Calcium, pH and the Cytoskeleton in Pollen Tube Growth

花粉管生长是开花植物将雄配子运送到卵器进行受精的过程，这是种子生产的必要先决条件。 伸长过程的特征在于快速和高度的极性，由于其经济意义及其与植物细胞生长和发育的基本方面的相关性而引起极大的兴趣。 该项目的重点是钙（Ca 2+），质子（H+）和肌动蛋白细胞骨架的作用，并建立在最近的证明，花粉管生长速率振荡，并有潜在的振荡离子和细胞骨架活性。 利用百合和烟草的花粉管，将试图在高时间分辨率的细胞内Ca ~（2+）和H ~+的振荡与生长速率的振荡相关联。 此外，将探索当细胞壁性质被各种试剂修饰时，这些振荡是如何改变的，例如，Ca 2+、H+、硼、果胶甲酯酶或Yariv苯基糖苷。 通过确定这些试剂是否以及如何修改振荡行为，以及其与细胞内Ca 2+和H+的梯度以及这些离子的细胞外通量的关系，似乎可以开发一个时间层次结构，用于控制生长的因子的活性。 这里涉及的技术包括细胞内Ca 2+和H+的比率成像，和离子选择性振动探针分析，以确定细胞外通量的大小和方向。 在对细胞骨架的研究中，将注意力放在透明区中F-肌动蛋白的结构和动态分布上，假定这些元素的快速周转和形成发生在透明区中。 将这些周转过程与增长的振荡模式联系起来，这将是特别有趣的，同样是为了确定哪些事件先于快速增长阶段，哪些事件随后发生。 在这些研究中，新开发的GFP-talin融合蛋白将用于荧光标记活花粉管中的F-肌动蛋白，当这些研究结合在一起时，预计这些研究将提供对控制花粉管生长和发育的生理和分子因素的深入了解。 在某种程度上，其他尖端生长细胞，例如，根毛、真菌菌丝、蕨类和苔藓原丝体使用类似的机制，花粉管的结果可能是相关的，并帮助我们获得涉及细胞生长的基本机制的一般理解。

Pollen tube growth is the process by which flowering plants deliver the male gamete to the egg apparatus for fertilization, a necessary prerequisite to seed production. Characterized by rapid rates and a high degree of polarity, the elongation process is of great interest, both because of its economic implications and its relevance to fundamental aspects of plant cell growth and development. This project focuses on the role of calcium (Ca2+), protons (H+), and the actin cytoskeleton, and builds upon the recent demonstration that pollen tube growth rate oscillates, and that there are underlying oscillations in both ions and cytoskeletal activity. Using pollen tubes of both lily and tobacco, an attempt will be made to correlate at high temporal resolution the oscillations in intracellular Ca2+ and H+ with those in the growth rate. In addition, an exploration will be made on how these oscillations are changed when cell wall properties are modified by various agents, e.g., Ca2+, H+, boron, pectin methyl esterase, or Yariv phenyl glycoside. By determining if and how these agents modify the oscillatory behavior, and its relationship to both the intracellular gradients of Ca2+ and H+ as well as the extracellular fluxes of these ions, it seems possible that a temporal hierarchy can be developed for the activity of factors that control growth. Techniques involved here include ratiometric imaging for intracellular Ca2+ and H+, and ion selective vibration probe analysis to determine the magnitude and direction of extracellular fluxes. In studies on the cytoskeleton, attention will be given to the structure and dynamic distribution of F-actin in the clear zone, where rapid turnover and formation of these elements is presumed to occur. It will be particularly interesting to correlate these turnover processes with the oscillatory pattern of growth, again with the view of determining which events precede the rapid growth phases and which events follow. For these studies the newly developed GFP-talin fusion will be used to fluorescently label F-actin in living pollen tubes.When taken together it is anticipated that these studies will provide insight into the physiological and molecular factors that control growth and development of the pollen tube. To the extent that other tip growing cells, e.g., root hairs, fungal hyphae, fern and moss protonemata, use similar mechanisms, the results from pollen tubes could be pertinent, and help us gain a general understanding of basic mechanisms involved in cell growth.