( New evidence from open-sea experiments ...)Scientists discover interplay between genes and viruses in tiny ocean plankton

Conducted by biological oceanographers Sallie Chisholm and her colleagues at the Massachusetts Institute of Technology, the research is uncovering a new facet of evolution and helping scientists see how microbes exploit changing conditions, such as altered light, temperature and nutrients.

"These results tell us that even the smallest organisms show genetic variation related to the environment in which they exist," said Philip Taylor, director of the National Science Foundation (NSF)'s biological oceanography program, which funded the research.

In addition to NSF, support for the research came from the Gordon and Betty Moore Foundation and from the U.S. Department of Energy.

"Our image of ocean microbes and their role in planetary maintenance is changing," Chisholm said. "We no longer think of the microbial community as being made up of species that have a fixed genetic make-up. Rather, it is a collection of genes, some of which are shared by all microbes and contain the information that drives their core metabolism, and others that are more mobile, which can be found in unique combinations in different microbes."

The distributors or carriers of new genes, the scientists suspect, are the massive numbers of viruses also known to exist in seawater. Some of them are adept at infecting ocean microbes like Prochlorococcus, the sea's most abundant plankton species. The ocean viruses, which carry their own genes as well as transport others, provide a way of transferring genes from old cells into new ones.

"We're beginning to get a picture of gene diversity and gene flow in Prochlorococcus," Chisholm said. "These photosynthesizing bacteria form an important part of the food chain in the oceans, supply som
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Source:National Science Foundation