarily rule out an entirely novel mechanism” for arsenate getting into cells. “There’s still a lot of interesting open questions,” she says.