Oscillatory Pollen Tube Growth: Integration of Secretion, pH and Actin

研究活动：花粉管的生长将精子细胞输送到高等植物的卵器，对于有性繁殖和食物生产是必不可少的。因为生长速度是振荡的，潜在的生理过程也是如此，所以可以使用互相关分析来确定某个过程是在生长速度变化之前还是之后。这个项目的主要目标是关注预期事件，因为它们被认为是生长的主要调节因素。预计生长速度增加的三个顶端事件将受到关注：细胞壁厚增加，碱性带pH增加，以及内质网(ER)的振荡内移。作为一个工作模型，有人认为分泌物预测生长并解释细胞壁增厚，碱度的变化调节肌动蛋白细胞骨架的结构，肌动蛋白的变化决定内质网和分泌囊泡的运动。使用不同的显微镜方法，包括比率离子成像、荧光共聚焦成像和电子显微镜(EM)，将检查分泌物、pH和肌动蛋白结构。分泌动力学将使用花粉特有的果胶甲基酯酶来探测，这种酶与绿色荧光蛋白有关。在注射了BCECF-葡聚糖的细胞中，将测定pH的波动。PH和/或H+-ATPase活性的实验改变将表征碱性带与生长的关系。肌动蛋白的结构将在EM水平上进行检查。最后，将通过检测内质网的运动来探讨肌动蛋白细胞骨架的活性。更广泛的影响：该项目强调将任职人数不足的少数群体作为主要调查者纳入研究/发现进程。S·麦肯纳博士是长岛大学(刘)的一名教员，那里有许多少数民族学生，他是一名高级合作者。他的参与有两个方面：第一，作为一名研究人员，他分享了发现过程，并极大地改善了他的职业生涯的上升轨迹。其次，作为导师，他将帮助寻找合格的少数民族学生，并让他们参与研究。

Research Activity: Pollen tube growth delivers the sperm cells to the egg apparatus in higher plants, and is essential for sexual reproduction and food production. Because the growth rate oscillates, as do the underlying physiological processes, it is possible, using cross-correlation analysis, to determine if a process precedes or follows the change in growth rate. The main objective of this project is to focus on anticipatory events, because they are thought to represent primary regulators of growth.Three apical events that anticipate increases in growth rate will receive attention as follows: increase in cell wall thickness, increase in pH in the alkaline band, and the oscillatory inward movement of endoplasmic reticulum (ER). As a working model it is suggested that secretion anticipates growth and accounts for the cell wall thickening, that changes in alkalinity modulate the structure of the actin cytoskeleton, and that changes in actin dictate the movement of ER and secretory vesicles. Using different microscopic methods, including ratiometric ion imaging, fluorescence confocal imaging, and electron microscopy (EM), secretion, pH, and actin structure will be examined. Secretion dynamics will be probed using a pollen specific pectin methylesterase, linked to GFP. Oscillations in pH will be determined in cells injected with BCECF-dextran. Experimental modification of pH and/or the activity of the H+-ATPase will characterize the relationship of the alkaline band to growth. The structure of actin will be examined at the EM level. Finally, the activity of the actin cytoskeleton will be probed by examining the motion of ER. Broader Impact: This project emphasizes the inclusion of underrepresented minorities as primary investigators in the research/discovery process. Dr. S. McKenna, who is a faculty member at Long Island University (LIU), where there are many minority students, is a Senior Collaborator. His involvement is two fold: firstly, as a researcher, he shares in the discovery process, and greatly improves the upward trajectory of his career. Secondly, as a mentor, he will help identify qualified minority students and engage them in research.