© AAAS; E. Pennisi, Science, 295: 1809–11, 2002
"This finding was an enormous surprise," says Jonathan Eisen, investigator at the Institute for Genomic Research, Rockville, Md., who together with Scott O'Neill, from the University of Queensland, Australia, formed a consortium to sequence the organism in 1999. Evolutionary forces typically shrink the genomes of intracellular bacteria, and junk DNA is generally thought to be lost with nonessential genes. But here, massive amounts are left over, says Eisen. "We argue that this is a symptom of inefficient natural selection in
Seth Bordenstein, staff scientist at the Marine Biological Laboratory, Woods Hole, Mass., says the "finding debunks an emerging consensus that the genomes of obligate bacterial endosymbionts are perfectly streamlined," but also raises questions as to why so much mobile DNA remains. Regardless of the reason, Mark Taylor, Liverpool School of Tropical Medicine notes that "it will have an enormous impact and will change the way we research this symbiosis." He adds that the finding will spark practical applications including a "search for new antibiotics for filariasis."
- David Secko