Reproduction is a process that involves interactions between males and females at the level of the organism, at a cellular and molecular level, and at the level of the genotype. For D. melanogaster, several studies have demonstrated that natural variation in male genes involved in male-female genotype interactions affects female post-mating behavior and reproductive success. How natural variation in male genes affects female gene expression after mating is less well known.
To learn how male-female genotype interactions affect female gene expression after mating, we performed RNA-seq on female flies to detect transcriptome changes before mating and six hours after they had mated with genotypically different males. We used males and females from melanogaster inbred lines derived from five geographically dispersed populations. Females from each line were singly mated to a male from each of the same five inbred lines.
Post-mating mRNA levels were compared to those of unmated females from the same population. If a gene’s expression changed after mating, we determined if its fold change differed depending on the genotype of the female or the male with which she mated. Linear models were fitted to assess the magnitude of the effect of male genotype, female genotype, and their interaction. Among the genes significant for this interaction effect, we found a highly significant enrichment of immune response genes (EASE score = 2.2 x 10-6).
Additionally, over 20 transcripts that derive from genes exclusively expressed in male reproductive tissue were found in females after mating. This indicates that D. melanogaster males transfer RNAs, along with sperm and seminal fluid proteins during mating, as was reported previously in D. mojavensis and D. arizonae and in Aedes mosquitos. Our dataset expands the suite of male derived transcripts found in female flies after mating and opens the door to apply the technologies available to D. melanogaster to investigate potential functional roles of these transcripts.
This work was supported by NIH R01-HD059060.