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PubMed2004

Tec1p-independent activation of a hypha-associated Candida albicans virulence gene during infection.

The Tec1p transcription factor is involved in the expression of hypha-specific genes in Candida albicans. Although the induction of the hypha-associated SAP5 gene by serum in vitro depends on Tec1p, deletion of all Tec1p binding site consensus sequences from the SAP5 promoter did not affect its activation. In two different animal models of candidiasis, the SAP5 promoter was induced even in a Deltatec1 deletion mutant, demonstrating that the requirement for Tec1p in gene expression in C. albicans depends on the environmental conditions within the host.

Animals↗
PubMed2005

Developmental-stage-specific assembly of ParB complexes in Streptomyces coelicolor hyphae.

In Streptomyces coelicolor ParB is required for accurate chromosome partitioning during sporulation. Using a functional ParB-enhanced green fluorescent protein fusion, we observed bright tip-associated foci and other weaker, irregular foci in S. coelicolor vegetative hyphae. In contrast, in aerial hyphae regularly spaced bright foci accompanied sporulation-associated chromosome condensation and septation.

Bacterial Proteins↗
PubMed1996

Polarized Growth of Fungal Hyphae Is Defined by an Alkaline pH Gradient

Robson, G. D., Prebble, E., Rickers, A., Hosking, S., Denning, D. W., Trinci, A. P. J., and Robertson, W. 1996. Polarized growth of fungal hyphae is defined by an alkaline pH gradient. Fungal Genetics and Biology 20, 289-298. Polarized cell growth is exhibited by a diverse range of eukaryotic and prokaryotic cells. The events which are responsible for this growth are poorly understood. However, the existence of ion gradients may play an important role in establishing and driving cell polarity. Using a pH-sensitive, ratiometric fluorescent dye to monitor intracellular pH in growing fungal hyphae, we report a gradient at the extending hyphal tip that is up to 1.4 pH units more alkaline than more distal regions. Both the magnitude and the length of the pH gradient were strongly correlated with the rate of hyphal extension and eradication of the gradient-arrested growth. These results suggest that alkaline pH gradients may be integral to hyphal extension in fungi.

Journal Article↗
PubMed1993

Determination of anti-Aspergillus activity of antifungal agents based on the dynamic growth rate of a single hypha.

The dynamic growth rate of a single hypha of Aspergillus niger was analysed using an automatic system. A colony of A. niger was in contact with saline, saline containing an antifungal agent, and flushing saline, in sequence. The growth rate of a test hypha selected arbitrarily from the colony responded dynamically to the antifungal agent. The minimum concentration that caused the complete inhibition of hyphal growth was defined as the minimum inhibitory concentration (MIC). The MIC values obtained were compared with those determined by conventional methods based on increasing rate of colony diameter or dry matter weight.

Amphotericin B↗
PubMed1977

Cell wall formation in zoospores of Allomyces arbuscula. III. Carbohydrate composition of cell walls during development from meiospores to hyphae.

Carbohydrate composition was determined in isolated cell walls of meiospores of Allomyces arbuscula after incubation for 15 min (encysted meiospores: cysts), 150 min (germlings: cysts + rhizoids) and 24 h (cysts + rhizoids + hyphae). The principal constituent in all cell wall samples is chitin, accounting for about 75% of the recovered carbohydrates. In addition, cell walls of all stages examined contain polysaccharides which release galactose, glucose, mannose, arabinose, xylose, fucose, and rhamnose on acid hydrolysis. While different developmental stages show minor quantitative changes in chitin, the ratio of galactose to glucose decreases sharply during differentiation of ungerminated cysts into germlings with rhizoids and hyphae. The increase in glucose is accompanied by a decrease in the amount of xylose and/or fucose and of galactose.

Carbohydrates↗
PubMed1983

Pathogenicity of the hyphae of Filobasidiella neoformans.

The pathogenicity of the purified hyphae of Filobasidiella neoformans was determined. The hyphal particles were inoculated into white Swiss female mice via the intracranial and intravenous route. Upon autopsy, infection was seen with as few as 25 hyphal elements. The brain, liver, and spleen were examined culturally and the brain examined histologically to prove the pathogenicity of the purified hyphae.

Animals↗
PubMed1992

Automatic antifungal activity analyzing system on the basis of dynamic growth process of a single hypha.

A system for the evaluation of antifungal activity of volatile compounds has been developed that is based on dynamic growth of a single hypha. The newly developed system is composed of a reaction vessel under a microscope, automatic stage, charge coupled device (CCD) camera, TV monitor, video tape recorder (VTR), and a microcomputer. A fungus was inoculated in the reaction vessel containing agar medium and then was treated with an antifungal reagent in the gas phase either in batch or flow reaction manner. The apex of a growing hypha displayed on a TV monitor was followed automatically. From the ratio of the growth rate under exposure of a reagent (UEXPO) to the growth rate before the exposure (UPRE), the antifungal activity was expressed quantitatively.

