James W. Lane

Scanning-beam electron microscopy of the conidia of the brown and albino filamentous varieties of Histoplasma capsulatum

Aspects of the surface appearance and external morphology of the conidial forms of the albino and brown filamentous varieties ofHistoplasma capsulatum as seen by scanning-beam electron microscopy are described and illustrated by electron micrographs. Septal areas between the hyphal cells of the supporting mycelium are seen as slightly elevated annular rings or ridges. The smooth micro- and macroconidia of the albino filamentous variety show a fine wrinkling and delicate irregularities of surface texture. Macroconidia of the brown filamentous variety are illustrated showing variations in numbers and respective length of the conspicuous wall projections or tubercles. The 3-dimensional perspective, unusual depth of focus, and high resolving power of the stereoscan technique permitted observations of external conidia morphology unattainable by other methods of study.

Drug—induced alterations in the ultrastructural organization of Histoplasma capsulatum and Blastomyces dermatitidis

Aspects of the fine structure as seen in thin section of yeastlike cells ofHistoplasma capsulatum andBlastomyces dermatitidis exposed to polyenic antibiotics are described and illustrated by electron micrographs. The exposure of log phase yeastlike cells to minimal fungicidal concentrations of both amphotericin B (Fungizone) and hamycin resulted in detectable alterations of the plasma membrane, and, to a lesser extent, the mitochondria. WithH. capsulatum, ultrastructural changes were observed to occur within 1 h exposure to amphotericin B. Marked degenerative changes and plasmolysis were observed to occur within 6 hrs exposure of the yeastlike cells to both polyenes. The observed changes in ultrastructural appearance are compatible with the concept of binding of the polyene with membrane sterol and subsequent damage due to alterations of permeability.

Electron microscopy of the transitional conversion cell of Histoplasma capsulatum

Aspects of the fine structure of the transitional conversion cell formed during the early stages of the yeast to mold morphogenesis ofHistoplasma capsulatum as seen in ultrathin sections are described and illustrated by electron micrographs. Formation of the transitional cell was observed to occur with the highest degree of frequency between the 18th and 24th hr following induction of the conversional stimulus, although many yeastlike cells were observed to undergo degeneration or to initiate conversion only to abort the process. Cytoplasmic streaming and organelle migration from the parent yeast to the transitional cell was observed to occur prior to septation. The cell wall of the transitional form is thinner than that of the yeast and appears to arise from the inner portion of the laminated cell wall adjacent to the plasma membrane of the converting yeastlike cell. Interseptal or Woronin bodies were observed in association with the septal pore of the completed septum and were observed in the cytoplasm of both the yeastlike and transitional cell. The presence of these structures support strongly the pre-hyphal character of the converting cell complex.

Electronmicroscopy of self-parasitism by Histoplasma capsulatum and Blastomyces dermatitidis

Intrahyphal as well as intrayeast hyphae were demonstrated by electron-microscopy in bothHistoplasma capsulatum andBlastomyces dermatitidis yeastlike and mycelial phase cells grown in agitated liquid media. These structures appeared to be rather common in cultures of yeastlike cells induced to convert to the mycelial phase. In many cases there was excellent preservation of ultrastructural detail of the “parasitized” cell which suggested that the cell may still be viable. InHistoplasma capsulatum so wie auch inBlastomyces dermatitidis wurden in Hyphen und Zellen der Hefe- so wie auch der Mycelphase intracellular Hyphen durch Elektronmikrokopie nachgewiesen, wenn sie in flüssigen Schüttelkulturen gezüchtet worden sind. Diese Strukturen waren in Zellen der Hefephase, die zur Überleitung in die Myzelphase angeregt worden sind, sehr häufig. In vielen Fällen war eine sehr gute Bewahrung der ultrastrukturalen Einzelheiten der “parasitierten” Zelle, die es nahegelegt hat, dass die Zelle noch immer lebendig ist.

The fine structure of the microconidium of Blastomyces dermatitidis.

Aspects of the fine structure of the microconidium of the mycelial phase of the dimorphic fungal pathogenBlastomyces dermatitidis as seen by techniques of scanning and transmission electron microscopy are described and illustrated by electron micrographs. The conidia ofB. dermatitidis undergo changes in the ultrastructural appearance of the cell wall as the spore matures. The cell wall becomes irregular in its thickness and possesses two distinct layers. No discrete or unique surface spines or projections were evident when the conidium ofB. dermatitidis was viewed by scanning electron microscopy. Upon maturity there is a marked deposition of lipid material in large, multiple storage bodies which occupy much of the cytoplasmic area. However, the cytoplasmic organelles appear to retain their structural integrity.

Yeastlike to mycelial phase transformation of Histoplasma capsulatum as observed by scanning electron microscopy

Details of the sequential events occurring during the critical phases of yeast to mold morphogenesis of the dimorphic fungal pathogenHistoplasma capsulatum as seen by the new technique of scanning electron microscopy are described and illustrated by electron micrographs. No conspicuous surface sculpturing was observed for the normal yeastlike cell immediately before or the newly formed hyphal cell after the critical period of transformation. However, both the parent yeastlike cell as well as the intermediate conversional cell shows a furrowing of the external cell surface which is due possibly to changes in internal cell pressure resulting from the migration of cell contents into the newly forming hyphal cell.

Bacterium anitratum. II. Biological activities of non-viable fractions.

It has been shown previously that, although Bacterium anitrwtgm could be isolated with a rather high degree of frequency from soils originating from a wide geographic area, the viable soil isolates possessed only questionable virulence for the laboratory mouse (Lane et al, 1966). Therefore) it seemed of interest to determine the nature and zn ?vivo effed of certain non-viable fractions prepared from different strains of B. anitratgm. This report presents data on the isolation chemical properties, and biological activity of both intracellular and extracellular fractions isolated from strains of human and soil origin.

Bacterium anitratum. I. Mouse virulence of strains from midwestern soils.

Bacterigm anitrdtGm is a short, Gram negative, bi-polar staining rod which has been reported to be associated with human infections with increasing frequency. Preliminary evidence from our laboratories (Garrison, 1963) (Lane, et v1., 1965) suggests that this unusual organism is probably a more common member of the soil microflora than previously suspected. Unpublished data from our laboratories indicate that strains of B. anitrvX?n isolated from human sources possess a degree of mouse virulence of about the magnitude of that reported fot certain strains of Protevx aglgaris (Miles, 1951), Psegdomons vergginosa (Rosenthal et al, 1957), certain strains of enteropathogenic Esaherichiv oli (Erlandson et al, 1961), and Serrativ marcescesgs (Gale and Sonnenwirth) 1962). In order to obtain more information on the frequency of occurrence and plathogenic potentials of soil strains of B. vsitratgm} an examination of a large number of soil samples obtained from a wide geographic area was undertaken. Selected soil strains were assayed in the laboratory mouse to determine their relative virulence. The results of this study are described in this paper.