single nucleus RNA-seq study profiling the transcriptional response of Aedes aegypti spermathecal secretory cells to mating and injection with male accessory glad lysate
Aedes aegypti mosquitoes are important vectors of major arboviruses impacting human health including dengue, yellow fever, Zika and chikungunya. There is a desperate need for new control strategies for this mosquito and reproductive control holds promise as a strategy. Females require only a single mating to store enough sperm for a lifetime of fertilization, capable of producing hundreds of viable and potentially disease-transmitting offspring. During copulation, males transfer sperm and seminal fluid proteins (SFPs) synthesized in the male accessory glands (MAGs) into the female bursa. Within minutes, sperm travel through the spermathecal ducts into the spermathecae, where they are stored and remain viable for the female's lifetime, likely sustained by secretions from spermathecal secretory cells (SSCs). However, the molecular mechanisms that enable SSCs to maintain sperm viability remain poorly understood. We used single-nucleus RNA sequencing (snRNA-seq) to profile individual cell types within the spermathecae, confirming SSC populations through RNA fluorescence in situ hybridization (FISH). We then examined the transcriptional response of SSCs to natural mating and MAG lysate injection, using virgin and saline-injected females as controls. Our results indicate that natural mating triggers a stronger transcriptional response in SSCs compared to MAG injection alone after 24 hours, suggesting that sperm receipt is a key factor in SSC activation. These findings provide new insights into the cellular and molecular dynamics of sperm storage in Ae. aegypti.