Single-cell profiling of mosquito spermatogenesis defines the onset of meiotic silencing and pre-meiotic overexpression of the X chromosome.

Abstract

Abstract Understanding of the Anopheles gambiae germline has been essential to acquiring effective genetic control strategies targeting this malaria mosquito vector. This includes targeting germline genes to induce sterility or using regulatory sequences to drive transgene expression for applications such as gene drive. However, only very few germline regulatory elements have been characterised with the majority showing leaky expression. This has been shown to significantly reduce the efficiency of current genetic control strategies, which rely on regulatory elements that are more tightly restricted in their spatial and/or temporal expression. Additionally, meiotic silencing of the sex chromosomes during spermatogenesis limits the flexibility of transgene expression for design of novel genetic control strategies. In this work, we build on our previous study that dissected gametogenesis into four distinct cell populations. We used single-cell RNA sequencing to further discriminate these populations and define distinct germline cell-types. In doing so, we revealed an overexpression of X-linked genes in the germline stem cells (GSCs) and were able to pinpoint the onset of meiotic silencing of the X chromosome in the spermatogonia/primary spermatocytes. This study provides a comprehensive dataset to identify genes expressed at specific stages of spermatogenesis, widening the toolkit for genetic control of malaria mosquitoes.