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 451 records · Page 25Linked to original sources
PubMed1977

Ultrastructural observations of an unusual osmiophilic body in the hyphae of Sporothrix schenckii and Ceratocystis stenoceras.

Electron microscopy of 8 strains of Sporothrix schenckii and 1 strain each of Ceratocystis stenoceras, C. pluriannulata, C. ulmi, and C. minor revealed the presence of unusual osmiophilic structures (EOB) which appeared as normal organellar components of young cells of these fungi. In S. schenckii and C. stenoceras, these structures were markedly osmiophilic, reacted strongly with thiocarbohydrazide, could be partially solubilized with the lipid solvent sodium methoxide, and appeared to possess lipase activity. On subsequent cellular ageing, lipid bodies were commonly seen in intimate association with the EOB. Eventually, the EOB underwent degeneration and extensive vacuolization. It is suggested that these structures are composed in part of lipoidal material in possible association with a protein matrix, and may be in some manner involved with lipid metabolism of mechanisms of lipid storage.

Ascomycota↗
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↗
PubMed1981

Monocyte-mediated serum-independent damage to hyphal and pseudohyphal forms of Candida albicans in vitro.

Human peripheral blood monocytes attached to Candida albicans hyphae in the absence of serum and damaged the hyphae without completely ingesting them. Attachment and damage was not augmented by the addition of serum. Damage to hyphae was quantitated by a previously developed metabolic assay that measured leukocyte-induced reduction in uptake of [(14)C]cytosine by the hyphae. Use of cells from patients with hereditary disorders of leukocyte function, chronic granulomatous disease, and myeloperoxidase deficiency indicated that myeloperoxidase-independent and nonoxidative mechanisms could sometimes damage hyphae where oxidative mechanisms were impaired. Damage to hyphae by normal monocytes was inhibited by concentrations of sodium azide and sodium cyanide that primarily affect myeloperoxidase activity, as well as by halide-free conditions, catalase, and putative antagonists of hypochlorous acid or singlet oxygen. Iodination of hyphae, a myeloperoxidase and hydrogen peroxide-dependent process of monocytes, was similarly inhibited by sodium azide, sodium cyanide, and catalase. Under anaerobic conditions, damage to hyphae was reduced by 64.0-68.4%. In contrast, inhibitors of potential nonoxidative antifungal mechanisms, iron salts to saturate iron chelators, and polyanionic amino acid polymers to neutralize cationic proteins did not block damage to hyphae by monocytes. Preparations rich in lysosomal granules from fractionated normal monocytes also did not damage hyphae. Overall, it appeared that oxidative mechanisms were most important for damage to hyphae by normal monocytes. Electron microscopy confirmed that Candida hyphae were damaged and probably killed by monocytes, but monocytes appeared to sustain significant damage in the process. In the absence of serum, monocyte cell membranes became closely approximated to Candida cell walls. It appeared that some Candida could escape this partial engulfment, as they were seen floating free with vesicular trilaminar membrane remnants covering hyphal surfaces. In general, monocytes appeared to be damaged by interactions with Candida hyphae more than neutrophils had been in previous studies.

Candida albicans↗
PubMed2006

rag genes: novel components of the RamR regulon that trigger morphological differentiation in Streptomyces coelicolor.

The filamentous bacterium, Streptomyces coelicolor, undergoes a complex cycle of growth and development in which morphological differentiation coincides with the activation of the orphan response regulator RamR and the biosynthesis of a morphogenic peptide called SapB. SapB is a lantibiotic-like molecule derived from the product of the ramS gene that promotes formation of aerial hyphae by breaking the aqueous tension on the surface of the substrate mycelium. A ramR-disrupted mutant is delayed in aerial hyphae formation while constitutive overexpression of ramR accelerates aerial hyphae formation in the wild-type strain and restores SapB biosynthesis and aerial hyphae formation in all developmental mutants (bld) tested. Using DNA microarrays to globally identify S. coelicolor genes whose transcription was affected by ramR mutation or overexpression, we discovered a ramR-activated locus of contiguous cotranscribed developmental genes that modulate both aerial hyphae formation and sporulation. The genes of this cluster of ramR-activated genes (rag), which are chromosomally distant from previously known RamR-regulated genes, include: ragA (sco4075) and ragB (sco4074), which encode two subunits of an ABC transporter, ragK (sco4073), a putative histidine kinase, and ragR (sco4072), a ramR paralogue. Promoter mapping and protein-DNA binding experiments indicate that RamR activates ragABKR transcription directly, by binding to three sequence motifs in the ragABKR promoter region. A constructed ragABKR null mutant was able to synthesize SapB and erect aerial hyphae; however, these hyphae were unusually branched, reminiscent of substrate hyphae. Subsequent stages of differentiation, septation and sporogenesis were delayed. The role of ragABKR in aerial hyphae formation was shown both by epistasis (ragR-activated aerial hyphae formation in bld mutants) and extracellular complementation (ragR-induced synthesis of an activity allowing aerial hyphae formation in bld mutants) experiments. In conclusion, the ragABKR locus activates a SapB-independent developmental pathway that is involved in both aerial hyphae formation and sporulation, serving to integrate sequential morphogenic changes.

