MOLECULAR EVOLUTION OF MARINE PROTISTS

自由生活群体和寄生群体的进化模式 单细胞原生生物在种群、物种和 一般级别。现代分子和形态计量学方法很少 应用于这些形式，因此，它们的模式 进化是不能准确推断的。少量的现代 确实存在的数据表明，进化模式的模型 从更高的多细胞形式的研究中推断出的可能是 适用于单细胞形式。自然界的现代研究进展 原生动物的数量和物种一直很慢，因为缺乏 来自不同国家和地区的研究努力的适当的“模式生物” 实验室可以集中精力。海洋硅藻，中肋骨条藻， 提出作为自由生活光合作用研究的模式系统 色藻谱系中的原生生物。过去在此进行的工作 实验室已经确定这种微生物的种群是 在分子水平上的遗传差异，因为不同的属 高等植物，但在形态上没有显著差异 水平。叶绿体DNA(CpDNA)的分化模式是 目前正在接受检查。这是首次对cpdna进行定量研究。 任何原生生物在种群水平上的变异。这项研究是 目前正在扩展到核基因，包括基因和间隔区 RDNA顺反子中的区域和单拷贝核序列。 任意启动的聚合酶链式反应也被用来开发新的探针。这个 从分子水平推断的遗传多样性模式的一致性 差异正在与所获得的细胞形态模式进行比较 从扫描电子显微镜的形态分析由一个 计算机集成数字成像系统。这项工作的相关性 对生物医学研究的意义在于生物体被用作模型 在分子水平上研究原生生物种群遗传学的系统和 许多研究结果具有广泛的适用性。学生们参与了 工作的所有阶段，并由P.I.直接密切监督。

The patterns of evolution in groups of free-living and parasitic unicellular protists are poorly understood at the population, species and generic levels. Modern molecular and morphometric methods have rarely been applied to these forms, and consequently, their patterns of evolution cannot be inferred with accuracy. The small amount of modern data that do exist indicate that models of the patterns of evolution inferred from research on higher multicellular forms probably cannot be applied to unicellular forms. The progress of modern research on natural populations and species of protists has been slow due to the lack of appropriate "model organisms" on which research efforts from different labs can be focused. The marine diatom, Skeletonema costatum, is proposed as a model system for the study of free-living photosynthetic protists in the chromophyte lineage. Past work conducted in this laboratory has already established that populations of this organism are as genetically different at the molecular level as different genera of higher plants, but are not significantly different at the morphological level. Patterns of differentiation in chloroplast DNA (cpDNA) are currently being examined. This is the first quantitative study of cpDNA variation at the population level in any protist. This research is currently being extended to nuclear genes, including genes and spacer regions in the rDNA cistron and a single-copy nuclear sequence. Arbitrarily primed PCR is also being used to develop new probes. The concordance of the patterns of genetic diversity inferred from molecular differences are being compared to patterns of cell morphology obtained from scanning electron micrographs analyzed morphometrically by a computer-integrated digital imaging system. The relevance of this work to biomedical research is that the organism is being used as a model system to study protist population genetics at the molecular level and many of the findings have broad applicability. Students are involved in all phases of the work and are closely supervised directly by the P.I.