Since Wolbachia typically live within the reproductive organs of their hosts, Werren reasoned that gene exchanges between the two would frequently pass on to subsequent generations. Based on this and an earlier discovery of a Wolbachia gene in a beetle by the Fukatsu team at the University of Tokyo, Japan, the researchers in Werrens lab and collaborators at J. Craig Venter Institute (JCVI) decided to systematically screen invertebrates. Julie Dunning-Hotopp at JCVI found evidence that some of the Wolbachia genes seemed to be fused to the genes of the fruitfly, Drosophila ananassae, as if they were part of the same genome.
Michael Clark, a research associate at Rochester then brought a colony of ananassae into Werrens lab to look into the mystery. To isolate the flys genome from the parasites, Clark fed the flies a simple antibiotic, killing the Wolbachia. To confirm the ananassae flies were indeed cured of the wolbachia, Clark tested a few samples of DNA for the presence of several Wolbachia genes.
To his dismay, he found them.
For several months, I thought I was just failing, says Clark. I kept administering antibiotics, but every single Wolbachia gene I tested for was still there. I started thinking maybe the strain had grown antibiotic resistance. After months of this I finally went back and looked at the tissue again, and there was no Wolbachia there at all.
Clark had cured the fly of the parasite, but a copy of the parasites genome was still present in the flys genome. Clark was able to see that Wolbachia genes were present on the second chromosome of the insect.
Clark confirmed that the Wolbachia genes are inherited like normal insect genes in the chromosomes, and Dunning-Hotopp showed that
|Contact: Jonathan Sherwood|
University of Rochester