Degradative Tubular Lysosomes Link Pexophagy To Starvation And Early Aging In C. Elegans

Organelle-specific autophagy directs degradation of eukaryotic organelles under certain conditions. Like other organelles, peroxisomes are subject to autophagic turnover at lysosomes. However, peroxisome autophagy (pexophagy) has yet to be analyzed in a live-animal system, limiting knowledge on its regulation during an animal\u27s life. Here, we generated a tandem-fluorophore reporter that enabled real-time tracking of pexophagy in live Caenorhabditis elegans. We observed that pexophagy occurred at a population of non-canonical, tubular lysosomes specifically during starvation and aging. Remarkably, in these contexts, tubular lysosomes were the predominant type of lysosome in the intestine, transforming from vesicles. Though we found that peroxisomes were largely eliminated in early adulthood, they appeared restored in new generations. We identified peroxisomal genes that regulated age-dependent peroxisome loss and demonstrated that modifying this process altered animal lifespan. These findings reveal new facets of peroxisome homeostasis relevant to aging and challenge the prevailing perception of lysosome homogeneity in autophagy

The categorization effect in hedonic contrast: Experts differ from novices

Test stimuli are rated as less good when they follow very good context stimuli than when they are presented alone. This diminution in rating is called hedonic contrast. Contrast is attenuated if the context and the test stimuli are perceived as being in different categories. Because experts use as their basic-level categories what are the subordinate levels for novices, they will categorize when novices do not. Therefore, in the following studies, both experts and novices showed hedonic contrast when attractive context orchids preceded more neutral test orchids. However, only the novices showed hedonic contrast when attractive context irises preceded the test orchids. Novices viewed the irises and the orchids as flowers and therefore members of the same category, resulting in contrast. Experts.\u27however, viewed the irises and the orchids as being in different categories; therefore, hedonic contrast did not occur