Scileppi, Elyse M

Malaria transmission requires Plasmodium invasion of the Anopheles mosquito midgut. This critical first step involves adhesion to chondroitin sulfate (ChSO 4 )[Dinglasan et al, PNAS 2007], a midgut epithelial ligand. Sulfate (SO 4 2− ) for ChSO 4 biosynthesis is supplied by midgut SO 4 2− uptake. Slc26 proteins transport many anions: Cl − , HCO 3 − , oxalate (ox 2− ), and SO 4 2− . Recently, we found that Drosophila Slc26a5 is an electrogenic Cl − /SO 4 2− , Cl − /ox 2− and Cl − / n HCO 3 − exchanger [Hirata et al, JASN 2009], and SO 4 2− transport exceeded ox 2− transport. Therefore we searched EST and genomic databases to identify two Slc26a5 orthologues (AgSlc26a5A and ‐ B). We expressed AgSlc26a5A and B in Xenopus oocytes to evaluate transport using microelectrodes. AgSlc26a5A is found in the salivary glands and gastric caeca. However, AgSlc26a5A did not obviously transport Cl − , HCO 3 − , SO 4 2− or ox 2− . On the other hand, AgSlc26a5B has transport properties similar to mouse Slc26a6 and Drosophila Slc26a5. That is, AgSlc26a5B mediates electrogenic Cl − /SO 4 2− , Cl − /ox 2− and Cl − / n HCO 3 − exchange. And, AgSlc26a5B is enriched in the hindgut (including Malpighian tubules) and the posterior midgut. These results suggest that AgSlc26a5B can alkalinize the Anopheles midgut and is also a candidate for SO 4 2− supplier to midgut cell. Thus, we hypothesize that control of AgSlc26a5B activity could control parasite ( Plasmodium ) invasion.