Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/99921
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Type: | Journal article |
Title: | Lack of sex chromosome specific meiotic silencing in platypus reveals origin of MSCI in therian mammals |
Author: | Daish, T. Casey, A. Grutzner, F. |
Citation: | BMC Biology, 2015; 13(1):106-1-106-13 |
Publisher: | BioMed Central |
Issue Date: | 2015 |
ISSN: | 1741-7007 1741-7007 |
Statement of Responsibility: | Tasman J. Daish, Aaron E. Casey and Frank Grutzner |
Abstract: | Background: In therian mammals heteromorphic sex chromosomes are subject to meiotic sex chromosome inactivation (MSCI) during meiotic prophase I while the autosomes maintain transcriptional activity. The evolution of this sex chromosome silencing is thought to result in retroposition of genes required in spermatogenesis from the sex chromosomes to autosomes. In birds sex chromosome specific silencing appears to be absent and global transcriptional reductions occur through pachytene and sex chromosome-derived autosomal retrogenes are lacking. Egg laying monotremes are the most basal mammalian lineage, feature a complex and highly differentiated XY sex chromosome system with homology to the avian sex chromosomes, and also lack autosomal retrogenes. In order to delineate the point of origin of sex chromosome specific silencing in mammals we investigated whether MSCI exists in platypus. Results: Our results show that platypus sex chromosomes display only partial or transient colocalisation with a repressive histone variant linked to therian sex chromosome silencing and surprisingly lack a hallmark MSCI epigenetic signature present in other mammals. Remarkably, platypus instead feature an avian like period of general low level transcription through prophase I with the sex chromosomes and the future mammalian X maintaining association with a nucleolus-like structure. Conclusions: Our work demonstrates for the first time that in mammals meiotic silencing of sex chromosomes evolved after the divergence of monotremes presumably as a result of the differentiation of the therian XY sex chromosomes. We provide a novel evolutionary scenario on how the future therian X chromosome commenced the trajectory toward MSCI. |
Keywords: | Sex Chromosomes Animals Platypus Immunohistochemistry In Situ Hybridization, Fluorescence Gene Expression Profiling Evolution, Molecular Meiotic Prophase I Meiosis Epigenesis, Genetic Gene Silencing Male |
Rights: | © 2015 Daish et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. |
DOI: | 10.1186/s12915-015-0215-4 |
Grant ID: | ARC |
Published version: | http://dx.doi.org/10.1186/s12915-015-0215-4 |
Appears in Collections: | Aurora harvest 7 Molecular and Biomedical Science publications |
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hdl_99921.pdf | Published version | 3.76 MB | Adobe PDF | View/Open |
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