摘要:
以血培养细胞为材料,研究了三种水龟的核型与NORs,结果表明,染色体数均为2n=52,核型模式9＋5＋12,属龟科核型中的原始类型。但眼斑水龟NF＝76,而四眼斑水龟和黄喉拟水龟的NF＝78。从核型结构看,眼斑水龟与四眼斑水龟相似,而黄喉拟水龟则有较大差别,作者还发现黄喉拟水龟核型的一些重要特征,即其A组No.3和No.6染色体有次缢痕,No.6长臂呈清晰的随体,这些是拟水龟属枝型的主要特征,但在以往的资料中都未曾记载过。三种水龟的雌雄个体间均未见有异型的性染色体。仅显示一对NORs,并均位于A组较小的一对中部着丝粒染色体上,表明其NORs核型的保守性和NORs位置的一致性。
Abstract:
The karyotypes and NORs of three species of turtles, i.e.Sacalia bealei,S.quadriocellata and Mauremys mutica were studied from mitotic metaphase ofcultured blood cells prepared by the colchicine-hypotonic-air drying method.Thediploid chromo-some numberis = 52 consisting of 9 meta-or submetacentric pairs,5 ter-orsubterminal pairs and 12 pairs of microchromosomes.The karyotypic formulais 9 + 5 + 12, being the primitive type in karyotypes of Emydidae.The nombrefondamental (NF) of S.bealei is 76 and those of S.quadriocellata and M.muticaare 78 respechvely.The feature of karyotypic structure of S.bealei is similar to thatof M.quadriocellata.The secondary constriction and satellite were reported for thefirst time in M.mutica.The secondary constriction locates on the short arm of 3rdand the long arm of 6th chromosome of group A, and the satellite is on the 6thchromosome of group A.NO dimorphic sex chromosomes were observed in either sexof the three species examined.The NORs occurred on the long arm of the 7th pair of chromosomes in S.bealia,and located on long arm of the sib pair of chromosomes in S. quadriocellata and M.mutica.The evidence of NORs indicated in mis paper for the three species rereals theextreme conservativeness with regard tO karyotype and it is reported hitherto.
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