Female meiotic sex chromosome inactivation in chicken.
During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2009-05-01
|
| Series: | PLoS Genetics |
| Online Access: | http://europepmc.org/articles/PMC2678266?pdf=render |
| _version_ | 1818174593101201408 |
|---|---|
| author | Sam Schoenmakers Evelyne Wassenaar Jos W Hoogerbrugge Joop S E Laven J Anton Grootegoed Willy M Baarends |
| author_facet | Sam Schoenmakers Evelyne Wassenaar Jos W Hoogerbrugge Joop S E Laven J Anton Grootegoed Willy M Baarends |
| author_sort | Sam Schoenmakers |
| collection | DOAJ |
| description | During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs) may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis. |
| first_indexed | 2024-12-11T19:46:52Z |
| format | Article |
| id | doaj.art-032f8631883c433f8091d66823b2e37b |
| institution | Directory Open Access Journal |
| issn | 1553-7390 1553-7404 |
| language | English |
| last_indexed | 2024-12-11T19:46:52Z |
| publishDate | 2009-05-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Genetics |
| spelling | doaj.art-032f8631883c433f8091d66823b2e37b2022-12-22T00:52:53ZengPublic Library of Science (PLoS)PLoS Genetics1553-73901553-74042009-05-0155e100046610.1371/journal.pgen.1000466Female meiotic sex chromosome inactivation in chicken.Sam SchoenmakersEvelyne WassenaarJos W HoogerbruggeJoop S E LavenJ Anton GrootegoedWilly M BaarendsDuring meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs) may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.http://europepmc.org/articles/PMC2678266?pdf=render |
| spellingShingle | Sam Schoenmakers Evelyne Wassenaar Jos W Hoogerbrugge Joop S E Laven J Anton Grootegoed Willy M Baarends Female meiotic sex chromosome inactivation in chicken. PLoS Genetics |
| title | Female meiotic sex chromosome inactivation in chicken. |
| title_full | Female meiotic sex chromosome inactivation in chicken. |
| title_fullStr | Female meiotic sex chromosome inactivation in chicken. |
| title_full_unstemmed | Female meiotic sex chromosome inactivation in chicken. |
| title_short | Female meiotic sex chromosome inactivation in chicken. |
| title_sort | female meiotic sex chromosome inactivation in chicken |
| url | http://europepmc.org/articles/PMC2678266?pdf=render |
| work_keys_str_mv | AT samschoenmakers femalemeioticsexchromosomeinactivationinchicken AT evelynewassenaar femalemeioticsexchromosomeinactivationinchicken AT joswhoogerbrugge femalemeioticsexchromosomeinactivationinchicken AT joopselaven femalemeioticsexchromosomeinactivationinchicken AT jantongrootegoed femalemeioticsexchromosomeinactivationinchicken AT willymbaarends femalemeioticsexchromosomeinactivationinchicken |