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Saturday, January 16, 2010

Wasp genome sequenced

The genomes of three species of parasitic wasp, all from the genus Nasonia, have been sequenced. John Werren of the University of Rochester was one of the team leaders of the international consortium of scientists who achieved this multiyear project.

Why is this finding significant?

Parasitic wasps are major predators of insects. There are 600,000 different species of parasitic wasp, each of which has a specific preferred prey. Being able to raise wasps could be a huge boon to agriculturalists and environmentalists who prefer to limit pesticide usage. In addition, the venoms employed by these tiny creatures (Nasonia or 'jewel' wasps are no more than 2 mm long) could prove to have a range of pharmaceutical uses.

The value of this data goes far beyond simply using the wasps for pest control. Now that we have its entire genome sequenced, Nasonia may be an even more valuable animal model than that gold standard of insects models, Drosophila melanogaster (the fruit fly). For one thing, the genomic analysis has uncovered almost 7000 wasp genes that have recognizable equivalents in humans.

For another, unlike flies, the male wasps have only a single set of chromosomes. This makes genetic analysis much simpler. In diploid organisms such as ourselves, you may need to alter both copies of a gene to see any differences. With only one copy of each gene, the effects of a single change can be immediately visible.

Also unlike flies but like humans, wasps use methylation to regulate their genes. It is becoming increasing evident that methylation plays a major role in development and regulation.

Another advantage is that the different species of wasp can crossbreed with each other. Researchers can use this ability to finesse out the causes of speciation. A major controversy in evolutionary biology is whether regulatory changes (changes in non-coding regions) or protein changes (alterations in the coding portions of genes) are more often responsible for differences between species. The first experiments to test this are already underway. For example, Werren and his colleagues found that the non-coding regions of DNA are responsible for wing size differences between two Nasonia species.

One last point of interest to come from this data: Werren and his colleagues found bacterial and viral genes in Nasonia.

Werren says:

“We don’t yet know what these genes are doing in Nasonia, but the acquisition of genes from bacteria and viruses could be an important mechanism for evolutionary innovation in animals, and this is a striking potential example.”

Image of female Nasonia vitripennis (one of the three sequenced species) by M.E.Clark.