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At least 19 recordsLinked to original sources
PubMed1975

Electron microscopy of vesicular-arbuscular mycorrhizae of yellow poplar. II. Intracellular hyphae and vesicles.

Intracellular hyphae and vesicles in mycorrhizal roots of yellow poplar were examined by electron microscopy. An investing layer of host wall material and cytoplasm enclosed the endophyte within the cells. Young developing hyphae contained abundant cytoplasm and few vacuoles. As hyphae matured, they became highly vacuolated and accumulated carbohydrate (glycogen) and lipid reserves. Mature vesicles were engorged with lipid droplets, possessed a trilaminate wall and were also enclosed by host wall material and cytoplasm. Compared with uninfected cells, infected cortical cells showed an increase in cytoplasmic volume, enlarged nuclei, and a reduction of starch reserves. Host nuclei were always proximal to the hyphae during hyphal development and deterioration. While other cytoplasmic components of infected and uninfected cells were comparable large electron-dense bodies occurred in vacuoles of most cells containing hyphae. Deterioration of intracellular hyphae occurred throughout the samples examined. Septa separated functional and degenerating portions of the hyphae. Hyphal deterioration involved degeneration and ultimate disappearance of fungal cytoplasm as well as collapse of hyphal walls. Based on these observations, the authors hypothesize that deterioration of the endophyte may release significant quantities of mineral nutrients, via hyphal contents, which are absorbed by the host.

Cell Wall↗
PubMed1976

Acid phosphatase activity in the wild-type and B-mutant hyphae of Schizophyllum commune.

In the wild-type and B-mutant hyphae of Schizophyllum commune, acid phosphatase activity was found in association with vacuoles, lipid bodies, and endoplasmic reticulum. Small granules containing acid phosphatase also occurred in mitochondria and along the nuclear envelope. Both ultrastructural and biochemical studies indicated greater acid phosphatase activity in the B-mutant than in the wild-type hyphae, which suggests that the mutation in the B incompatibility factor increases the production of the acid phosphatase in the mutant hyphae.

Acid Phosphatase↗
PubMed1976

Fine cytochemical detection of acid mucopolysaccharides in growing hyphae of Neurospora crassa.

The presence of mucopolysaccharides (MP) in Neurospora crassa hyphae was detected in samples of cultures from 4 h to 5 days. Using a modification of the method of Rothman (1969), acid MP were identified by electron microscopy in vesicles located at the apex, septae, and throughout the cytoplasm of the hyphae. The size, number, and localization of these vesicles was related to the stage of growth of the fungus. The mechanisms of release and transport of these macromolecules are compared to the process of secretion in cells endowed with a better developed endoplasmic reticulum and Golgi system. The specificity of the method was evaluated histochemically. The structures displaying greater electron density corresponded to the Alcian blue positive areas.

Alcian Blue↗
PubMed1975

Morphology and growth kinetics of hyphae of differentiated and undifferentiated mycelia of Neurospora crassa.

A comparison was made of the morphology and growth kinetics of hyphae of differentiated and undifferentiated mycelia of Neurospora crassa. Undifferentiated mycelia were formed during exponential growth on solid media or submerged culture. Hyphae at the margin of differentiated mycelia (colonies) differed from undifferentiated mycelia in diameter, extension rate, extension zone length, and intercalary and apical compartment length. The mean hyphal extension rate (E) of an undifferentiated mycelium was a function of the length of the mycelium's hyphal growth unit (G) and the organism's specific growth rate (alpha). Thus, E=Galpha.

Culture Media↗
PubMed1978

Distribution of autolysins in hyphae of Aspergillus nidulans: evidence for a lipid-mediated attachment to hyphal walls.

Preparations of broken Aspergillus nidulans hyphae contained both free and wall-bound autolysins. The bound enzymes were not solubilized by 8 M LiCl or neutral or anionic detergents; they were readily detached from walls by a cationic detergent or by autodigestion. Once detached, the enzymes did not reassociate with wall to give salt-resistant complexes. Six enzymes hydrolyzing wall polymers were bound to the envelope, and the same activities were also detected among soluble proteins in the cytoplasmic fraction. It is suggested that cytoplasmic vesicles, containing autolysins, are inserted into or trapped by newly formed wall in the growing hypha; these constitute the wall-bound autolysin fraction. Starvation for a carbon source derepressed the synthesis of five out of the six autolysins, and the amounts of both soluble and wall-bound activities increased by one to two orders of magnitude.

Aspergillus nidulans↗
PubMed1976

A method for staining infection hyphae in pine leaves.

