Transcriptional response of spermathecal secretory cells to mating and receipt of seminal fluid proteins in Aedes aegypti.

Aedes aegypti mosquitos are major vectors of arboviruses including dengue, yellow fever, Zika, and chikungunya, highlighting the need for innovative control strategies. Females typically mate only once yet store sufficient sperm to produce hundreds of offspring over their lifetime. During mating, males transfer sperm and seminal fluid proteins from the male accessory glands (MAGs) into the female reproductive tract. Sperm rapidly migrate to the spermathecae, where they remain viable, likely supported by spermathecal secretory cells (SSCs). However, the molecular mechanisms underlying long-term sperm maintenance are poorly understood. We used single-nucleus RNA sequencing to characterize cell types within the spermathecae and confirmed SSC populations using RNA fluorescence in situ hybridization. We then compared SSC transcriptional responses following natural mating and MAG lysate injection. Natural mating induced a stronger SSC response after 24 h, suggesting that sperm receipt is critical for SSC activation and sperm storage regulation.