title: A gene catalogue of the euchromatic male-specific region of the horse Y chromosome: comparison with human and other mammals.
abstract: Studies of the Y chromosome in primates, rodents and carnivores provide compelling evidence that the male specific region of Y (MSY) contains functional genes, many of which have specialized roles in spermatogenesis and male-fertility. Little similarity, however, has been found between the gene content and sequence of MSY in different species. This hinders the discovery of species-specific male fertility genes and limits our understanding about MSY evolution in mammals. Here, a detailed MSY gene catalogue was developed for the horse--an odd-toed ungulate. Using direct cDNA selection from horse testis, and sequence analysis of Y-specific BAC clones, 37 horse MSY genes/transcripts were identified. The genes were mapped to the MSY BAC contig map, characterized for copy number, analyzed for transcriptional profiles by RT-PCR, examined for the presence of ORFs, and compared to other mammalian orthologs. We demonstrate that the horse MSY harbors 20 X-degenerate genes with known orthologs in other eutherian species. The remaining 17 genes are acquired or novel and have so far been identified only in the horse or donkey Y chromosomes. Notably, 3 transcripts were found in the heterochromatic part of the Y. We show that despite substantial differences between the sequence, gene content and organization of horse and other mammalian Y chromosomes, the functions of MSY genes are predominantly related to testis and spermatogenesis. Altogether, 10 multicopy genes with testis-specific expression were identified in the horse MSY, and considered likely candidate genes for stallion fertility. The findings establish an important foundation for the study of Y-linked genetic factors governing fertility in stallions, and improve our knowledge about the evolutionary processes that have shaped Y chromosomes in different mammalian lineages.
authors.affiliation: Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Nandina
authors.initials: N
authors.lastname: Paria
authors.forename: Terje
authors.initials: T
authors.lastname: Raudsepp
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Pearks Wilkerson
authors.forename: Patricia C M
authors.initials: PC
authors.lastname: O'Brien
authors.forename: Malcom A
authors.initials: MA
authors.lastname: Ferguson-Smith
authors.forename: Charles C
authors.initials: CC
authors.lastname: Love
authors.forename: Carolyn
authors.initials: C
authors.lastname: Arnold
authors.forename: Peter
authors.initials: P
authors.lastname: Rakestraw
authors.forename: William J
authors.initials: WJ
authors.lastname: Murphy
authors.forename: Bhanu P
authors.initials: BP
authors.lastname: Chowdhary
mesh_terms: D000818:Animals; D002415:Cats; D002417:Cattle; D020451:Contig Mapping; D018076:DNA, Complementary / Q000235:genetics; D022041:Euchromatin / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D005298:Fertility / Q000235:genetics; D018628:Gene Dosage / Q000235:genetics; D006736:Horses / Q000235:genetics* / Q000502:physiology; D006801:Humans; D008297:Male; D051379:Mice; D016366:Open Reading Frames / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012727:Sex Characteristics; D013737:Testis / Q000378:metabolism; D014960:X Chromosome / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D022041:Euchromatin; D012333:RNA, Messenger