中国四种龟的细胞遗传研究

A Cytogenetic Study of Four Species of Turtle from China

本文研究了我国四种龟类动物的核型、Ｃ带和Ａｇ－ＮＯＲ＿ｓ。结果表明金头闭壳龟的核型２ｎ＝５２（１４Ｍ＋２ＳＭ＋４ＳＴ＋６Ｔ＋２６ｍ），ＮＦ＝７２，核型模式为８＋５＋１３，一对次缢痕位于Ｉ组的Ｎｏ．１ｐｉｎｔｅｒ；三线闭壳龟核型２ｎ＝５２（１２Ｍ＋４ＳＭ＋４ＳＴ＋６Ｔ＋２６ｍ），ＮＦ＝７２，８＋５＋３，黄缘盒龟的核型 ２ｎ＝５２（１６Ｍ＋４ＳＴ＋６Ｔ＋２６ｍ），ＮＦ＝７２，８＋５＋１３，一对次缢痕位于Ｉ组Ｎｏ．１ｐｉｎｔｅｒ；黄额盒龟２ｎ＝５２（１６Ｍ＋２ＳＭ＋４ＳＴ＋６Ｔ＋２４ｍ），ＮＰ＝７４，９＋５＋１２，有４对次缢痕，分别位于Ｉ组的Ｎｏ．１ｐｉｎｔｅｒ，Ｎｏ．３ｐｐｅｒ，Ｎｏ．７ｐｐｅｒ和Ｎｏ．６（Ｘ染色体）ｑｐｅｒ。黄额盒龟有１对异型（ＸＹ型）性染色体，其余３个种没有。这四种龟的全部染色体都出现着丝粒区Ｃ带正染。它们都仅出现１对ＡｇＮＯＲｓ，其中黄额盒龟的Ａｇ－ＮＯＲｓ。位于ＩＩ组的Ｎｏ．５ｑｐｅｒ，其余３个种的Ａｇ－ＮＯＲ＿ｓ位于Ｉ组的Ｎｏ．７ｑｔｅｒ。本文还阐述了近缘种间核型的演化机制和黄额盒龟性染色体分化的途径。

The karyotypes, C-banding and Ag-NORs of four species of turtle from China have been studied. The results demonstrated that Cuora aurocapitata has 2n=52(14M + 2SM+4ST+6T+26m), NF=72,8+5+13(karyotypic formulae).Its secondary constrictions(SC)located on No.1 p inter of group Ⅰ; C. trifasciata has 2n=52(12M +4SM+1+4ST+6T+26m), NF=72,8+5+13, Cistoclemmys flavomarginatus has 2n=52(16M+4ST+6T+26m), NF=72,8+5+13.The SC is also on No.1 p inter of group Ⅰ; C. galbinifrons has 2n=52(16M+2SM+4ST+6T+24m), NF=74,9+5+12.Four pairs of SC of C. galbinifrons are on No.1 p inter, No.3,7 p par and No.6(X chromosome) q per of group Ⅰ. The heteromorphic chromosomes related with sexuelity were discovered in C. galbinifrons,while there is no that in other three species. All the centrometic regions of the chromosomes for the four studied species showed the various degree staining of Cpositive. Only one homologous pair of Ag-NORs is found for C. galbinifons,which locate on No.5 q per of group Ⅱ. The Ag-NORs of other three species lies in No.7 q ter of group Ⅰ.The mechanism of the karyotypic evolution is discussed.Individual evolutional mechanism of an heteromorphic sex pair of chromosomes.