Bacterial Proteins↗
PubMed2000

Dynein and dynactin deficiencies affect the formation and function of the Spitzenkörper and distort hyphal morphogenesis of Neurospora crassa.

The impact of mutations affecting microtubule-associated motor proteins on the morphology and cytology of hyphae of Neurospora crassa was studied. Two ropy mutants, ro-1 and ro-3, deficient in dynein and dynactin, respectively, were examined by video-enhanced phase-contrast microscopy and image analysis. In contrast to the regular, hyphoid morphology of wild-type hyphae, the hyphae of the ropy mutants exhibited a great variety of distorted, non-hyphoid morphologies. The ropy hyphae were slow-growing and manifested frequent loss of growth directionality. Cytoplasmic appearance, including organelle distribution and movement, were ostensibly different in the ropy hyphae. The Spitzenkörper (Spk) of wild-type hyphae was readily seen by phase-contrast optics; the Spk of both ro-1 and ro-3 was less prominent and sometimes undetectable. Only the fast-growing ropy hyphae displayed a Spk, and it was smaller and less phase-dark than the wild-type Spk. Growth rate in both wild-type and ropy mutants was directly correlated with the size of the Spk. Spk efficiency, measured in terms of cell area generated per Spk travelled distance, was lower in ropy mutants. Another salient difference between ropy mutants and wild-type hyphae was in Spk trajectory. Whereas the Spk of wild-type hyphae maintained a trajectory close to the cell growth axis, the Spk of ropy hyphae moved much more erratically. Sustained departures in the trajectory of the ropy Spk produced corresponding distortions in hyphal morphology. A causal correlation between Spk trajectory and cell shape was tested with the Fungus Simulator program. The characteristic morphologies of wild-type or ropy hyphae were reproduced by the Fungus Simulator, whose vesicle supply centre (VSC) was programmed to follow the corresponding Spk trajectories. This is evidence that the Spk controls hyphal morphology by operating as a VSC. These findings on dynein or dynactin deficiency support the notion that the microtubular cytoskeleton plays a major role in the formation and positioning of the Spk, with dramatic consequences on hyphal growth and morphogenesis.

Computer Simulation↗
PubMed2002

Deprogrammed sporulation in Streptomyces.

The bacterial genus Streptomyces forms chains of spores by septation at intervals in aerial hyphae and subsequent maturation on solid medium. Substrate hyphae undergo extensive lysis, liberating nutrients on which aerial hyphae develop. Some mutant strains, however, ectopically form spores by septation in substrate hyphae on solid medium or in vegetative hyphae in liquid medium, which suggests that all hyphae have the potential to differentiate into spores. A Streptomyces griseus mutant strain NP4, which has a mutation in the regulatory system for an ATP-binding cassette (ABC) transporter gene, forms ectopic spores in substrate hyphae only on glucose-containing medium. In addition, overexpression of a substrate-binding protein of the ABC transporter in the wild-type strain causes ectopic septation in very young substrate hyphae and subsequent sporulation in response to glucose. These ectopic spores germinate normally. The ectopic sporulation is independent of A-factor, a microbial hormone that determines the timing of aerial mycelium formation during normal development. Thus, substrate hyphae of Streptomyces have a potential to develop into spores without formation of aerial hyphae. For programmed development, therefore, the strict repression of septum formation in substrate mycelium should be necessary, as well as the positive signal relay leading to aerial mycelium formation followed by septation and sporulation.

4-Butyrolactone↗
PubMed1991

Invasion and survival of Fusarium solani in the dexamethasone-treated cornea of rabbits.

