Dosage Compensation

In mammals, birds, snakes and many lizards and fish, sex is determined genetically (either male XY heterogamy or female ZW heterogamy), whereas in alligators, and in many reptiles and turtles, the temperature at which eggs are incubated determines sex. Different sex-determining systems (and sex chromosome pairs) have evolved independently in different vertebrate lineages. Homology shared by Xs and Ys (and Zs and Ws) within species demonstrates that differentiated sex chromosomes were once homologous, and that the sex-specific non-recombining Y (or W) was progressively degraded. Consequently, genes are left in single copy in the heterogametic sex, which results in an imbalance of the dosage of genes on the sex chromosomes between the sexes, and also relative to the autosomes. Dosage compensation has evolved in diverse species to compensate for these dose differences, with the stringency of compensation apparently differing greatly between lineages, perhaps reflecting the concentration of genes on the original autosome pair that required dosage compensation.

Discovery

Publications

Hanrahan, B.J., Chang, J King, Milton, A.M., Lister, N.C., Dissanayake, D.S.B., Hammond, J.M., Reis, A.L.M., Deveson, I.W., Ruiz-Herrera, A., Patel, H.R., Graves, J.A.M., Georges, A., and Waters, P.D. 2024. Partial sex chromosome dosage compensation in a sex reversing skink. [submitted]

Lister NC, Milton AM, Patel HP, Waters SA, Hanrahan BJ, McIntyre KL, Livernois AM, Horspool WB, Wee LK, Ringel AR, Mundlos S, Robson MI, Shearwin-Whyatt L, Grützner F, Graves JAM, Ruiz-Herrera A, and Waters PD. 2024. Incomplete transcriptional dosage compensation of chicken and platypus sex chromosomes is balanced by post-transcriptional compensation. PNAS

McIntyre KL, Waters SA, Zhong L, Hart‑Smith G, Raftery M, Chew ZA, Patel HR, Graves JAM and Waters PD. 2024. Identification of the RSX interactome in a marsupial shows functional coherence with the Xist interactome during X inactivation. Genome Biology 25:134 [https://doi.org/10.1186/s13059-024-03280-0]

Milton AM, Laia Marín-Gual L, Lister NC, McIntyre KL, Grady PGS, Laird MK, Bond DM, Hore TA, O’Neill RJ, Pask AJ, Renfree MB, Ruiz-Herrera A and Waters, PD. 2024. Imprinted X chromosome inactivation in marsupials: The paternal X arrives at the egg with a silent DNA methylation profile. PNAS 121(36):e2412185121 [https://doi.org/10.1073/pnas.2412185121]

Lister, N. 2018. RNA directed epigenetic regulation and modification of the human genome. PhD Thesis, University of New South Wales, Sydney Australia [pdf]

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