June 23, 2011

Arsenic and Scientific Controversy

by Anthony Carpi

The June 3 issue of Science contained a research article written by a NASA astrobiologist fellow, Felisa Wolfe-Simon, and her colleagues titled “A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus.” The manuscript reports on research in which the bacterium GFAJ-1 was grown in an environment low in phosphorous and high in arsenic, traditionally considered a toxic and unstable metal. The authors hypothesize that not only does the bacterium tolerate arsenic, but it thrives in the environment, replacing some of the phosphorous normally used to manufacture biomolecules such as DNA, with arsenic. Steven Benner, an astrobiologist at the Foundation for Applied Molecular Evolution in Gainesville, Florida stated that if the authors’ hypothesis proves true, it would “set aside nearly a century of chemical data concerning arsenate and phosphate molecules.”

While the findings of the research are significant, even more remarkable is the discussion and debate that began after the article was first published online by Science on 2 December 2010. By the time of its print publication in the June 3 issue, the manuscript had spawned a record eight Technical Comment articles that were published in the same issue, and a Response to the Technical Comments by the lead author Wolfe-Simon. Several of the Technical Comments questioned whether the DNA was simply contaminated with arsenic instead of having incorporated it into its genome. Others questioned whether arsenate compounds would be stable enough to be utilized in the bacterium’s DNA. In her response, Wolfe-Simon provides further explanation of their work and interpretations. But the controversy over the hypothesis will take much longer to play out. Bruce Alberts, Science’s editor-in-chief, remarked in a note introducing the Technical Comments that “The discussion published … is only a step in a much longer process.” That process will likely involve further research, additional publications, and continued debate until a preponderance of evidence eventually supports or disputes the hypothesis put forth. The research stimulated by scientific controversy is not only a healthy aspect of scientific discourse, it is, in many ways, essential to the process of science as we know it. As we wait for this particular controversy to play out, you can read more about the role that controversy plays in scientific discovery in our website module Scientific Controversy.

Anthony Carpi

Written by

Anthony is the founder and president of Visionlearning. He is a Professor of Environmental Toxicology at John Jay College of the City University of New York with extensive experience in teaching and educational research. He has authored articles for the Journal of Chemical Education and the Journal of College Science Teaching on the design and effectiveness of Web-based teaching resources. He is the recipient of two National Science Foundation grants for the development of online science teaching resources, and he was one of the designers of the HETS virtual plaza, an online education cooperative for Hispanic students. He has published extensively on the fate, behavior and toxicity of mercury as an environmental pollutant. In addition, he is active in research in the area of environmental forensics.