Johnston F P, Church R B, Lin C C
Can J Biochem. 1982 May;60(5):497-506. doi: 10.1139/o82-059.
The organizations of the genomes of two related species of Asian deer, the Indian (2n = 6 female, 7 male) and Chinese muntjac (2n = 46), were compared at the cytogenetic and molecular levels. These dramatically different karyotypes preserve little apparent G-banding homology. The difference in chromosome number is coincident with a 22% reduction in haploid DNA content from 2.7 to 2.1 pg in the Chinese and Indian muntjac, respectively. The kinetics of reassociation of the Indian muntjac (equivalent Cot = 4285 M-1. s-1) and Chinese muntjac DNA (equivalent Cot - 4362 M-1.s-1) in 2.4 M tetraethylammonium chloride suggests conservation in amount of "single-copy" DNA. Two middle repetitive DNA sequence classes differ in both amount and in degree of repetition between the two species. A middle repetitive frequency component (935-fold repeated) represents 13% of the Indian muntjac DNA. A similar component (644-fold repeated) represents 17% of the Chinese muntjac DNA. Low repetition DNA sequence components (repeated 5- and 50-fold) represent 30 and 40% of the Indian and Chinese muntjac DNAs, respectively. These differences quantitatively account for the 0.6 pg haploid DNA content variation between species. The deletion of middle repetitive DNA has not substantively altered the distribution of restriction endonuclease DNA base composition classes as defined by buoyant density in cesium chloride. These results represent the first time that middle repetitive DNA has been directly implicated in a chromosome rearrangement within the vertebrates.
对两种亚洲鹿——印度麂（2n = 6，雌性；2n = 7，雄性）和中国麂（2n = 46）的基因组组织进行了细胞遗传学和分子水平的比较。这两种截然不同的核型几乎没有明显的G带同源性。染色体数目的差异与中国麂和印度麂单倍体DNA含量分别从2.7 pg降至2.1 pg（减少了22%）相吻合。印度麂（等效Cot = 4285 M⁻¹·s⁻¹）和中国麂DNA（等效Cot = 4362 M⁻¹·s⁻¹）在2.4 M四乙基氯化铵中的复性动力学表明“单拷贝”DNA数量保守。两种中等重复DNA序列类别在数量和重复程度上在两个物种之间都存在差异。一个中等重复频率成分（重复935倍）占印度麂DNA的13%。一个类似成分（重复644倍）占中国麂DNA的17%。低重复DNA序列成分（分别重复5倍和5倍）分别占印度麂和中国麂DNA的30%和40%。这些差异定量地解释了物种间0.6 pg单倍体DNA含量的变化。中等重复DNA的缺失并未实质性改变由氯化铯浮力密度定义的限制性内切酶DNA碱基组成类别的分布。这些结果首次表明中等重复DNA直接参与了脊椎动物的染色体重排。
