A 450 kb transgene displays properties of the mammalian X-inactivation center

Article Abstract:

The introduction of 450 kb murine Xic/Xist sequences into autosomes was found to activate female dosage compensation in male embryonic stem cells. Xist was induced upon differentiation and can be expressed from both endogenous and ectopic loci. This implies that the transgene contains the elements for counting and choosing Xs. The Xic is believed to be contained within 450 kb. In addition, the sequences are found to suffice for chromosome counting and for choosing and initiating X inactivation.

Genetic aspects, Genetically modified animals, Mammals

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Role of the Xist gene in X chromosome choosing

Article Abstract:

Research was conducted to study female embryos and newly born mice with a deletion in one of the two copies of the Xist gene to examine whether somatic cells had inactivated the wild-type X chromosome. Double-stranded Xist sequence was determined with Cy3 nucleotides by nick translation while embryos were dissociated into individual cells utilizing trypsin. Results indicated the deletion of the binding site of a negative factor would block and activate the wild-type X chromosome.

Physiological aspects, Mice, Mice (Rodents), Embryology, Animal embryology, Somatic hybrids, Hybrid cells

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X chromosome inactivation is mediated by Xist RNA stabilization

Article Abstract:

Low level Xist expression is detected from active X chromosomes (Xa) in female embryonic stem cells before X inactivation. It is expressed at higher levels after differentiation, only from the inactive X chromosome (Xi). Xist expression from the Xi is increased by differentiating female cells. Regulation of the transition from low to high level is by the stabilization of Xist transcripts at the Xi. Such changes could be regulated by many different mechanisms.

Observations, Cell research, Cytological research

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