Antifungal Agents↗
PubMed1988

Selective staining of fungal hyphae in parasitic and symbiotic plant-fungus associations.

A cytochemical method for light microscopical studies is described which allows the specific detection of fungal hyphae in plant-fungus associations: e.g. lichens, mycorrhiza, or fungal infections of plant tissue. The specimens were fixed and embedded in epoxy resin by a standard protocol for electron microscopy. Semithin sections were successively incubated with fluorescein isothiocyanate labelled wheat germ agglutinin (FITC-WGA) and calcofluor white (CW). FITC-WGA stained exclusively the fungal cell walls while CW stained both the fungal and the plant cell walls. Therefore, FITC-WGA is an excellent marker for the fungal hyphae.

Ascomycota↗
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↗
PubMed1981

Technique for the purification of the hyphae of Filobasidiella neoformans.

A technique for the purification of the hyphae of Filobasidiella neoformans is described. Cultural conditions and strains for maximal hyphal production were determined. Blastospores were separated from hyphae by sonification of mycelial suspensions. Following this, the initial density ranges of all cell types were determined by isopycnic centrifugation, using Renografin-60 as a supporting medium. Based on these data, rate centrifugation with different density ranges was used to obtain cell separation. The final percentage of non-hyphal cells to total population was 0.007%. These were determined to be still viable at the end of separation.

Centrifugation, Density Gradient↗
PubMed2006

Soil salinity delays germination and limits growth of hyphae from propagules of arbuscular mycorrhizal fungi.

Colonisation of plant roots by some arbuscular mycorrhizal (AM) fungi is reduced in the presence of sodium chloride (NaCl), probably due to a direct effect of NaCl on the fungi. However, there appear to be differences between the fungi in their ability to colonise plants in the presence of NaCl. This experiment tested the hypothesis that propagules of different isolates and species of AM fungi from saline and nonsaline soils would differ in their ability to germinate and grow in the presence of NaCl in the soil solution. Spores or pieces of root colonised by a range of AM fungi were incubated between filters buried in soil to which NaCl had been added at concentrations of 0, 150 or 300 mM in the soil solution. At regular intervals, filters were removed from the soil and both the percentage of propagules which had germinated and the length of proliferating hyphae were determined. Germination of spores of AM fungi studied was delayed in the presence of NaCl, but the fungi differed in the extent to which germination was inhibited. Two isolates of Scutellospora calospora reached maximum germination in 300 mM NaCl, but neither of two isolates of Acaulospora laevis germinated in the presence of NaCl. Germination of spores of the other fungi, including some isolated from saline soil, fell between these extremes. For some fungi, the specific rate of hyphal extension was reduced by NaCl. For others, the specific rate of growth was similar in the presence of NaCl to that in the control treatment, but overall production of hyphae was reduced in the NaCl treatments because germination was reduced.

Germination↗
PubMed2005

Evaluation of Fusarium solani hyphae and conidia susceptibility to amphotericin B and itraconazole: study of a clinical case.

Fusarium species are hyaline moulds belonging to the hyalohyphomycosis group that are usually found in the soil and plants. This organism has emerged as a cause of disseminated invasive disease. The correlation between in vitro value and clinical efficacy is low and many patients remain unresponsive to treatment despite in vitro susceptibility. We determined growth control for Fusarium solani using the BioCell-Tracer system that measures the growth rate of a single fungal hypha, and the effect of different concentrations of amphotericin B and itraconazole. The MIC for these two drugs was also determined by a broth microdilution technique, using RPMI 1640. Different MICs for amphotericin B were obtained by the two different methods. This paper describes a case of infection due to Fusarium solani in an allogeneic bone marrow transplanted patient, the microbiological diagnostic, antifungal susceptibility tests for conidia and hypha and clinical correlation.

Adult↗
PubMed1991

Localization of actin and characterization of its isoforms in the hyphae of Neurospora crassa.

The actin of Neurospora crassa wild type Strain St. Lawrence has been purified, characterized and localized. A fungal 43 kDa protein was isolated by affinity chromatography on DNase I-Sepharose. This protein was identified as actin on immunoblots when an anti-actin monoclonal antibody raised against chicken gizzards was used as a probe. After two-dimensional gel electrophoresis three actin isoforms were detected. The distribution of actin in hyphae was examined by FITC-phalloidin staining of formaldehyde fixed hyphae. F-actin was found to be mainly concentrated in the hyphal tips in which it formed a uniform cap. Apical actin could be involved in hyphal morphogenesis, organelle motility and maintenance of polarity.

