Longevity mutants and dauer larvae have distinctive metabolic profiles. A. PCA of four IIS mutants and a long-lived translation-defective mutant, ife-2(ok306); cluster analysis separates the mutants into distinct groups. daf-2(e1370) is the most similar to wild-type. ife-2(ok306), while distinctive relative to wild-type and all other mutants, is not distinctive relative to the IIS mutants as a class. In this experiment mutant and wild-type worms were initially raised at 15°C, transferred to 25°C at L4, and assayed at 240 hours post bleaching. The first three PCs respectively account for 40, 20 and 16% of the variance. B. PCA shows that daf-2(m41) has a distinctive profile even at L1 (15 hours); and appears to become successively more distinctive as a middle-aged adult (144 hours) and old (240 hours) adult. The first three PCs explain, respectively, 35, 26 and 11% of the variance. C. PCA of dauers and wild-type worms (240 hours) raised at two temperatures, 20°C and 25°C. The PCA and cluster analysis shows that dauers and adults clearly have distinct metabolomes as do worms raised at 20°C rather than 25°C. The first three PCs explain, respectively, 48, 16 and 11% of the variance, with PC1 distinguishing stages and PCs 2 and 3 distinguishing temperature. Note that the relative position of the samples raised at the two temperatures is reversed along PC2, a consequence of strong temperature × stage interaction.
Fuchs et al. BMC Biology 2010 8:14 doi:10.1186/1741-7007-8-14