Genetic and environmental conditions that increase longevity in Caenorhabditis elegans decrease metabolic rate

Forward and reverse selection for longevity in Drosophila is characterized by alteration of antioxidant gene expression and oxidative damage patterns

Patterns of antioxidant gene expression and of oxidative damage were measured throughout the adult life span of a selected long-lived strain (La) of Drosophila melanogaster and compared to that of their normal-lived progenitor strain (Ra). Extended longevity in the La strain is correlated with enhanced antioxidant defense system gene expression, accumulation of CuZnSOD protein, and an increase in ADS enzyme activities. Extended longevity is strongly associated with a significantly increased resistance to oxidative stress. Reverse-selecting this long-lived strain for shortened longevity (RevLa strain) yields a significant decrease in longevity accompanied by reversion to normal levels of its antioxidant defense system gene expression patterns and antioxidant enzyme patterns. The significant effects of forward and reverse selection in these strains seem limited to the ADS enzymes; 11 other enzymes with primarily metabolic functions show no obvious effect of selection on their activity levels whereas six other enzymes postulated to play a role in flux control may actually be involved in NADPH reoxidation and thus support the enhanced activities of the ADS enzymes. Thus, alterations in the longevity of these Drosophila strains are directly correlated with corresponding alterations in; 1) the mRNA levels of certain antioxidant defense system genes; 2) the protein level of at least one antioxidant defense system gene; 3) the activity levels of the corresponding antioxidant defense system enzymes, and 4) the ability of the organism to resist the biological damage arising from oxidative stress.

Metabolic mechanisms of longevity: Caloric restriction in mammals and longevity mutations in Caenorhabditis elegans; a common pathway??

Several recent studies in Caenorhabditis elegans have reported significant extension of the lifespan by probable loss of function mutations in various genes. When sequenced, many of these genes exhibited significant homology to genes in the mammalian insulin signaling cascade. For example, the daf-2 gene that has been shown to regulate lifespan in C elegans shares significant sequence homology with the insulin and IGF-1 receptor genes in mammals. Another longevity gene in the nematode, age-1, is homologous with the p110 subunit of phosphatidylinositol 3-kinase in mammals. This enzyme functions early in the mammalian insulin response cascade to influence many important cellular growth and metabolic processes. These findings and others have led to the suggestion that lifespan regulation in nematodes is controlled by a mechanism similar to that involved in lifespan extension by caloric restriction in mammals. Many intriguing similarities exist between these two model systems providing some support for this idea. However, at present there is insufficient data to conclude that similar genes or mechanisms regulate lifespan determination in nematodes and in mammals.

The spe-10 mutant has longer life and increased stress resistance

We investigated the life span of spe-10 mutant nematodes. We also tested resistance of spe-10 mutants to ultraviolet (UV) light, heat, and paraquat and examined the relationship between resistance to UV light and the fertility defect of these animals. The spe-10 mutation significantly increased mean life span. Additionally, the mutation significantly increased resistance to both UV light and to heat. Resistance to paraquat was not significantly different from that of wild-type, nor were any dauers formed at 27 degrees C. No significant correlation was found between the UV resistance and the fertility defect, nor was the UV resistance attributable to a hormetic effect. These results reinforce the importance of stress resistance in specifying increased life span and indirectly suggest that this fertility defect is not a direct cause of life span extension.