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BioMed Research International
Volume 2013, Article ID 243938, 8 pages
Research Article

In Situ Gene Mapping of Two Genes Supports Independent Evolution of Sex Chromosomes in Cold-Adapted Antarctic Fish

1Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, 16132 Genoa, Italy
2Department of Animal Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
3SSM and CNRS UMR 7138, Département Systématique et Evolution, MNHN, 43 rue Cuvier, 75231 Paris, France

Received 31 August 2012; Revised 3 December 2012; Accepted 17 December 2012

Academic Editor: Marcelo de Bello Cioffi

Copyright © 2013 Laura Ghigliotti 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.


Two genes, that is, 5S ribosomal sequences and antifreeze glycoprotein (AFGP) genes, were mapped onto chromosomes of eight Antarctic notothenioid fish possessing a X1X1X2X2/X1X2Y sex chromosome system, namely, Chionodraco hamatus and Pagetopsis macropterus (family Channichthyidae), Trematomus hansoni, T. newnesi, T. nicolai, T. lepidorhinus, and Pagothenia borchgrevinki (family Nototheniidae), and Artedidraco skottsbergi (family Artedidraconidae). Through fluorescence in situ hybridization (FISH), we uncovered distinct differences in the gene content of the Y chromosomes in the eight species, with C. hamatus and P. macropterus standing out among others in bearing 5S rDNA and AFGP sequences on their Y chromosomes, respectively. Both genes were absent from the Y chromosomes of any analyzed species. The distinct patterns of Y and non-Y chromosome association of the 5S rDNA and AFGP genes in species representing different Antarctic fish families support an independent origin of the sex heterochromosomes in notothenioids with interesting implications for the evolutionary/adaptational history of these fishes living in a cold-stable environment.