title: Evolution of vertebrate sex chromosomes and dosage compensation.
abstract: Differentiated sex chromosomes in mammals and other vertebrates evolved independently but in strikingly similar ways. Vertebrates with differentiated sex chromosomes share the problems of the unequal expression of the genes borne on sex chromosomes, both between the sexes and with respect to autosomes. Dosage compensation of genes on sex chromosomes is surprisingly variable - and can even be absent - in different vertebrate groups. Systems that compensate for different gene dosages include a wide range of global, regional and gene-by-gene processes that differ in their extent and their molecular mechanisms. However, many elements of these control systems are similar across distant phylogenetic divisions and show parallels to other gene silencing systems. These dosage systems cannot be identical by descent but were probably constructed from elements of ancient silencing mechanisms that are ubiquitous among vertebrates and shared throughout eukaryotes.
authors.affiliation: Trobe Institute of Molecular Science, La Trobe University, Bundoora, Victoria 3186, Australia, and the Australian National University and University of Canberra, Canberra, Australian Capital Territory 2000, Australia.
authors.forename: Jennifer A Marshall
authors.initials: JA
authors.lastname: Graves
mesh_terms: D000818:Animals; D004303:Dosage Compensation, Genetic; D019143:Evolution, Molecular; D015870:Gene Expression; D006801:Humans; D008957:Models, Genetic; D012730:Sex Chromosomes / Q000235:genetics*