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. gH2AX 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 gH2AX 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.
Subject(s)
Apoptosis , Cell Cycle , Chromosome Pairing , DNA Repair , Spermatocytes/metabolism , Animals , Caspase 9/metabolism , Cell Cycle Proteins , DNA-Binding Proteins , Male , Mice , Nuclear Proteins/metabolism , Rad51 Recombinase/metabolism , Spermatocytes/pathologyABSTRACT
The central or peripheral distribution of condensed chromatin (CC) was studied in pachytene spermatocyte nuclei in Mus domesticus, 2n = 40; Pudu puda, 2n = 70; Ctenomys opimus, 2n = 26 and Octodon degus, 2n = 58. Species were chosen according to the morphological characteristics of their chromosomal complements and in particular, the terminal or medial chromosomal localisation of the pericentromeric constitutive heterochromatin. Counts were made by defining the areas corresponding to peripheral and central location in each nuclear section from a series. The null hypothesis (i.e. random distribution of CC) was rejected. In the nuclear sections of Mus domesticus and Pudu puda, 69% and 74% of CC, respectively, was found in the peripheral nuclear space, while in those of Octodon degus and Ctenomys opimus, 69% and 65% of CC, respectively, was found in the central nuclear space. We estimate that if the CC measured in spermatocyte nuclei corresponds mainly to pericentromeric constitutive heterochromatin, the distribution found is consistent with that expected in accordance with the nuclear architecture model for meiocytes (Fernández-Donoso, 1982; Fernández-Donoso & Berrios, 1985). This model proposes a peripheral nuclear localisation for pericentromeric heterochromatin of telocentric bivalents and a relatively central nuclear localisation for pericentromeric heterochromatin of metacentric bivalents. We also discuss some of the biological consequences that could arise from the conservation of such distributions.
Subject(s)
Heterochromatin/metabolism , Heterochromatin/ultrastructure , Meiosis , Spermatocytes/physiology , Spermatocytes/ultrastructure , Animals , Cell Nucleus/genetics , Cell Nucleus/metabolism , Cell Nucleus/ultrastructure , Deer , Male , Mammals , Mice , Models, Biological , Prophase , Rodentia , Species SpecificityABSTRACT
En los últimos años la menopausia ha adquirido notoriedad por las serias consecuencias que tiene sobre el esqueleto y el sistema cardiovascular. Con el objeto de conocer algunas características de esta etapa de la vida se entrevistó a 722 mujeres entre 35 y 65 años: 412 fueron consideradas menopáusicas. La mediana edad de menopausia (EM) fue 47,8 años; el promedio, 47,6 + - 4,6, y el normalizado con Longit-Log, 47,0 + - 4,4 años. El 46,1% de las mujeres cesó de menstruar sin alteraciones previas de sus ciclos. En las restantes, 84,3% presentó trastornos durante menos de un año. El 34% de las mujeres jamás presentó bochornos. De las 223 (53,7%) que mantenían vida sexual activa, el 61,9% presentó dispareunia. En nuestra población estudiada la EM es menor que la publicada por autores extranjeros. Es menor en las esterilizadas quirúrgicamente (p. 0,003); en las fumadoras, (p. 0,01), y en las que tuvieron una menarquia más precoz (p. 0,05)
