Richler C, Soreq H, Wahrman J
Department of Genetics, Hebrew University of Jerusalem, Israel.
Nat Genet. 1992 Nov;2(3):192-5. doi: 10.1038/ng1192-192.
X chromosome inactivation occurs twice during the mammalian life cycle. In females one of the two X chromosomes of somatic nuclei is inactive, while in males the solitary X chromosome is inactivated during germ cell development. Despite the different properties of the inactivated chromosomes of females and males, the molecular initiation of inactivation may be the same. X inactive-specific transcripts, XIST, are produced from somatic inactivated X chromosomes. We demonstrate here the existence of XIST transcripts in testes of man and mouse. Inactivation of X chromosomes in males, as in females, may thus be mediated through XIST. Conceivably, the silencing of X-linked genes is the price paid for the evolution of successful mechanisms of chromosomal sex determination.
X染色体失活在哺乳动物生命周期中发生两次。在雌性中，体细胞核中的两条X染色体之一是失活的，而在雄性中，单条X染色体在生殖细胞发育过程中失活。尽管雌性和雄性失活染色体的特性不同，但失活的分子起始过程可能是相同的。X染色体失活特异性转录本XIST是由体细胞中失活的X染色体产生的。我们在此证明了人类和小鼠睾丸中存在XIST转录本。因此，雄性X染色体的失活可能与雌性一样，是通过XIST介导的。可以想象，X连锁基因的沉默是成功的染色体性别决定机制进化所付出的代价。
