Interferência da condição climática na integridade de espermatozoides ovinos submetidos à criopreservação / Climate condition interference on ram spermatozoa integrity submitted to cryopreservation

Avaliou-se a integridade de espermatozoides ovinos colhidos e criopreservados em diferentes situações climáticas na região semiárida do estado da Paraíba. As colheitas de sêmen foram realizadas em duas épocas do ano, período seco e período chuvoso, utilizando cinco machos adultos da raça Santa Inês, com histórico favorável de fertilidade. Os ejaculados foram avaliados quanto à motilidade, vigor, concentração e morfologia espermática, após a formação do pool e diluição em Tris-gema, na concentração final de 240x10(6) espermatozoides/mL. Motilidade total e vigor espermático não diferiram entre as épocas seca e chuvosa. Valores de integridade do acrossoma e da membrana plasmática, e o potencial de membrana mitocondrial foram mais baixos (P<0,05) na época com menor índice pluviométrico. Conclui-se que a reprodução de ovinos criados na região do semiárido paraibano sofre ação da condição climática e sugere-se que a criopreservação de espermatozoides ovinos seja realizada no período de maior índice pluviométrico na região.

Ram spermatozoa integrity collected and cryopreserved in different climatic situations in the semiarid region of Paraíba state was evaluated. Semen samples were collected in two periods: a dry and a rainy season, using five mature Santa Inês males, with favorable historical fertility. Ejaculates were evaluated for motility, vigor, concentration and morphology, after a pool formation and dilution in Tris-yolk egg, at 240x10(6)/mL final concentration. Motility and sperm vigor did not differ between dry and rainy seasons. Acrosome integrity, plasma membrane and mitochondrial membrane potential were lower (P>0.05) at the time with less rainfall. We concluded that sheep reproduction raised in semi-arid Paraiba region suffers climatic condition influence and the lowest rainfall period is deleterious to the sperm cells integrity subjected to cryopreservation process. It is suggested that ram spermatozoa cryopreservation be done in period of greatest rainfall in this region.

Intracellular pH is a Critical Element in Apoptosis Triggered by GM-CSF Deprivation in TF1 Cells

BACKGROUND: Hemopoietic cells require the constant presence of growth factors for survival in vitro and in vivo. Caspases have been known as central executors of apoptotic cell death. We have, therefore, investigated the pathways that regulate caspase activity and apoptosis using the CD34+ cell line, TF-1 which requires GM-CSF for survival. METHODS: Apoptosis was measured by annexin V staining and mitochondrial membrane potential was measured by DiOC6 labelling. Intracellular pH was measured using pH sensitive fluorochrome, BCECF or SNARF-1, followed by flow cytometry analysis. Caspase activation was analyzed by PARP cleavage using anti-PARP antibody. RESULTS: Removal of GM-CSF induceed PARP cleavage, a hallmark of caspase activity, concomitant with pHi acidification and a drop in mitochondrial potential. Treatment with ZVAD, a competitive inhibitor of caspases, partially rescued cell death without affecting pHi acidification and the reduction of mitochondrial potential, suggesting that both these events act upstream of caspases. Overexpression of Bcl-2 prevented cell death induced by GM-CSF deprivation as well as pHi acidification and the reduction in mitochondrial membrane potential. In parental cells maintained with GM-CSF, EIPA, a competitive inhibitor of Na+/H+ antiporter induced apoptosis, accompanied by a drastic reduction in mitochondrial potential. In contrast, EIPA induced apoptosis in Bcl-2 transfectants without causing mitochondrial membrane depolarization. CONCLUSION: Taken together, our results suggest that the regulation of H fluxes, either through a mitochondrion- dependent or independent pathway, is central to caspase activation and apoptosis.

Effects of rotenone on mitochondrial potential and cell cycles in PC12 cells / 第三军医大学学报

Objective To observe the effects of rotenone on the mitochondrial membrane potential and cell cycles in pheochromocytoma (PC12) cells and to explore the injury mechanism of rotenone on dopaminergic neuron. Methods The mitochondrial membrane potential and cell cycles were determined by flow cytometry. Results After treatment with 5.0 ?mol/L rotenone for 12 and 24 h, the percentage of G 0/G 1 phase and S phase in cultured PC12 cells decreased gradually (P