CRYO-ELECTRON TOMOGRAPHY OF GIARDIA INTESTINALIS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 肠贾第鞭毛虫(又称兰氏贾第鞭毛虫)是一种单细胞、有鞭毛的原生动物，生命周期分为两个阶段。贾第鞭毛虫病是由摄取囊状寄生虫引起的，然后这些寄生虫在十二指肠内排出，进入滋养体。滋养体有一个高度特化的微管细胞骨架(八个鞭毛，“中体”和“腹盘”)，这允许寄生虫逃避宿主肠道的蠕动运动。感染贾第鞭毛虫是寄生虫直接附着在肠道上皮细胞的结果；从上皮层的粘膜分泌物中获取营养。附着的机制尚不完全清楚，但最近的证据表明，这种寄生虫使用的是腹盘构象变化所产生的吸力。腹侧盘由逆时针方向的微管阵列组成，这些微管起源于直接位于尾部和后外侧鞭毛基本体前面的电子致密带。微管的腹面附着在质膜上。在每个微管的背侧是一条微带，它通过交联剂与相邻的微带相连。以前对贾第鞭毛虫细胞骨架的研究主要集中在使用低分辨率技术，如光学显微镜、化学固定塑料包埋样品和负染色法来了解基本的盘状结构。在我们的研究中，我们使用冷冻电子断层扫描分离洗涤剂提取的细胞骨架来确定腹侧盘不同组成部分之间的结构-功能关系。我们已经使用我们的程序Peet来平均腹侧盘的微管。

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. Giardia intestinalis (also known as Giardia lamblia) is a unicellular, flagellated protist with a two-stage lifecycle. Giardiasis is caused by ingestion of the cyst form of the parasite which then excysts in the duodenum into the trophozoite form. The trophozoite form has a highly specialized microtubule cytoskeleton (eight flagella, the "median body" and the "ventral disc"), which permits the parasite to evade peristaltic movement in the host's intestine. Infection with Giardia is the results of parasite attachment directly to the intestinal epithelium; deriving nutrients from the mucosal secretions of the epithelial layer. The mechanism of attachment is not fully understood, but recent evidence suggests the parasite uses suction created by conformational changes of the ventral disc. The ventral disc consists of a counterclockwise array of microtubules that originate from electron dense bands directly anterior to the caudal and posterior-lateral flagellar basal bodies. The ventral surface of the microtubules is attached to the plasma membrane. On the dorsal side of each microtubule is a microribbon that is connected to neighbor microribbons by cross-linkers. Previous studies of the Giardia cytoskeleton have focused on understanding the basic disc structure using low-resolution techniques such as light microscopy, chemically fixed plastic embedded samples, and negative stain. In our study, we are using cryo-electron tomography of isolated detergent-extracted cytoskeletons to determine the structural-functional relationships between the various components of the ventral disc. We have used our program PEET to average the microtubules of the ventral disc.