Ca(2+)-dependent polarization of axis establishment in the tip-growing organism, Saprolegnia ferax, by gradients of the ionophore A23187.
Ca(2+)-dependent polarization of axis establishment in the tip-growing organism, Saprolegnia ferax, by gradients of the ionophore A23187.
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发表时间：
1995-08
影响因子：
6.6
通讯作者：
G. Hyde;I. Heath
中科院分区：
文献类型：
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作者：
G. Hyde;I. Heath
二价阳离子离子载体A23187极化轴在顶端生长卵菌Saprolegnia ferax再生菌丝原生质体和萌发孢囊中的梯度建立。从最初的球形原生质体出现的新菌丝的平均百分之六十三是面向离子载体源。这种极化依赖于Ca2+的存在，并且不能由1 mM Mn2+或Mg2+的存在引起。一个类似的，但不太显着（56%）的方向显示发芽的囊肿，无论有或没有预处理的抗微管药物，诺考达唑。此外，最初不面向离子载体源出现的孢囊衍生的菌丝后来表现出重新定向其生长的趋势。由于已知A23187促进Ca 2+进入细胞，并且由于至少在原生质体中，响应是Ca 2+依赖的，这些结果暗示细胞内离子载体产生的Ca2+梯度可能是观察到的对原生质体和孢囊的极化影响的原因。这是可能的，Ca2+的作用在两个系统中基本上是相同的：在建立的生长轴的主要共同因素。结果提供的证据表明，Ca2+极化菌丝生长和支持的想法，Ca2+有一个普遍存在的，主要的作用，在尖端生长细胞的极性启动。
A gradient of the divalent cation ionophore A23187 polarized axis establishment in regenerating hyphal protoplasts and germinating cysts of the tip-growing oomycete Saprolegnia ferax. An average of sixty-three percent of new hyphae emerging from initially spherical protoplasts were oriented towards the ionophore source. This polarization was dependent on the presence of Ca2+ and could not be elicited by the presence of either 1 mM Mn2+ or Mg2+. A similar but less marked (56%) orientation was shown by germinating cysts, either with or without pretreatment with the anti-microtubule drug, nocodazole. Further, cyst-derived hyphae which did not originally emerge facing the ionophore source later showed a tendency to reorient their growth towards it. Since A23187 is known to facilitate the entry of Ca2+ into cells, and since, in protoplasts at least, the response is Ca2+ dependent, these results imply that an ionophore-generated Ca2+ gradient within the cells may be responsible for the observed polarizing influence on protoplasts and cysts. It is likely that the role of Ca2+ is essentially the same in both systems: a primary common factor in the establishment of the growth axis. The results provide evidence that Ca2+ polarizes hyphal growth and support the idea that Ca2+ has a ubiquitous, primary role in the initiation of polarity in tip-growing cells.