SIRT2 regulates apoptosis by inducing mitophagy in sheep cumulus cells.

Cumulus cells surrounding oocytes furnish nutritional support crucial for oocyte maturation in vitro, and thereby enhance oocyte quality significantly. Our previous studies affirmed the role of SIRT2 in regulation of mitochondrial function in sheep granulosa cells. However, the effect of SIRT2 action on mitophagy in these cells remain unclear. Here, RNA-seq was used to scrutinize pathways where differentially expressed genes (DEGs) are enriched following SIRT2 knockdown in cumulus cells. Prior to SIRT2 knock down, cumulus cells were treated with the mitophagy inhibitor Mdivi-1. Potential mechanisms by which SIRT2 affects apoptosis via mitophagy were explored. Results indicated that DEGs after SIRT2 knockdown were enriched in various pathways including mitochondria, mitophagy, and apoptosis. The expression levels of CASP3/CASP9 were significantly increased after mitophagy activation (P < 0.01), whereas inhibition of mitophagy had no effect on apoptosis (P > 0.05). Pretreatment of cumulus cells with Mdivi-1 prior to SIRT2 knockdown significantly reduced the expression of mitophagy-related genes, the number of autolysosomes, the expression of CASP3/CASP9, and the levels of Ca2+ and cytochrome C (P < 0.05). In addition, an improvement in mitochondrial morphology and increases in ATP levels and mitochondrial DNA (mtDNA) copy numbers were observed. Interestingly, double knockdown of SIRT2 and MAPK15 was found to reverse increased mitophagy and apoptosis activity caused by SIRT2 knockdown. Our findings indicate that SIRT2 modulate apoptosis in cumulus cells by regulating mitophagy, with MAPK15 likely playing a pivotal role in this process.

[National survey of urban sewage reuse in China].

On the basis of the national survey of the urban sewage treatment, the survey of 2007 national urban sewage reuse was conducted under the charge of the Ministry of Water Resources. The survey results indicated that the amount of urban sewage reuse was 17.9 x 10(8) m3 x a(-1), mainly used for industry, landscape, agriculture forestry, animal husbandry, urban non-potable water, and groundwater recharge. The urban sewage reuse rate was 5.23%. There were 127 sewage reclaiming plants in China, of which the production capacity of reclaimed water reached 347.75 x 10(4) m3 x d(-1), which produced 5.74 x 10(8) m3 reclaimed water in 2007. The total investment of sewage reclaiming plants was 56.44 x 10(8) Yuan, in which the central government investment, local fiscal investment and other investments accounted for 16%, 26% and 58%, respectively. The reclaimed water price varied greatly with the purposes or areas.