Alterations in chromosomal synapses and DNA repair in apoptotic spermatocytes of Mus m. domesticus

  • E. Ayarza Universidad de Chile, Programa Genética Humana, Chile.
  • M. González Universidad de Chile, Programa Genética Humana, Chile.
  • F. López Universidad de Chile, Programa Genética Humana, Chile.
  • R. Fernández-Donoso Universidad de Chile, Programa Genética Humana, Chile.
  • J. Page Universidad Autonoma de Madrid, Departamento de Biologí­a Celular, Spain.
  • S. Berrios | sberrios@med.uchile.cl Universidad de Chile, Programa Genética Humana, Chile.

Abstract

We investigated whether apoptotic spermatocytes from the mouse Mus m. domesticus presented alterations in chromosomal synapses and DNA repair. To enrich for apoptotic spermatocytes, the scrotum's temperature was raised by partially exposing animals for 15 min to a 42ºC water bath. Spermatocytes in initial apoptosis were identified in situ by detecting activated Caspase-9.  SYCP1 and SYCP3 were markers for evaluating synapses or the structure of synaptonemal complexes and Rad51 and γH2AX for detecting DNA repair and chromatin remodeling. Apoptotic spermatocytes were concentrated in spermatogenic cycle stages III-IV (50.3%), XI-XII (44.1%) and IX-X (4.2%). Among apoptotic spermatocytes, 48% were in middle pachytene, 44% in metaphase and 6% in diplotene. Moreover, apoptotic spermatocytes showed several structural anomalies in autosomal bivalents, including splitting of chromosomal axes and partial asynapses between homologous chromosomes. γH2AX and Rad51 were atypically distributed during pachytene and as late as diplotene and associated with asynaptic chromatin, single chromosome axes or discontinuous chromosome axes. Among apoptotic spermatocytes at pachytene, 70% showed changes in the structure of synapses, 67% showed changes in γH2AX and Rad51 distribution and 50% shared alterations in both synapses and DNA repair. Our results showed that apoptotic spermatocytes from Mus m. domesticus contain a high frequency of alterations in chromosomal synapses and in the recruitment and distribution of DNA repair proteins. Together, these observations suggest that these alterations may have been detected by meiotic checkpoints triggering apoptosis.

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Author Biography

E. Ayarza, Universidad de Chile, Programa Genética Humana

Programa Genética Humana, ICBM, Facultad de Medicina

Departamento de Tecnologí­a Médica, Facultad de Medicina

Published
2016-06-14
Section
Original Papers
Supporting Agencies
FONDECYT Project #1120160, VID Universidad de Chile, Project CGL2014-53106-P from Ministerio de Economía y Competitividad (Spain)
Keywords:
Apoptosis, chromosome synapsis and recombination, heat stress, meiosis, Mus m. domesticus, spermatocytes.
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How to Cite
Ayarza, E., González, M., López, F., Fernández-Donoso, R., Page, J., & Berrios, S. (2016). Alterations in chromosomal synapses and DNA repair in apoptotic spermatocytes of Mus m. domesticus. European Journal of Histochemistry, 60(2). https://doi.org/10.4081/ejh.2016.2677