NORMAL HUMAN FEMALE AS A MOSAIC OF X-CHROMOSOME ACTIVITY - STUDIES USING GENE FOR G-6-PD-DEFICIENCY AS A MARKER
NORMAL HUMAN FEMALE AS A MOSAIC OF X-CHROMOSOME ACTIVITY - STUDIES USING GENE FOR G-6-PD-DEFICIENCY AS A MARKER
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DOI：
10.1073/pnas.48.1.9
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发表时间：
1962-01-01
影响因子：
11.1
通讯作者：
YEH, M
中科院分区：
文献类型：
--
作者：
BEUTLER, E;FAIRBANKS, VF;YEH, M
Ohno已经证明，在人类女性的体细胞中，两条X染色体是不一样的。一个与常染色体的行为方式完全相同，在间期和前期保持伸展状态，而另一个呈现高度浓缩状态，形成巴尔性染色质体。另一方面，在男性体细胞中，单个X染色体从不表现出正的异固缩作用，它总是显得纤细和细长。在我们看来，在分裂间期凝聚的雌性X染色体在遗传上是不活跃的，这是完全可能的。活性染色体并不总是来自母亲或父亲，因为这会产生性连锁突变的遗传模式，与我们所知道的模式截然不同。因此，似乎有必要假设，至少在发育的一段时间内，在身体的分裂细胞中，活性和非活性染色体是随机的。这样一来，女性就由一系列细胞组成，其中一些细胞带有功能性的父方X染色体，另一些则带有功能性的母方X染色体。葡萄糖-6-磷酸脱氢酶（g-6-pd）缺乏症是一种先天性的人类代谢缺陷，9代表了一个理想的测试系统，在其中检查这一假设。许多患有这种疾病的杂合子女性红细胞g-6-pd水平约为正常水平的50%。如果杂合子女性红细胞的前体细胞如我们的假设所示，是一种镶嵌体，由一些具有活跃的母体X染色体的细胞和另一些具有活跃的父体X染色体的细胞组成。
Ohno has shown that in somatic cells of human females, the two X-chromosomes are not alike. One behaves in exactly the same manner as the autosomes, remaining in an extended state during interphase and prophase, while the other assumes a heavily condensed state, forming the Barr sex chromatin body. In male somatic cells, on the other hand, the single X never manifests positive heteropycnosis; it always appears fine and elongated. It seemed to us entirely possible that thefemale X which condenses during interphase is genetically inactive. The active chromosome could not always be derived either from the mother or from the father, since this would give a pattern of inheritance of sex-linked mutations quite different from the pattern as we know it to exist. It seems necessary, therefore, to assume that there is, at least for some period of time during development, randomization of the active and inactive chromosome among the dividing cells of the body. Women would then be composed of a mosaic of cells, some with a functional paternal X-chromosome, others with a functional maternal X-chromosome. Glucose-6-phosphate dehydrogenase (g-6-pd) deficiency, an inborn error of metabolism of humans, 9 represents an ideal test system in which to examine this hypothesis. Many heterozygous females with this disorder have red cell g-6-pd levels which are approximately 50 per cent of normal. If the precursors of a heterozy-gous female's erythrocytes were, as our hypothesis suggests, a mosaic consisting of some cells with the maternal X-chromosome active, others with the paternal X-