| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1991: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
1. In Candida tropicalis that grows in pseudomycelial(PM) form with ethanol, transient accumulation of inositol 1,4,5-trisphosphate (IP_3) occurred immediately after the beginning of cultivation with ethanol, followed by the second peak of IP_3 accumulation at the early-log phase. Transient increase in cellular Ca^<2+> concentration accompanied by IP_3 accumulation was detected. These ethanol effects were abolished by myo-inositol. 2. The ethanol-induced PM development was enhanced by linoleic or linolenic acid, and prevented by D-sorbitol, suggesting that an ethanol-induced increase in membrane fluidity triggers the activation of phospholipase C (PLC) causing IP_3 accumulation and finally PM development. 3. Upon cultivation with myo-inositol, cellular phosphatidylinositol that is rich in palmitic acid was increased and phosphatidylethanolamine rich in linolenic acid was decreased, implying that inositol prevents the ethanol-induced increase in membrane fluidity, and consequently PLC a
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ctivation and the morphological change. 4. Fe^<2+> prevented the ethanol-induced PLC activation and PM formation. The Fe^<2+> effect was enhanced by H_2O_2. These results support the idea that ethanol exerts its effect by scavenging OH.. In fact, all of the hydrophobic OH. scavengers tested caused PM development. 5. An adenine auxotroph isolated formed red colonies on agar plates and underwent alterations in chromosomal DNA. Theses characteristics may be utilyzed for analysis of dimorphism by cell fusion. 6. beta-1,3 Glucan synthesis was found to be important in PM formation and colony morphogenesis, and chitin synthesis that is essential for PM formation was sensitive to polyoxin D. These results give a clue to the mechanism of dimorphism from the standpoint of the control of cell wall and septum formation. 7. Saccharomyces yeasts were also found to grow in PM form with ethanol through PLC activation. cAMP and other stresses also caused PM development. These findings would serve to clarify the genetic and biochemical mechanism of dimorphism. Less
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