Casavant N C, Sherman A N, Wichman H A
Department of Biological Sciences, University of Idaho, Moscow 83844, USA.
Genetics. 1996 Apr;142(4):1289-98. doi: 10.1093/genetics/142.4.1289.
LINE-1, the major family of long, interspersed repeats in the mammalian genome, moves via an RNA intermediate and encodes its own reverse transcriptase. Comparative sequence analysis was used to reconstruct the phylogenetic history of LINE-1 dynamics in the deer mouse, Peromyscus. As is the case in Mus and Rattus, a very small number of active templates produce the majority of LINE-1 copies in Peromyscus. However, in contrast to the single LINE-1 lineage seen in the muroid rodents, Peromyscus has at least two LINE-1 lineages whose most recent common ancestor probably existed before the peromyscine radiation. Species-specific variants of Lineage 1, and intact open reading frames in the youngest elements of both Lineages 1 and 2, suggest that both lineages have remained active within the same genome. The higher number of shared-sequence variants in Lineage 1 relative to Lineage 2 suggests that Lineage 1 has replaced its master template much more frequently than Lineage 2 or that the reverse transcriptase Lineage 1 is more error prone. The implications of the method used to acquire LINE-1 sequences for analysis are discussed.
LINE-1是哺乳动物基因组中长散布重复序列的主要家族，它通过RNA中间体移动并编码自身的逆转录酶。采用比较序列分析来重建鹿鼠（白足鼠属）中LINE-1动态变化的系统发育史。与小家鼠和大鼠的情况一样，在白足鼠中，极少数活跃模板产生了大部分LINE-1拷贝。然而，与鼠形啮齿动物中所见的单一LINE-1谱系不同，白足鼠至少有两个LINE-1谱系，其最近的共同祖先可能在白足鼠辐射之前就已存在。谱系1的物种特异性变体，以及谱系1和2最年轻元件中的完整开放阅读框，表明这两个谱系在同一基因组中一直保持活跃。相对于谱系2，谱系1中共享序列变体的数量更多，这表明谱系1比谱系2更频繁地替换其主模板，或者谱系1的逆转录酶更容易出错。文中讨论了用于获取LINE-1序列进行分析的方法的意义。
