Transcriptional profiling and physiological roles of Aedes aegypti spermathecal-related genes

Abstract

Background: Successful mating of female mosquitoes typically occurs once, with the male sperm being stored in the female spermatheca for every subsequent oviposition event. The female spermatheca is responsible for the maintenance, nourishment, and protection of the male sperm against damage during storage. Aedes aegypti is a major vector of arboviruses, including Yellow Fever, Dengue, Chikungunya, and Zika. Vector control is difficult due to this mosquito high reproductive capacity. Results: Following comparative RNA-seq analyses of spermathecae obtained from virgin and inseminated females, eight transcripts were selected based on their putative roles in sperm maintenance and survival, including energy metabolism, chitin components, transcriptional regulation, hormonal signaling, enzymatic activity, antimicrobial activity, and ionic homeostasis. In situ RNA hybridization confirmed tissue-specific expression of the eight transcripts. Following RNA interference (RNAi), observed outcomes varied between targeted transcripts, affecting mosquito survival, egg morphology, fecundity, and sperm motility within the spermathecae. Conclusions: This study identified spermatheca-specific transcripts associated with sperm storage in Ae. aegypti. Using RNAi we characterized the role of eight spermathecal transcripts on various aspects of female fecundity and offspring survival. RNAi-induced knockdown of transcript AeSigP-66,427, coding for a Na + /Ca 2+ protein exchanger, specifically interfered with egg production and reduced sperm motility. Our results bring new insights into the molecular basis of sperm storage and identify potential targets for Ae. aegypti control.

Mating and blood-feeding induce transcriptome changes in the spermathecae of the yellow fever mosquito Aedes aegypti

“…However, AAEL004814 had a greater response to blood-feeding: AAEL004814 transcripts were significantly down-regulated at 6 h, and significantly up-regulated at 24 and 72 h in the BF female group (File S4). The regulation of AAEL004814 by blood-ingestion is consistent with its role in oocyte development 31 .…”

“…gambiae 23 . In mosquitoes and most insects, spermathecae function as long-term storage compartments for sperm after insemination 21,23,25,31 . Here, we report transcript abundance profiles of the spermathecae at three distinct timepoints after mating and blood-feeding to understand the molecular mechanisms that allow females to maintain viable sperm.…”

“…However, the potential link between blood-feeding and the post-mating regulation of gene expression in reproductive tissues has not been explored. While mating induces a transcriptional response in reproductive tract tissues of female mosquitoes 23,31,41 , the extent to which this transcriptional response is mating-vs. blood-meal-induced is not yet known. The mating encounter site for Ae.…”

“…comparison of the early and late mated female spermathecae transcriptome. A recent study by Pascini et al 31 reported the spermathecae transcriptome in mated females at 7 d post-eclosion. We compared Table 1.…”

“…Four up-regulated transcripts observed at 6 h in the NBF female group were found to be up-regulated at 7 d post-eclosion (File S10), suggesting that these genes return to high expression levels in the spermathecae nearly a week after mating. Pascini et al 31 performed functional analysis on 8 genes found to be differentially regulated at 7 d posteclosion. Of these 8 genes, we found only one in our dataset: the putative potassium-dependent sodium-calcium exchanger AAEL004814.…”