【摘要】 在130只中华大蟾蜍中有17只个体(占13％)在第6染色体的随体部位出现了巨大随体。它们的大小在个体之间有显著的不同。这些大随体是额外增加的染色质,在染色质的性质上不同于次缢痕,也没有rDNA的转录活性。这些额外增大的随体与性别、年龄、季节和表型都没有相关的联系,并且以简单的孟德尔方式遗传。更多还原

【Abstract】 The karyotypes of 130 individuals of Bnfo bufo gargarizans were analyzed by the method of blood leukocytes culture in vitro. It was confirmed that the 6th chromosome was the NOE-chromosome, and its end of the long arm was found to carry a clear secondary constriction and satellite. The size of these satellites showed a complicated polymorphic patterns. In usual cases, a pair of the satellites was the form of a small ball, but in the 17 individuals (about 13%) the giant satellites appeared at the original position of the satellites. 16 animals of them were heterozygotes on the size of the satellite, i.e. only one 6th chromosome earring a distinctly enlarged satellite, one of them was the homozygote, i.e. both the 6th chromosomes carrying the giant satellites. All of the cells from any individual showed the same pattern, but the size of the giant satellites displayed a clear differences from one animal to another. The results of these observations and careful measurements made it clear that these giant satellites came reither from any chromosomal translocations nor from the difference in location of the secondary constrictions. They apparently resulted from the addition of extra chromatin. After treatment of C-banding and silver staining, the chromatin of the giant satellite not only failed to give evidence of being related to rDNTA, but also showed differences in properties from the chromatin of the secondary constriction. These extra enlarged satellites had no relationship directly with the sex, age. and other characters of the individuals, and might have been transmitted as a simple Mendelian character.更多还原