Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hyphae”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Contact-sensing by hyphae of dermatophytic and saprophytic fungi.

Contact-sensing or thigmotropism is the directional growth response of cells in relation to topographical guidance cues. Thigmotropism is thought to play a major role in the location of infectable sites on plants by phytopathogenic fungi and has recently been shown to be a property of hyphae in the human pathogenic fungus Candida albicans. Here we show that hyphae of the dermatophytes Epidermophyton floccosum, Microsporum canis and Trichophyton mentagrophytes reorientate their direction of growth in response to grooves and pores of membrane substrata as did hyphae of the saprophytes Mucor mucedo and Neurospora crassa. This suggests that the thigmotropic behaviour of hyphae is not a specific property of pathogens, but rather a general feature of the growth of fungal hyphae that must forage for nutrients on surfaces and within solid materials.

Arthrodermataceae↗
PubMed2000

Dendritic cells discriminate between yeasts and hyphae of the fungus Candida albicans. Implications for initiation of T helper cell immunity in vitro and in vivo.

The fungus Candida albicans behaves as a commensal as well as a true pathogen of areas highly enriched in dendritic cells, such as skin and mucosal surfaces. The ability of the fungus to reversibly switch between unicellular yeast to filamentous forms is thought to be important for virulence. However, whether it is the yeast or the hyphal form that is responsible for pathogenicity is still a matter of debate. Here we show the interaction, and consequences, of different forms of C. albicans with dendritic cells. Immature myeloid dendritic cells rapidly and efficiently phagocytosed both yeasts and hyphae of the fungus. Phagocytosis occurred through different phagocytic morphologies and receptors, resulting in phagosome formation. However, hyphae escaped the phagosome and were found lying free in the cytoplasm of the cells. In vitro, ingestion of yeasts activated dendritic cells for interleukin (IL)-12 production and priming of T helper type 1 (Th1) cells, whereas ingestion of hyphae inhibited IL-12 and Th1 priming, and induced IL-4 production. In vivo, generation of antifungal protective immunity was induced upon injection of dendritic cells ex vivo pulsed with Candida yeasts but not hyphae. The immunization capacity of yeast-pulsed dendritic cells was lost in the absence of IL-12, whereas that of hypha-pulsed dendritic cells was gained in the absence of IL-4. These results indicate that dendritic cells fulfill the requirement of a cell uniquely capable of sensing the two forms of C. albicans in terms of type of immune responses elicited. By the discriminative production of IL-12 and IL-4 in response to the nonvirulent and virulent forms of the fungus, dendritic cells appear to meet the challenge of Th priming and education in C. albicans saprophytism and infections.

Adoptive Transfer↗
PubMed1989

Temporal allocation of (14)C to extramatrical hyphae of ectomycorrhizal ponderosa pine seedlings.

Ponderosa pine seedlings were inoculated with Hebeloma crustuliniforme either in growth pouches before they were transplanted to root-mycocosms (P seedlings), or at the time of transfer to root-mycocosms (V seedlings). Uninoculated seedlings served as controls (U seedlings). The use of root-mycocosms allowed examination of portions of hyphae separate from roots and rooting substrate but still in symbiosis with the host. The results thus provided a quantitative basis for estimating hyphal mass and carbon allocation to extramatrical hyphae. The amount of (14)CO(2) fixed after a 2-h exposure was greatest for P seedlings and least for uninoculated seedlings. Four and nine days after exposure, (14)C content was greatest in uninoculated seedlings and least in inoculated seedlings. In isotope distribution and dry mass accumulation, V seedlings were more similar to U than to P seedlings. Calculated on a dry weight basis, the allocation of isotope to mycelium suggested that extramatrical hyphae of P seedlings were a stronger sink for carbon than extramatrical hyphae of V seedlings. Differences in inoculation methods resulted in differences in carbon allocation and physiology of extramatrical hyphae that could affect seedling establishment and survival. Seedlings inoculated by one method cannot serve as surrogates for mycorrhizal seedlings produced by other inoculation techniques.

