An XX/XY sex microchromosome system in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae) with genetic sex determination
An XX/XY sex microchromosome system in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae) with genetic sex determination
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DOI：
10.1007/s10577-006-1029-6
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发表时间：
2006-03-01
影响因子：
2.6
通讯作者：
Graves, JAM
中科院分区：
文献类型：
--
作者：
Ezaz, T;Valenzuela, N;Graves, JAM
异型性染色体在海龟中很少见，只在四个物种中被描述过。与许多龟类一样，澳大利亚淡水龟也有遗传性别决定，但在先前的核型研究中没有发现可区分的（异型）性染色体。通过比较基因组杂交（CGH），我们发现长鼻草具有XX/XY染色体性别决定系统，涉及一对微染色体。c -显带和反向荧光染色也可以在70%的细胞中区分出男性和女性具有不同显带模式的微染色体。gtg带带未发现任何异型染色体，复制带带未观察到X和Y微染色体上的复制异步性。我们得出结论，在这个物种中，X和Y染色体之间的序列差异非常小，这种差异只有通过高分辨率的分子细胞遗传学技术（如CGH）才能始终检测到。这是首次在龟类中鉴定出一对微染色体为性染色体。
Heteromorphic sex chromosomes are rare in turtles, having been described in only four species. Like many turtle species, the Australian freshwater turtle Chelodina longicollis has genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes were identified in a previous karyotyping study. We used comparative genomic hybridization (CGH) to show that C. longicollis has an XX/XY system of chromosomal sex determination, involving a pair of microchromosomes. C-banding and reverse fluorescent staining also distinguished microchromosomes with different banding patterns in males and females in similar to 70% cells examined. GTG-banding did not reveal any heteromorphic chromosomes, and no replication asynchrony on the X or Y microchromosomes was observed using replication banding. We conclude that there is a very small sequence difference between X and Y chromosomes in this species, a difference that is consistently detectable only by high-resolution molecular cytogenetic techniques, such as CGH. This is the first time a pair of microchromosomes has been identified as the sex chromosomes in a turtle species.