Relationship between the composition of phospholipids and respiratory activity of choline-deficient mutants ofNeurospora crassa

Phosphatidylcholine is one of the most frequent phospholipid components of the inner mitochondrial membrane ofNeurospora crassa. Quantitative analysis of phospholipids of the wild strain ofNeurospora crassa and of its twocho mutants showed that these strains did not significantly differ in the content of phosphatidylcholine. Mutants cultivated in a medium without choline contained, as compared with the wild strain, an increased amount of phosphatidylserine and a decreased quantity of phosphatidic acid. Respiratory activity increased and sensitivity to inhibitors of respiration changed. It is likely that the presence of choline in the growth medium exerts a regulatory effect on the cell metabolism of these mutants.