A Unlikely Star of Science

Jonathan Freedman Looks to Microscopic Roundworms to Document the Effects of Toxic Chemicals p.4

  While some transition metals can be both toxic and beneficial depending on the concentration, scientists have found no positive benefits from cadmium, he says. As his group’s scientific papers have noted, cadmium is introduced into the atmosphere when ores are smelted and fossil fuels are burned. And it is frequently found in “Superfund” cleanup sites. It also can end up in food. Known toxicological responses to the metal include kidney damage, respiratory and neurological diseases and cancers of the lung, kidney, prostate and testicles.

  Freedman’s specific interest in cadmium goes back to his undergraduate days at Rutgers University, where his work in the university’s department of microbiology included probing the metal’s relationship to marine bacteria.
After refocusing on the transition metal copper for his doctoral program in molecular pharmacology at Albert Einstein College of Medicine, he began working with C. elegans during his postdoctoral fellowship at Bell Labs studying the metabolic effects of cadmium.

  He came to the Nicholas School as an assistant professor in 1989. In 1998 his research group announced in the Journal of Biological Chemistry that it had used the nematode to identify as many as 31 different genes that may react to cadmium. Twenty-two of those genes were previously unknown and unlinked to cadmium exposure.

  His current count of about 400 cadmium-responsive genes was ascertained via a tool of the genomic revolution: “microarrays” of thousands of genetic sequences arranged not in living nematodes but on tiny glass microchips.

  Besides continuing work with C. elegans, Freedman’s lab is now studying how metals affect genes in other living models such as zebrafish, mice, even yeast. Yes, he acknowledges, yeast is “just” a fungus. But it shares a
surprising number of genetic traits with animals, humans included. And since the yeast’s genome is smaller than the roundworm’s, the fungus is “faster to work with and easier to manipulate.”

  In the past few years he and his students—including one budding researcher still in high school and another who, at the time, was still an undergraduate—published several papers exploring molecular details of how cadmium and other metals affect cells in C. elegans.

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