Do Cytoskeleton-bound Polysomes Exist in Plants?

戴维斯博士的研究计划的总体目标是了解植物对伤害的反应，从创伤产生的初始化学(或电生理)信号，到细胞内调节机制，再到负责植物适应性反应的特定基因表达的变化。他观察到，在创伤后的几分钟内，可以检测到一些特定的信使RNA，并增加了多聚体的形成。然而，出乎意料的是，即使在伤口后几分钟内就可以检测到新的信息，总体蛋白质合成也下降了75%。戴维斯博士提出了几种可能解释这一现象的机制的替代假设。其中一个假设是，存在多聚体从它们活跃的一个亚细胞部位到它们不活跃的另一个部位的受控易位。与这种可能性一致的是，他观察到受伤和未受伤植物的多聚体沉积方式发生了变化。伤后大部分多聚体颗粒具有较大的细胞结构。该项目的短期目标是识别和定位创伤反应基因编码的蛋白质和创伤后出现的多聚体。特别是，他将尝试确定多聚体的沉积特性的变化是否与细胞骨架有关。长期以来，多聚体与细胞角质粒之间的联系是否是一种具有生物学意义的现象一直备受争议。该项目的成果将做出双重贡献。首先，它们可能会解决长期存在的争议，即多聚体与植物细胞中的细胞骨架是否在生理条件下发生关联(但这是高风险的)。其次，这些结果应该确定参与创伤诱导基因产物翻译的多聚体的位置，从而加强对创伤反应翻译阶段的了解。

The broad goals of Dr. Davies' research program are to understand the plant response to wounding all the way from the initial chemical (or electrophysiological) signal produced by the wound, through intracellular regulatory mechanisms, to alterations in the expression of specific genes responsible for the plant's adaptive response. He has observed that within a few minutes after a wound, a number of specific messenger RNAs can be detected, and there is an increase in polysome formation. Unexpectedly, however, even though new messages can be detected within a few minutes of the wound, overall protein synthesis drops by 75%. Dr. Davies has formulated several alternative hypotheses as to mechanisms that might account for this. One of the hypotheses is that there is a regulated translocation of polysomes from one subcellular site at which they are active, to another site where they are inactive. Consistent with this possibility is his observation of a shift in the way polysomes from wounded and unwounded plants sediment. After wounding, a large fraction of polysomes pellet with larger cellular structures. The short-term goals of this project are to identify and localize the proteins that are encoded by the wound- responsive genes and the polysomes that appear after wounding. In particular he will attempt to determine whether the shift in sedimentation properties of the polysomes is caused by association with the cytoskeleton. The question of whether polysome association with the cytoskelton is a biologically significant phenomenon has been controversial for a long time. The results of this project will make a two-fold contribution. First, they may resolve the long- standing controversy over whether association of polysomes with the cytoskeleton in plant cells occurs under physiological conditions (but this is high risk). Second, the results should establish the location of polysomes involved in translation of wound inducible gene products and so enhance knowledge of the translation stage of the wound response.