The project aims to look at the functions of all 7,000 genes in Nostoc punctiforme, said principal investigator John Meeks, professor in the section of microbiology at UC Davis.

"We're trying to understand everything that it does, and it does a lot," Meeks said.

Nostoc grows in gelatinous strands in freshwater and a wide range of land habitats. It can photosynthesize, using sunlight, carbon dioxide and water to feed itself, and can fix nitrogen into a usable form. To do that, some regular Nostoc cells switch themselves into a different type of cell specialized for nitrogen fixation.

A number of non-crop higher plants form associations with Nostoc to take advantage of its nitrogen-fixing abilities. Those plants direct the bacterium to make more nitrogen-fixing cells than necessary and to produce more fixed nitrogen, a process Meeks compares to domestication of cattle to produce milk.

An ultimate goal of the research is to learn about the process so that crop plants could be engineered to domesticate Nostoc, Meeks said.

Existing crop plants that fix nitrogen, such as beans, form a relationship with a different bacteria, Rhizobia. Unlike Nostoc, Rhizobia don't fix nitrogen when they live outside a plant.

The researchers will study how groups of genes are turned on or off as Nostoc grows and responds to changes in its environment, for example when switching to a nitrogen-fixing form.

Nostoc belongs to the cyanobacteria, thought to be one of the earliest groups of living things to evolve on Earth and the first to use oxygen-producing photosynthesis. Chloroplasts, the structures that carry out photosynthesis in algae and plants, are thought to have developed from cyanobacteria captured or engulfed by other cells.

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Contact: Andy Fell
ahfell@ucdavis.edu
530-752-4533
University of California - Davis
12-Dec-2003