Wolfner, M. F. | bioRxiv Science

bioRxiv2018

Reproductive functions and genetic architecture of the seminal fluid and sperm proteomes of the mosquito Aedes aegypti

The yellow fever mosquito, Aedes aegypti, transmits several viruses, including dengue, Zika, and chikungunya. Some proposed efforts to control this vector involve manipulating reproduction to suppress wild populations or replacing them with disease-resistant mosquitoes. The design of such strategies requires an intimate knowledge of reproductive processes, yet our basic understanding of reproductive genetics in this vector remains largely incomplete. To accelerate future investigations, we have comprehensively catalogued sperm and seminal fluid proteins (SFPs) transferred to females in the ejaculate using tandem mass spectrometry. By excluding female-derived proteins using an isotopic labelling approach, we identified 870 sperm proteins and 280 seminal fluid proteins. Functional composition analysis revealed parallels with known aspects of sperm biology and SFP function in other insects. To corroborate our proteome characterization, we also generated transcriptomes for testes and the male accessory glands--the primary contributors to Ae. aegypti sperm and seminal fluid, respectively. Differential gene expression of accessory glands from virgin and mated males suggests that protein translation is upregulated post-mating. Several SFP transcripts were also modulated after mating, but >90% remained unchanged. Finally, a significant enrichment of SFPs was observed on chromosome 1, which harbors the male sex determining locus in this species. Our study provides a comprehensive proteomic and transcriptomic characterization of ejaculate production and composition and thus provides a foundation for future investigations of Ae. aegypti reproductive biology, from functional analysis of individual proteins to broader examination of reproductive processes.

genomics↗

bioRxiv2017

Maternal proteins that are phospho-regulated upon egg activation include crucial factors for oogenesis, egg activation and embryogenesis in Drosophila melanogaster

Egg activation is essential for the successful transition from a mature oocyte to a developmentally competent egg. It consists of a series of events including the resumption and completion of meiosis, initiation of translation of some maternal mRNAs and destruction of others, and changes to the vitelline envelope. This drastic change of cell state is accompanied by large scale alteration of the phospho-proteome of the cell. Despite the importance of this transition in cell and developmental state, it has been difficult to find many of its regulators. We hypothesize that phosphorylation state changes between oocyte and early embryo regulate the activities of proteins that are necessary during or after this transition, and thus that the set of phospho-regulated proteins would be an enriched source for finding critical players in the egg-to-embryo transition. To test this, we used germline-specific RNAi to examine the function of 189 maternal proteins that are phospho-regulated during egg activation in Drosophila melanogaster. We identified 53 genes whose knockdown reduced or abolished egg production, as well as 50 genes for which maternal knockdown led to significant impairment or abolishment of the eggs ability to hatch (hatchability). We observed different stages of developmental arrest in the embryos with impaired hatchability and several distinct categories of abnormalities in the maternal knockdown embryos that arrest early in development, suggesting potential roles of the candidates in egg activation and early embryogenesis. Our results, validated by our detection of multiple genes with previously-documented maternal-effect phenotypes among the proteins we tested, revealed 15 genes with new roles in egg activation and early embryogenesis. Given that protein phospho-regulation also occurs during this transition in other organisms, we suggest that the phospho-regulated proteins may provide an enriched dataset for identifying important players in the egg-to-embryo transition.

developmental biology↗