Dosage compensation is less effective in birds than in mammals

Yuichiro Itoh, Esther Melamed, Xia Yang, Kathy Kampf, Susanna Wang, Nadir Yehya, Atila Van Nas, Kirstin Replogle, Mark R. Band, David F. Clayton, Eric E. Schadt, Aldons J. Lusis, Arthur P. Arnold

Research output: Contribution to journalArticle

Abstract

Background. In animals with heteromorphic sex chromosomes, dosage compensation of sex-chromosome genes is thought to be critical for species survival. Diverse molecular mechanisms have evolved to effectively balance the expressed dose of X-linked genes between XX and XY animals, and to balance expression of X and autosomal genes. Dosage compensation is not understood in birds, in which females (ZW) and males (ZZ) differ in the number of Z chromosomes. Results. Using microarray analysis, we compared the male:female ratio of expression of sets of Z-linked and autosomal genes in two bird species, zebra finch and chicken, and in two mammalian species, mouse and human. Male:female ratios of expression were significantly higher for Z genes than for autosomal genes in several finch and chicken tissues. In contrast, in mouse and human the male:female ratio of expression of X-linked genes is quite similar to that of autosomal genes, indicating effective dosage compensation even in humans, in which a significant percentage of genes escape X-inactivation. Conclusion. Birds represent an unprecedented case in which genes on one sex chromosome are expressed on average at constitutively higher levels in one sex compared with the other. Sex-chromosome dosage compensation is surprisingly ineffective in birds, suggesting that some genomes can do without effective sex-specific sex-chromosome dosage compensation mechanisms.

Original languageEnglish (US)
Article number2
JournalJournal of Biology
Volume6
Issue number1
DOIs
StatePublished - Mar 29 2007

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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  • Cite this

    Itoh, Y., Melamed, E., Yang, X., Kampf, K., Wang, S., Yehya, N., Van Nas, A., Replogle, K., Band, M. R., Clayton, D. F., Schadt, E. E., Lusis, A. J., & Arnold, A. P. (2007). Dosage compensation is less effective in birds than in mammals. Journal of Biology, 6(1), [2]. https://doi.org/10.1186/jbiol53