Altmanová Marie, Rovatsos Michail, Johnson Pokorná Martina, Veselý Milan, Wagner Florian, Kratochvíl Lukáš
Department of Ecology, Faculty of Science, Charles University, CZ-12844 Prague, Czech Republic; Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, CZ-27721 Liběchov, Czech Republic.
Department of Ecology, Faculty of Science, Charles University, CZ-12844 Prague, Czech Republic.
Zoology (Jena). 2018 Feb;126:98-102. doi: 10.1016/j.zool.2017.11.007. Epub 2017 Nov 22.
Once believed to be restricted only to endotherms (mammals and birds), several poikilothermic amniote lineages have recently been documented to possess long-term evolutionary stability in their sex chromosomes. However, many important lineages were not included in these tests. Previously, based on molecular evidence, we documented the homology of well-differentiated sex chromosomes among seven families of iguanas (Pleurodonta), with basilisks (Corytophanidae) being the only exception, as the tested genes linked to X, but missing on the Y chromosome, in other iguanas were autosomal or pseudoautosomal in basilisks. In this study, we test the homology of sex chromosomes in the remaining, previously unstudied iguana families (Hoplocercidae, Leiosauridae, Liolaemidae, Polychrotidae) and in the basilisk genus Corytophanes. Our results show that 12 currently recognized families of iguanas share X-specific gene content conserved from the common ancestor living in the Cretaceous period. However, the results in the genus Corytophanes indicate the loss of the ancestral differentiated sex chromosomes from the ancestor of basilisks. Our new data further confirm the extensive stability of sex chromosomes in iguanas, thus enabling molecular sexing based on the comparison of the number of X-specific genes by quantitative PCR (qPCR) in all but one family of this widely diversified clade.
曾经人们认为只有恒温动物（哺乳动物和鸟类）才有性染色体，然而最近有文献记载，一些变温羊膜动物谱系的性染色体具有长期的进化稳定性。但是，许多重要的谱系并未包含在这些测试中。此前，基于分子证据，我们记录了鬣蜥科（侧齿鬣蜥）七个家族中分化良好的性染色体的同源性，只有盔蜥科是唯一的例外，因为在其他鬣蜥中与X染色体连锁但在Y染色体上缺失的测试基因，在盔蜥中是常染色体或假常染色体。在本研究中，我们测试了其余先前未研究过的鬣蜥家族（盔头鬣蜥科、滑蜥科、鬃狮蜥科、变色蜥科）以及盔蜥属的性染色体同源性。我们的结果表明，目前公认的12个鬣蜥家族共享来自生活在白垩纪的共同祖先的X特异性基因内容。然而，盔蜥属的结果表明，从盔蜥的祖先开始，祖先分化的性染色体已经丢失。我们的新数据进一步证实了鬣蜥中性染色体的广泛稳定性，因此除了这个广泛多样化类群中的一个家族外，在所有其他家族中都能够基于通过定量PCR（qPCR）比较X特异性基因的数量来进行分子性别鉴定。
