Collaborative Research: Analysis of Cold TubulinSequences and Their Implication for Cold-Adaptation of Microtubules

这是由海洋生物实验室和伍兹霍尔海洋研究所的主要研究人员合作提出的一项建议。尽管地球上普遍存在极端寒冷的环境，但与我们对温带生物如何运作的了解相比，我们对生物如何适应这种环境知之甚少。主要研究人员感兴趣的一个领域是原生生物微管的冷适应。微管是真核生物必不可少的细胞成分，在温带生物中，在低温下是不稳定的。这种不稳定性可能与低温下的生命相冲突，但考虑到极冷环境中原生生物的多样性和丰度相对较高，这些生物显然已经适应了。几项研究的结果导致了目前的理解，即冷适应微管的稳定性是微管蛋白亚基本身固有的特性。然而，总的来说，只有相对较少的冷适应微管蛋白序列被研究过，而且由于很少有研究将冷适应序列与密切相关的中温物种的序列进行比较，因此很难确定是否存在与冷适应相对应的保守（常见）变化类型或位置。首席研究员将从密切相关的嗜冷（来自北极和南极）和嗜温原生生物物种中恢复a和b微管蛋白序列。使用新的统计方法，他们将分析微管蛋白序列，以确定可能代表微管冷稳定性修饰的共享序列变化。这项研究不仅将确定微管蛋白序列中是否存在特定的冷适应序列标志，而且还将提供有关在嗜冷动物中通常增强蛋白质亚基之间相互作用的修饰的信息。该项目还将开始评估北极地区的原生生物群落在基因和生理上是否与南极地区相似。由于这些生物在极端寒冷环境中具有重要的生态影响，地方性与世界性微生物物种分布的问题对极地地区来说是一个重要的问题。它们是微生物食物网的重要组成部分，往往是主要的初级生产者。主要研究者将在本项目中收集的分子序列数据（核糖体和微管蛋白）进行分析，以比较来自两极地区的推定相似的原生生物物种/分离物的遗传亲缘性。有报道称，在北极和南极都观察到和收集到了类似的原生物种，但只完成了很少的基因比较，而且这些生物中有多少实际上是相关的，这仍然是一个问题。更广泛的影响：该项目的更广泛的影响包括主要研究人员参与了WHOI和MBL与从高中到大学的不同教育水平相关的几门课程和项目。参与这些课程和研究项目的学生，包括那些从代表性不足的群体中招募的学生，将直接（通过参与数据分析）或间接（通过一般信息外展）接触到这项研究。他们正在生成的数据集，以及他们正在研究的独特生物，将有助于拓宽这些学生对亲心理原生生物的进化、分布和功能的看法。

ABSTRACTGast OPP-0324771CummingsOPP-0324378This is a collaborative proposal by Principal Investigators at the Marine Biological Laboratory and Woods Hole Oceanographic Institution. Despite the prevalence of extremely cold environments on our earth, we understand very little about how organisms have adapted to live in them compared to what we know about how temperate organisms function. An area of interest to the Principal Investigators is the cold-adaptation of microtubules in protists. Microtubules are essential eukaryotic cellular components, and in temperate organisms, are unstable at low temperatures. This instability would be in conflict with life at low temperatures, but considering the relatively high level of diversity and abundance or protists in extremely cold environments, the organisms have obviously adapted. The results of several studies have led to the current understanding that the stability of cold-adapted microtubules is a property intrinsic to the tubulin subunits themselves. Yet overall, only a relatively small number of cold-adapted tubulin sequences have been examined, and because there are very few studies that compare cold-adapted sequences with ones from closely related mesophilic species, it has been difficult to determine whether there are conserved (common) types of changes or positions that correspond to cold-adaptation. The Principal Investigators will recover both a and b tubulin sequences from closely related psychrophilic (from the Arctic and the Antarctic) and mesophilic protist species. Using novel statistical methods, they will analyze tubulin sequences to identify shared sequence changes that potentially represent modifications for cold-stability of microtubules. This study will not only determine whether there are specific sequence hallmarks of cold-adaptation in tubulin sequences, but it will also provide information on modifications that generally enhance interactions between protein subunits in psychrophiles. This program will also begin an assessment of whether the protistan communities in the Arctic region are genetically and physiologically similar to those of the Antarctic. The question of endemic versus cosmopolitan microbial species distribution is a significant one for polar regions due to the important ecological impact these organisms have in extreme cold environments. They are essential components of the microbial food webs and are often the dominant primary producers. The molecular sequence data that the Principal Investigators will collect in this project (both ribosomal and tubulin) will be analyzed to compare the genetic relatedness of putatively similar protistan species/isolates from the two polar regions. There have been reports of similar protist species being observed and collected in both the Arctic and Antarctic, but only a few genetic comparisons have been accomplished and it remains a question as to how closely many of these organisms are actually related. Broader Impacts: Among the broader impacts of this project include the participation of the Principal Investigators in several courses and programs at WHOI and MBL associated with different levels of education, ranging from high school through college. Students involved in these courses and research programs, including those recruited from under-represented groups, will be exposed either directly (through participation in data analysis) or indirectly (through general information outreach) to this research. The dataset that they are generating, and the unique organisms that they are working with, will help to broaden the perspective that these students have regarding evolution, distribution and function of psychrophilic protists.