Kominami R, Sudo K, Yoshikura H, Suzuki H, Moriwaki K, Hilgers J, Muramatsu M
J Mol Biol. 1985 Jun 5;183(3):301-9. doi: 10.1016/0022-2836(85)90002-6.
When EcoRI digests of mouse genomic DNA were subjected to Southern blot analysis with the polymorphic repetitive sequence PR1 as a probe, one satellite-like band of 3.5 X 10(3) base-pairs, designated as PR1 family B, was detected in BALB/c-strain mice, but not in the DDD/1- or MOA-strain mice. Analysis of recombinant phage clones revealed that the repeating unit of the PR1 family B was 13.5 X 10(3) base-pairs long. This family consisted of a tandem array of repeating units and occupied as much as 2% of one BALB/c chromosome. Since the BALB/c-specific PR1 family B is not present in DDD/1 or MOA mice, the unpaired portion of the BALB/c chromosome may be looped out in a synaptonemal complex during meiosis in F1 hybrids of the BALB/c strain with DDD/1 or MOA. To determine the fate of this extra DNA, we examined the genotypes of the F1 hybrid mice and of the segregating populations. Although the PR1 patterns of F1 and most N2 mice are consistent with typical Mendelian inheritance, some N2 progeny showed an abnormal 3.5 X 10(3) base-pair band of unexpectedly reduced intensity. This indicated that the extra DNA of PR1 family B occasionally underwent recombination during meiosis in F1 mice, resulting in its apparent excision. Examination of PstI digests supported this interpretation.
当用多态性重复序列PR1作为探针，对小鼠基因组DNA的EcoRI酶切片段进行Southern印迹分析时，在BALB/c品系小鼠中检测到一条3.5×10³碱基对的卫星样条带，命名为PR1家族B，但在DDD/1或MOA品系小鼠中未检测到。对重组噬菌体克隆的分析表明，PR1家族B的重复单元长度为13.5×10³碱基对。该家族由重复单元的串联阵列组成，占据了一条BALB/c染色体多达2%的区域。由于DDD/1或MOA小鼠中不存在BALB/c特异性的PR1家族B，在BALB/c品系与DDD/1或MOA的F1杂种减数分裂过程中，BALB/c染色体未配对的部分可能会在联会复合体中形成环状。为了确定这条额外DNA的命运，我们检测了F1杂种小鼠和分离群体的基因型。尽管F1和大多数N2小鼠的PR1模式与典型的孟德尔遗传一致，但一些N2后代显示出一条强度意外降低的异常3.5×10³碱基对条带。这表明PR1家族B的额外DNA在F1小鼠减数分裂过程中偶尔会发生重组，导致其明显切除。对PstI酶切片段的检测支持了这一解释。
