Peptidoglycan types of bacterial cell walls and their taxonomic implications.

The peptidoglycan (murein) sacculus is a unique and essential structural element in the cell wall of most bacteria. Made of glycan strands cross-linked by short peptides, the sacculus forms a closed, bag-shaped structure surrounding the cytoplasmic membrane. There is a high diversity in the composition and sequence of the peptides in the peptidoglycan from different species. Furthermore, in several species examined, the fine structure of the peptidoglycan significantly varies with the growth conditions. Limited number of biophysical data on the thickness, elasticity and porosity of peptidoglycan are available. The different models for the architecture of peptidoglycan are discussed with respect to structural and physical parameters.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1574-6976.2007.00094.x

Peptidoglycan structure and architecture

Mechanism of assembly of the outer membrane of Salmonella typhimurium. Isolation and characterization of cytoplasmic and outer membrane.

http://science.sciencemag.org/content/sci/192/4236/218.full.pdf

Surface modulation in cell recognition and cell growth.

Transmembrane control of the receptors on normal and tumor cells: I. Cytoplasmic influence over cell surface components☆

Ultrastructure of the cell wall of Escherichia coli and chemical nature of its constituent layers

The effect of concanavalin A (Con A) on the capping of mouse lymphocyte surface immunoglobulin (surface Ig), cross-linked by rabbit anti-mouse Ig antibody, and on the capping of mouse thymocyte theta antigen, cross-linked by anti-theta alloantibody and rabbit anti-mouse Ig antibody, has been studied by immunofluorescence, using fluorescein conjugated Con A and rhodamine-conjugated anti-mouse Ig antibody, and by electron microscopy, using native or fluorescein-conjugated Con A and ferritin-conjugated anti-mouse Ig antibody. Prior incubation of the cells with Con A inhibited only partially capping os surface Ig, whereas it blocked almost completely capping of theta antigens. Both on cells with rings and on cells with caps the staining for surface Ig or theta antigen was superimposed to the staining for Con A. When Con A receptors on spleen cells were capped by Con A at concentrations of 10 mug/ml or higher, and the distribution of surface Ig was examined under noncapping conditions, all detectable surface Ig were found in the caps. As shown by electron microscopy, surface Ig remained dispersed in a layer of Con A. The ability of Con A to cap surface Ig was not altered by the presence of cohchicine or vinblastine. These results suggest that surface Ig are cross-linked by Con A to other Con A receptors. In these conditions surface Ig behave essentially as Con A receptors, as for example, in their sensitivity to cytochalasin B during inhibition or reversal of capping induced by this drug. The behavior of surface Ig parallels that of Con A receptors also in the presence of vinblastine. It is concluded that in the presence of Con A, antimitotic drugs do not modify directly the interaction between Con A receptors and surface Ig, but probably influence the capping ability of the Con A receptors or, more in general, affect the ability to elicit movements over the cell surface. The role in capping of cytochalasin-sensitive and vinblastine-sensitive structures is discussed. Both types of structures appear to play an active role in the formation of a cap, although the former probably corresponds to the main mechanical system responsible for the active displacement of cytoplasmic and surface material.

/pdf/concanavalin-a-receptors-immunoglobulins-and-theta-antigen-2enfk0561h.pdf

Concanavalin A receptors, immunoglobulins, and theta antigen of the lymphocyte surface. Interactions with concanavalin A and with Cytoplasmic structures.

Filamentous structures in the cytoplasm of normal mononuclear phagocytes.

The development of antibody-producing cells in the early stages of the secondary or hyperimmune response has been studied with the electron microscope in lymph nodes of adult chinchilla rabbits immunized with ferritin or apoferritin. The intracellular distribution of antiferritin antibodies was determined in the lymph node cells at 1 to 5 days after a booster injection, employing the labelling technique previously used by the authors (12) to demonstrate the localization of antibodies in mature plasma cells. Antibodies were first detected at 48 hours in blasts; i.e., cells which have a poorly developed endoplasmic reticulum and a cytoplasm filled with many ribosomes grouped in clusters. The label was subsequently found in forms intermediate between blasts and plasma cells (plasmoblasts, immature plasma cells), in which the endoplasmic reticulum appeared progressively more developed. Antiferritin antibodies were also found in cells in mitosis. In all the above cell types, antigen-antibody precipitates were consistently found in the perinuclear space and in the cisternae of the granular endoplasmic reticulum, from an early stage in the development of the latter. Evidence was also obtained for the presence of antibody in the Golgi area. The results are discussed in relation to the possible cellular sites of antibody synthesis.

/pdf/localization-of-antibodies-by-electron-microscopy-in-3mm2faiiok.pdf

S. de Petris

Papers

Ultrastructure of the cell wall of Escherichia coli and chemical nature of its constituent layers

Concanavalin A receptors, immunoglobulins, and theta antigen of the lymphocyte surface. Interactions with concanavalin A and with Cytoplasmic structures.

Filamentous structures in the cytoplasm of normal mononuclear phagocytes.

Localization of antibodies by electron microscopy in developing antibody-producing cells

Ultrastructure of the cell wall of Escherichia coli