Table of Contents
International Journal of Evolutionary Biology
Volume 2014, Article ID 873935, 10 pages
Research Article

A Syntenic Region Conserved from Fish to Mammalian X Chromosome

1Key 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
2Laboratory of Reproduction, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
3Laboratory of Molecular Reproductive Biology, School of Marine Sciences, Sun Yat-sen University, 135 Xingang West Road, Guangzhou, China
4Lab of Molecular Developmental Biology, Institute for Environmental Sciences, University of Shizuoka, Yada, Shizuoka 422-8526, Japan
5Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
6South Ehime Fisheries Research Center, Institution for Collaborative Relations, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577, Japan

Received 23 June 2014; Revised 30 October 2014; Accepted 2 November 2014; Published 18 November 2014

Academic Editor: E. N. Trifonov

Copyright © 2014 Guijun Guan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.