Arsenic DeathJuly 9th, 2012
Yesterday, Science magazine published what are effectively two death certificates for arsenic life (1 2). These twin papers delve back into the experiments first conducted on the GFAJ-1 bacterium that led Felisa Wolfe-Simon and coworkers to conclude that this organism can grow using arsenic instead of phosphorus.
In the newest reports, Redfield and coworkers were more fastidious than FWS in their experimentation and reported that the presence of arsenate did not affect the growth of the bacterium when phosphate was limiting. They also found no covalently incorporated As in the DNA of GFAJ-1. Erb, et al. found similar results. You can read the papers for yourselves, but suffice it to say that these are findings that jive with everything we know about biochemistry excluding the one paper published by Wolfe-Simon. The only reasonable analysis is that until bona fide experimental evidence to the contrary is presented, there are no organisms we know of that can function by substituting As for P in their DNA.
To follow up on one of my earlier posts, unfortunately, Felisa Wolfe-Simon *still* does not get it. The first rule of getting out of a hole is to stop digging. Giving a statement like the following to USA Today does not help FWS’s cause:
The “new research shows that GFAJ-1 does not break the long-held rules of life,” says the editorial statement by Science. The bacteria, “is likely adept at scavenging phosphate under harsh conditions, which would help to explain why it can grow even when arsenic is present within the cells,” it says.
Wolfe-Simon says in response, “There is nothing in the data of these new papers that contradicts our published data.” Her team hopes to submit more data on the microbe for publication within a few months, she suggests.
Her latest collaborator also decided to pick up a shovel in commenting to the Washington Post:
Wolfe-Simon, now on a NASA fellowship at the Lawrence Berkeley National Laboratory, is collaborating with senior scientist John A. Tainer on wide-ranging studies of the bacterium. In an interview Saturday, Wolfe-Simon and Tainer said that they had produced tentative results in the Berkeley lab almost identical to the original results at a U.S. Geological Survey laboratory, and that they were busy finishing the research and preparing another paper.
Tainer said the two new studies in Science may have come to different results than theirs because of the methodologies used, the precision used to detect arsenates and the provenance of the cells. He said the authors of the two new papers “may well regret some of their statements” in the future.
“There are many reasons not to find things — I don’t find my keys some mornings,” he said. “That doesn’t mean they don’t exist. The absence of a finding is not definitive.”
Wolfe-Simon and her numerous collaborators had made samples of GFAJ-1 broadly available after her initial results caused a storm of controversy, but she and Tainer said they may have been contaminated or modified in transit.
Even the Catholic Church admitted it was wrong when faced with the overwhelming evidence that the Sun does not revolve around the Earth. And we’ve just discussed scientific megablunders with regard to Ronald Breslow and the space dinosaurs paper: when you are spectacularly wrong, you need to admit it for people to let you move on. Denying or ignoring your mistakes prolongs the story.
The second rule of getting yourself out of a hole is to grab a life-line if someone offers you one. Wolfe-Simon could have easily jumped on the “good news” of the GFAJ-1 story by embracing the bacterium’s remarkable resistance to arsenic—which was verified. Instead, it appears as though FWS has doubled down behind the initial report. I’ll keep an open mind when she presents her newest results, but I don’t expect much.
As an aside, it is interesting to note that Science (with a capital “S”) got dragged through the mud again. As if publishing the flawed initial report wasn’t bad enough, the magazine was forced to publish the Redfield and Erb papers prematurely because Redfield
broke the embargo on her own paper at a decided to present the results yesterday at a popular conference on evolution. What a mess for Science!