Journal Article↗
PubMed2000

Serum-induced hypha formation in the dimorphic yeast Yarrowia lipolytica.

The dimorphic yeast Yarrowia lipolytica forms true hyphae in a medium containing N-acetylglucosamine. We made a new finding that serum is a very effective inducer of hypha formation of Y. lipolytica: serum induced its hyphal growth very quickly compared to N-acetylglucosamine (4 h vs. 10 h). Osmotic and oxidative stresses (0.2 M NaCl and 20 mM H2O2) inhibited the hypha formation induced by N-acetylglucosamine, but did not suppress the hypha formation triggered by serum. Serum-specific morphological mutants, which formed hyphae in the N-acetylglucosamine medium but not in serum medium, could be isolated. These results suggest that the signal triggered by serum may be transduced through a different pathway, at least in part, from that used for the N-acetylglucosamine signal in Y. lipolytica.

Acetylglucosamine↗
PubMed1991

In vitro study of contact-mediated killing of Candida albicans hyphae by activated murine peritoneal macrophages in a serum-free medium.

Activated peritoneal macrophages obtained from Listeria-immune mice were demonstrated to kill nonphagocytosable Candida albicans hyphae by contact-mediated mechanisms in a serum-free synthetic medium. The actual killing of hyphae was confirmed by a microculture technique utilizing the dimorphic nature of the fungus. The most efficient candidacidal activity was demonstrated by the macrophages obtained from mice first immunized with live Listeria monocytogenes and then elicited with heat-killed L. monocytogenes cells. Resident macrophages from control mice showed only low candidacidal activity against C. albicans hyphae and yeast cells. Direct physical contact appeared to be required for macrophages to efficiently kill oversized C. albicans hyphae. Efficient in vitro killing of hyphae also required relatively high effector/target cell ratios (50 or higher). The contact-mediated candidacidal activity of activated macrophages was not significantly abrogated by oxygen-radical scavengers, suggesting the involvement of oxygen-independent mechanisms. These results suggest that the enhanced nonspecific immunity to candidiasis seen in Listeria-immune hosts can be attributed, at least in part, to activated fungicidal macrophages. The ability of macrophages to detect and destroy both yeast and hyphal C. albicans cells is clearly an important element of the host defense against candidiasis.

Animals↗
PubMed2000

A PAK-like protein kinase is required for maturation of young hyphae and septation in the filamentous ascomycete Ashbya gossypii.

Filamentous fungi grow by hyphal extension, which is an extreme example of polarized growth. In contrast to yeast species, where polarized growth of the tip of an emerging bud is temporally limited, filamentous fungi exhibit constitutive polarized growth of the hyphal tip. In many fungi, including Ashbya gossypii, polarized growth is reinforced by a process called hyphal maturation. Hyphal maturation refers to the developmental switch from slow-growing hyphae of young mycelium to fast-growing hyphae of mature mycelium. This process is essential for efficient expansion of mycelium. We report for the first time on the identification and characterization of a fungal gene important for hyphal maturation. This novel A. gossypii gene encodes a presumptive PAK (p21-activated kinase)-like kinase. Its closest homolog is the S. cerevisiae Cla4 protein kinase; the A. gossypii protein is therefore called AgCla4p. Agcla4 deletion strains are no longer able to perform the developmental switch from young to mature hyphae, and GFP (green fluorescent protein)-tagged AgCla4p localizes with much higher frequency in mature hyphal tips than in young hyphal tips. Both results support the importance of AgCla4p in hyphal maturation. AgCla4p is also required for septation, indicated by the inability of Agcla4 deletion strains to properly form actin rings and chitin rings. Despite the requirement of AgCla4p for the development of fast-growing hyphae, AgCla4p is not necessary for actin polarization per se, because tips enriched in cortical patches and hyphae with a fully developed network of actin cables can be seen in Agcla4 deletion strains. The possibility that AgCla4p may be involved in regulatory mechanisms that control the dynamics of the actin patches and/or actin cables is discussed.