Electron microscopic observations, as well as in vitro experiments, on experimental Fusarium solani keratitis of rabbits were performed to study the mode of fungal invasion into the corneal stroma, the interactions between F. solani and inflammatory cells under the influence of topical dexamethasone (DXM) treatment, and the survival mechanism of the fungi in the DXM-treated cornea. Electron microscopy showed that, while the fungus invaded into the corneal stroma, digestion of collagen fibrils occurred around the hyphae, where amorphous material was often noted. In DXM-nontreated cornea, the fungal hyphae were entrapped by pseudopodia of the neutrophils and destruction of the hyphae was noted on day 3 of infection, most hyphae having disappeared by day 7. In the DXM-treated cornea, however, neutrophils could not ingest and destroy the hyphae. In qualitative nitroblue tetrazolium (NBT)-reduction tests using rabbit peripheral blood neutrophils, DXM significantly suppressed the rate of NBT-reduction and the rate of adherence to the fungal microconidia. In the DXM-treated corneal lesions, a considerable increase in both number and size of fungal peroxisomes was noted. Furthermore, the hyphae, surrounded by neutrophils, showed double or triple cell wall formation or sometimes a hypha-in-hypha structure. Similar hypha-in-hypha structures were also observed when the organisms were treated in vitro with a fungistatic concentration of H2O2. We suggest that this special structure is a protective device produced for the survival of F. solani when subject to neutrophil attack in the DXM-treated cornea.

Animals↗
PubMed2005

[Evaluation of antifungal chemotherapeutic effects on fungal keratitis by confocal microscopy].

OBJECTIVE: To evaluate the validity of confocal microscopy in estimating curative effect and in directing the treatment for fungal keratitis in the process of antifungal chemotherapy. METHODS: Fifty-eight patients, who were confirmed fungal infection by confocal microscopy, were selected from 328 patients with fungal keratitis. All patients received routine topical and/or oral antifungal medication, and were examined by confocal microscopy once a week and one week after discontinuation of the treatment. The density of hyphae in the corneal lesion, the configuration of inflammatory cells and keratocyte were recorded. Antifungal chemotherapy was adjusted according to examination results and medicines were changed accordingly. If no hyphae were detected by confocal microscopy, antifungal medication was maintained for one week and then discontinued. All patients were followed up for two months to ensure no relapse of fungal infection. RESULTS: Fifty three patients were cured. The area of corneal lesions began to reduce 7 days after the beginning of antifungal chemotherapy. Confocal microscopy examination revealed that the hypha positive sites and the density of hypha were reduced gradually; inflammatory cells also decreased, the configuration of corneal lesion was transformed from asymmetry to symmetry; and normal keratocytes could be detected gradually. After 14 days of treatment, ulcers healed up in 37 cases and no hyphae and inflammatory cells were found in 23 cases. After 28 days of treatment, all corneal ulcers healed up; hyphae and inflammatory cells were completely disappeared in 31 patients, but a few hyphae still could be found in 22 patients. Antifungal chemotherapy was tapered gradually if no hyphae and inflammatory cells were detected by confocal microscopy. There was no relapse of fungus infection during 2-month follow-up. Infection deteriorated in the other five patients within 7 days, which showed increased density of hypha and inflammatory cells under confocal microscopy examination. All of them were treated with a penetrating keratoplasty to save the eyeball. CONCLUSIONS: Confocal microscopy is an ideal method for the evaluation of curative effects of fungal keratitis in the process of antifungal chemotherapy. This is also a valuable objective tool in directing antifungal medication.

Adolescent↗
PubMed2001

Effects of tebuconazole on morphology, structure, cell wall components and trichothecene production of Fusarium culmorum in vitro.

The effects of tebuconazole, a systemic fungicide, on the morphology, structure, cell wall components and toxin production of Fusarium culmorum were investigated in vitro. Treatment was by application of four filter paper strips (0.75 cm x 5.0 cm) soaked in 20 micrograms ml-1 fungicide placed around a point inoculum in Petri dishes. Mycelial growth was strongly inhibited by fungicide treatment. Scanning electron microscopic observations showed that the fungicide caused irregular swelling and excessive branching of hyphae. The morphological changes induced by the fungicide at the ultrastructural level included considerable thickening of the hyphal cell walls, excessive septation, the formation of the incomplete septa, extensive vacuolisation, accumulation of lipid bodies and progressing necrosis or degeneration of the hyphal cytoplasm. Non-membrane inclusion bodies were often detected in the hyphal cytoplasm. Furthermore, the formation of new hyphae (daughter hyphae) inside collapsed hyphal cells was common following treatment. The daughter hyphae also displayed severe alterations such as irregular thickening of the cell walls and necrosis of the cytoplasm. Using cytochemical techniques, the labelling densities of chitin and beta-1,3-glucan in the cell walls of the fungicide-treated hyphae were more pronounced than in those of the control hyphae. Moreover, immunogold labelling with antiserum against deoxynivalenol (DON) revealed that Fusarium toxin DON was localized in the cell walls, cytoplasm, mitochondria and vacuoles of the hyphae from the control and the fungicide treatment, but the labelling density in the fungicide-treated hyphae decreased dramatically compared with the control hyphae, indicating that tebuconazole reduced Fusarium toxin production of the fungus.

Acetylglucosamine↗