Britten R J, Stout D B, Davidson E H
Kerckhoff Marine Laboratory, California Institute of Technology, Corona del Mar 92625.
Proc Natl Acad Sci U S A. 1989 May;86(10):3718-22. doi: 10.1073/pnas.86.10.3718.
A significant fraction of human Alu repeated sequences are members of the precise, recently inserted class. A cloned member of this class has been used as a probe for interspecies hybridization and thermal stability determination. The probe was reassociated with human, mandrill, and spider monkey DNA under conditions such that only almost perfectly matching duplexes could form. Equally precise hybrids were formed with human and mandrill DNA (Old World monkey) but not with spider monkey DNA (New World). These measurements as well as reassociation kinetics show the presence in mandrill DNA of many precise class Alu sequences that are very similar or identical in quantity and sequence to those in human DNA. Human and mandrill are moderately distant species with a single-copy DNA divergence of about 6%. Nevertheless, their recently inserted Alu sequences arise by retroposition of transcripts of source genes with nearly identical sequences. Apparently a gene present in our common ancestor at the time of branching was inherited and highly conserved in sequence in both the lineage of Old World monkeys and the lineage of apes and man.
人类Alu重复序列中有很大一部分是精确的、近期插入的类别成员。该类别的一个克隆成员已被用作种间杂交和热稳定性测定的探针。在仅能形成几乎完美匹配双链体的条件下，该探针与人、山魈和蜘蛛猴的DNA进行了重新杂交。与人及山魈（旧世界猴）的DNA形成了同样精确的杂种，但与蜘蛛猴（新世界猴）的DNA未形成杂种。这些测量以及重新杂交动力学表明，山魈DNA中存在许多精确类别的Alu序列，其数量和序列与人类DNA中的非常相似或相同。人类和山魈是亲缘关系适中的物种，单拷贝DNA差异约为6%。然而，它们近期插入的Alu序列是由具有几乎相同序列的源基因转录本逆转录产生的。显然，在分支时我们共同祖先中存在的一个基因被继承下来，并在旧世界猴谱系以及猿和人类谱系中在序列上高度保守。