Actins↗
PubMed2002

Contribution of aerial hyphae of Aspergillus oryzae to respiration in a model solid-state fermentation system.

Oxygen transfer is for two reasons a major concern in scale-up and process control in industrial application of aerobic fungal solid-state fermentation (SSF): 1) heat production is proportional to oxygen uptake and it is well known that heat removal is one of the main problems in scaled-up fermenters, and 2) oxygen supply to the mycelium on the surface of or inside the substrate particles may be hampered by diffusion limitation. This article gives the first experimental evidence that aerial hyphae are important for fungal respiration in SSF. In cultures of A. oryzae on a wheat-flour model substrate, aerial hyphae contributed up to 75% of the oxygen uptake rate by the fungus. This is due to the fact that A. oryzae forms very abundant aerial mycelium and diffusion of oxygen in the gas-filled pores of the aerial hyphae layer is rapid. It means that diffusion limitation in the densely packed mycelium layer that is formed closer to the substrate surface and that has liquid-filled pores is much less important for A. oryzae than was previously reported for R. oligosporus and C. minitans. It also means that the overall oxygen uptake rate for A. oryzae is much higher than the oxygen uptake rate that can be predicted in the densely packed mycelium layer for R. oligosporus and C. minitans. This would imply that cooling problems become more pronounced. Therefore, it is very important to clarify the physiological role of aerial hyphae in SSF.

Aspergillus oryzae↗
PubMed2001

Motile tubular vacuoles in extramatrical mycelium and sheath hyphae of ectomycorrhizal systems.

Extramatrical mycelium and outer hyphae of the sheath of Eucalyptus pilularis-Pisolithus tinctorius mycorrhizas contain abundant motile tubular vacuoles which accumulate the carboxyfluorescein analogue Oregon Green 488 carboxylic acid. The fluorochrome accumulates in a system of small vacuoles, tubules, and larger vacuoles, which are interlinked, motile, and pleiomorphic, in external hyphae, cords, and hyphae of the outer sheath. There is often a difference in fluorescence between two neighbouring cells, indicating that the dolipore septum exercises control on the movement of material between cells. Generally the motile tubular vacuole system in mycorrhizas resembles that previously found in isolated mycelium. The majority of fungal cells in the sheath contain no fluorochrome even after long exposure of the mycorrhiza to the solution, but with differential interference optics the cells are clearly seen to be alive and to contain vacuoles resembling those in the outer hyphae. In translocation experiments, long-distance transport of the fluorochrome is slow and slight, or even nonexistent in some cases.

Basidiomycota↗
PubMed2005

Comparison between Aspergillus fumigatus conidia and hyphae susceptibilities to amphotericin B, itraconazole, and voriconazole by use of the mold rapid susceptibility assay.

Although hyphae are the morphological form observed in tissue during invasive Aspergillus fumigatus infections, antifungal susceptibility testing for A. fumigatus utilizes conidial inocula. Previous studies have yielded conflicting results as to whether conidia adequately reflect antifungal susceptibility of hyphae, but the ease of handling and quantification of conidia have prompted their use in such assays. The mold rapid susceptibility assay, which utilizes a conidial inoculum (cRSA), was adapted as a novel method to assess the utility of conidial versus hyphal inocula (hRSA) to further evaluate the susceptibility of A. fumigatus conidia and hyphae to amphotericin B (AMB), itraconazole (ITC), and voriconazole (VRC). Conidial inocula were prepared as previously described for the cRSA and minimum inhibitory values (MIC) were determined. For the hRSA, microtiter test wells lacking antifungal drug were inoculated with a standardized conidial inoculum and incubated for 12 h at 35-37 degrees C to allow formation of hyphae. Following addition of antifungal drug and 48 h incubation at 35-37 degrees C, hRSA antifungal minimum inhibitory concentration (MIC) values were determined by analysing the pattern of residual glucose levels in hRSA test wells. hRSA MIC values of each strain were influenced by hyphal inoculum size, with increasing hyphal inoculum size corresponding to increased AMB, ITC and VRC MIC values. Comparisons between the hRSA and cRSA MIC values demonstrated insignificant differences in conidial and hyphal susceptibility to drug, thus justifying the use of either fungal form in RSA-based susceptibility testing of A. fumigatus isolates. The RSA may be adapted for use of similar testing of other invasive molds that predominate as hyphal forms in tissue.

