Abstract
In marsupials, dosage compensation involves silencing of the father's X-chromosome. Because no XIST orthologue has been found, how imprinted X-inactivation occurs is unknown. In eutherians, the X is subject to meiotic sex chromosome inactivation (MSCI) in the paternal germ line and persists thereafter as postmeiotic sex chromatin (PMSC). One hypothesis proposes that the paternal X is inherited by the eutherian zygote as a preinactive X and raises the possibility of a similar process in the marsupial germ line. Here we demonstrate that MSCI and PMSC occur in the opossum. Surprisingly, silencing occurs before X-Y association. After MSCI, the X and Y fuse through a dense plate without obvious synapsis. Significantly, sex chromosome silencing continues after meiosis, with the opossum PMSC sharing features of eutherian PMSC. These results reveal a common gametogenic program in two diverse clades of mammals and support the idea that male germ-line silencing may have provided an ancestral form of mammalian dosage compensation.
Original language | English (US) |
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Pages (from-to) | 9730-9735 |
Number of pages | 6 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 104 |
Issue number | 23 |
DOIs | |
State | Published - Jun 5 2007 |
Externally published | Yes |
Keywords
- Meiosis
- X-inactivation
ASJC Scopus subject areas
- General