PHILADELPHIA -- Biologists at the University of Pennsylvania have discovered the first biochemical pathway in animals responsible for the detoxification of heavy metals such as arsenic, mercury and cadmium. They have established that the enzyme phytochelatin synthase, which had previously been found only in plants and some fungi, is also present in some animals.
A Penn team led by Philip A. Rea, professor of biology, and including plant scientist Olena K. Vatamaniuk and animal cell and developmental biologists Elizabeth A. Bucher and James T. Ward made the discovery in work with the nematode worm Caenorhabditis elegans. They reported their results in the Journal of Biological Chemistry.
"Despite two decades of research into the biochemical basis of heavy metal detoxification in animals, never before had the involvement of phytochelatins been even cursorily mentioned or speculated," said Rea, a member of Penn's Plant Science Institute. "Discovery of this pathway in C. elegans establishes a firm basis for determining its ubiquity in other animals and for clarifying how animals eliminate, sequester and metabolize heavy metals."
Because preliminary work suggests that genes encoding PC synthase may also be found in parasitic invertebrates, the findings of Rea's group could help guard against growing resistance to certain heavy metal-based drugs. Diseases caused by these parasites, which include elephantitis and lymphatic filariasis, kill millions of people worldwide each year, but physicians have noted with some alarm that traditional treatments are waning in effectiveness.
Researchers say it's rare for a genetic find originating in a plant to ultimately shed light on such fundamental processes in animals.
"Often studies in animals and microorganisms have tended to inform our understanding of many aspects of plant biology," said plant geneticist Chris Cobbett of the University of Melbourne, an expert on plant processing of heavy
Contact: Steve Bradt
University of Pennsylvania