The dragon lizard Pogona vitticeps has ZZ/ZW micro-sex chromosomes

被引:162
作者
Ezaz, T
Quinn, AE
Miura, I
Sarre, SD
Georges, A
Graves, JAM
机构
[1] Australian Natl Univ, Res Sch Biol Sci, Comparat Genom Grp, Canberra, ACT 2601, Australia
[2] Univ Canberra, Inst Appl Ecol, Canberra, ACT 2601, Australia
[3] Hiroshima Univ, Grad Sch Sci, Inst Amphibian Biol, Hiroshima 7398526, Japan
基金
澳大利亚研究理事会;
关键词
agamid; CGH; comparative genomic hybridization; heterochromatinization; microchromosomes; sex chromosomes;
D O I
10.1007/s10577-005-1010-9
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The bearded dragon, Pogona vitticeps (Agamidae: Reptilia) is an agamid lizard endemic to Australia. Like crocodilians and many turtles, temperature-dependent sex determination (TSD) is common in agamid lizards, although many species have genotypic sex determination (GSD). P. vitticeps is reported to have GSD, but no detectable sex chromosomes. Here we used molecular cytogenetic and differential banding techniques to reveal sex chromosomes in this species. Comparative genomic hybridization (CGH), GTG- and C-banding identified a highly heterochromatic microchromosome specific to females, demonstrating female heterogamety (ZZ/ZW) in this species. We isolated the P. vitticeps W chromosome by microdissection, re-amplified the DNA and used it to paint the W. No unpaired bivalents were detected in male synaptonemal complexes at meiotic pachytene, confirming male homogamety. We conclude that P. vitticeps has differentiated previously unidentifable W and Z micro-sex chromosomes, the first to be demonstrated in an agamid lizard. Our finding implies that heterochromatinization of the heterogametic chromosome occurred during sex chromosome differentiation in this species, as is the case in some lizards and many snakes, as well as in birds and mammals. Many GSD reptiles with cryptic sex chromosomes may also prove to have micro-sex chromosomes. Reptile microchromosomes, long dismissed as non-functional minutiae and often omitted from karyotypes, therefore deserve closer scrutiny with new and more sensitive techniques.
引用
收藏
页码:763 / 776
页数:14
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