Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Genetics
Selected Highlights from Research Findings
The reading of a will can tear the most serene family apart. Normally families stand together and come up for one another, but when a will is under discussion, the strongest competition comes from one’s closest relatives. Animals and plants have evolved mechanisms to reduce or even avoid direct competition with relatives, dispersal being the most important, but, sometimes it is inevitable. Fig wasps are a fascinating exception. These inconspicuous wasps, barely 2mm long, are famous for pollinating fig trees. They take the expression “keeping it in the family” to the extreme. Normally, a single mother lays all her eggs in a fig and her offspring mate exclusively with one another. Clearly, this incestuous lifestyle creates some problems. Most people would assume that the dangers of inbreeding would eliminate the species. However, Prof Jaco Greeff and his research team found that the wasps show very limited detrimental effects from inbreeding. Far more startling, is how the competition pans out. The biggest competition is between the adult wasp’s sons, because they compete with each other to mate with their sisters. The mother alleviates some of this competition by producing very few sons (10%) – just enough to fertilize all the sisters. In species where mothers fail to control competition and produce too many males (> 20%), evolution has shaped the sons’ behaviour instead. In some species, some males will expose themselves to great risks (being dragged off by ants 100 times their own size) to search for females “abroad”. In some species, males have evolved formidable fighting machinery and massive jaws to eliminate their toughest competitors – their brothers.
Contact person: Prof JM Greeff.
Dr Vida van Staden’s research group has generated a set of novel “reassortant” strains of African horse sickness virus (AHSV), which could help clarify the contribution of specific virus proteins to disease symptoms. This virus is endemic to southern Africa, and is a serious threat to the horse industry, as regular outbreaks occur despite the availability of a vaccine. The symptoms of African horse sickness can range from a mild fever to severe breathing problems and death, depending on the virulence of the virus. Because the viral genes occur on discrete segments of nucleic acid, one can infect cells with two different parent strains of the virus, and obtain progeny viruses with a random mixture of the parental genes. Using this approach, the group generated a panel of reassortant progeny viruses, and assayed them for their effect on infected cells. This enabled them to identify specific genes, and the proteins they encode, which play a role in virus release, membrane permeability and the cytopathic effect of the virus on the host cell.
Contact person: Dr V van Staden.
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