Actins↗
PubMed2001

Human immunodeficiency virus type 1 Tat binds to Candida albicans, inducing hyphae but augmenting phagocytosis in vitro.

Tat, the human immunodeficiency virus type 1 (HIV-1) transactivating protein, binds through its RGD-motif to human integrin receptors. Candida albicans, the commonest cause of mucosal candidiasis in subjects infected with HIV-1, also possesses RGD-binding capacity. The present study reveals that Tat binds to C. albicans but not to C. tropicalis. Tat binding was markedly reduced by laminin and to a lesser extent by a complement C3 peptide containing the RGD motif, but not by a control peptide. The outgrowth of C. albicans was accelerated following binding of Tat, but phagocytosis of opsonized C. albicans was also increased after Tat binding. Thus, Tat binding promotes fungal virulence by inducing hyphae but may also reduce it by augmenting phagocytosis. The net effect of Tat in vivo is difficult to judge but in view of the many disease-promoting effects of Tat we propose that accelerating the formation of hyphae dominates over the augmentation of phagocytosis.

ATPases Associated with Diverse Cellular Activitie↗
PubMed2000

ER-Tracker dye and BODIPY-brefeldin A differentiate the endoplasmic reticulum and golgi bodies from the tubular-vacuole system in living hyphae of Pisolithus tinctorius.

Two fluorochromes, ER-TrackerTM Blue-White DPX dye and the fluorescent brefeldin A (BFA) derivative, BODIPY-BFA, label the endoplasmic reticulum (ER) in hyphal tips of Pisolithus tinctorius and allow its differentiation from the tubular-vacuole system at the light microscope level in living cells. The ER-Tracker dye labels a reticulate network similar in distribution to ER as seen in electron micrographs of freeze-substituted hyphae. BODIPY-BFA stains a thicker axially aligned structure with an expanded region at the apex, which is similar to that seen when hyphae are stained with ER-Tracker dye in the presence of unconjugated BFA. This structure is considered to be ER modified by BFA, a view supported by ultrastructural observations of the effect of BFA on the fungal ER. Both fluorescent probes also stain punctate structures, which are most likely to be Golgi bodies. Neither probe labels the tubular-vacuole system.

Basidiomycota↗
PubMed1997

Nuclear traffic in fungal hyphae: in vivo study of nuclear migration and positioning in Aspergillus nidulans.

Nuclear migration and nuclear positioning are fundamental processes in all eukaryotic cells. They are easily monitored during hyphal growth of filamentous fungi. We expressed the green fluorescent protein (GFP) as a fusion protein with the putative nuclear localization domain of the transcriptional activator stuA in nuclei of Aspergillus nidulans and visualized these organelles in living cells. Nuclear staining was observed in interphase nuclei but not during mitosis. Nuclear division, nuclear migration, septum formation and branching were analysed with time-lapse video microscopy during hyphal extension. Hyphae elongated at 0.1-1.2 microm min(-1) and nuclei moved with similar speeds towards the hyphal tip until they had reached a defined position. An individual regulation of nuclear mobility in a given hyphal compartment was observed. Some representative movies are available on the Internet (http://www.blacksci.co.uk/products/journals/molextra.htm). Nuclear positioning was also studied at the molecular level. The ApsA protein, which regulates nuclear migration, was localized at the cytoplasmic membrane in germlings and hyphae by immunofluorescence and GFP tagging. A model of nuclear migration, nuclear positioning and the role of ApsA is presented.

Aspergillus nidulans↗
PubMed2002

In vitro studies on the activity of amphotericin B and lipid-based amphotericin B formulations against Aspergillus conidia and hyphae.

The minimum inhibitory concentrations (MICs) of amphotericin B and lipid-based amphotericin B formulations against isolates of Aspergillus spp. were tested using a broth microdilution method. Twelve isolates of Aspergillus fumigatus, eight of Aspergillus flavus, six of Aspergillus niger and seven of Aspergillus terreus were examined. In addition, an assay for hyphae of Aspergillus spp. was performed since the invasive form is manifested by the appearance of hyphal structures. MICs of hyphae against lipid-based amphotericin B formulations were within three dilutions higher than those against conidia for almost all isolates of Aspergillus spp. (P < 0.01). In contrast, the differences in the in vitro efficacies of amphotericin B were the lowest for Aspergillus spp. This study demonstrates the importance of the type of inoculum used to test antifungal susceptibilities of Aspergillus spp. The significance of these results for in vivo outcome needs to be determined.

Amphotericin B↗