Inositol deficiency resulting in death: an explanation of its occurrence in Neurospora crassa.

The incorporation of radio-active inositol and choline into the cytoplasmzic membranes of inositol-and choline-auxotrophic mnutants of Neuros-pora crassa revealed that the membrane of particles which contain proteases is relatively poor in lecithin and rich in inositol-phospholipid. In mycelia of the mutant requiring inositol, grown in a suboptimum amount of exogenous inositol, the strlctural initegrity of the protease particles is lost, and the bulk of intracellular protease activity is recovered in the soluble fraction of the cell. Death from this kind of inositol deficiency is interpreted as autolysis of the cytoplasm cautsed by free proteases.