Rikke B A, Garvin L D, Hardies S C
Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284.
J Mol Biol. 1991 Jun 20;219(4):635-43. doi: 10.1016/0022-2836(91)90660-x.
LINE-1 is a family of repetitive DNA sequences interspersed among mammalian genes. In the mouse haploid genome there are about 100,000 LINE-1 copies. We asked if the subspecies Mus spretus and Mus domesticus have developed species-specific LINE-1 subfamilies. Sequences from 14 M. spretus LINE-1 elements were obtained and compared to M. domesticus LINE-1 sequences. Using a molecular phylogenetic tree we identified several differences shared among a subset of young repeats in one or the other species as candidates for species-specific LINE-1 variants. Species specificity was tested using oligonucleotide probes complementary to each putative species-specific variant. When hybridized to genomic DNAs, single-variant probes detected an expanded number of elements in the expected mouse. In the other species these probes detected a smaller number of matches consistent with the average rate of random divergence among LINE-1 elements. It was further found that the combination of two species-specific sequence differences in the same probe reduced the detection background in the wrong species below our detection limit.
LINE-1是一类散布于哺乳动物基因间的重复DNA序列家族。在小鼠单倍体基因组中约有100,000个LINE-1拷贝。我们探究了西班牙小鼠和家鼠这两个亚种是否形成了物种特异性的LINE-1亚家族。获取了14个西班牙小鼠LINE-1元件的序列，并与家鼠的LINE-1序列进行比较。利用分子系统发育树，我们在一个或另一个物种的一部分年轻重复序列中鉴定出了几个共同的差异，作为物种特异性LINE-1变体的候选序列。使用与每个假定的物种特异性变体互补的寡核苷酸探针来测试物种特异性。当与基因组DNA杂交时，单变体探针在预期的小鼠中检测到数量增多的元件。在另一个物种中，这些探针检测到的匹配数量较少，这与LINE-1元件之间随机分歧的平均速率一致。进一步发现，同一探针中两种物种特异性序列差异的组合将在错误物种中的检测背景降低到我们的检测限以下。
