Novel discoveries in the male accessory secretions of the tsetse fly Glossina morsitans (A transcriptomic/proteomic analysis)

Vector population control is one of the primary methods to prevent African trypanosomiasis transmission. However, little is known about the reproductive biology of tsetse flies. A particularly important aspect of tsetse reproductive biology, male seminal secretions, remains unstudied. The proteins contained within these secretions play an important role in regulating sperm storage, sperm motility, sperm competition, female sexual receptivity, egg production, ovulation, reproductive tract morphology, feeding behavior and other aspects of fly biology. We undertook a project to sequence the transcriptome and proteome of the male tsetse accessory gland. Analysis of these data sets resulted in the identification of a novel set of male accessory genes/proteins. Our initial analysis has identified a total of 25 putative accessory gland proteins via cross referencing our tissue specific transcriptome and the spermatophore proteome. Of these proteins, only one of the predicted genes (a serine protease inhibitor from the BPTI/Kunitz family) is orthologus to an accessory protein identified within Drosophila. Many proteins identified are tsetse specific and novel. Three of these novel proteins are the most abundant proteins in the spermatophore. These three proteins form a novel tsetse specific gene family that appears to have arisen through tandem gene duplication events. Many of the proteins we have identified are not true orthologs to other characterized accessory proteins. However, their function appears to have remained orthologus to those of accessory proteins from other Dipteran species. These include serine protease inhibitors, odorant binding proteins, antioxidants, immune proteins, glycoproteins, endocuticle proteins and sperm binding proteins.