大仓鼠的核型与B染色体研究

采用骨髓细胞染色体制片法，对分布于山东济南、泰山、东北长白山和陕西西安的大仓鼠的染色体组型、Ｇ－带、Ｃ－带和银染核型进行了分析研究。济南、西安和长白山的标本的二倍体数目和核型相似，２ｎ＝２８，２２ｔ＋４ｍ＋ＸＹ（ｓｔ，ｍ）。泰山标本的二倍体数目为２ｎ＝２８～２９，即在６７５％的中期相中多出了一条形态最小的端着丝粒染色体，这条染色体为Ｂ染色体，可能起源于Ｘ染色体。泰山标本的Ａ染色体组与上述３地标本相同。４地标本的Ｇ－带、Ｃ－带和银染核型相似。除Ｂ染色体外，每个端着丝粒染色体都具有着丝粒异染色质，ＡｇＮＯＲｓ较恒定地出现在Ｎｏｓ２，４，８，９，１３染色体上。也就是说大仓鼠的Ｂ染色体为Ｃ－带阴性，不携带核仁组织者。这种Ｂ染色体Ｃ－带阴性的特征在赤狐、黑家鼠和大林姬鼠朝鲜亚种中亦有报道。

KARYOTYPES AND B CHROMOSOME OF GREATER LONG-TAILED HAMSTER (CRICETULUS TRITON)

The karyotypes of greater long-tailed hamster(Cricetulus triton)from Jinan,Mt. Tai,Shandong Province,Mts. Changbai,Jilin Province and Xi＇an,Shaanxi Province in China were observed by conventional and banding technique. The diploid chromosome number and karyotype are identical in the samples of Jinan,Mts. Changbai and Xi＇an,i. e.,2n=28,and the karyotype consists of 11 pairs of telocentric and 2 pairs of metacentric chromosomes,X chromosome is subtelocentric and Y metacentric. Diploid number of the sample from Mt. Tai is 28～29,one extrau npaired chromosome existed in the observed metaphases by 67.5%. It is B chromosome which is the smallest telocentric in the complement. A chromosomes of the sample were identical with that of samples from Jinan,Xi＇an and Mts. Changbai.The G-banded,C-banded,and silver stained karyotypes have been observed,no difference was found among samples from four localities. The origin of B ch romosome was discussed in the paper.