4 Analysis of Refractile (R) Bodies

Abstract

This chapter discusses the analysis of refractile (R) bodies that are bacterial inclusion bodies consisting of a convoluted proteinaceous ribbon, found naturally in Caedibacter and in some strains of the genus Pseudomonas . For most investigations on R bodies it is necessary to purify them to some extent or to homogeneity. In all investigations, it is recommended to start with cultures having a high ratio of R body-containing cells. Negative staining is used preferentially for investigating isolated R bodies and also for detecting R bodies inside cells. Metal shadowing is used for detecting R bodies inside whole cells and for examining isolated R bodies in the extended form, allowing the differentiation of two surfaces, one with a more granular texture in the inner side and the other, at the outer surface, relatively smooth. Ultra-thin sections of whole cells show that the R bodies are rolled-up double membrane systems with two electron-dense zones. The average thickness is 11–16 nm. Most of the R bodies sectioned contain a fibrous core material or spherical bodies, which could be associated with their assembly.