The Drosophila melanogaster Y-linked gene, WDY, is required for sperm to swim in the female reproductive tract

Abstract

Unique patterns of inheritance and selection on Y chromosomes have led to the evolution of specialized gene functions. We report CRISPR mutants in Drosophila of the Y-linked gene, WDY, which is required for male fertility. We demonstrate that the sperm tails of WDY mutants beat approximately half as fast as those of wild-type and that mutant sperm do not propel themselves within the male ejaculatory duct or female reproductive tract. Therefore, although mature sperm are produced by WDY mutant males, and are transferred to females, those sperm fail to enter the female sperm storage organs. We report genotype-dependent and regional differences in sperm motility that appear to break the correlation between sperm tail beating and propulsion. Furthermore, we identify a significant change in hydrophobicity at a residue at a putative calcium-binding site in WDY orthologs at the split between the melanogaster and obscura species groups, when WDY first became Y-linked. This suggests that a major functional change in WDY coincided with its appearance on the Y chromosome. Finally, we show that mutants for another Y-linked gene, PRY, also show a sperm storage defect that may explain their subfertility. Overall, we provide direct evidence for the long-held presumption that protein-coding genes on the Drosophila Y regulate sperm motility.

Paralog-dependent Specialization of Paf1C subunit, Ctr9, for Sex Chromosome Gene Regulation and Male Germline Differentiation in Drosophila

“…Nevertheless, we found 15 out of 33 genes showing log2FC>0 located in a specific region (Y:3,258,406-3,365,197) on Y chromosome, implying the effect of ctr9t loss depends on the chromosomal topology (Figure 5G S5D). Two more fertility genes on Y chromosome, WDY (kl-1) and CCY (ks-2) [40,41,44], showed -0.75 and -0.56 of log2FC, and thus were grouped by their ctr9t-dependency with kl-2, kl-3, kl-5, and ORY (Figure 5G S5D). In contrast, other genes (FDY, Ppr-Y, and Pp1-Y2) dispensable for male fertility did not show ctr9t-dependency (log2FC>0).…”