TAILIEUCHUNG - Báo cáo sinh học: "A balancing act between the X chromosome and the autosomes"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: A balancing act between the X chromosome and the autosomes. | J. Biol. Journal of Biology BioMed Central Minireview A balancing act between the X chromosome and the autosomes Mimi K Cheng and Christine M Disteche Address Departments of Pathology and Medicine University of Washington Seattle WA 98195 USA. Correspondence Christine Disteche. Email cdistech@ Published 16 February 2006 Journal of Biology 2006 5 2 The electronic version of this article is the complete one and can be found online at http content 5 1 2 2006 BioMed Central Ltd Abstract Dosage compensation equalizes gene dosage between males and females but its role in balancing expression between the X chromosome and the autosomes may be far more important. Now DNA microarrays have shown equality between the average expression of X-linked genes and that of autosomal genes in male and female tissues of flies worms and mice. Sex chromosomes have evolved from an ordinary pair of autosomes many times including in the lineages of flies worms mammals and many others. In each case the lack of recombination between the X and Y chromosomes led to loss and differentiation of genes on the Y chromosome leaving males with a single copy of most X-linked genes 1 . To protect organisms against deleterious effects of this X-chromosome monosomy mechanisms of dosage compensation evolved. The regulated dosage of any one gene is not necessarily important for the viability of an organism but the gene dosage of a whole chromosome or even a part of a chromosome is vital. In Drosophila having only one copy of being haploid for as little as 1 of the genome reduces viability and being haploid for more than 3 of the genome is lethal 2 . Given that the Drosophila X chromosome makes up about 20 of the genome flies cannot tolerate X-chromosome deletions 2 3 and yet Drosophila females have two X chromosomes whereas males only have one. How is this tolerated An early clue to the mechanism of dosage compensation between the sexes was found in autoradiographs of salivary gland

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