NEW YORK, March 16 (GenomeWeb News) - An international team of researchers led by the Institute for Genomic Research has sequenced and analyzed the genome of Wolbachia pipientis wMel, a sexually selective parasitic bacteria that targets the males of its host organisms.
Preying on more than a million species of insects, spiders, crustaceans, and worms, members of the Wolbachia family of bacteria either kill their host males, convert them into females, or prohibit successful fertilization. The misandrist microbes are of particular interest to researchers studying evolutionary biology and insect-transmitted disease.
Wolbachia pipientis wMel, which infects the fruit fly Drosophila melanogaster, is the first strain of Wolbachia to be sequenced. A study describing the analysis of the genome appears in the March 2004 issue of PloS Biology.
The investigators found that the 1,267,782-base-pair wMel genome has accumulated more repetitive and "junk" DNA than any other intracellular bacteria. TIGR's Jonathan Eisen, principal investigator on the project, said in a statement that "it appears that natural selection has been inefficient in this species, most likely because it repeatedly experiences very small population sizes."
According to the researchers, the male-targeted effects may be due to the fact that Wolbachia are transmitted specifically from females to their offspring and thus can increase their transmission by eliminating the non-transmitting males, or by converting them to females.
The Wolbachia genome may be useful for researchers seeking to develop new antibiotics to treat victims of lymphatic filariasis, elephantiasis, and other human diseases caused by small worms that cannot survive or reproduce without Wolbachia inside their cells. For example, sequencing the sMel genome identified several genes that are likely to play roles in interacting with the insect host and that may also be involved in interacting with the worm hosts for other Wolbachia, the researchers said.