115 Oral - Evolution II
Friday April 08, 5:15 PM - 5:30 PM

Authors:
Yassi Hafezi; Arsen Omurzakov; Mariana Wolfner; Andrew Clark

Affiliation: Cornell University

Keywords:
n. genotype to phenotype; a. spermatogenesis

Only 13 single-copy protein-coding genes are known on the Drosophila melanogaster Y-chromosome -- a chromosome that is 40 Mb, haploid, paternally inherited, entirely heterochromatic, repeat-dense, and lacks recombination. These genes display remarkable “functional coherence,” with five Y-linked genes (three of which encode dynein motor components) being necessary to produce mature sperm past the early individualization stage of spermatogenesis. The significance of placing these fertility-essential genes in a heterochromatic and degenerating region of the genome is not understood. We are now discovering additional, more subtle functions associated with the Y chromosome. We and others recently demonstrated by knockdown that the gene, WDY, is responsible for the sterility of the kl-1 region of the Y chromosome. Here we further investigate the phenotype of WDY using CRISPR mutants we generated. Using compound sex chromosomes, we established several stable mutant lines for WDY. Mutant males were sterile, as expected, but surprisingly produced mature, motile sperm. WDY mutant sperm were transferred to females, albeit at lower rates. Consistent with prior reports associated with the kl-1 region, we found that WDY mutant sperm are unable to enter storage in the female. This failure may be caused by a motility defect of the sperm or an inability to interact with female molecules that enable storage. Further analysis of WDY may reveal mechanisms by which sperm are stored, as well as clues to the underlying evolutionary logic of locating a gene on the Y chromosome.