organ distribution and expression profile of glossina morsitans morsitans odorant binding protein homolog genes sequences in glossina fuscipes fuscipes

Abstract

The tsetse fly, Glossina fuscipes fuscipes, is a riverine species and major vector of Human African Trypanosomiasis (HAT). Olfaction plays critical role in determining tsetse fly behavior. Odorant Binding Proteins (OBPs) are expressed abundantly in insect olfactory tissues and are postulated to be involved in the first step of odorant reception. A total of 33 OBPs have been reported from G. m. morsitans genome sequence while antennal transcriptome analysis of G. morsitans morsitans identified 22 OBPs. In this study, detection of G. m. morsitans OBPs was determined in male and female G. f. fuscipes head, thorax, abdomen and legs by polymerase chain reaction while expression levels were quantified in male and female G. f. fuscipes antennae and legs by quantitative real time polymerase chain reaction (qRT-PCR). A total of 31.8% of the OBPs identified were detected in the female head while 22.7% were detected in male head. From the thorax 31.8% of the OBPs were identified in males and 18.2 in females; 18.2% were identified in male abdomen tissues while 27% were identified in female leg tissues and then 22.7% of the tissues were identified in male leg tissues against 18.2% in females. Relative expression rate revealed that majority of G. m. morsitans OBP genes are highly transcribed in female antennae than in males while the male legs had the least expression levels. This study confirms the presence and expression of G. m. morsitans OBP genes in both male and female G. f. fuscipes tissues implying, that G. m. morsitans (Savannah tsetse) and G. f. fuscipes (Riverine tsetse) OBPs could be playing similar roles in the two species and that the antennae is the main olfactory organ. Future functional characterization of Glossina fuscipes fuscipes OBPs will go a long way in elucidating the function of these genes in the riverine species.