Figure 3.—

Clk mutants have decreased energy production but normal levels of ATP. To determine whether energy utilization is decreased in Clk mutants, we examined mitochondrial function and ATP levels. (A) Whole-worm oxygen consumption was measured to assess mitochondrial function in day 1 adult worms. With the exception of clk-3, all of the Clk mutants showed decreased oxygen consumption compared to wild-type N2 worms. This suggests that Clk mutants produce less energy than wild-type worms. (B) Measurement of ATP levels in day 1 adult worms revealed that Clk mutants do not have decreased ATP. In combination with their decreased mitochondrial function, this finding suggests decreased energy utilization. (C) We also examined the decline in mitochondrial function among the Clk mutants. With the exception of clk-8/tpk-1 worms, we found that oxygen consumption declined more gradually in the Clk mutants than in wild type, suggesting a more balanced production of energy throughout their life span than in wild-type worms. *P < 0.05, **P < 0.01, ***P < 0.001.