title: In situ gene mapping of two genes supports independent evolution of sex chromosomes in cold-adapted Antarctic fish.
abstract: 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.
authors.affiliation: Department of Earth, Environment and Life Sciences (DISTAV), University of Genoa, 16132 Genoa, Italy. laura.ghigliotti@gmail.com
authors.forename: Laura
authors.initials: L
authors.lastname: Ghigliotti
authors.forename: C-H Christina
authors.initials: CH
authors.lastname: Cheng
authors.forename: Céline
authors.initials: C
authors.lastname: Bonillo
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Coutanceau
authors.forename: Eva
authors.initials: E
authors.lastname: Pisano
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D021301:Antifreeze Proteins / Q000235:genetics; D002871:Chromosome Banding; D002874:Chromosome Mapping; D019143:Evolution, Molecular; D005260:Female; D005399:Fishes / Q000235:genetics* / Q000502:physiology; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D012341:RNA, Ribosomal, 5S / Q000378:metabolism; D012730:Sex Chromosomes / Q000235:genetics*; D013045:Species Specificity
chemical_list: D021301:Antifreeze Proteins; D012341:RNA, Ribosomal, 5S