Lifespan is regulated by a complex combination of environmental and genetic factors. Autophagy, which is a bulk degradation system of macromolecules and organelles, has an important role in various biological events. In Caenorhabditis elegans, several autophagy genes have been shown to have a role in promoting longevity, but many other autophagy genes have not been examined for their role in the lifespan regulation. Here we have systematically examined the effect of RNAi suppression of 14 autophagy genes on lifespan. While maternal RNAi of autophagy genes in wild-type worms tended to reduce lifespan, maternal RNAi of each of seven autophagy genes in the insulin/IGF-1 receptor daf-2 mutants extended lifespan. Remarkably, RNAi of unc-51/atg-1, bec-1/atg-6 or atg-9, from young adult, i.e. after development, extended lifespan in both wild-type animals and daf-2 mutants, although RNAi of one or two genes shortened it. Moreover, our analysis suggests that the lifespan extension, which is induced by RNAi of unc-51, bec-1 or atg-9 after development, does not require the transcription factor daf-16, the NAD + -dependent protein deacetylase sir-2.1 or the genes related to mitochondrial functions. Collectively, our results suggest that autophagy may not always be beneficial to longevity, but may also function to restrict lifespan in C. elegans.

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Thixomolded magnesium products have been applied as an alternative for plastic moldings in body frames for electronic equipments. AZ91D magnesium alloy chips are ordinarily used for thixomolding process. The carbon nanoparticle was fixed in the magnesium chip surface in order to improve the castability of thixomolding process. The manufacture of magnesium-carbon alloy is not easy, because carbon does not have the wettability for magnesium. However, the magnesium alloy chips fixed carbon nanoparticles make it possible to produce the magnesium-carbon alloy by thixomolding process. Since the fluidity of the magnesium alloy chip with carbon nanoparticle was improved in comparison with the AZ91D magnesium alloy chip, thin thickness molding became possible. In addition, mechanical properties of the thixomolded magnesium alloy made of the magnesium alloy chips fixed carbon nanoparticle were also improved.