Use of short tandem repeats to describe genetic variability in Anopheles Gambiae from three countries in Africa.

Abstract

Macrogeographic variation in An. gambiae was measured by analysing four polymorphic STR loci in four populations by electrophoresis on horizontal slab polyacrylamide gels. Mosquitoes were sampled from inland (Asembo) and coastal (Kilifi) Kenya in East Africa, Ghana (Navrongo province) in West Africa and Malawi (Mangochi district) in Central Africa. On average 3 to 12 alleles were detected per locus per population. The mean unbiased heterozygosity (HE) was 0.598 (Asembo), 0.591 (Ghana), 0.516 (Kilifi) and 0.432 (Malawi}. Departures from Hardy-Weinberg equilibrium were not significant in Asembo and Ghana populations but allele frequency data revealed heterozygote deficiency in Kilifi and Malawi. Mean pairwise FST was 0.1290 (Asembo Vs Kilifi), 0.0085 (Asembo Vs Ghana) and 0.1596 (Kilifi Vs Ghana). Apparently no barriers to gene flow occur between Asembo and Ghana. Estimates of genetic differentiation in Asembo Vs Kilifi and Kilifi Vs Ghana matched low effective migra~ion indices (Nm) suggesting restricted gene flow between. the regions. The Rift Valley, in East Africa, might be a barrier-to gene flow in natural An. gambiae populations. However should the resulf6f limited genetic differentiation across large distances (Asembo Vs Ghana) be confimed, An. gambiae may be a good candidate for genetic modification.