Berkeley -- Two new studies by University of California, Berkeley, scientists highlight the amazing promiscuity of genes, which appear to shuttle frequently between organisms, especially more primitive organisms, and often in packs.
Such gene flow, dubbed horizontal gene transfer, has been seen frequently in bacteria, allowing pathogenic bacteria, for example, to share genes conferring resistance to a drug. Recently, two different species of plants were shown to share genes as well. The questions have been: How common is it, and how does it occur?
In a report appearing this week in the Proceedings of the National Academy of Sciences (PNAS), UC Berkeley and Lawrence Berkeley National Laboratory (LBNL) researchers analyzed more than 8,000 different families of genes coding for proteins - families that represent the millions of proteins in all living creatures - to assess the prevalence of horizontal gene transfer.
They found that more than half of all the most primitive organisms, Archaea, have one or more protein genes acquired by horizontal gene transfer, as compared to 30 to 50 percent of bacteria that have acquired genes this way. Fewer than 10 percent of eukaryotes - plants and animals - have genes acquired via horizontal gene transfer.
In a second report published online by Nature on March 7, two species of bacteria living together in the pink slime of an acidic California mine were found to share large groups of genes. These genes code for proteins that work together, so by acquiring the entire block from another organism, bacteria can gain a new function that helps them adapt more quickly to the same type of environment - in this case, a hot, highly acidic, metal-rich broth.
This is the first observation of exchange of very large genomic blocks between organisms in a natural microbial community, according to UC Berkeley's Jill Banfield, who led the team of researchers from LBNL, Oak Ridge National Laboratory
Contact: Robert Sanders
University of California - Berkeley