Levina N N, Lew R R, Heath I B
York University Biology Department, Ontario, Canada.
J Cell Sci. 1994 Jan;107 ( Pt 1):127-34. doi: 10.1242/jcs.107.1.127.
Growing hyphal tips of the oomycete Saprolegnia ferax possess a tip-high gradient of stretch-activated ion channels permeable to calcium. These mechanosensitive channels appear to play a direct role in the polarized tip growth process. Treatment of S. ferax hyphae with cytochalasin E leads to the disruption of plasmalemma-associated, peripheral cytoplasmic actin populations and altered morphology of apical protoplasts, and eliminates the tip-high gradient of stretch-activated channels. Cytochalasin E did not alter the normal aggregation of stretch-activated channels. The density of spontaneous K+ channels was decreased in all regions of the hyphae after treatment with cytochalasin E. These results suggest that the peripheral F-actin network in the growing tip of S. ferax hyphae establishes or maintains the tip-high gradient of SA channels, either by the delivery of channel-bearing vesicles to the apex or by the interactions between the channels and the peripheral actin network.
卵菌纲真菌水霉的生长菌丝尖端存在一个钙通透性拉伸激活离子通道的尖端高梯度。这些机械敏感通道似乎在极化的尖端生长过程中发挥直接作用。用细胞松弛素E处理水霉菌丝会导致质膜相关的外周细胞质肌动蛋白群体被破坏，顶端原生质体形态改变，并消除拉伸激活通道的尖端高梯度。细胞松弛素E并未改变拉伸激活通道的正常聚集。用细胞松弛素E处理后，菌丝所有区域的自发钾离子通道密度均降低。这些结果表明，水霉菌丝生长尖端的外周F-肌动蛋白网络通过将携带通道的囊泡运输到顶端或通过通道与外周肌动蛋白网络之间的相互作用来建立或维持SA通道的尖端高梯度。
