RESUMEN
The increased lifespan caused by food limitation has been observed in a wide range of animals including the nematode Caenorhabditis elegans. We show here that the lifespans of eat-2 and eat-5 feeding-defective mutants and a mutant of dbl-1 encoding a TGFß ligand significantly change between the cultures fed on Escherichia coli strain OP50 or a more nutrient-rich strain HB101. On HB101 food, the eat-2, eat-5 and dbl-1 mutants show increased lifespan compared to that of the wild type. This result is probably due to nutrient limitation because the eat mutations reduce food uptake and the mutation of dbl-1 that regulates expression of several digestive enzymes leads to nutrient limitation. In contrast, the lifespans of the eat-2 and dbl-1 mutants decreased from that of the wild type on OP50 food. We found that live OP50 cells within a worm were markedly more in these mutants than in the wild type, which suggests that impaired digestion of pathogenic OP50 decreased lifespan in the eat-2 and dbl-1 mutants.