Fungus-inoculated Pinus radiata leaves were fixed and then stained with periodic acid-Schiff reagent. Pieces of leaf with fungal material on the surface were removed. These pieces were stained in lactophenol cotton blue for a few minutes and then mounted in dilute lactophenol cotton blue. Microscopic examination of fungal material inside and outside the mounted leaf pieces revealed the following: condidia and germ tubes on the leaf surface were red, appressoria remained unstained, and infection hyphae within the leaf were stained blue. This differential staining method was particularly useful for distinguishing germ tubes from infection hyphae arising from appressoria.

Fungi↗
PubMed1977

Antifungal antibiotic of the Basidiomycete Oudemansiella mucida. III. Nuclei in the hyphae of mono- and dikaryons.

Nuclear ratios were studied in terminal and subterminal cells of various mycelia of the basidiomycete Oudemansiella mucida, the producer of the antifungal antibiotic mucidin (MuciderminR Spofa). The dikaryon, the monokaryon, and the mucidin-producing strain that had been cultivated for a long time under submerged conditions were compared. Dedikaryotization was found to have taken place in the producing strain. The originally dikaryotic culture with characteristic clamp connections on the mycelium and with two nuclei in every hyphal cell lost permanently the clamp connections, probably owing to continuous intense agitation. The hyphae contained solely mononuclear cells. Mating with a compatible monokaryon yielded a dikaryon capable of normal fructification.

Antifungal Agents↗
PubMed1979

The effect of 5-fluorocytosine on the blastospores and hyphae of Candida albicans.

In Candida albicans the continued increase in dry weight, in cell volume and in hyphal length during 5FC treatment is mainly due to increased amount of carbohydrate despite the decreased amounts of nucleic acids. Incorporation studies with 32PO4 (for RNA) in C. albicans and with 3H-thymidine-monophosphate (for DNA) in a thymidine-utilising strain of Saccharomyces cerevisiae have shown that the decreased amounts of nucleic acids were due to an inhibition of synthesis of RNA and DNA by 5FC. Nuclear-staining techniques on the hyphal phase of C. albicans showed that 5FC inhibits nuclear division. The changes in amounts of protein during 5FC treatment do not wholly explain the changes in cell size although 14C-histidine incorporation experiments showed that protein synthesis continued in the presence of 5FC. 14C-glucose incorporation in the presence of 5FC showed an initial accelerated synthesis of carbohydrate with a maintained level of synthesis after 16 h. This abnormal pattern of synthesis correlates with the increase in amount of carbohydrate and in cell size and hyphal elongation. 5FC inhibits DNA synthesis, and all manifestations of unbalanced growth that culminate in the cell volume changes appear to be a consequence of that inhibition.

Candida albicans↗
PubMed1978

High molecular weight ribosomal ribonucleic acid from vegetative hyphae and spores of Streptomyces griseus.

High molecular weight ribosomal ribonucleic acids (rRNAs) were isolated from young vegetative cells and spores of a streptomycin non-producing Streptomyces griseus, and their electrophoretic mobility was compared to each other and to that of rRNAs of Escherichia coli K-12. The electrophoretic mobility of 23 and 16S rRNAs from vegetative cells and spores of S. griseus was identical, but the 23S rRNAs of streptomyces ribosomes migrated more slowly on polyacrylamide gel than those of E. coli ribosomes. Intact, electrophoretically homogenous rRNAs could be isolated from S. griseus (No. 45-H) only in the presence of diethyl 1 pyrocarbonate (DEP), and intact rRNAs could be obtained from spores only if DEP had been added before breaking the spores. Otherwise instead of two distinct bands, three were obtained on polyacrylamide gel.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

Damage to hyphal forms of fungi by human leukocytes in vitro. A possible host defense mechanism in aspergillosis and mucormycosis.

Evidence suggests that neutrophils are important in host defenses against invasive aspergillosis and mucormycosis, although hyphae in these lesions are too large to be phagocytized. Interactions of neutrophils with hyphae of Aspergillus fumigatus and Rhizopus oryzae were studed in vitro. Light and electron microscopic observations indicated that neutrophils attached to and spread over the surfaces of hyphae, even in the absence of serum. This was followed by dramatic morphologic changes which suggested severe damage and probably death of hyphae. An assay of neutrophil-induced reduction of uptake of radioisotopes was used to quantitate damage to the fungi by neutrophils from normal subjects. Damage to hyphae was inhibited by a variety of compounds which are known to affect neutrophil surface functions, motility, and metabolism. Use of inhibitors of oxidative microbicidal mechanisms of neutrophils indicated the central importance of these mechanisms in damage to hyphae. Inhibitors of neutrophil cationic proteins altered damage only to Rhizopus. Damage to hyphae by lysozyme suggested that it may play a secondary role in the neutrophil, primarily against Aspergillus. This new nonphagocytic mechanism may play an important role in host defenses against these and other hyphal forms of fungi.

