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The evolution of dosage‐compensation mechanisms
Author(s) -
Marín Ignacio,
Siegal Mark L.,
Baker Bruce S.
Publication year - 2000
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/1521-1878(200012)22:12<1106::aid-bies8>3.0.co;2-w
Subject(s) - dosage compensation , heterogametic sex , biology , genetics , hermaphrodite , gene dosage , evolution of sexual reproduction , gene , chromosome , x chromosome , doublesex , caenorhabditis elegans , evolutionary biology , gene expression , rna , zoology , rna splicing
Abstract Dosage compensation is the process by which the expression levels of sex‐linked genes are altered in one sex to offset a difference in sex‐chromosome number between females and males of a heterogametic species. Degeneration of a sex‐limited chromosome to produce heterogamety is a common, perhaps unavoidable, feature of sex‐chromosome evolution. Selective pressure to equalize sex‐linked gene expression in the two sexes accompanies degeneration, thereby driving the evolution of dosage‐compensation mechanisms. Studies of model species indicate that what appear to be very different mechanisms have evolved in different lineages: the male X chromosome is hypertranscribed in drosophilid flies, both hermaphrodite X chromosomes are downregulated in the nematode Caenorhabditis elegans , and one X is inactivated in mammalian females. Moreover, comparative genomic studies demonstrate that the trans ‐acting factors (proteins and non‐coding RNAs) that have been shown to mediate dosage compensation are unrelated among the three lineages. Some tantalizing similarities in the fly and mammalian mechanisms, however, remain to be explained. BioEssays 22:1106–1114, 2000. © 2000 John Wiley & Sons, Inc.