Acidic intracellular pH shift during Caenorhabditis elegans larval development.

During recovery from the developmentally arrested, nonfeeding dauer stage of the nematode Caenorhabditis elegans, metabolic activation is accompanied by a decrease in intracellular pH (pHi). Phosphorus-31 nuclear magnetic resonance (31P NMR) analyses of perchloric acid extracts show that inorganic phosphate predominates in dauer larvae, whereas ATP and other high-energy metabolites are abundant within 6 hr after dauer larvae have been placed in food to initiate development. Although metabolic activation has been associated with an alkaline pHi shift in other organisms, in vivo 31P NMR analysis of recovering dauer larvae shows a pHi decrease from approximately 7.3 to approximately 6.3 within 3 hr after the animals encounter food. This shift occurs before feeding begins, and it coincides with, or soon follows, the developmental commitment to recover from the dauer stage, suggesting that control of pHi may be important in the regulation of larval development in nematodes.