Meiotic Silencing in Pigs: A Case Study in a Translocated Azoospermic Boar

Carriers of balanced constitutional reciprocal translocations usually present a normal phenotype, but often show reproductive disorders. For the first time in pigs, we analyzed the meiotic process of an autosome-autosome translocation associated with azoospermia. Meiotic process analysis revealed the presence of unpaired autosomal segments with histone gamma H2AX accumulation sometimes associated with the XY body. Additionally, gamma H2AX signals were observed on apparently synapsed autosomes other than the SSC1 or SSC15, as previously observed in Ataxia with oculomotor apraxia type 2 patients or knock-out mice for the Senataxin gene. Gene expression showed a downregulation of genes selected on chromosomes 1 and 15, but no upregulation of SSCX genes. We hypothesized that the total meiotic arrest observed in this boar might be due to the silencing of crucial autosomal genes by the mechanism referred to as meiotic silencing of unsynapsed chromatin (MSUC).

Automated summary

Balanced constitutional reciprocal translocations in carriers typically result in a normal phenotype but can lead to reproductive disorders. A study in pigs found that an autosome-autosome translocation associated with azoospermia can cause unpaired autosomal segments in the meiotic process, potentially leading to total meiotic arrest. Gene expression analysis revealed downregulation of genes on chromosomes 1 and 15, without upregulation of SSCX genes, suggesting a mechanism involving the silencing of autosomal genes during meiosis.