Balancing the dose in the mouse.
Organisms that use a chromosomal basis of sex determination have a problem of gene inequality. In the mouse, this dimorphism is evident by the presence of two X-chromosomes in females, while males have a single X- and a single Y-chromosome. To balance this disparity, one of the two female X-chromosomes is transcriptionally silenced to neutralize the gene dose with the XY male. Dosage compensation in mammals is known as X-chromosome inactivation (XCI) and is a crucial early developmental process. XCI is an example of epigenetics: a phenotype resulting in changes on a chromosome without a change in nucleic acid sequence. Studies in mouse embryology and genetics have answered many questions about the process of balancing the dose. In this chapter, I highlight how the mouse dosage compensates the gene disparity between XX females and XY males in a crucial epigenetic process called X-chromosome inactivation (XCI).
The Department of Neuroscience, Weill Cornell Medical College, White Plains, NY 10605, USA. Med2008@med.cornell.edu
Mary E
ME
Donohoe
D000818:Animals; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D018628:Gene Dosage / Q000502:physiology*; D020868:Gene Silencing / Q000502:physiology*; D008297:Male; D051379:Mice; D019849:Sex Determination Processes / Q000502:physiology*; D014960:X Chromosome / Q000235:genetics / Q000378:metabolism*; D049951:X Chromosome Inactivation / Q000502:physiology*; D014998:Y Chromosome / Q000235:genetics / Q000378:metabolism*