Polarization of Fucus Zygotes and Protoplasts

对植物胚胎极化最早事件的研究主要集中在两属密切相关的褐藻，Fucus和Pelvetia。目前的工作假设是，在极化过程中，质膜上的离子通道迁移到卵子的一端。这种不对称导致水道积聚区域的净流入和另一端的净流出。因此，离子流流过卵子，表示发育轴的形成。作为电流的结果，细胞质电压和离子梯度被建立，这些被认为是调节卵细胞内的区域分化。这个有吸引力的模型的一个主要方面是，当轴建立时，质膜成分（如离子通道）是否发生了物理重组，这一点尚未得到仔细研究。克罗夫博士最近证明，由年轻受精卵制成的黑角藻原生质体可以在单向光下发生偏振。这提供了在轴建立过程中直接进入质膜的途径。他将研究原生质体表面膜受体的重排，并研究在黑角菌合子和光极化原生质体中由膜不对称产生的离子电流。最终目标是监测离子电流、质膜受体和f -肌动蛋白在单细胞中建立轴时的空间分布。在生物发育的早期，轴的建立（即哪一端是哪一端）是该生物模式形成的基本第一步。这一事件在植物中很难分析。克罗夫夫博士正在研究褐藻的这一过程，因为它相对于许多其他植物具有实验优势。

Investigation of the earliest events in embryonic polarization in plants have focused on two genera of closely related brown algae, Fucus and Pelvetia. Current working hypotheses postulate that during polarization ion channels in the plasma membrane migrate to one end of the egg. This asymmetry gives rise to net influx in the region of channel accumulation and net efflux from the other end. Thus, an ionic current flows through the egg and denotes formation of the developmental axis. As a consequence of the current, cytoplasmic voltage and ionic gradients are established and these are thought to regulate regional differentiation within the egg. One major aspect of this attractive model that has yet to be scrutinized is whether a physical reorganization of plasma membrane components (e.g.ion channels) takes place as the axis is established. Dr. Kropf has recently shown that Fucus protoplasts made from young zygotes can be polarized with unidirectional light. This provides direct access to the plasma membrane during axis establishment. He will examine rearrangements of membrane receptors on the surface of protoplasts undergoing polarization and investigate ionic currents generated by the membrane asymmetries in Fucus zygotes and in photopolarized protoplasts. The ultimate goal is to monitor the spatial distributions of ionic currents, plasma membrane receptors and F-actin in single cells as they establish an axis. %%% The establishment of the axis (i.e. which end is which) of an organism early in development is a fundamental first step in the pattern formation of that organism. This event has been hard to analyze in plants. Dr. Kropf is studying this process in the brown algae because of the experimental advantages it presents relative to many other plants.