The sensory system acts with a neuromedin U signaling pathway to mediate food type-dependent effects on lifespan

In order to survive, the animal uses its sensory system to interpret the complexity of its environment. Interestingly, a subset of sensory neurons, which function in taste or olfaction, has been found to influence the lifespan of C. elegans and Drosophila. Although the mechanisms by which these neurons affect lifespan are unknown, the nature of these neurons suggest that the sensory influence on lifespan is mediated by food-derived cues. This thesis shows that sensory neurons recognize different food types to affect C. elegans lifespan through a mechanism distinct from that of calorie restriction, which is commonly studied by restricting the levels of food intake. Moreover, this work identifies a neuropeptide signaling pathway, the neuromedin U pathway, which acts with the sensory system to affect C. elegans lifespan in response to specific food-derived cues, such as the lipopolysaccharide (LPS) structure of its E. coli bacterial food source. The neuromedin U neuropeptide receptor nmur-1, which is expressed in sensory neurons, interneurons and the somatic gonad, shortens lifespan on E. coli food sources that have short LPS. In contrast, a neuromedin U ligand precursor, nlp-44, which is expressed in only two pairs of sensory neurons, lengthens lifespan in a food source-dependent manner. Genetic epistasis analysis suggests that nlp-44 might encode ligands that act downstream of or in parallel to nmur-1. Since C. elegans has three other members of the neuromedin U receptor (NMUR) family, future studies are needed to determine whether nlp 44 encodes different peptide ligands that could then act on several NMUR proteins, including NMUR-1. The identification of a neuromedin U pathway that mediates the sensory recognition of food quality provides a genetic framework to elucidate further the mechanisms that underlie this sensory influence on lifespan. In addition, the observation that a neuropeptide signaling pathway promotes the sensory influence on lifespan raises the intriguing possibility that other neuropeptides might also affect lifespan in response to other types of sensory cues. These neuropeptide pathways might thus integrate different sensory information with signaling pathways already known to regulate lifespan

A Neuromedin U Receptor Acts with the Sensory System to Modulate Food Type-Dependent Effects on C. elegans Lifespan

Different food types modulate worm lifespan and involve the neuropeptide receptor NMUR-1, which acts with the sensory neurons in a bacterial lipopolysaccaharide structure-dependent manner

Numerical approach for estimation of stress strain state of deep tunnels

Numerical approach and results of theoretical calculation of deep tunnels are described in this issue. Here described surrounding continuum is fractured rocks. Calculation provided in static case. Results of this investigation aimed for estimation of stress state and development of strengthening measures of deep excavations