Ca^(2+)参与水霉菌丝细胞壁修饰的证据

EVIDENCE FOR Ca^(2+) INVOLVEMENT IN MODIFICAMON OF HYPHAL CELL WALL OF SAPROLEGNIA FERAX

以细胞壁崩溃酶－Driselase短时间处理水霉（Saprolegniaferax）菌丝，pH5．0时可使原生质从菌丝亚顶端喷出，pH6．0～8．0时则不导致该现象发生；适当浓度EGTA的存在，可提高pH5．0时酶解引起的原生质喷出频率、使pH6．0～8．0时生长菌丝的顶端原生质也喷出、并且喷出多发生在菌丝最顶端。外加CaCl2不抑制菌丝顶端原生质的喷出，排除了Ca2+抑制酶活性的可能。随后的跟踪观察显示，长时间以缺Ca2+培养介质培养菌丝，同样能够导致菌丝顶端原生质喷出。上述研究结果表明，培养介质中Ca2+和H+对菌丝完整性的维持起调节作用，细胞壁上的Ca2+可能参与了水霉菌丝细胞壁物理特性的修饰。

Short bine treatment with driselase, a cell wall lytic enzyme, in various conditions resulted in the tip bursting at subapical region of Saprolegnia ferax hyphae grown in pH5.0 medium, whereas tip bursting could not occur in pH6.0～8.0 medium. At certain concentrations of EGTA, the bursting was enhanced at pH5.0 ed took place at pH6.0～8.0 in extreme apical zone. Because tip bursting was not inhibited by adding Ca2+,the possibility that Ca2+ inhibit driselase activity could be excluded. Long bine treatment with medium (pH6.8) lashing Ca2+ also could induce automatical tip bursting. Above results showed that the concentration of Ca2+ and H+ in medium may regulate the integration of the hyphae and Ca2+ may involved in modification of physical physical Properties of cell wall.