Lew Roger R, Levina Natalia N, Walker Sophie K, Garrill Ashley
Department of Biology, York University, 4700 Keele Street, Toronto, Ont., Canada M3J 1P3.
Fungal Genet Biol. 2004 Nov;41(11):1007-15. doi: 10.1016/j.fgb.2004.07.007.
Turgor regulation in two saprophytic hyphal organisms was examined directly with the pressure probe technique. The ascomycete Neurospora crassa, a terrestrial fungi, regulates turgor after hyperosmotic treatments when growing in a minimal medium containing K(+), Mg(2+), Ca(2+), Cl(-), and sucrose. Turgor recovery by N. crassa after hyperosmotic treatment is concurrent with changes in ion transport: hyperpolarization of the plasma membrane potential and a decline in transmembrane ion conductance. In contrast the oomycete Achlya bisexualis, a freshwater hyphal organism, does not regulate turgor after hyperosmotic treatment, although small transient increases in turgor were occasionally observed. We also monitored turgor in both organisms during hypoosmotic treatment and did not observe a turgor increase, possibly due to turgor regulation. Both hyphal organisms grow with similar morphologies, cellular expansion rates and turgor (0.4-0.7 MPa), yet respond differently to osmotic stress. The results do not support the assumption of a universal mechanism of tip growth driven by cell turgor.
采用压力探针技术直接研究了两种腐生菌丝生物体中的膨压调节。子囊菌粗糙脉孢菌是一种陆生真菌，当在含有钾离子（K⁺）、镁离子（Mg²⁺）、钙离子（Ca²⁺）、氯离子（Cl⁻）和蔗糖的基本培养基中生长时，在高渗处理后能调节膨压。粗糙脉孢菌在高渗处理后的膨压恢复与离子转运的变化同时发生：质膜电位超极化和跨膜离子电导下降。相比之下，卵菌双游水霉是一种淡水菌丝生物体，在高渗处理后不调节膨压，尽管偶尔会观察到膨压有小的短暂增加。我们还监测了两种生物体在低渗处理期间的膨压，未观察到膨压增加，这可能是由于膨压调节所致。两种菌丝生物体的生长形态、细胞扩张速率和膨压（0.4 - 0.7兆帕）相似，但对渗透胁迫的反应不同。这些结果不支持由细胞膨压驱动尖端生长的普遍机制这一假设。
