Study provides new insights into genetics and evolution

Researchers from the University of Geneva and the SIB Swiss Institute of Bioinformatics led an analysis of the sequenced genomes of parasitic wasps. Generally unknown to the public, the parasitic wasps kill pest insects. They are like 'smart bombs' that seek out and kill only specific kinds of insects. Harnessing their full potential would thus be vastly preferable to chemical pesticides, which broadly kill or poison many organisms in the environment, including humans. The results of this large study are featured in today's issue of Science. Professor Evgeny Zdobnov from the University of Geneva Medical School and the SIB Swiss Institute of Bioinformatics directed the comparative evolutionary genomics studies as part of this international project, which revealed many features that could be useful to pest control and medicine, and to enhance our understanding of genetics and evolution.

The scientists sequenced and analysed the genomes of three parasitoid Nasonia wasp species. "Comparing the genes and genomes of those wasps revealed almost 7'000 genes that have recognisable counterparts in humans (orthologues)", says Zdobnov. "However, the wasp is more different from its closest sequenced relative, the honeybee, than humans are from chickens". In addition to being useful for controlling pests and offering pharmaceutically interesting venoms, the wasps could act as a new genetic system with a number of unique advantages. So far, fruit flies have been the standard model for genetic studies, mainly because they are small, can be grown easily in a laboratory, and reproduce quickly. On top of sharing these traits, Nasonia present another advantage. Male Nasonia have only one set of chromosomes, instead of two sets like fruit flies and people, so that "A single set of chromosomes, which is more commonly found in lower single-celled organisms such as yeast, is a handy genetic tool, particularly for studying how genes interact with each other," says John H. Werren from the University of Rochester, who led the project together with Stephen Richards from the Genome Sequencing Centre at the Baylor College of Medicine.

Unlike fruit flies, these wasps also modify their DNA in ways similar to humans and other vertebrates, a process called "methylation" which plays an important role in regulating how genes are turned on and off during development. "Importantly", says Zdobnov, "our comparative analyses discovered hundreds of Nasonia genes that are shared with humans but absent from fruit flies, opening new avenues for their functional investigation in these genetically tractable wasps". "We identified changes to metabolic pathways that may reflect the amino-acid rich carnivorous diet of these parasitoids. Such information could support efforts to produce artificial diets for parasitoid wasp mass rearing in biological control and improve hymenopteran cell culture methods".

Emerging from these genome studies are many opportunities for exploiting Nasonia wasps in topics ranging from pest control to medicine, genetics, and evolution. "Insects are the most diverse group of terrestrial animals", says Zdobnov, "and the sequencing of the wasp genome significantly augments the opportunities for scientists to examine the genetic basis of this incredible diversity that underlies their success".