Distribution of nuclei in macroconidia of dermatophytes

The distribution of nuclei in macroconidia was appraised in the following five dermatophyte species:Epidermophyton floccosum, Microsporum cookei, Microsporum gypseum, Trichophyton ajelloi andTrichophyton vanbreuseghemii. In all strains under investigation the number of cells in a macroconidium displays no correlation with the average number of nuclei in a cell of a given macroconidium; cells situated in the central part of the macroconidium tend to have a higher number of nuclei than cells at the periphery. The explored strains mutually differ significantly in the prevalence of nuclei in the left (basal) and right (apical) part of the macroconidium.     

Effect of environmental factors on the limpid composition membrane structure and permeability ofMicrosporum gypseum

Supplementation with unsaturated fatty acids, substitution of glucose by glycerol as carbon source and lowered growth temperature (20°C) increased the total phospholipid content ofMicrosporum gypseum spheroplasts. Levels of sterols increased with glycerol substitution and decreased in other growth conditions. Substantial changes were seen in the ratios of unsaturated to saturated fatty acids and phosphatidylcholine to phosphatidylethanolafne under all the experimental conditions. Changed lipid composition resulted in altered uptake of amino acids (L-lysine, L-aspartic acid and L-glycine) and increased number of binding sites for a fluorescent probe, 1-anilinonaphthalene-8-sulfonate.     

Effect of altered sterol levels on the transport of amino acids and membrane structure ofMicrosporum gypseum

Ergosterol and cholesterol supplementation resulted in a significant increase (1·5-fold) in the sterol content while phospholipid remained unaffected inMicrosporum gypseum. The levels of phosphatidylethanolamine and phosphatidylcholine increased in ergosterol supplemented cells. However, a decrease in phosphatidylcholine and an increase in phosphatidylethanolamine was observed in cholesterol grown cells. The ratio of unsaturated to saturated fatty acids decreased on ergosterol/cholesterol supplementation. The uptake of amino acids (lysine, glycine and aspartic acid) decreased in sterol supplemented cells. Studies with fluorescent probe l-anilinonaphthalene-8-sulfonate showed structural changes in membrane organisation as evident by increased number of binding sites in such cells.     

Morphogenesis in germinating Fusarium graminearum macroconidia

Fusarium graminearum (teleomorph Gibberella zeae) is a significant pathogen of wheat and corn. F. graminearum forms multicellular macroconidia that play an important role in dissemination of the disease. The spatial pattern of morphogenesis in germinating macroconidia is described. Germ tubes preferentially emerge from the apical cells in a bipolar pattern that appears to be common to filamentous fungi. Chitin deposition occurs at two locations: the spore apices and cortical regions of macroconidial cells that subsequently produce a germ tube. The spatial pattern of morphogenesis requires the presence of functional microtubules, which may be responsible for the transport of key polarity factors to specific sites. These observations suggest that F. graminearum possesses a regulatory system that marks germ tube emergence sites. Perturbation of this system may represent an effective approach for inhibiting colonization of host plant surfaces.     

A method for the isolation of nuclei from the dermatophytic fungus,Microsporum gypseum

A method is reported for the isolation of nuclei from the dermatophytic fungus,Microsporum gypseum. The yield ranged from greater than 90% in crude preparations to less than 20% in highly purified preparations as judged by the recovery of DNA. Nuclei isolated in this manner appeared intact in electron microscopic observations and possessed chemical compositions, i.e. low protein/DNA and RNA/DNA ratios, which indicated a low degree of cytoplasmic contamination.     

Heterokaryosis in Microsporum gypseum

The basic properties of heterokaryosis have been studied with the use of morphological and biochemical mutants ofMicrosporum gypseum. A direct proof of heterokaryosis was given with the help of the isolation of hyphal tips. Heterokaryons formed from aconidial components conidiate abundantly. The heterokaryotic constitution is preserved only with the transfer of mycelium; by microconidia the transfer is not effected.     

Diploids in Microsporum gypseum

The paper studies diploids in dermatophyteMicrosporum gypseum. They were isolated as the more rapidly growing sectors from heterokaryons on minimal medium. They are characterized by their wild morphology, conidiation and growth rate, and they are prototrophic. In their genome they contain all the markers present in both mutant components.     

Macroconidial Germination in Microsporum gypseum

Biochemical events which occur during macroconidial germination have been studied in the dermatophyte Microsporum gypseum. The specific activity levels of various metabolic enzymes have been assayed during germination time periods. The accumulated levels of several of these enzymes, as a function of exogenous carbohydrate source, have been investigated. M. gypseum was found to possess a constitutive glyoxalate shunt, a constitutive glucokinase, a fructose phosphoenolpyruvate transferase, and a mannitol phosphoenolpyruvate transferase. The integration of endogenous reserve utilization during germination is discussed. The purification and properties of an alkaline phosphatase and its possible relationship to sporulation and spore germination also are described.     

Studies on the macroconidia of Microsporum canis

The characteristics of an in vitro polyuridylic acid dependent amino acid incorporating system prepared from germinating macroconidia of Microsporum canis are described. The incorporation of ¹⁴C-phenylalanine into polyphenylalanine is dependent on S-30 extract, adenosine triphosphate, magnesium ions and polyuridylic acid. Incorporation is slightly enhanced by yeast transfer ribonucleic acid and pyruvate kinase. The system is highly sensitive to ribonuclease, puromycin and miconazole (an antifungal agent), moderately sensitive to sodium fluoride and much less sensitive to phenethylalcohol, cycloheximide, chloramphenicol and deoxyribonuclease. Cell-free extract from ungerminated conidia has less capacity to synthesize the protein and during germination a marked increase in the protein synthetic activity is observed. The results from experiments wherein ribosomes and S-100 fraction from germinated and ungerminated spores are interchanged, revealed that the defect in the extract from the ungerminated spore is in the ribosomes.Abbreviations Poly(U) polyuridylic acid - tRNA transfer ribonucleic acid - ATP adenosine triphosphate - GTP guanosine triphosphate - BSA bovine serum albumin - RNase ribonuclease - DNase deoxyribonuclease - POPOP 1,4-bis-2(5-phenyl oxazolyl)benzene - PPO 2,5-diphenyl oxazole - TCA trichloracetic acid     

Heat-induced Macroconidia Germination in Microsporum gypseum

A method for obtaining purified ungerminated macroconidia is described, and a technique for obtaining 85 to 90% germination of macroconidia under normal nutritional conditions is presented.