Aspergillosis↗
PubMedDate not supplied

[Morphofunctional study of the development of Actinomyces aureofaciens under conditions of regulated and unregulated fermentation].

Actinomyces aureofaciens producing tetracycline and its inactive proactinomyces-like variant were studied by electron microscopy during their growth under conditions of regulated and non-regulated fermentation. The ultrastructure of the active variant changed: the cell wall and ribosomes underwent modification, amorphous electron-transparent structures appeared, and tubular membrane structures were formed. No changes were found in the inactive variant. When Act. aureofaciens grows in conditions of non-regulated fermentation, it shows rapid disintegration and autolysis; then, wide fragmented hyphae are formed. The morphology of these hyphae is similar to that of spore forming hyphae of the aerial mycelium. Viable hyphae exist for a long time if the active culture grows in conditions of regulated fermentation with periodic addition of nutrient substances. Amorphous electron-transparent structures, apparently of the antibiotic nature, are formed in the hyphae and liberated into the medium.

Fermentation↗
PubMed1979

A model for hyphal growth and branching.

A mathematical model for hyphal growth and branching is described which relates cytological events within hyphae to mycelial growth kinetics. Essentially the model quantifies qualitative theories of hyphal growth in which it is proposed that vesicles containing wall precursors and/or enzymes required for wall synthesis are generated at a constant rate throughout a mycelium and travel to the tips of hyphae where they fuse with the plasma membrane, liberating their contents into the wall and increasing the surface area of the hypha to give elongation. The hypothesis that there is a duplication cycle in hyphae which is equivalent to the cell cycle observed in unicellular micro-organisms is also included in the model. Predictions from the model are compared with experimentally observed growth kinetics of mycelia of Geotrichum candidum and Aspergillus nidulans. The finite difference model which was constructed is capable of predicting changes in hyphal length and in the number and positions of branches and septa on the basis of changes in vesicle and nuclear concentration. Predictions were obtained using the model which were in good agreement with experimentally observed data.

Aspergillus nidulans↗
PubMed1976

Wall structure of the Neurospora hyphal apex: immunofluorescent localization of wall surface antigens.

Antisera have been raised in rabbits against three wall fractions from Neurospora crassa. Fractions were separated according to Mahadevan & Tatum (1965), i.e. fraction I, glucan-peptide-galactosamine complex; fraction III, laminarin-like glucan; and fraction IV, chitin. Distinct patterns of immunofluorescent staining were obtained using an indirect staining method. Hyphae stained with antiserum to fraction I showed maximum fluorescence in the apical and/or subapical regions: in both cases, fluorescence showed a sharp decrease with distance behing the subapical region. Hyphae stained with antiserum to fraction III showed faintly fluorescent tips with fluorescence increasing with distance from the tip. Hyphae stained with antiserum to fraction IV showed faint fluorescence, equivalent to levels of autofluorescence, except at the sites of hyphal fractures. Antisera were also raised against whole walls from 24 and 120 h cultures. Hyphae stained with antisera against whole walls which had previously been absorbed to remove antibodies to fractions I, III, and IV showed preferential staining of apices. The uncharacterized tip antigen(s) thus revealed was also demonstrated on immunodiffusion plates. This pattern of immunofluorescence was compared to the fluorescence of apices after staining with an optical brightener. Enzymic dissection procedures did not generally give reliable results with apices from 24 h cultures. Untreated apices appeared amorphous, while a drastic chemical treatment revealed randomly oriented microfibrils which were shown to be alpha-chitin. The apical hyphal walls were significantly thinner than those from more mature hyphal regions.

Antigens, Fungal↗
PubMed1978

Chitin synthesis in Candida albicans: comparison of yeast and hyphal forms.

Chitin synthesis was studied in both yeast and hyphae of the dimorphic fungus Candida albicans. Incorporation of N-acetyl-d-[1-(3)H]glucosamine ([(3)H]GluNAc) into an acid-alkali-insoluble fraction was 10 times greater in hyphal-phase cells. A crude preparation of chitin synthetase was obtained from sonically treated protoplasts of both forms of Candida. Enzyme activity, which was determined by using [(14)C]UDP-GLuNAc as a substrate, was exclusively associated with the 80,000 x g pellet from sonically treated protoplasts of both forms. It was determined that enzyme activity (nanomoles of [(14)C]UDP-GluNAc incorporated per milligram of protein) was approximately 2 times greater in hyphae versus yeast cells. Enzyme activity in both yeast and hyphae increased six- to sevenfold when the enzyme preparations were preincubated with trypsin. A vacuolar fraction, obtained from yeast cells but not from hyphae, stimulated enzyme activity when incubated with either yeast or hyphal enzyme preparations. Membrane fractions from protoplasts coated with [(3)H]concanavalin A before disruption were isolated by Renografin density gradient centrifugation. Chitin synthetase activity was preferentially associated with the concanavalin A-labeled fraction, suggesting that the enzyme was located on the plasma membrane. In addition, enzyme activity in protoplasts treated with cold glutaraldehyde before disruption was significantly greater than in protoplasts that were sonically disrupted and then treated with cold glutaraldehyde, indicating that the enzyme resides on the inner side of the plasma membrane.

