Ultrastructural changes and biochemical events in basidiospore germination of Schizophyllum commune

Temporal accumulation of mannitol and arabitol in Geotrichum candidum

The temporal depletion and accumulation of polyols were investigated in the fungus Geotrichum cnadidum. The major intracellular polyols were tentatively identified by paper chromatography as mannitol and arabitol. Inositol was also present in small quantities, and trehalose was also detected in appreciable concentrations. Germination and vegetative growth depended on the type and concentration of the sole exogenous carbon source. Mannitol occurred in arthrospores at 9.4% of the dry weight after several days growth in 2% (w/v) glucose solid medium, and became depleted during germination and vegetative growth in liquid medium containing 2% (w/v) glucose, 2% (w/v) sodium acetate or 25% (w/v) glucose as sole carbon source. This hexitol latter accumulated during arthrosporulation. The depletion and accumulation of ethanol-soluble carbohydrate believed to be primarily trehalose was temporally similar to that of mannitol. Arabitol accumulated intracellularly during germination and vegetative growth in sodium acetate medium and 25% glucose medium. This pentitol was not detected intracellularly at any culture age during growth in 2% glucose medium. Prolonged incubation of the culture in 25% glucose medium after stationary phase was reached resulted in the gradual disappearance of arabitol from the arthrospores simultaneously with an increase in intracellular mannitol. In comparison, ethanol-soluble carbohydrate did not change with prolonged incubation in this medium.

Enzyme activities associated with arabitol and mannitol biosynthesis and catabolism in Schizophyllum commune

Enzymes of polyol metabolism were studied in basidiospore germination of Schizophyllum commune during periods of in vivo arabitol and mannitol pool depletion (growth on glucose-asparagine) and during their subsequent synthesis (growth on acetate-NH+4). Optimal conditions for assays were established and specific activities of enzymes employing D-arabitol, D-mannitol, D-ribulose, D-fructose and D-xylulose as substrates. were traced. Inquiries into the products formed during these reactions showed that D-ribulose generated arabitol while D-fructose produced mannitol with D-xylulose giving rise to xylitol. The dehydrogenase reactions were further investigated using polyacrylamide disc gel electrophoresis. Here was revealed the existence of at least two separate enzymatic activities pertaining to the catabolism of arabitol and mannitol. Also noted were the electrophoretic patterns when D-sorbitol, ribitol, xylitol and ethanol were used as substrates

Macromolecular synthesis during the germanation of Saccharomyces cerevisiae spores

After the dormancy of Saccharomyces cerevisiae ascospores had been broken, the synthesis of proteins was observed first, followed rapidly by synthesis of ribonucleic acid (RNA) and much later by deoxyribonucleic acid (DNA) synthesis. Phosphoglucomutase activity increased in a periodic (step) fashion, whereas the activity of five other enzymes increased linearly during germination and outgrowth. The rate of synthesis of these enzymes was highest at about the period of DNA replication. The amino acid pools of dormant spores contained high levels of proline, glutamic acid, and histidine. At 2 h after onset of germination, the pools of phenylalanine and methionine had disappeared and the other components had decreased significantly. By 3.5 h, with the exception of proline and cystine, most amino acid pool components had significantly increased.