Cheng S M, Schildkraut C L
Nucleic Acids Res. 1980 Sep 25;8(18):4075-90. doi: 10.1093/nar/8.18.4075.
When mouse DNA is digested to completion with restriction endonuclease Eco R1, a distinct band of 1.3 kb segments comprising about 0.5-3% of the genome is observed upon agarose gel electrophoresis. This DNA is not tandemly repeated in the genome and is not derived from mouse satellite DNA. Restriction endonuclease analysis suggested that the 1.3 kb segments are heterogeneous. Specific sequences were selected from the 1.3 kb segments and amplified by cloning in plasmid pBR322. Southern transfer experiments indicated that three separately cloned mouse DNA inserts hybridized predominantly to the Eco R1 1.3 kb band and to the conspicuous subsegments generated by secondary restriction endonuclease cleavage of the sucrose gradient purified 1.3 kb segments. Segments were also excised by Hha I (Hha I segments) from the chimeric plasmids containing mouse DNA inserts and subjected to restriction endonuclease and cross-hybridization analysis. It was found that the three Hha I segments were different, although two of them exhibited partial sequence homology. Cot analysis indicated that each of the Hha I segments are repeated about 10(4) times in the mouse genome. These findings indicate that a family of related but non-identical, moderately repetitive DNA sequences, rather than a single homogeneous repeat, is present in the 1.3 kb Eco R1 band.
当用限制性内切酶Eco R1将小鼠DNA完全消化后，在琼脂糖凝胶电泳上可观察到一条明显的1.3 kb片段带，该片段约占基因组的0.5 - 3%。这种DNA在基因组中不是串联重复的，也不是来自小鼠卫星DNA。限制性内切酶分析表明，1.3 kb片段是异质的。从1.3 kb片段中选择特定序列，并通过克隆到质粒pBR322中进行扩增。Southern印迹转移实验表明，三个分别克隆的小鼠DNA插入片段主要与Eco R1 1.3 kb条带以及蔗糖梯度纯化的1.3 kb片段经二级限制性内切酶切割产生的明显亚片段杂交。片段也从含有小鼠DNA插入片段的嵌合质粒中用Hha I酶切（Hha I片段），并进行限制性内切酶和交叉杂交分析。发现三个Hha I片段是不同的，尽管其中两个表现出部分序列同源性。Cot分析表明，每个Hha I片段在小鼠基因组中重复约10⁴次。这些发现表明，在1.3 kb Eco R1条带中存在一个相关但不相同的中度重复DNA序列家族，而不是单一的均匀重复序列。
