Structure, composition, and morphogenesis of the cell wall of Chiamydomonas reinhardi: II. Electron microscopy and optical diffraction analysis

Abstract

As a prelude to in vitro experiments on the problem of assembly processes, the detailed three-dimensional architecture of the cell wall of Chlamydomonas reinhardi is being investigated. Optical diffraction techniques have been applied to electron micrographs of purified cell walls, and the Fourier transform derived from a single cell wall has been identified. Similar micrographs, subjected to photographic linear integration, or optical reconstitution after image filtering, have clarified the structures comprising the complex lattice within the wall. Optical diffraction techniques, applied to micrographs of rotary-shadowed cell walls, have enabled a correlation between the structure of the outer surface of the wall and the negatively stained wall to be established. Our results demonstrate the presence within the cell wall of a highly ordered complex glycoprotein lattice for which we have proposed a two-dimensional structural model to a resolution of about 2.5 nm. The repeating morphological unit of the model can be described as a parallelogram, composed of several discrete components, with sides of 28.5 nm and 23.6 nm and an angle of 80°. Such a highly crystalline cell wall component is at present unique among plant cells, but may be of more general occurrence as its extreme lability has made detection difficult by conventional methods.