两种长臂猿染色体的C带和Ag－NORs的比较研究

本文对长臂猿属（Ｈｙｌｏｂａｔｅｓ）中白眉长臂猿（Ｈ．ｈｏｏｌｏｃｋ）２ｎ＝３８和白颊长臂猿（Ｈ．ｌｅｕｃｏｇｅｎｙｓ）２ｎ＝５２的染色体Ｃ带和Ａｇ－ＮＯＲｓ进行了比较研究。结果表明，两种长臂猿的Ｃ带核型中除多数染色体有着丝点Ｃ带外，一些染色体上还出现插入Ｃ带和着丝点Ｃ带弱化或减少现象；白眉长臂猿有全异染色质臂；白颊长臂猿有较多的端位Ｃ带。白眉长臂猿有两个Ａｇ－ＮＯＲｓ，而白颊长臂猿的Ａｇ－ＮＯＲｓ雌体有４个，雄体有５个，Ｙ染色体上有ＮＯＲ．本文对长臂猿的核型进化作了讨论。

COMPARATIVE STUDIES OF C-BAND AND Ag-NORs ON THE CHROMOSOMES BETWEEN TWO SPECIES GIBBONS

This paper deals with the comparison of C-banding patterns and Ag-NORs between white-browed gibbon (Hylobates hoolock ) and white-cheeked gibbon (H. leucogenys).The results are given as below:The diploid number of H. hoolock is 38, and its karyotype formula is 18 (M or SM), XY (M, dot). The white-cheeked gibbon has a diploid number of 2n= 52, and the karyotype formula is 44 (M or SM) 6 (A), XY (M, A).There are common characteristics of C-banded patterns in H. hoolock and H.leucogenys, Which are centromeric distribution of heterochromatin, loss of centromeric heterochromatin and interstitial heterochromatin. There are also some differences among their C-banded patterns, Which are the C-banded also karyotype with constitutive heterochromatic arms only in H. hoolock, and with terminal heterochromatin only in H.leucogenys. Their the whole Y chromosomes are C-band positive.Silver staining revealed one pair of SM chromosomes with NORs in H. hoolock.There are 5 chromosomes with Ag-NORs in male H. leucogenys, one of them is located on the Y chromosome which has been confirmed by fluorescence in situs hybridization (FISH) in the same cell. The presence of an NOR on the Y Chromosome is unusual in mammals. The female H. leucogenys has 4 chromosomes with Ag-NORs. Moreover, the association of Ag-NORs has been observed in H. leucogenys. However, it has not been observed in H. hoolock.Based on these results, the chromosomal evolution in gibbons has been discussed.