The limited availability of biological samples hinders phylogenetic efforts to define structural differences among various biological groups. A novel workflow enabling the analysis of protists in low cell numbers by electron microscopy (EM) is described with cysts of Giardia intestinalis, a single-celled eukaryotic parasite. Correlative light and electron microscopy (CLEM) allows for the selection of individual cells and is economical in terms of time and cost. We describe a cyst purification protocol in combination with an adhesive coating for fixation and ultrathin embedding that results in excellent preservation of cell morphology. The application of advanced structural and analytical EM methods, such as high-resolution field emission scanning electron microscopy (FESEM), focused ion beam tomography (FIB/SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis, is demonstrated. The workflow represents a new approach for studying the cellular and organelle architecture of rare and "difficult to culture" microorganisms.

中文翻译：

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通过使用相关的光学和电子显微镜表征少数单细胞真核生物的快速工作流程。

生物样品的有限可用性阻碍了系统进化努力来定义各种生物组之间的结构差异。描述了一种新颖的工作流程，该流程能够通过贾第鞭毛虫的囊肿（单细胞真核寄生虫）通过电子显微镜（EM）分析低细胞数量的原生生物。相关的光电子显微镜（CLEM）允许选择单个细胞，并且在时间和成本方面都很经济。我们描述了与固定和超薄包埋的粘合剂涂层相结合的囊肿纯化方案，可导致优异的细胞形态保存。先进的结构和分析EM方法的应用，例如高分辨率场发射扫描电子显微镜（FESEM），聚焦离子束断层扫描（FIB / SEM），并进行了能量色散X射线光谱（EDX）分析。该工作流程代表了一种研究稀有和“难于培养”微生物的细胞和细胞器结构的新方法。