Mechanism of Transmembrane Signal Transduction Involved in Yeast Cell Morphogenesis

1.在以假菌丝体(PM)形式生长的热带假丝酵母中，三磷酸肌醇(IP_3)在乙醇开始培养后立即出现瞬时积累，随后IP_3积累的第二个高峰出现在对数早期。细胞内Ca~(2+)浓度一过性升高并伴有IP_3蓄积。这些乙醇效应可被肌醇消除。2.乙醇诱导的质膜发育可被亚油酸或亚麻酸促进，而D-山梨醇则可抑制，提示乙醇诱导的膜流动性增加触发了磷脂酶C(PLC)的激活，导致IP_3的积累，最终导致PM的发生。3.经肌醇培养后，细胞内富含棕榈酸的磷脂酰肌醇含量增加，富含亚麻酸的磷脂酰乙醇胺含量降低，提示肌醇可拮抗乙醇诱导的细胞膜流动性增加，从而抑制…。更多的活化和形态变化。4.Fe~(2+)~(2+)可抑制乙醇诱导的PLC激活和PM的形成。H_2O_2对Fe~(2+)~(2+)-Gt~(2+)效应有增强作用。这些结果支持乙醇是通过清除羟基发挥作用的。事实上，所有的疏水羟基。经过测试的清道夫导致了PM的发展。5.分离的腺嘌呤营养缺陷菌在琼脂平板上形成红色菌落，并发生了染色体DNA的改变。这些特征可用于细胞融合的二型性分析。6.β-1，3葡聚糖的合成在质膜形成和菌落形态发生中起重要作用，而质膜形成所必需的甲壳素合成对多毒素D很敏感。这些结果从控制细胞壁和隔膜形成的角度提供了一条线索。7.在乙醇的作用下，酵母菌也可以通过PLC的激活以PM形式生长。CAMP和其他压力也导致了PM的发展。这些发现将有助于阐明二型性的遗传和生化机制。较少

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 … More 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