Figure 1.

The AMP:ATP ratio predicts life expectancy. (A) Survival curve and increasing AMP:ATP ratio with age. fem-1(hc17); fer-15(b26) animals were grown at 25°C; their lack of sperm at this temperature facilitates growing a large number of animals. In parallel cultures, either the number of surviving animals or adenine nucleotide measurements were recorded at the times indicated. (B) AMP:ATP ratios of 12- and 14-d animals divided based on their motility. “Not selected” represents a group of animals that was not separated based on motility. ^★P < 0.01 and †P < 0.0001, compared with “not selected”; #P < 0.0001 compared with Class I (unpaired t-test). (C) Survival curves of 12-d Class I or Class II or “not selected” animals based on motility. Similar data were obtained for 14-d animals. For statistical data on lifespans see Supplementary Table 1. (D) Least squares regression of the AMP:ATP ratio as a function of life expectancy of animals described in A. The age of “not selected” animals is noted next to the data points. The fit and R² values were determined from “not selected” animals only. Twelve- and fourteen-day Class I and Class II animals were plotted on this graph according to AMP:ATP ratio and life expectancy (measured in B,C); actual life expectancy closely correlated with values predicted based on AMP:ATP ratio. The increase in the AMP:ATP ratio with age is not due solely to an increase in the fraction of Class II relative to Class I animals, because the AMP:ATP ratio of day-12 Class I animals is higher than that of day-4 animals, which are all Class I (P < 0.0001, unpaired t-test).