The question of the regulation of the X in the presence of three sets of autosomes has long fascinated researchers 50 Subsequently, global analyses of gene expression in multiple species and tissues demonstrated upregulation of expressed X-linked versus autosomal genes 3958 AMELY itself encodes a protein expressed in developing tooth-buds 49and has an X-homologue 50mutation of which causes X-linked amelogenesis imperfecta Evidence of evolutionary up-regulation of the single active X chromosome in mammals based on Clc4 expression levels in Mus spretus and Mus musculus.
The mouse four-core genotype system pioneered by Burgoyne and Arnold 6 has helped sort out effects of hormones from those of the sex chromosomes on phenotypes by producing XX males and XY females. The master sex-determination locus in threespine sticklebacks is on a nascent Y chromosome.
In mammals and C. Haldane JBS. Y-specific STSs [primer sequences available from the literature 33637 ] were amplified by PCR and analysed by agarose gel electrophoresis.
The molecular mechanisms of dosage compensation are not completely understood in mammals, especially those responsible for X upregulation. Sex-Specific Differences and Disease Susceptibility Sex-specific differences are usually ascribed to hormonal effects.
Recurrent duplication and deletion polymorphisms on the long arm of the Y chromosome in normal males.
However, random X inactivation may be the norm, as shown in human and rabbit Genomic imprinting effects on brain development and function. In contrast, sex chromosome aneuploidy is comparatively well tolerated because of the paucity of essential genes on the Y and inactivation of all but one upregulated X copy per diploid genome.
Imprinted gene clusters have features redolent of the inactive X: Long noncoding RNAs and epigenetic changes are often involved in their regulation, suggesting common regulatory and evolutionary pathways These studies suggest that the presence of two active X chromosomes can be tolerated at specific developmental stages but cannot be sustained throughout development.
I would like to thank the members of my laboratory, in particular, X.