The role of the cell surface in social and adventurous behaviour of myxobacteria.

The myxobacteria are an unusually social group of prokaryotic organisms that form fruiting bodies containing dormant myxospores in response to nutritional stress. Social behaviour is controlled by a multigene system known as 'S' and by a series of intercellular signals that are released during development. The genes controlling these communication systems have been identified by mutational analysis and current research is directed toward examining the functions of these genes. S- mutants are generally nondevelopmental and noncohesive. They lack pili, a Congo red receptor, and 50-nm-wide fibrils which extend outward from the cell surface. Changes in the architecture of the cell surface have been studied by means of surface labelling and with monoclonal antibodies directed against cell-surface antigens. The cell surface undergoes dramatic changes during the course of development. Most vegetative antigens decrease in concentration or disappear completely while new development-specific antigens appear.