A catalog of mRNAs transferred from males to females during mating in Drosophila arizonae and D. mojavensis

mRNA is a common component of male ejaculates across diverse organisms, yet whether these male-derived mRNAs (mdRNAs) serve biological functions in females or represent incidental byproducts of ejaculate composition remains unresolved. Recent work in Drosophilq arizonae demonstrated that mdRNAs are translated by female reproductive tract cells into proteins, and that genes encoding them have functional postmating effects, suggesting that at least some mdRNAs are biologically important. A systematic characterization of the mdRNA repertoire in this species is therefore a necessary next step. Here we present a catalog of mdRNAs in D. arizonae and its sister species D. mojavensis , identified through RNA-seq profiling of the female reproductive tract following heterospecific crosses, with expression data from male reproductive tract organs to classify candidates by tissue of origin. We identified 270 candidate mdRNAs whose abundance in the reproductive tract of mated females correlates with expression in testes, sperm-filled seminal vesicles, and accessory glands, consistent with multiple tissues contributing to the pool of mdRNAs. Functional enrichment analyses reveal overrepresentation of ribosomal proteins, suggesting potential roles in translational regulation within the female reproductive tract. To investigate how sperm-associated mdRNAs might become available for translation in the female reproductive tract, we generated a GFP-tagged sperm line and tracked sperm fate following mating. A substantial proportion of transferred sperm became trapped within the insemination reaction mass that forms in the uterus during copulation, possibly releasing RNA into the female reproductive environment. This catalog provides a foundation for future studies on the biological significance of mdRNAs.