title: A syntenic region conserved from fish to Mammalian x chromosome.
abstract: Sex chromosomes bearing the sex-determining gene initiate development along the male or female pathway, no matter which sex is determined by XY male or ZW female heterogamety. Sex chromosomes originate from ancient autosomes but evolved rapidly after the acquisition of sex-determining factors which are highly divergent between species. In the heterogametic male system (XY system), the X chromosome is relatively evolutionary silent and maintains most of its ancestral genes, in contrast to its Y counterpart that has evolved rapidly and degenerated. Sex in a teleost fish, the Nile tilapia (Oreochromis niloticus), is determined genetically via an XY system, in which an unpaired region is present in the largest chromosome pair. We defined the differences in DNA contents present in this chromosome with a two-color comparative genomic hybridization (CGH) and the random amplified polymorphic DNA (RAPD) approach in XY males. We further identified a syntenic segment within this region that is well conserved in several teleosts. Through comparative genome analysis, this syntenic segment was also shown to be present in mammalian X chromosomes, suggesting a common ancestral origin of vertebrate sex chromosomes.
authors.affiliation: Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, College of Fisheries and Life Sciences, Shanghai Ocean University and Laboratory of Reproductive Biology, Ministry of Education, Huchenghuan Road 999, Shanghai 201306, China ; Laboratory of Reproduction, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan.
authors.forename: Guijun
authors.initials: G
authors.lastname: Guan
authors.affiliation: Laboratory of Reproduction, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan ; Laboratory of Molecular Reproductive Biology, School of Marine Sciences, Sun Yat-sen University, 135 Xingang West Road, Guangzhou, China.
authors.forename: Meisheng
authors.initials: M
authors.lastname: Yi
authors.affiliation: Laboratory of Reproduction, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan ; Lab of Molecular Developmental Biology, Institute for Environmental Sciences, University of Shizuoka, Yada, Shizuoka 422-8526, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.
authors.forename: Yunhan
authors.initials: Y
authors.lastname: Hong
authors.affiliation: Laboratory of Reproduction, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan ; South Ehime Fisheries Research Center, Institution for Collaborative Relations, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nagahama