Authors

N N Dawam¹; M Pazmino²; A Ganatra¹; A Carmicheal²; F Tripet¹;  ¹ Keele University;  ² Salford University

Discussion

The M and S molecular forms of Anopheles gambiae ss known as Anopheles coluzzii and Anopheles gambiae are two of the most important vectors of malaria in sub-Saharan Africa. The pericentromeric X-island of speciation is thought to contain genes responsible for assortative mating in these sibling species. This island, estimated to be about 6Mb-long and extending from position ~18.1 to 24.2Mb contains about 153 genes. In order to narrow in on candidate mate choice genes, we investigated differential gene expression of 27 putative genes located in the X-island of speciation and containing fixed or common protein-coding differences between the two sibling species. Differential gene expression at the larval, pupal, virgin adult and mated stages was compared among 4 populations from both sibling species. Genes that had fixed or frequent protein changes, stage specific differences and differentially expressed between M and S were considered as best candidate assortative mating genes and used for RNA interference studies. Results from the gene expression studies showed 33% of the genes were expressed differently between the M and S forms, 60% between virgin males and virgin females and 63% between life stages. RNA silencing was then carried out on the two best candidate genes AGAP001009 and AGAP013526. Delivery of double stranded RNA was done by injection. This led to a surprising outcome, as injections per se appeared to disrupt assortative mating genes.