Kominami R, Urano Y, Mishima Y, Muramatsu M, Moriwaki K, Yoshikura H
J Mol Biol. 1983 Apr 5;165(2):209-28. doi: 10.1016/s0022-2836(83)80254-x.
A middle repetitive sequence, PR1, originally found in mouse rDNA appeared as satellite-like bands when EcoRI and BglII digests of genomic DNA were subjected to Southern blot hybridization using PR1 as probe. The copy number and sizes of PR1-related satellite-like bands, designated as PR1 families, differed remarkably among the subspecies and laboratory strains of mice when the EcoRI digests of genomic DNAs were compared. These bands were not detected in rat and human DNAs. A unit of PR1 sequence was determined by examining cloned EcoRI 3.5 kb (kb, 10(3) bases) fragment and 6.6 kb rDNA by cross-hybridization and sequence analysis: 3.5 kb and 6.6 kb DNAs are composed of homologous PR1 regions and the flanking non-homologous sequences. The results indicate that amplification of different sequences containing PR1 has occurred in different subspecies and strains of mice, and that the segments of satellite-like bands are likely to have been created by recombination of the PR1 sequence with other DNA segments before amplification. The chromosomal distribution of the 3.5 kb PR1 family was studied by back-crossing the female F1 between BALB/c and DDD/1 to male DDD/1. The segregation data strongly suggest that most, if not all, of this family are located on a single chromosome. The stability of these PR1 families in the genomes of cultured cells of a given strain was also examined. An extra band homologous to PR1 appeared in their genomes, but was not detected in other tissues, indicating that some PR1 families may change even during cell propagation.
一个中间重复序列PR1最初在小鼠核糖体DNA中被发现，当用PR1作为探针，对基因组DNA的EcoRI和BglII酶切产物进行Southern杂交时，它呈现出卫星样条带。当比较基因组DNA的EcoRI酶切产物时，被指定为PR1家族的与PR1相关的卫星样条带的拷贝数和大小在小鼠的亚种和实验室品系之间有显著差异。在大鼠和人类DNA中未检测到这些条带。通过交叉杂交和序列分析，对克隆的EcoRI 3.5 kb（kb，10³个碱基）片段和6.6 kb核糖体DNA进行检测，确定了PR1序列的一个单元：3.5 kb和6.6 kb的DNA由同源的PR1区域和侧翼非同源序列组成。结果表明，含有PR1的不同序列在小鼠的不同亚种和品系中发生了扩增，并且卫星样条带的片段可能是在扩增之前由PR1序列与其他DNA片段重组产生的。通过将BALB/c和DDD/1之间的雌性F1与雄性DDD/1回交，研究了3.5 kb PR1家族的染色体分布。分离数据强烈表明，这个家族的大部分（如果不是全部）位于一条染色体上。还检测了这些PR1家族在给定品系培养细胞基因组中的稳定性。在它们的基因组中出现了一条与PR1同源的额外条带，但在其他组织中未检测到，这表明一些PR1家族甚至在细胞增殖过程中也可能发生变化。
