Figure 1.

Sirtuins, longevity, and CR. The indicated sirtuins have been shown to promote longevity when activated in yeast, worms, flies, and mice, as discussed in the text. The requirement for these sirtuins for the effects of CR is also shown. The asterisks indicate that different laboratories and protocols have elicited different requirements in the lower organisms; i.e., some studies show a requirement, and others do not.