Phenotypic plasticity in fungi is reviewed in the context of observations on phenotypic changes in the colony morphology of the fungus Aureobasidium pullulans. The variation in colony form is shown to depend on (i) the types of single carbon substrates (sugars and sugar alcohols) used in the growth medium, (ii) colony age, (iii) incubation temperature, (iv) light cycle and (v) substrate type. Expanding colonies grow in a developmental sequence that show synchronize growth phase shifts as well as unusual transitions from homogeneous to sectored, yeast to mycelial and giant to microcolonial growth forms. Epigenetic influences on phenotypic switches are suggested to be potential causes of form changes. The desirable properties of a model organism for studying phenotypic plasticity are discussed and past work on the yeast-mycelial transition of fungi is reviewed.

https://www.jstor.org/stable/pdfplus/20619246.pdf

Phenotypic plasticity in fungi: a review with observations on Aureobasidium pullulans.

https://mmbr.asm.org/content/mmbr/17/1/51.full.pdf

The dimorphism phenomenon in yeasts

Blastomyces dermatitidis possesses two morphological forms, a yeastlike form in tissue and a mycelial form on Saboraud's medium at room temperature. A yeastlike form similar to the form appearing in tissue may be obtained if the organism is grown on blood agar at 37 C. An extensive literature has developed around blastomycosis as a clinical entity, but only a small proportion of the papers have been concerned with the biological nature of the etiological agent, Blastomyces dermatitidis. Ricketts (1901) described the two morphological forms. Hamburger (1907) concluded that temperature was the most important factor influencing morphology, and that room temperature favored mycelial formation, but incubator temperatures favored the yeastlike form. He did not determine the effect of intermediate temperature or of hydrogen ion concentration. Michelson (1928) studied the effect of higher temperatures and noted that temperatures of 37, 41, and 45 C favored the growth of the yeastlike form. Moore (1933) studied the organism for the purpose of determining its position in botanical classification. He studied its growth in media of different hydrogen ion concentrations, but each hydrogen ion concentration was represented by a different medium. The purpose of the present study was to determine the effect of various controlled changes in the environment, such as nutrition, hydrogen ion concentration, temperature, and type of inoculum on the two morphological forms of Blastomyces dermatitidis.

Factors Influencing the Morphology of Blastomyces dermatitidis.

Blastomyces dermatitidis, the etiologic agent of blastomycosis, is a thermally dimorphic fungus that grows as a filamentous mold in the environment and as budding yeast in human tissue. This pathogen is endemic to North America, particularly in the states bordering the Mississippi and Ohio rivers, the Great Lakes, and the St. Lawrence Seaway. Infection with B. dermatitidis causes a broad array of clinical manifestations ranging from asymptomatic infection to fulminant sepsis with acute respiratory distress syndrome and death. B. dermatitidis can infect almost any organ in the body, but has a predilection for lungs and skin. There have been recent advances in the understanding of the pathogenesis, diagnosis, and treatment of this fungus. The Infectious Diseases Society of America published updated guidelines in 2008 to guide clinicians in the treatment of this important pathogen.

/pdf/new-developments-in-blastomycosis-52th9t0yyp.pdf

New Developments in Blastomycosis.

INTRODUCTION 237 THE ERA OF DISCOVERY, 1894 TO 1919 237 Overview, 1894 to 1900 237 Scientific Contributions, 1894 to 1900 237 Blastomycosis 237 Coccidioidomycosis 239 Sporotrichosis 239 Mycotic mycetoma 239 Dermatophytosis 239 Overview, 1900 to 1919 239 Scientific Contributions, 1900 to 1919 239 Coccidioidomycosis 239 Sporotrichosis 240 Blastomycosis 240 Histoplasmosis 240 Chromoblastomycosis 240 Zygomycosis 241 THE FORMATIVE YEARS, 1920 TO 1949 241 Overview, 1920 to 1929 241 Scientific Contributions, 1920 to 1929 241 Mycotic mycetoma 241 Cryptococcosis 241 Histoplasmosis 241 Sporotrichosis, an occupational disease 241 Laboratory diagnosis 242 Skin test development 242 First training and research center 242 Overview, 1930 to 1939 242 Scientific Contributions, 1930 to 1939 242 Coccidioidomycosis 242 Meningeal infections 243 Histoplasmosis 243 Chromoblastomycosis 243 Taxonomy and classification 243 Fungal endotoxins 244 Training and research centers 244 Overview, 1940 to 1949 244 Scientific Contributions, 1940 to 1949 244 Systemic candidiasis 244 Zygomycosis 244 Mycotic mycetoma 244 Pseudallescheriasis 244 Epidemiology and ecology 245 Laboratory diagnosis 245 Antifungal agents 245 Training and research centers 245 THE ADVENT OF ANTIFUNGAL AND IMMUNOSUPPRESSIVE THERAPIES, 1950 TO 1969 246 Overview, 1950 to 1959 246 Scientific Contributions, 1950 to 1959 246 Opportunistic fungal infections in compromised patients 246

History of medical mycology in the united states.

TECHNIQUE. The usual cultural methods were used?growth on various liquid and solid media at room and incubator temperature under aerobic and anaerobic conditions, etc. In addition, methods employed in botanical research were used, such as the Van Tieghem cell, Wolbach's agar slides, and liquid paraffin cells. The Van Tieghem cell consists of a hollow cylinder of glass a centimeter in height and diameter. The edges may be ground to secure firm union with glass slide and cover-slip which complete the cell. The glass ring and cylinder are cemented to a slide, and liquid media or distilled water are filled in to about one-third the height of the cylinder. A cover-slip is prepared as in a hanging-drop preparation and inverted over the upright cylinder. It may be fixed with paraffin or balsam. The purpose of the preparation is to afford means of watching day by day, for a period varying at the will of the investigator, the growth and development of an individual cell or group of cells. If the hanging-drop be broth, media of the same density should cover the bottom of the cell. If it be agar, distilled water should be used. By diffusion the inoculated portion remains constant in concentration, evaporation and absorption going on equally. * Received for publication December 10, 1906. 1 Jour. Infect. Dis., 1906, 3, p. 91. a Ibid., p. 666. 3 Jour. Amer. Med. Assoc, 1906, 47, p. 247-

/pdf/a-comparative-study-of-four-strains-of-organisms-isolated-v85xsk3zj3.pdf

Walter W. Hamburger

Papers

A Comparative Study of Four Strains of Organisms Isolated from Four Cases of Generalized Blastomycosis