frequency of heterologous synapsis increases with aging in Robertsonian heterozygous male mice

The house mouse is characterised by highly variable chromosome number due to the presence of Robertsonian (Rb) chromosomes. During meiosis in Rb heterozygotes, intricated chromosomal figures are produced, and many unsynapsed regions are present during the first prophase, triggering a meiotic silenci...

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Bibliographic Details
Published in:Chromosome research 2012-02, Vol.20 (2), p.269-278
Main Authors: Vasco, Chiara, Manterola, Marcia, Page, Jesus, Zuccotti, Maurizio, de la Fuente, Roberto, Redi, Carlo Alberto, Fernandez-Donoso, Raul, Garagna, Silvia
Format: Article
Language:English
Subjects:
Aging
Aging - genetics
Animal Genetics and Genomics
Animals
Biomedical and Life Sciences
Cell Biology
cell death
Cell division
chromatin
chromosome number
Chromosome Pairing
Chromosomes
Genetic research
heterozygosity
Heterozygote
Human Genetics
Life Sciences
Male
Mice
Mus musculus
Plant Genetics and Genomics
prophase
Rodents
Sex Chromosomes
Spermatocytes - metabolism
spermatogenesis
spermatozoa
Translocation, Genetic
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Summary:The house mouse is characterised by highly variable chromosome number due to the presence of Robertsonian (Rb) chromosomes. During meiosis in Rb heterozygotes, intricated chromosomal figures are produced, and many unsynapsed regions are present during the first prophase, triggering a meiotic silencing of unsynapsed chromatin (MSUC) in a similar mode to the sex chromosome inactivation. The presence of unsynapsed chromosome regions is associated with impaired spermatogenesis. Interestingly, in male mice carrying multiple Rb trivalents, the frequency of germ cell death, defective tubules, and altered sperm morphology decreases during aging. Here, we studied whether synapsis of trivalent chromosomes and MSUC are involved in this improvement. By immunocytochemistry, we analysed the frequency of unsynapsed chromosomes and of those positive to γH2AX (a marker of MSUC) labelling in spermatocytes of 3-, 5- and 7-month-old Rb heterozygotes. With aging, we observed a decrease of the frequency of unsynapsed chromosomes, of spermatocytes bearing them and of trivalents carrying γH2AX-negative unsynapsed regions. Our quantitative results show that both synapsis and MSUC processes are better accomplished during male aging, partially accounting for the improvement of spermatogenesis.
ISSN:0967-3849
1573-6849
DOI:10.1007/s10577-011-9272-x