Lifespan regulation under axenic dietary restriction: a close look at the usual suspects.

In Caenorhabditis elegans, there are several ways to impose dietary restriction (DR) all of which extend lifespan to a different degree. Until recently, the molecular mechanisms underlying the DR-mediated lifespan extension were completely unknown but extensive efforts led to the identification of several key players in this process. Culture in sterile axenic medium is a method of DR (ADR), leading to an impressive doubling of lifespan. Earlier, we established that ADR-mediated longevity is independent of Ins/IGF signaling and eat-2. The only gene reported to be indispensable for the ADR lifespan effect is cbp-1 (Zhang et al., 2009) which was confirmed in this study. In an attempt to identify more genes involved in ADR-mediated longevity, we tested several candidate genes known to regulate lifespan extension in other DR regimens. We found that cup-4 is equally important as cbp-1 in ADR-mediated longevity and we identified some genes that may contribute to ADR-induced longevity, but are not required for the full lifespan effect.