title: Gene discovery and comparative analysis of X-degenerate genes from the domestic cat Y chromosome.
abstract: Mammalian sex chromosomes are the remnants of an ancient autosomal pair present in the ancestral mammalian karyotype. As a consequence of random decay and chromosome rearrangements over evolutionary time, Y chromosome gene repertoires differ between eutherian lineages. To investigate the gene repertoire and transcriptional analysis of the domestic cat Y chromosome, and their potential roles in spermatogenesis, we obtained full-length cDNA sequences for all known Y genes and their X chromosome gametologues and used those sequences to create a BAC-based physical map of the X-degenerate region. Our results indicate the domestic cat Y chromosome has retained most X-degenerate genes that were present on the ancestral eutherian Y chromosome. Transcriptional analysis revealed that most feline X-degenerate genes have retained housekeeping functions shared by their X chromosome partners and have not been specialized for testis-specific functions. Physical mapping data indicate that the cat SRY gene is present as multiple functional copies and that very little of the felid Y chromosome may be single copy. X-Y gene divergence time estimates obtained using Bayesian methods confirm an early origin of Stratum 1 genes prior to the origin of therian mammals. We observed no statistical difference in the ages of Stratum 2 and Stratum 3 gene pairs, suggesting that eutherian and marsupial Stratum 2 genes may have been independently retained in each lineage.
authors.affiliation: Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Pearks Wilkerson
authors.forename: Terje
authors.initials: T
authors.lastname: Raudsepp
authors.forename: Tina
authors.initials: T
authors.lastname: Graves
authors.forename: Derek
authors.initials: D
authors.lastname: Albracht
authors.forename: Wesley
authors.initials: W
authors.lastname: Warren
authors.forename: Bhanu P
authors.initials: BP
authors.lastname: Chowdhary
authors.forename: Loren C
authors.initials: LC
authors.lastname: Skow
authors.forename: William J
authors.initials: WJ
authors.lastname: Murphy
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000235:genetics; D002415:Cats; D022202:Chromosomes, Artificial, Bacterial; D018076:DNA, Complementary / Q000235:genetics* / Q000378:metabolism; D004285:Dogs; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D015723:Gene Library; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D051876:Sex-Determining Region Y Protein / Q000235:genetics; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D051876:Sex-Determining Region Y Protein