One Species' Genome Found Within Another

THURSDAY Aug. 30, 2007 --The discovery of an entire genome from one species inside another adds a twist to the study of evolution, new research suggests.

Writing in the Aug. 30 issue of Science, the U.S. researchers theorized that including large amounts of genetic code from another species may allow the host species to develop new cellular functions more rapidly.

"The chance that a chunk of DNA of this magnitude is totally neutral, I think, is pretty small, so the implication is that it has imparted some selective advantage to the host," principal investigator Jack Werren said in a prepared statement. "The question is, are these foreign genes providing new functions for the host? This is something we need to figure out."

In their study, the scientists found the entire genome of the parasite Wolbachia inside a fruit fly (Drosophila ananassae ). Wolbachia is a common parasite that invades cells in the reproductive organs of its insect hosts. As a result, Wolbachia genes are occasionally passed on to the next generation through sperm and eggs.

Scientists have long known that bacteria DNA may be accidentally -- although rarely -- moved into a host's cells as the cells go through normal repair and maintenance routines. As a result, genes that appear to be remnants of bacteria are discarded when scientists sequence a species' genes.

However, the research team from the University of Rochester and the J. Craig Venter Institute wrote that this discovery implies that transferring genetic code between species and then to the offspring of the new species is more common than previously thought.

Wolbachia is found in the majority of invertebrates worldwide. The Rochester team studied the impact of Wolbachia genes in fruit flies by treating the flies with antibiotics so that they no longer carried the parasite. They then analyzed the flies' genetic codes and found that genetic code from the parasite was fused to the flies' genetic code, as if they were one and the same. Further, the DNA from the parasite was then passed on to the next generation of fruit flies just like any other gene, the researchers said.

Wolbachia do not invade mammal or human cells.

The next step for the researchers is to find out if the Wolbachia DNA benefit the fruit fly in some way.

More information

To learn more about gene sequencing, visit the Genome News Network.

Posted: August 2007


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