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The mechanisms related to hyperglycemia-induced pancreatic beta-cell apoptosis are poorly defined. Rat insulin-producing cells (RINm5F) cultured in high glucose concentrations (30 mM) showed increased apoptosis and protein p53 translocation to mitochondria. In addition, hyperglycemia induced both the disruption of mitochondrial membrane potential (Delta psi (m)), and an increase in reactive oxygen species (ROS), as shown by fluorescence changes of JC-1 and dichlorodihydrofluorescein-diacetate (DCDHF-DA), respectively. The increased intracellular ROS by high glucose exposure was blunted by mitochondrial-function and NADPH-oxidase inhibitors. We postulate that the concomitant mobilization of p53 protein to the mitochondria and the subsequent changes on the Delta psi (m), lead to an important pancreatic beta-cell apoptosis mechanism induced by oxidative stress caused by hyperglycemia.

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Populations of annual killifishes persist in temporary water bodies over the dry season through the expression of diapause in their drought-resistant embryos. Environmental cues may influence expression of the diapause phenotype during embryonic incubation. Millerichthys robustus is the only annual killifish distributed in North America. The aim of this review is to analyze the ecology of M. robustus development and contrast this with that of annual killifishes in austral locations. The temporary water bodies inhabited by M. robustus present the following environmental conditions: flood, drought, and humidity. During the flooding period, the environment presents the lowest temperatures, shortest photoperiod, and highest precipitation, and embryos were found in diapause I. The drought period features the highest temperatures and lowest precipitation, and embryos were found in diapause II. In contrast, during the humid period at the beginning of the rainy season, embryos were found in diapause I, II, and III, associated with the longer photoperiod and high temperatures. These dynamics of the diapause phenotypes can be explained by a combination of the strategies of phenotypic plasticity during flood and drought periods, and bet-hedging during the humid period. Moreover, the microenvironmental conditions in which embryos were buried could influence developmental trajectories. Developmental Dynamics 246:802-806, 2017. © 2017 Wiley Periodicals, Inc.

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