Frances Wilkerson, lecturer and senior research scientist at the Romberg Tiburon Center for Environmental Studies, was among a group of 45 distinguished marine scientists, botanists and geneticists from several countries who recently became the first to sequence a marine phytoplankton species. The scientists, who were selected by the Joint Genome Institute, met over one week in October 2002 to launch the genetic sequencing of the oceanic diatom Thalassiosira pseudonana. Researchers believe that their findings, which are published in the Oct. 1 issue of Science Magazine, will accelerate work in bio- and nanotechnology as well as the marine sciences.

Among the team's surprising observations is that T. pseudonana has the genes for a urea cycle, a nitrogen waste pathway common to animal species but never before seen in diatoms and other photosynthetic organisms. Diatoms, which are a tiny fraction of the size of a human hair, have existed in Earth's marine and fresh waters for more than 180 million years and are thought of as the base of the short food web that supports large-scale coastal fisheries. Photosynthesis by marine diatoms is believed to generate as much as 40 percent of the 40 to 50 billion tons of organic carbon produced each year in the Earth's oceans.

Scientists believe that the marine diatom's role in global carbon cycling is comparable to that of all terrestrial rain forests combined. Their silica coverings act as natural ballast that helps sequester organic carbon to the deep ocean. It is possible that over geological time, diatoms may have influenced global climate by pulling the flux of atmospheric carbon dioxide into the oceans.

Genome work on ocean diatoms bodes well for Silicon Valley industries. Unique to the diatom is its ornately patterned silicified cell wall which displays nano-structures so fine that they have been used to test the resolution of optical microscopes. "Once we understand how it is that the diatom deposits silicon to form its ornate cell walls," Wilkerson notes, "the work of material scientists in the field of microchip nanotechnology will no doubt significantly advance."

For marine scientists, this genome work will lead to new investigations of the biology and environmental interaction of the ocean diatom. Scientists will soon know more about how these ecologically important organisms react to such changes in the sea as temperature fluctuations and the amount of light beneath the ocean surface. With this study, genome sequencing will become a common tool to test theories in ocean ecology and will add to researchers' knowledge of the structure of oceanic ecosystems.

Much like the Human Genome Project, Wilkerson says that the Diatom Genome Project "opens the door to years and years of important work by hundreds of scientists around the world." It has already facilitated several projects in her lab at SFSU. Wilkerson adds that SFSU's Romberg Tiburon Center is "well-known for its molecular approach to understanding the ocean" and was recently awarded funding by the National Science Foundation to improve its molecular genetic instrumentation.

-- Denize Springer
Photo: Nils Kröger, University of Regensburg