Comparative Study of the Cell Walls of the Yeastlike and Mycelial Phases ofHistoplasma capsulatum

Abstract

Cell walls were prepared from the yeastlike and mycelial phases (YP and MP) of Histoplasma capsulatum and from Saccharomyces cerevisiae by mechanical disruption and washing. Lipids were extracted with methanol-ether, chloroform, and acidified methanol:ether; a final extraction was made with ethylenediamine. The lipid contents of H. capsulatum YP and MP walls were about the same. Qualitative and quantitative analyses were made of the products obtained from treatment of the cell walls, or fractions from them, with weak acid or with enzymatic preparations containing glucanase and chitinase activities. YP walls contained much larger quantities of chitin and smaller quantities of mannose and amino acids than the MP walls. H. capsulatum MP was shown to resemble S. cerevisiae by low chitin content and by the presence of a mannose polymer, soluble in ethylenediamine and water. H. capsulatum MP chitin appeared to be intimately associated with glucose in the wall, since enzymatic hydrolysis of the residue after mild acid hydrolysis of cell walls or fractions from them resulted in the release of glucose and acetylglucosamine; only acetylglucosamine was released from YP walls with such treatment. By electron microscopic observations, the unextracted MP cell walls were much thinner than the YP, and neither wall appeared laminated.

Effects of cyclophosphamide on murine candidiasis

“…f CY was given 3 days before a first inoculation (CYl'). 9 CY was given 3 days before a second inoculation (10CY20).…”

“…C. albicans B311 (serotype A; originally obtained from H. Hasenclever) was maintained by monthly transfer on glucose-peptone agar slants and stored at 40C. Most of the cultural and fractionation techniques used in these studies have been reported elsewhere (9,10,14).…”

“…Viable blastospores either for inoculation into mice or for preparation of subcellular fractions were grown in soy dialysate broth (31) for 18 h at 370C on a gyratory shaker. To obtain subcellular fractions, washed blastospores were disrupted in a Braun model MSK homogenizer (Bronwill Scientific Inc., Roches-ter, N.Y.), and fractions rich in cell walls, membranes and mitochondria, or soluble cytoplasmic substances were obtained after a series of three differential centrifugations, beginning with 400 x g and ending with 144,000 x g. The cell wall fraction was extracted with ethylenediamine to obtain water-soluble glycoproteins (9). The soluble cytoplasmic substance fraction was dialyzed (retention, -10,000 daltons) to remove lowmolecular-weight components, lyophilized, and not fractionated further.…”

Electron microscopy of yeastlike cell development from the microconidium of Histoplasma capsulatum

“…The sequential ultrastructural changes associated with morphological alterations occurring during conversion of the microconidial cell might suggest possible changes in the biochemical nature of the cell wall during the various stages of morphogenesis. It is known that the cell wall of H. capsulatum consists predominantly of chitin and glucan (5,6,7,12,14). The ratio of chitin to glucan (7), the configuration of the glucan as aor fl-linked polymers (4,7,13), and the presence of autolytic extracellular or wall-associated glucanases (4) may be important factors in determining whether the cells grow as a yeast or a mycelium.…”

“…It is known that the cell wall of H. capsulatum consists predominantly of chitin and glucan (5,6,7,12,14). The ratio of chitin to glucan (7), the configuration of the glucan as aor fl-linked polymers (4,7,13), and the presence of autolytic extracellular or wall-associated glucanases (4) may be important factors in determining whether the cells grow as a yeast or a mycelium. The development of techniques employing electron cytochemical methods might be useful in localization studies associated with cell wall synthesis or degradation that might occur during the conversion process of cell systems such as those described here.…”