3-D FINE STRUCTURE OF THE APICAL POLAR RING IN TOXOPLASM GONDII

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。刚地弓形虫是一种专性细胞内寄生虫，与疟原虫有关，疟原虫是疟疾的病原体。弓形虫由猫传播，猫携带传染性孢子并通过粪便传播。孕妇体内的弓形虫可导致出生缺陷或流产；在免疫功能低下的个体中，它可引起危及生命的感染。弓形虫、疟原虫和其他顶端复合体寄生虫都有形态相似的微管细胞骨架。我们对顶端极环的结构安排感兴趣，这是一个微管组织中心，形成22个膜下微管。今年，我们利用化学固定制剂，制作了野生型细胞细胞质区域的断层图。为了改善细胞的结构保存，Morrissette一直在使用圣路易斯丹佛斯中心的巴尔查斯高压冷冻机，并生产了一些有希望的样品。此外，Morrissette实验室目前正在开发分子遗传技术，以补充其他地方正在进行的细胞和生化研究。他们正在构建弓形虫的遗传工具，包括基因组图谱、用于DNA转化和蛋白质表达的载体，以及用于基因发现的大规模cdna测序。这些方法被应用于鉴定毒力的分子基础，并产生在粘附、侵袭和细胞内存活方面表型改变的突变体。3-D实验室将描述这些突变体的表型，当它们可用时。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Toxoplasma gondii is an obligate intracellular parasite that is related to Plasmodium, the agent of malaria. Toxoplasma is disseminated by cats, which harbor infectious spores and pass them in their feces. Toxoplasma in pregnant women can cause birth defects or miscarriage; in immunocompromised individuals it can cause life- threatening infection. Toxoplasma, Plasmodium and other Apicomplexan parasites all have morphologically similar microtubule cytoskeletons. We are interested in the structural arrangement of the apical polar ring, a microtubule organizing center that nucleates 22 subpellicular microtubules. This year we have produced tomograms of this cytoplasmic region from wild type cells, using chemically-fixed preparations. To improve the structural preservation of the cells, Morrissette has been using the Balzers high pressure freezer at the Danforth Center in St. Louis and has produced some promising samples. In addition, the Morrissette lab is currently developing molecular genetic techniques to complement cellular and biochemical studies that are going on elsewhere. They are constructing genetic tools for Toxoplasma including a genomic map, vectors for DNA transformation and protein expression, and large-scale sequencing of cDNAs for gene discovery. These approaches are being applied to identify the molecular basis of virulence and to generate mutants with altered phenotypes in adhesion, invasion, and intracellular survival. The 3-D lab will characterize the phenotypes of these mutants, as they become available.