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Cytogenet Genome Res 2015;147:48-54
(DOI:10.1159/000441646)

Differentiation of Sex Chromosomes and Karyotype Characterisation in the Dragonsnake Xenodermus javanicus (Squamata: Xenodermatidae)

Rovatsos M.a · Johnson Pokorná M.a, b · Kratochvíl L.a

Author affiliations

aDepartment of Ecology, Faculty of Science, Charles University in Prague, Prague, and bInstitute of Animal Physiology and Genetics, The Czech Academy of Sciences, Liběchov, Czech Republic

Corresponding Author

Lukáš Kratochvíl

Department of Ecology, Faculty of Science

Charles University in Prague

CZ-128 44 Prague (Czech Republic)

E-Mail lukas.kratochvil@natur.cuni.cz

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Abstract

Highly differentiated heteromorphic ZZ/ZW sex chromosomes with a heterochromatic W are a basic principle among advanced snakes of the lineage Colubroidea, while other snake lineages generally lack these characteristics. For the first time, we cytogenetically examined the dragonsnake, Xenodermus javanicus, a member of the family Xenodermatidae, which is phylogenetically nested between snake lineages with and without differentiated sex chromosomes. Although most snakes have a karyotype with a stable chromosomal number of 2n = 36, the dragonsnake has an unusual, derived karyotype with 2n = 32 chromosomes. We found that heteromorphic ZZ/ZW sex chromosomes with a heterochromatic W are present in the dragonsnake, which suggests that the emergence of a highly differentiated W sex chromosome within snakes predates the split of Xenodermatidae and the clade including families Pareatidae, Viperidae, Homalopsidae, Lamprophiidae, Elapidae, and Colubridae. Although accumulations of interstitial telomeric sequences have not been previously reported in snakes, by using FISH with a telomeric probe we discovered them in 6 pairs of autosomes as well as in the W sex chromosome of the dragonsnake. Similarly to advanced snakes, the sex chromosomes of the dragonsnake have a significant accumulation of repeats containing a (GATA)n sequence. The results facilitate the dating of the differentiation of sex chromosomes within snakes back to the split between Xenodermatidae and other advanced snakes, i.e. around 40-75 mya.

© 2015 S. Karger AG, Basel


Article / Publication Details

First-Page Preview
Abstract of Original Article

Received: October 01, 2015
Published online: November 18, 2015

Number of Print Pages: 7
Number of Figures: 2
Number of Tables: 0

ISSN: 1424-8581 (Print)
eISSN: 1424-859X (Online)

For additional information: http://www.karger.com/CGR


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