Topic: One Species' Genome Discovered Inside Another's

[Nemesis]

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Scientists at the University of Rochester and the J. Craig Venter Institute have discovered a copy of the genome of a bacterial parasite residing inside the genome of its host species.

The research, reported in today's Science, also shows that lateral gene transfer—the movement of genes between unrelated species—may happen much more frequently between bacteria and multicellular organisms than scientists previously believed, posing dramatic implications for evolution.

Evolutionary biologists will certainly take note of this discovery, but scientists conducting genome-sequencing projects around the world also may have to readjust their thinking.

In the early days of the Human Genome Project, some studies appeared to show bacterial DNA residing in our own genome, but those were shown indeed to be caused by contamination. Wolbachia is not known to infect any vertebrates such as humans.

Such transfers have happened before in the distant past" notes Werren. "In our very own cells and those of nearly all plants and animals are mitochondria, special structures responsible for generating most of our cells' supply of chemical energy. These were once bacteria that lived inside cells, much like Wolbachia does today. Mitochondria still retain their own, albeit tiny, DNA, and most of the genes moved into the nucleus in the very distant past. Like wolbachia, they have passively exchanged DNA with their host cells. It's possible wolbachia may follow in the path of mitochondria, eventually becoming a necessary and useful part of a cell.

A mechanism for mutation and therefore evolution?