DECODING THE SENSE OF SMELL IN TSETSE FLIES (GLOSSINA)
Tsetse flies are the main vectors of African Trypanosomiasis, a neglected tropical disease that is transmitted by protozoan trypanosomes to humans and animals in sub-Saharan African countries. Olfaction play a key role in tsetse behaviour in identification of hosts, mates and larviposition sites and is mediated by olfactory proteins. To better understand chemoreception in Glossina, we used real-time quantitative PCR (qPCR) to examine the expression profile of odorant binding proteins (OBPs) identified from Glossina morsitans morsitans genome in G. fuscipes fuscipes antennae and legs. Expression profiles of OBP genes in G. brevipalpis larvae, pupae and tenerals and odorant receptors (ORs) genes in G. m. morsitans antennae and legs were also assessed by qPCR. Examination of expression profile of odorant binding proteins identified from G. m. morsitans in G. f. fuscipes suggests high expression of G. m. morsitans OBP genes in female G. f. fuscipes antennae. Two OBPs (GbrOBP2 and GbrOBP7) were significantly expressed in larval and pupal stage respectively while three OBPs (GbrOBP6, GbrOBP8 and GbrOBP13) were observed to be significantly expressed in tenerals of G. brevipalpis. The OR genes were highly expressed in antennae than the legs with GmmOR3 and GmmOR45 transcript level being high in the female and male antennae respectively while GmmOR26 and GmmOR20 were high in female and male G. m. morsitans legs respectively. These findings indicate that chemoreception in savannah tsetse (G. m. morsitans) and riverine tsetse (G. fuscipes fuscipes) as defined by OBP expression profiles, could be conserved in function. The expression of OBPs in G. brevipalpis larval and pupal stages may be implicated to have a role in the development of the fly. The G. m. morsitans OR genes were highly expressed in antennae than the legs, confirming that the antenna is the main olfactory organ. These findings may pin point probable roles of olfactory proteins in tsetse flies and could be used as basis for development of novel and innovative ways for controlling tsetse flies based on olfactory-mediated behaviours.