Faculty Articles


X-chromosome Linked Mutations Affecting Mosaic Expression of the Mouse X Chromosome



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Current Topics in Microbiology and Immunology



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In eutherian females, one of the two sex chromosomes is inactive. The inactivated status is established relatively early during embryogenesis and is somatically heritable within a cell lineage throughout development. The inactivation event is generally random with respect to the parental origin of an X chromosome, such that equal numbers of cells expressing the paternal (XP) and maternal (Xm) chromosome can be seen as a mosaic mixture in adult tissues using a variety of direct and indirect measures of X chromosome gene function. Using allelic variants of ubiquitous X-linked enzymes that are separable electrophoretically, the relative contributions of XP and Xm gene product can be qualitatively identified. Deviations from the equal occurrence of cells which express and occur by either non-random inactivation or by random inactivation followed by selection for cells which express one copy of the X chromosome. We used ethyl-nitrosourea as a mutagen to ask whether we could induce X-linked mutations that alter the mosaic expression of the X chromosomes in heterozygous females as a consequence of either altering the process of inactivation itself or by inducing mutations which could cause a selective growth of cells expressing only one kind of X chromosome. In this report, we describe our initial findings of nine non-mosaic female progeny of ENU-treated male mice. Further, we demonstrate the heritability of this phenotype from two of these progeny and show that the effect is primarily limited to the blood lineages.


Medical Specialties | Medicine and Health Sciences | Osteopathic Medicine and Osteopathy

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