Cryo- Electron Tomography and Fluorescence Microscopy of Unicellular Algae in Vitreous Cryosections

Abstract

Cryo-electron tomography allows the visualisation of the internal structure of vitreous biological material at a resolution of 3-5 nm Physical fixation of cells and tissues by rapid freezing and maintenance of this state during tomography ensures optimal preservation of ultrastructure Due to the strong interaction of electrons with matter, vitreous samples thicker than ca. 0.8 m cannot be visualised in toto. We have combined mechanical sectioning ('cryosectioning') and subsequent tomographic analysis to visualise subcellular detail in the unicellular algae Cyanidioschyzon merolae and Cyanidium caldarium. The more general aim of our study is to determine the molecular architecture and spatial organisation of eukaryotic cells in a non-invasive manner.