Evidence for X-linkage and non-inactivation of steroid sulphatase locus in wood lemming
One of the two X chromosomes is inactivated in somatic cells of adult female mammals to compensate for unequal amounts of X-chromosomal genes in the two sexes 1 . Although the general validity of this concept is not in doubt, there is evidence that a segment of the distal short arm of the human X ch...
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Veröffentlicht in: | Nature (London) 1982-04, Vol.296 (5859), p.766-767 |
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Zusammenfassung: | One of the two X chromosomes is inactivated in somatic cells of adult female mammals to compensate for unequal amounts of X-chromosomal genes in the two sexes
1
. Although the general validity of this concept is not in doubt, there is evidence that a segment of the distal short arm of the human X chromosome carrying the gene, or genes for the Xg blood group system, the steroid sulphatase (STS) locus
2,3
, and a gene controlling a serologically defined male-specific antigen
4,5
, is never inactivated. It is not known whether this non-inactivated segment is a special feature of the human X chromosome or whether it is a general feature of the ancestral, highly conserved, mammalian X chromosome
6
. In man the number of functional STS gene copies can be deduced from intracellular STS activity
7
. With this in mind we have investigated the number of active gene copies on the X chromosome of the wood lemming (
Myopus schistfcolor
, Lilljeborg), by assaying STS in cultured cells of this species. We report here that STS activity is directly correlated to the number of X chromosomes and unrelated to the phenotypic sex. This suggests that in the wood lemming the STS gene is also X-linked and not subject to inactivation. |
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ISSN: | 0028-0836 1476-4687 |
DOI: | 10.1038/296766a0 |