Biomedical subjects
Publications and source records attributed to G Vigers.
A side-entry cold holder for cryo-electron microscopy has been constructed which can be used with no loss of image resolution or contrast at 3.4 A resolution compared to the normal room-temperature holder. A description is presented of some of the ideas and tests which we have developed during its construction and are included in the design, together with a briefer outline of the remaining limitations.
Tubulin crystals produced by incubation with vinblastine sulphate have been investigated by X-ray diffraction, electron microscopy and density measurement. The results show that crystals produced in vitro from bovine brain tubulin are made of packed helices, each consisting of a single continuous protofilament, whereas crystals produced in vivo in sea urchin eggs are built from pairs of such helices. The symmetry, cell dimensions, percentage protein and composition of the crystals are consistent with either 24 or 30 tubulin monomers per turn of the helix. The sea urchin egg crystals are more highly ordered and thus more suitable for further analysis.
The electron microscopy of frozen-hydrated specimens has the potential to allow biological material to be examined in conditions very similar to the native state, and so has excited considerable interest. Although not all of the problems associated with the method have been solved, the technique has already provided important insights into macromolecular structure and assembly and promises to be a powerful tool for investigating the structure of cellular components and their interactions.