31P-NMR-studies on intracellular pH and metabolite concentrations in relation to the circadian rhythm, temperature and nutrition in Neurospora crassa.

Perfused mycelia of Neurospora crassa were analyzed in vivo with 31P-NMR. Both the cytoplasmatic and the vacuolar pH and the concentrations of phosphate metabolites were followed up to 30 h under constant conditions. No circadian changes were detected. However, slight changes in the nutrition or oxygen supply induced distinct changes in the intracellular pH and in the concentrations of metabolites. An increase of temperature from 21 to 43 degrees C lowered the intracellular pH and the metabolite concentrations. Changes in the perfusion rate affect the temperature responses, probably due to different availability of carbon sources and exhaustion of acid catabolites.