[Cytochemical study of glycogen localization and accumulation in cells of the psychrophile Cryptococcus laurentii]

The synthesis and intracellular localization of glycogen were studied cytochemically on sections and by electron-microscopic cryofractography in the psychrophilic yeast Cryptococcus laurentii under different conditions of cultivation. Glycogen synthesis started in the phase of growth deceleration at the periphery of the cell at the same time as another reserve substance (lipid inclusions) was formed. The degree of glycogen accumulation in the cytoplasm depended on the composition of the medium and the temperature of growth. The maximal accumulation of glycogen in the cels was detected at a low growth temperature (4 degrees C) in a minimal medium. Under these conditions, glycogen was a predominant component in the cytoplasm at the stationary phase of growth, and was not noticeably utilized over a long period of time. The ribosomes were scattered in a diffuse manner between glycogen granules. The results are indicative of the fact that temperature plays a significant role in glycogen synthesis and that this carbohydrate is important for survival of yeast organisms at low temperatures.