Amphotericin B↗
PubMed2002

Differential secretion of Sap4-6 proteins in Candida albicans during hyphae formation.

Secreted aspartyl proteinases (Saps) from Candida albicans are encoded by a multi-gene family and are considered to be putative virulence factors for candidiasis. SAP4-6 mRNAs were first detected during hyphae formation and were assumed to play roles in the development of disseminated candidiasis. Recombinant Sap proteins (Sap2-6) were prepared and specific antibodies were generated against Sap2-6. The presence of Sap4, Sap5 and Sap6, but not Sap2 or Sap3, was demonstrated in culture supernatants of C. albicans after induction of hyphae formation. In parallel to hyphae formation, Sap5 (approximately 40 kDa) was detected as early as approximately 6 h after induction at neutral pH, and Sap4/6 (approximately 43 kDa) were detected after approximately 24 h when the culture medium became acidic. The differential secretion of Sap5 and Sap4/6 was affected when the culture medium pH was buffered at pH 6.5 or pH 4.5. In addition, intracellular pools of Sap4-6 seem to exist, and protein is not necessary for Sap4-6 induction. This study provides the first evidence that Sap4-6 proteins in C. albicans are differentially produced and secreted during hyphae formation.

Antibodies↗
PubMed2003

Integrative, multifunctional plasmids for hypha-specific or constitutive expression of green fluorescent protein in Candida albicans.

The authors have engineered plasmid constructs for developmental and constitutive expression of yeast-enhanced green fluorescent protein (yEGFP3) in Candida albicans. The promoter for the hyphae-specific gene Hyphal Wall Protein 1 (HWP1) conferred developmental expression of yEGFP3 in germ tubes and hyphae but not in yeasts or pseudohyphae when targeted to the ENO1 (enolase) locus in single copy. The pHWP1GFP3 construct allows for the easy visualization of HWP1 promoter activity in individual cells expressing true hyphae without having to prepare RNA for analysis. Constitutive expression of yEGFP was seen in all cell morphologies when the HWP1 promoter was replaced with the ENO1 promoter region. The use of the plasmids for expression of genes other than yEGFP3 was examined by substituting the putative C. albicans BCY1 (SRA1) gene, a component of the cAMP signalling pathway involved in yeast to hyphae transitions, for yEGFP3. Strains overexpressing BCY1 from the ENO1 promoter were inhibited in germ tube formation and filamentation in both liquid and solid media, a phenotype consistent with keeping protein kinase A in its inactive form by association with Bcy1p. The plasmids are suitable for studies of germ tube induction or assessing germ tube formation by measuring yEGFP3 expression, for inducible expression of genes concomitant with germ tube formation by the HWP1 promoter, for constitutive expression of genes by the ENO1 promoter, and for expressing yEGFP3 using a promoter of choice.

Candida albicans↗
PubMed2003

A novel class of secreted hydrophobic proteins is involved in aerial hyphae formation in Streptomyces coelicolor by forming amyloid-like fibrils.

Streptomycetes exhibit a complex morphological differentiation. After a submerged mycelium has been formed, filaments grow into the air to septate into spores. A class of eight hydrophobic secreted proteins, ChpA-H, was shown to be instrumental in the development of Streptomyces coelicolor. Mature forms of ChpD-H are up to 63 amino acids in length, and those of ChpA-C are larger (+/-225 amino acids). ChpA-C contain two domains similar to ChpD-H, as well as a cell-wall sorting signal. The chp genes were expressed in submerged mycelium (chpE and chpH) as well as in aerial hyphae (chpA-H). Formation of aerial hyphae was strongly affected in a strain in which six chp genes were deleted (DeltachpABCDEH). A mixture of ChpD-H purified from cell walls of aerial hyphae complemented the DeltachpABCDEH strain extracellularly, and it accelerated development in the wild-type strain. The protein mixture was highly surface active, and it self-assembled into amyloid-like fibrils at the water-air interface. The fibrils resembled those of a surface layer of aerial hyphae. We thus conclude that the amyloid-like fibrils of ChpD-H lower the water surface tension to allow aerial growth and cover aerial structures, rendering them hydrophobic. ChpA-C possibly bind ChpD-H to the cell wall.

