Sex is determined by XX/XY sex chromosomes in Australasian side-necked turtles (Testudines: Chelidae)
Sex is determined by XX/XY sex chromosomes in Australasian side-necked turtles (Testudines: Chelidae)
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DOI：
10.1038/s41598-020-61116-w
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发表时间：
2020-03-09
影响因子：
4.6
通讯作者：
Rovatsos, Michail
中科院分区：
文献类型：
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作者：
Mazzoleni, Sofia;Augstenova, Barbora;Rovatsos, Michail
海龟在性别决定方面表现出可变性，因此，它们构成了性染色体进化的一个极好的模型。值得注意的是，龟科淡水龟的性别决定，一个物种丰富的群体，在南半球广泛的地理分布，仍然很少被探索。本文通过常规（核图重建、c带）和分子细胞遗传学（比较基因组杂交、用GATA微卫星基序、rDNA位点和端粒重复序列特异性探针进行原位杂交）方法，在澳大利亚Chelodina、Emydura和Elseya等7种Chelodina属chelydura和Elseya属chelydura中记录了XX/XY性别决定系统的存在。性染色体是微染色体在所有被检查的种类的切罗迪纳属。相比之下，性染色体是Emydura属和Elseya属中第4大的一对大染色体。它们的X染色体是亚稳心的，而Y染色体是稳心的。卵形Y染色体包含大量的男性特异性基因组区域，其中积累了GATA微卫星基序，偶尔也积累了rDNA位点和端粒重复序列。尽管性染色体在形态上存在差异，但我们得出结论，在中生代时期，Chelodina、Emydura和Elseya的共同祖先可能已经存在雄性异配子。
Turtles demonstrate variability in sex determination and, hence, constitute an excellent model for the evolution of sex chromosomes. Notably, the sex determination of the freshwater turtles from the family Chelidae, a species-rich group with wide geographical distribution in the southern hemisphere, is still poorly explored. Here we documented the presence of an XX/XY sex determination system in seven species of the Australasian chelid genera Chelodina, Emydura, and Elseya by conventional (karyogram reconstruction, C-banding) and molecular cytogenetic methods (comparative genome hybridization, in situ hybridization with probes specific for GATA microsatellite motif, the rDNA loci, and the telomeric repeats). The sex chromosomes are microchromosomes in all examined species of the genus Chelodina. In contrast, the sex chromosomes are the 4(th) largest pair of macrochromosomes in the genera Emydura and Elseya. Their X chromosomes are submetacentric, while their Y chromosomes are metacentric. The chelid Y chromosomes contain a substantial male-specific genomic region with an accumulation of the GATA microsatellite motif, and occasionally, of the rDNA loci and telomeric repeats. Despite morphological differences between sex chromosomes, we conclude that male heterogamety was likely already present in the common ancestor of Chelodina, Emydura and Elseya in the Mesozoic period.