Candida albicans↗
PubMed1979

Ageing of Neurospora crassa. IX. Microviscosity properties of mitochondrial membranes during normal and abnormal growth and development of an inositol auxotroph.

Microviscosity of mitochondrial membranes of an inositol auxotroph of Neurospora was measured by the method of Shinitzky, employing the fluorescent probe diphenyl-hexatriene. With high concentration of inositol, growth, morphogenesis, and cellular and biochemical phenotypes of the auxotroph are normal; whereas with low concentrations, these characteristics become abnormal and cellular and clonal senescence ensue. During normal growth and development, the critical temperatures of phase transition, the energies and volumes of fusion (delta E, V), and the microviscosities (n) at low and high temperatures changed in a cyclical "gaussian" manner; whereas the microviscosity at 25 degrees C remained constant. The normal developmental changes of the microviscosity properties were consistent with Brody's molecular packaging hypothesis, whereby the biochemical properties of conidia are pre-determined in conidiogenic hyphae. The microviscosity properties and their developmental change were closely correlated with other biochemical and biological properties such as the critical extremities of growth temperature, activity of membrane-bound cytochrome oxidase, and the stages of cellular differentiation. The thermodynamic properties of the membrane microviscosity support the genetic hypothesis that conidia and conidiogenic hyphae are more highly differentiated than growing hyphae. During abnormal growth and development, delta E and V of the liquid-crystalline phase underwent a precocious, but otherwise normal change at an early age; whereas subsequent cellular and mitochondrial senescence was accompanied by an abnormal increase of microviscosity and abnormally small delta E and V. With the results of other experiments and by analogy to proposed structural determinants of microviscosity properties of other biological membranes, a tentative interpretation of the molecular basis of the microviscosity properties and their normal and abnormal changes is derived. The effects of phospholipase treatment indicated that electrostatic interaction of phospholipid polar groups with membrane proteins may restrict mobility, increasing microviscosity and decreasing energies of fusion. Abnormal development or ageing of the membranes, leading to abnormally large n and small delta E, is probably a consequence of excessive lipid peroxidation and related abnormal changes of their structure.

Aging↗
PubMedDate not supplied

Denture stomatitis-yeast occurrence and the pH of saliva and denture plaque.

The study comprised 30 denture wearers with generalized simple or granular inflammation in the palate and 30 without (controls). )easts, mostly Candida species, were cultivated from the maxillary dentures of all subjects with inflammation and of 23 controls. Hyphae were found in the maxillary denture smears from 28 subjects with inflammation and from 18 controls. Thus it seems unjustified to consider the occurrence of hyphae pathognomonic of denture stomatitis. The pH of whole saliva did not differ in the two groups (inflammation:mean pH 6.5, control:6.6). There was no clear relation between the pH of resting saliva and the amount of fungal cultures. Thirty minutes after a mouthrinse with 10 ml of a 25% sucrose solution, the mean saliva pH had dropped equally in both groups. With regard to the denture plaque, samples taken 40 min after the rinse indicated a more pronounced acid production in the plaque associated with inflammation. The pH of "resting" plaque was also lower in the inflammation than in the control group (mean maxillary pH 5.7 and 6.3 respectively, a=0.002). No association was found between the pH and the occurrence of hyphae in "resting" denture plaque. This supports the view that the pH is of no major importance for filamentation in vivo.

Adult↗
PubMed1978

Direct observation of fungal aggregates in sand dune soil.

The mycorrhizal fungus Glomerus in association with bean hosts, Phaseolus vulgaris L., growing in pot cultures and grass hosts, Calamovilfa longiflora (Hook). Scribn and Andropogon sp. growing on Lake Huron sand dunes produced extensive external mycelium. This mycelium was the dominant factor in the aggregation of soil particles. Light and scanning electron microscope studies indicated that the sand grains were attached to the hyphae. An amorphous deposit was often present at the interfaces of sand grains and hyphae. It appeared to act as an adhesive. Staining procedures indicated that this material contained polysaccharide. Other microogranisms were observed in association with the Glomus hyphae and the amorphous deposits.

Bacteria↗