Gene and miR Expression in the Yellow Fever Mosquito Aedes aegypti

Abstract

When animals are exposed to new conditions they need to tune the expression of hundreds of genes in specific tissues and at a specific time requires the interplay of multiple processes. Females are required to locate suitable oviposition sites after acquiring a blood meal. Mosquitoes possess a variety of genes responsible for chemosensation, with four families standing out: Olfaction Receptors (ORs), Ionotropic Receptors (IRs), Odorant Binding Proteins (OBPs), and Gustatory Receptors (GRs). To investigate the genes that may be involved in host seeking behavior, mRNA was sequenced from samples of A. aegypti male and female tissues using RNA-seq analysis. Simultaneously, small RNA was isolated and sequenced. MicroRNAs (miRs) can regulate genes post-transcriptionally and are thought to be important for olfaction gene regulation in the antenna of mosquitoes. Or46 and Or99 are expressed only in unfed females, while Or49 is only expressed post blood meal. A total of 14 IRs, 6 ORs and 6 OBPs are up regulated post feeding, while 8 IRs, 4 ORs and 11 OBPs are down regulated post feeding. A total of 16 new miRs were discovered in the antenna of females. miR-34, miR-79, miR-929, and miR-965 are uniquely expressed in the female antenna; while miR-92b is uniquely expressed in male antenna, while miR-279 is up regulated in the antenna of both males and females. The expression of the miR-275, which is associated with blood meal digestion, increases 3h after blood feeding in the head and thorax and miR-305 displays a similar expression pattern. This is the first study to find miRs that are uniquely expressed in the antenna of mosquitoes. Although there are differences in the expression of olfaction genes in the antenna of 12h old females and 4-day-old females, no changes are observed after blood feeding and similar observations were noted for miRs. Changes may occur only in a specific subset of sensory neurons in the antenna of females and for this reason could not be detected. Olfaction transcripts with long 3’UTR may compete for miRs binding and gene regulation in the antenna of mosquitoes without dramatic changes at the transcript level.