This may represent a Selleck Mizoribine general evolutionary process, since after reproductive age individuals compete with their own progeny for available nutrients. Although the functionality of the C. selleck screening library elegans immune system during aging has been extensively examined [38, 63], we now have simultaneously examined longevity and control of bacterial proliferation across worm genotype, age, and bacterial strain differences. We confirm that viable bacteria accumulate in the C. elegans intestine as they age [15], and now show that both bacterial strain type and worm genotype related to gut immunity affect intestinal bacterial

accumulation, which might play a significant role in lifespan determination, since we found that lifespan and bacterial load are inversely correlated. Previous studies had quantified bacterial proliferation this website by CFU enumeration only in N2 worms [64]. More recent studies showed substantially fewer bacteria in the gut of certain long-lived C. elegans mutants; however, these observations were by semi-quantitative microscopy only [65]. By quantitatively characterizing the kinetics of bacterial proliferation in the C. elegans intestine, in wild type and mutant worms, we establish a basis to better dissect the interplay of bacteria, host genotypes, and age. One of the aims in this study was to characterize the kinetics of intestinal bacterial

Bacterial neuraminidase colonization. Salmonella is a pathogen of C. elegans that permits examining this question since it kills worms relatively slowly, rather than in a rapid manner. However, other than consistently higher numbers, there were few cases in which Salmonella and E. coli results differed greatly. These differ from previous data that reported significant differences in the lifespan of C. elegans when grown on Salmonella compared to

E. coli [23]. The discrepancy might be explained in part by differences in methodology, since in this work we grew the worms on lawns of Salmonella rather than exposing them as L4′s. However, E.coli also is pathogenic to C. elegans [15, 31, 64], and many C. elegans antimicrobial genes are induced, some even more strongly (lys-1 and spp-1) than in the presence of other pathogens [40]. As such, E. coli is just one other bacterial species to which C. elegans can sense and respond. In our experimental system, we found significant differences in bacterial accumulation at day 2 of adult life, and that variation in the intestinal bacterial loads among the immunodeficient mutants correlated with lifespan differences. Why were differences in bacterial proliferation significant at day 2? One explanation is that since C. elegans produces nearly all of its progeny within the first 2 days of its adult life [66], immunity is tightly regulated during development and early adult life, but not post-reproductively.