Amino Acid Sequence↗
PubMed2006

Vacuolar localization of phosphorus in hyphae of Phialocephala fortinii, a dark septate fungal root endophyte.

Phialocephala fortinii is a dark septate fungal endophyte that colonizes roots of many host species. Its effect on plant growth varies from being pathogenic to beneficial. The basic biology of this species has received little research, and thus the main objectives of this study were to determine cytological features of hyphae, including the nature of the vacuolar system, and whether polyphosphate was present in vacuoles. Both living hyphae and hyphae that had been rapidly frozen and freeze substituted before embedding were studied. A complex system of vacuoles, including a motile tubular vacuolar system, elongated vacuoles, and spherical vacuoles, was demonstrated in living hyphae by the fluorescent probe Oregon Green 488 carboxylic acid diacetate, using laser scanning confocal microscopy. The motile tubular vacuolar system was more prevalent at the hyphal tip than in more distal regions, whereas elongated vacuoles and spherical vacuoles were more abundant distal to the tip. All vacuoles contained polyphosphate as shown by labelling embedded samples with recombinant polyphosphate binding domain of Escherichia coli exopolyphosphatase, containing Xpress tag at the N-terminal end, followed by anti-Xpress antibody and a secondary antibody conjugated either to a fluorescent probe for laser scanning confocal microscopy or colloidal gold for transmission electron microscopy. The polyphosphate was dispersed in vacuoles. This was confirmed by staining embedded samples with 4',6-diamidino-2-phenylindole and viewing with UV light using epifluorescence microscopy. These cytological methods showed that the tubular vacuolar system had lower concentrations of polyphosphate than the spherical vacuoles. Lipid bodies were present around vacuoles.

Carboxylic Acids↗
PubMed2001

Potassium gradients in the growing hyphae of Neurospora crassa.

X-ray electron probe microanalysis of a Neurospora crassa hyphal preparation revealed a significant heterogeneity of the potassium content in the hyphae. Low-potassium areas were found in a close proximity of the growing tip and in the distal part of the hyphae in the submembrane area of about 1 microm width. The intracellular potassium concentration was shown to change more than 3-5 times from apical to distal regions of the leading hyphae, the potassium contents in the apical part of the hyphae usually being minimal. We suggest that the content of intracellular potassium is determined by the volume occupied by free intracellular water, i.e., by the size of the space available for diffusion of substances, including inorganic ions.

Electron Probe Microanalysis↗
PubMed1989

Occurrence and metabolic significance of microbodies in trophic hyphae of the nematophagous fungus Arthrobotrys oligospora.

This paper describes the results of an ultrastructural study on the subcellular events occurring in nematode-infecting (trophic) hyphae of the nematophagous fungus Arthrobotrys oligospora. In early stages of the infection process (30 min-4 h), the infection bulb and developing trophic hyphae are characterized by a highly proliferated endoplasmic reticulum (ER). Its membranes often appeared vesiculated and occur in close association with the cell membrane of the cells. Upon further invasion of the nematode, lipid droplets developed in the trophic hyphae; these droplets were first observed 4-5 h after the infection but were abundantly present after 24-36 h. Along with the formation of lipid droplets proliferation of microbodies was observed. These organeles were characterized by the presence of catalase and thiolase and were frequently observed in close association with the lipid droplets. Later on the lipid droplets disappeared. During this period new vegetative mycelium developed from the trap that had originally captured the nematode. Our results suggest that part of the nutrients released from the nematode are first converted into lipids by the fungus which in turn are degraded via the beta-oxidation pathway and further metabolized to support growth of new vegetative hyphae.

