Ellis N, Yen P, Neiswanger K, Shapiro L J, Goodfellow P N
Imperial Cancer Research Fund, Lincoln's Inn Fields, London, England.
Cell. 1990 Nov 30;63(5):977-86. doi: 10.1016/0092-8674(90)90501-5.
Mammalian sex chromosomes are divided into sex-specific and pseudoautosomal regions. Sequences in the pseudoautosomal region recombine between the sex chromosomes; the sex-specific sequences normally do not. The interface between sex-specific and pseudoautosomal sequences is the pseudoautosomal boundary. The boundary is the centromeric limit to recombination in the pseudoautosomal region. In man, an Alu repeat element is found inserted at the boundary on the Y chromosome. In the evolutionary comparison conducted here, the Alu repeat element is found at the Y boundary in great apes, but it is not found there in two Old World monkeys. During the evolution of the Old World monkey and great ape lineages, homology between the sex chromosomes was maintained by recombination in the sequences telomeric to the Alu insertion site. The Alu repeat element did not create the present-day boundary; instead, it inserted at the preexisting boundary after the Old World monkey and great ape lineages diverged.
哺乳动物的性染色体分为性别特异性区域和假常染色体区域。假常染色体区域的序列在性染色体之间发生重组；而性别特异性序列通常不会。性别特异性序列和假常染色体序列之间的界面就是假常染色体边界。该边界是假常染色体区域重组的着丝粒限制。在人类中，发现一个Alu重复元件插入在Y染色体的边界处。在本文进行的进化比较中，在大猩猩的Y染色体边界处发现了Alu重复元件，但在两种旧世界猴中未发现。在旧世界猴和大猩猩谱系的进化过程中，性染色体之间的同源性通过Alu插入位点端粒序列中的重组得以维持。Alu重复元件并非形成了现今的边界；相反，它是在旧世界猴和大猩猩谱系分化之后插入到预先存在的边界处的。
