An insight into the female and male Sabethes cyaneus mosquito salivary glands transcriptome

Knowledge about mosquitoes and their physiology are important for understanding how different species differ in their ability to feed on and transmits pathogens to humans. Worldwide, there are 3591 known species of mosquitoes and 113 genera, however only a handful are known to transmit disease to humans and many are still poorly understood. The Sabethini tribe consists primarily of forest dwelling mosquitoes some of which are thought to be potential vectors of several human diseases. Mosquito saliva plays an active role in blood feeding and pathogen transmission. The mosquito saliva consist of 60 to100 secreted proteins, many of which are unique to a specific mosquito species, and most do not have a known function but presumably affect hemostasis, inflammation, and sugar digestion or have antimicrobial activity. Due to the direct involvement of mosquito salivary glands in the transmission of pathogens to human hosts, information on gene transcription and the proteins produced in this organ provides indispensable tools for the systematic and comprehensive analysis of molecules that may play an active role in mosquito blood feeding and pathogen transmission. In this study we perform a transcriptomic analysis of male and female Sabethes cyaneus salivary glands and characterized the female salivary gland extract activity in vitro. We found a total of 5908 genes expressed in the SG, where 137 were exclusively found in males, and 509 were exclusively found in females. A differential expression analysis revealed 165 up-regulated and 18 down-regulated genes in female SGs compared to male SGs. Most of the up-regulated genes have unknown functions, however, odorant binding proteins, such as those in the D7 protein family, and mucins were among the top 30 genes. Antimicrobial products and cytoskeletal proteins were among the most down-regulated genes in female Sa. cyaneus. This is the first description of a Sabethes SG activity and transcriptomic analysis and our results show a unique SG activity in this species.