Regulation of Alginate Gelation During Wall Development in Fucus Embryos

褐藻的受精卵合成藻酸盐并重新组装成细胞壁。Fucus为研究植物细胞壁的形成提供了一个简单的系统。海藻酸盐是两种酸性糖甘露酸和古鲁酸的线性聚合物，排列在非凝胶和胶凝亚单位中。最近的工作确定了细胞内合成凝胶亚单位的位置是高尔基体。胞内和胞外藻酸盐的分子大小和亚基长度分布将在特定的酶切割后通过电泳法进行检测。将用已知链长的荧光杂交探针标记受精卵切片，研究受精卵藻酸盐在海水环境中凝胶化的能力。通过酶显微分析，两种酶的活性，一种是调节海藻酸凝胶形成的酶(差向异构酶将非凝胶亚基转化为凝胶亚基)，另一种是引起其裂解的酶(裂解酶切断海藻酸链以扩大壁面)，它们的活性与壁面的发育有关。纯化的酶的抗血清将被制备用于免疫金超微结构定位。受精卵在发育过程中制备的信使RNA的体外翻译产物将被免疫沉淀。该项目将提供有关酶和信使核糖核酸控制的合成、组装、结构和凝胶壁糖蛋白修饰的信息。这个项目将提供在碳水化合物、蛋白质和信使核糖核酸水平上控制凝胶化植物细胞壁聚合物的详细信息。这种凝胶化/非凝胶化允许细胞壁组件适应生长，同时保持有机体的完整性。

Alginate synthesis and de novo assembly into a cell wall by the fertilized egg of the brown alga. Fucus provides a simple system for studying plant cell wall formation. Alginate is a linear polymer of the two acidic sugars, mannuronate and guluronate, arranged in nongelling and gelling subunits. Recent work identified the intracellular site of synthesis of the gelling subunits as the Golgi apparatus. Alginate molecular size and the subunit length distributions of intracellular and extracellular alginate will be examined by electrophoresis after cleavage by specific enzymes. The ability of zygote alginate to gel in a seawater environment will be studied by labelling zygote sections with fluorescent hybridization probes of known chain length. The activities of two enzymes, one regulating alginate gelation (epimerase converts nongelling subunits to gelling subunits) and one causing its cleavage (lyase cuts alginate chains for wall expansion) will be correlated with wall development by enzyme microassays. Antisera to the purified enzymes will be prepared for immunogold ultrastructural localization during wall development. In vitro translation products of messenger RNA prepared form zygotes during development will be immunoprecipitated. This project will provide information on enzyme and mRNA controls of the synthesis, assembly, structure and modification of a gelling wall carbohydrate. %%% This project will provide detailed information on the control of a gelling plant cell wall polymer at the carbohydrate, protein and mRNA levels of control. This gelling/nongelling allows the cell wall components to adapt to growth while maintaining the integrity of the organism.