Animals↗
PubMed1992

The solid phase attachment of fungal hyphae in an ELISA to screen for antifungal antibodies.

A method to immobilize fungal hyphae onto the wells of 96-well microplates for use in an in-direct ELISA to screen for antifungal antibodies in sera and cell culture supernatants is described. The hyphae from three genera (Penicillium, Eurotium and Fusarium) were successfully attached by overnight drying onto wells precoated with poly-L-lysine and glutaraldehyde. Microscopy revealed that the hyphae remained attached to the wells throughout the ELISA and antiserum titrations showed that the attached hyphae were uniformly coated and remained reactive. Background absorbances were low and the plates could be stored at -20 degrees C without loss of reactivity.

Antibodies, Fungal↗
PubMed1998

A surface active protein involved in aerial hyphae formation in the filamentous fungus Schizophillum commune restores the capacity of a bald mutant of the filamentous bacterium Streptomyces coelicolor to erect aerial structures.

The filamentous bacterium Streptomyces coelicolor undergoes a complex process of morphological differentiation involving the formation of a dense lawn of aerial hyphae that grow away from the colony surface into the air to form an aerial mycelium. Bald mutants of S. coelicolor, which are blocked in aerial mycelium formation, regain the capacity to erect aerial structures when exposed to a small hydrophobic protein called SapB, whose synthesis is temporally and spatially correlated with morphological differentiation. We now report that SapB is a surfactant that is capable of reducing the surface tension of water from 72 mJ m-2 to 30 mJ m-2 at a concentration of 50 microgram ml-1. We also report that SapB, like the surface-active peptide streptofactin produced by the species S. tendae, was capable of restoring the capacity of bald mutants of S. tendae to erect aerial structures. Strikingly, a member (SC3) of the hydrophobin family of fungal proteins involved in the erection of aerial hyphae in the filamentous fungus Schizophyllum commune was also capable of restoring the capacity of S. coelicolor and S. tendae bald mutants to erect aerial structures. SC3 is unrelated in structure to SapB and streptofactin but, like the streptomycetes proteins, the fungal protein is a surface active agent. Scanning electron microscopy revealed that aerial structures produced in response to both the bacterial or the fungal proteins were undifferentiated vegetative hyphae that had grown away from the colony surface but had not commenced the process of spore formation. We conclude that the production of SapB and streptofactin at the start of morphological differentiation contributes to the erection of aerial hyphae by decreasing the surface tension at the colony surface but that subsequent morphogenesis requires additional developmentally regulated events under the control of bald genes.

Bacterial Proteins↗
PubMed1997

Specific, high affinity binding sites for an antifungal plant defensin on Neurospora crassa hyphae and microsomal membranes.

Hs-AFP1, an antifungal plant defensin from seed of the plant Heuchera sanguinea, was radioactively labeled using t-butoxycarbonyl-[35S]L-methionine N-hydroxysuccinimidyl ester, resulting in a 35S-labeled peptide with unaltered antifungal activity. [35S]Hs-AFP1 was used to assess binding on living hyphae of the fungus Neurospora crassa. Binding of [35S]Hs-AFP1 was found to be competitive, reversible, and saturable with an apparent Kd of 29 nM and a Bmax of 1.4 pmol/mg protein. [35S]Hs-AFP1 also bound specifically and reversibly to microsomal membranes derived from N. crassa hyphae with a Kd of 27 nM and a Bmax of 102 pmol/mg protein. The similarity in Kd value between binding sites on hyphae and microsomes indicates that Hs-AFP1 binding sites reside on the plasma membrane. Binding of [35S]Hs-AFP1 to both hyphae and microsomal membranes could be competed to some extent by four different structurally related plant defensins but not by various structurally unrelated antimicrobial peptides. In addition, an inactive single amino acid substitution variant of the antifungal plant defensin Rs-AFP2 from Raphanus sativus seed was also unable to displace [35S]Hs-AFP1 from its binding sites, whereas Rs-AFP2 itself was able to compete with [35S]Hs-AFP1.

Antifungal Agents↗