The male-specific region of the Y chromosome is one of the most divergent regions in the mammalian genome among species. Studies of the human and mouse Y chromosomes, and comparison to other mammals, have shown that Y chromosomes have acquired a unique repertoire of testis-specific genes that enhance male reproductive function. Several of these genes are associated with infertility. Though there is an extensive descriptive background on reproductive physiology and spermatogenic defects in felines, nothing is known about the genes involved in these processes. Furthermore, the existing shotgun-based feline whole genome is based on a female genomic DNA template, and there are no plans to sequence the Y chromosome of the domestic cat. To fill this void, Dr. Murphy will extend his initial studies of the cat Y chromosome by sequencing from a direct cDNA selection library enriched for Y chromosome transcripts. This procedure will isolate novel transcribed cat Y chromosome genes, which will be mapped in the cat genome. The expression patterns of each gene will be determined in a range of tissues to discern which genes have testis-specific expression patterns, and may therefore be good candidates for abnormal sperm morphology. The identification of novel Y chromosome genes involved in feline spermatogenesis will provide targets for future analysis in both domestic cat lines and exotic felid species, of which many have high frequencies of sperm abnormalities. This study will be critical for filling the final major ‘gap’ in the cat genome project.