Diatoms, most of which are far too tiny to see without magnification, are nevertheless thought to absorb carbon dioxide, a major greenhouse gas, in amounts comparable to all the world's tropical rain forests combined.

"These organisms are incredibly important in the global carbon cycle," says Virginia Armbrust, a University of Washington associate professor of oceanography and lead author of a research article in the Oct. 1 issue of Science. Together, these single-celled organisms generate as much as 40 percent of the 50 billion to 55 billion tons of organic carbon produced each year in the sea, and in the process use carbon dioxide and produce oxygen. And they are an important food source for many other marine organisms.

The genome work, funded by the Department of Energy and conducted at its Joint Genome Institute in California, gives insight into how the diatom species Thalassiosira pseudonana prospers in the marine environment, Armbrust says. It's important to understand because diatoms like Thalassiosira pseudonana and other phytoplankton are vital components of the biosphere's role in mediating global warming.

"Now that we have a glimpse at the inner workings of diatoms, we're better positioned to understand how changes in the environment will translate into increases or decreases in diatom abundance," says Dan Rokhsar, who heads computational genomics at the Joint Genome Institute and one of the co-authors on the article.

Scientists would like to better understand how these organisms react to changes in sea temperatures, the amount of light penetrating the oceans and nutrients.

"Oceanographers thought we understood how diatoms use nitrogen, but we discovered they have a
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Contact: Sandra Hines
shines@u.washington.edu
206-543-2580
University of Washington
30-Sep-2004