Opposing Effects of Sirtuins on Neuronal Survival: SIRT1-Mediated Neuroprotection Is Independent of Its Deacetylase Activity

Background: Growing evidence suggests that sirtuins, a family of seven distinct NAD-dependent enzymes, are involved in the regulation of neuronal survival. Indeed, SIRT1 has been reported to protect against neuronal death, while SIRT2 promotes neurodegeneration. The effect of SIRTs 3–7 on the regulation of neuronal survival, if any, has yet to be reported. Methodology and Principal Findings: We examined the effect of expressing each of the seven SIRT proteins in healthy cerebellar granule neurons (CGNs) or in neurons induced to die by low potassium (LK) treatment. We report that SIRT1 protects neurons from LK-induced apoptosis, while SIRT2, SIRT3 and SIRT6 induce apoptosis in otherwise healthy neurons. SIRT5 is generally localized to both the nucleus and cytoplasm of CGNs and exerts a protective effect. In a subset of neurons, however, SIRT5 localizes to the mitochondria and in this case it promotes neuronal death. Interestingly, the protective effect of SIRT1 in neurons is not reduced by treatments with nicotinamide or sirtinol, two pharmacological inhibitors of SIRT1. Neuroprotection was also observed with two separate mutant forms of SIRT1, H363Y and H355A, both of which lack deacetylase activity. Furthermore, LK-induced neuronal death was not prevented by resveratrol, a pharmacological activator of SIRT1, at concentrations at which it activates SIRT1. We extended our analysis to HT-22 neuroblastoma cells which can be induced to die by homocysteic acid treatment. While the effects of most of the SIRT proteins were similar to that observed in CGNs, SIRT6 was modestly protective against homocysteic acid toxicity in HT-22 cells. SIRT5 was generally localized in th

Sperm motility parameters for Steindachneridion parahybae based on open-source software

Summary: The objective of this work was to evaluate the sperm motility of 13 Steindachneridion parahybae males using open-source software (ImageJ/CASA plugin). The sperm activation procedure and image capture were initiated after semen collection. Four experimental phases were defined from the videos captured of each male as follows: (i) standardization of a dialogue box generated by the CASA plugin within ImageJ; (ii) frame numbers used to perform the analysis; (iii) post-activation motility between 10 and 20 s with analysis at each 1 s; and (iv) post-activation motility between 10 and 50 s with analysis at each 10 s. The settings used in the CASA dialogue box were satisfactory, and the results were consistent. These analyses should be performed using 50 frames immediately after sperm activation because spermatozoa quickly lose their vigor. At 10 s post-activation, 89.1% motile sperm was observed with 107.2 μm s-1 curvilinear velocity, 83.6 μm s-1 average path velocity, 77.1 μm s-1 straight line velocity; 91.6% were of straightness and 77.1% of wobble. The CASA plugin within ImageJ can be applied in sperm analysis of the study species by using the established settings. © 2013 Blackwell Verlag GmbH

Sperm characteristics of Steindachneridion parahybae (Steindachner, 1877) throughout 112h of storage at four temperatures

The objective of this study was to assess the effect of storage temperature on the fresh sperm quality of Steindachneridion parahybae over 112h of storage. Semen collected from five males was tested in a 12x4 factorial experimental design using the sperm storage times of: 0 (control), 1, 2, 4, 8, 16, 24, 36, 48, 64, 88, and 112h after collection. Temperatures tested were (mean +/- SD): 5.2 +/- 3.4, 12.9 +/- 1.6, 24.4 +/- 1.7 and 34.9 +/- 1.1 degrees C. Sperm parameters were motility rate (MOT), curvilinear velocity (VCL), average path velocity (VAP), straight line velocity (VSL), straightness (STR), sperm normality (NOR) and survival rate (SUR). The parameters VCL, VAP and VSL were grouped by principal component analysis to create the sperm velocity (VS). The parameters assessed exhibited effects (P<0.05) of the exposure time and temperature. Interactive effects between temperature and time (P<0.05) were observed for STR, NOR and SUR, and quadratic effects for factors MOT and VS (P<0.05). Pearson's linear correlation was verified between the parameters studied (P<0.05), indicating MOT, VCL and STR as good indicators of sperm quality. Chilling at temperatures around 5 degrees C and heating at around 35 degrees C were harmful to S. parahybae spermatozoa. It is suggested that short-term (up to 8h) semen storage - if necessary - should be within a range of 15-25 degrees C.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP