Leodocia Pope

Ultrastructure and composition of conidial wall fractions ofCoccidioides immitis

Abstract The composition of the conidial wall of Coccidioides immitis , causative agent of a respiratory infection of man and other animals, is examined using electron microscopic, biochemical, and immunological techniques. Structural differences as well as quantitative and certain qualitative differences in carbohydrate, protein, and lipid composition between the isolated outer and inner wall fractions are described. The antigenic composition of solubilized extracts of these same wall fractions is examined by two-dimensional immunoelectrophoresis (2D-IEP) using a coccidioidinanticoccidioidin reference system previously described. Specific antigenic differences between the outer and inner wall fractions are also revealed. Ease of isolation and consistency of the morphological, chemical, and immunological features of each wall fraction demonstrated here are prerequisites for ultimate characterization and purification of clinically relevant antigens from the wall of the infectious propagule.

Formation of protoplasts in Azotobacter vinelandii

Protoplasts of Azotobacter vinelandii were formed by incubating whole cells in lysozyme and EDTA in Tris-HCl buffer (0.05 M, pH 8.0) supplemented with sucrose (15% w/v). This appeared to be related to the special chelating ability of EDTA and Tris-HCl since substitution of the former by nitrilotriacetic acid or by trisodium citrate and the latter by veronal-acetate buffer or tris-maleate buffer over a pH range of 5.2 to 8.6 yielded only spheroplasts. Of nine strains of Azotobacter studied, only A. vinelandii strain 12837 and strain 0 formed protoplasts.