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 1,045 records · Page 58Linked to original sources
PubMed1998

Analysis of actin and actin-related protein 3 (ARP3) gene expression following induction of hyphal tip formation and apolar growth in Neurospora.

The genes encoding actin and ARP3 in the filamentous fungus Neurospora crassa were cloned and sequenced. The actin structural gene is interrupted by four introns and encodes a polypeptide of 375 amino acids, which shows very high degree of identity with actin from other sources. N. crassa ARP3 is 439 amino acids in length and is 71% to 80% identical to ARP3s from five other organisms, while actin is 40% to 50% identical to these same ARP3s. Transcript levels for actin and ARP3 decrease upon induction of asexual development (i.e. conidiation) and subsequently increase slightly when conidia are being formed. A concentration of filamentous actin is typically seen at sites of growth in eukaryotic organisms and, using indirect immunofluorescence, we showed that filamentous actin is localized primarily to hyphal tips in N. crassa. To determine if the level of actin increases in response to an increase in the number of growth sites and in the area of the growing surface, we used the temperature-sensitive mutants cot-1 and mcb. Growth of the cot-1 and mcb mutants at restrictive temperature induces hyphal tip formation and a loss of growth polarity, respectively. Unexpectedly, almost no increase in actin levels is observed following a > 20-fold increase in the number of hyphal tips or an increase in the area of the growing surface resulting from a loss of growth polarity. The results suggest that the level of actin monomers within N. crassa hyphae is sufficient to accommodate the need for additional actin patches and filaments that arises when the number of hyphal tips and the area of growing surface per unit length of hypha greatly exceeds that in wild-type.

Actin-Related Protein 3↗
PubMed1999

Molecular characterization of HymA, an evolutionarily highly conserved and highly expressed protein of Aspergillus nidulans.

Aspergillus nidulans reproduces asexually via uninucleate, haploid spores, which are produced on morphologically differentiated aerial structures, called conidiophores. These consist of four distinct cell types, a foot with a terminally swollen stalk, metulae, phialides and conidiospores. The molecular mechanisms underlying the morphological changes that occur during conidiophore development have been studied by mutant analysis. We have isolated the hym A mutant, in which conidiophore development is affected at the metula stage. In the mutant metulae do not differentiate properly but come to resemble hyphae (hym = hypha-like metulae). In this paper we have analyzed the corresponding gene. It encodes a highly expressed 44 kDa protein which resides in the cytoplasm and has homologues in yeast, plants, fly, worm, fish, mice and man. We constructed hym deletion strains of Saccharomyces cerevisiae and of A. nidulans and found that the gene is essential in S. cerevisiae but is dispensable in the filamentous fungus. A cellular function for the Hym protein has not yet been defined in any organism. To demonstrate functional conservation we constructed a chimeric protein comprised of the N-terminal half of the A. nidulans and the C-terminal half of the mouse homologue MO25. This hybrid protein could fully substitute for HymA function in A. nidulans. In addition, the mouse protein itself partially rescued the hym A mutation in the fungus. HymA is thus highly conserved in evolution and probably serves similar functions. The fact that hym A is required for conidiophore development in A. nidulans suggests that homologous genes in other organisms might also be involved in morphogenesis.

Amino Acid Sequence↗
PubMed1999

Cloning and characterization of a gene (arpA) from Aspergillus oryzae encoding an actin-related protein required for normal nuclear distribution and morphology of conidiophores.

We have isolated the arpA gene from Aspergillus oryzae as a homologue of the Neurospora crassa ro-4 gene. In N. crassa, mutations in the ro-4 gene, which encodes a major component of the dynactin complex Arp1, causes curling of hyphae and abnormalities in nuclear distribution. The arpA gene contains two introns and encodes a polypeptide of 381 amino acids, with a 78% sequence identity to the N. crassa Arp1. Overexpression of the arpA gene causes a defect in nuclear migration into elongating hyphae of germlings in A. oryzae. We constructed arpA disruptant strains of A. oryzae. The arpA null mutants showed poor growth and hyper-branched mycelia, as well as a nuclear distribution defect. Scanning electron microscopy revealed that the arpA null mutant has an aberrant conidiophore morphology with irregular phialides.

Actins↗
PubMed2002

Direct nocturnal water transfer from oaks to their mycorrhizal symbionts during severe soil drying.

Symbiotic mycorrhizal fungi play an important role in the absorption of soil nutrients and water by most plants. It has been suggested that hydraulically lifted water might maintain the integrity of the external mycorrhizal mycelium during drought. We tested this hypothesis in the obligately mycorrhizal species, coast live oak (Quercus agrifolia), using a microcosm system that separated the effects of hydraulic lift in roots from those in the external mycelium. Mycorrhizal oak seedlings were established in microcosms comprising three discrete compartments for (1) upper roots, (2) tap roots, and (3) external fungal mycelium. Eight months after planting, a drought treatment was initiated: irrigation to the upper root and fungal chambers was terminated and only irrigation to the taproot compartment was maintained. After 3, 12, 30, 50, 70 and 80 days of drought, tracers were injected into the taproot compartment at dusk. At dawn the following morning, mycorrhizal hyphae (EM and AM) and spores (AM) in upper root and fungal compartments were extensively labeled with the tracers. In contrast, no labeling was observed when tracers were injected into the taproot compartment during daytime. Nocturnal water translocation from plant to mycorrhizal fungi occurred in association with hydraulic lift. Saprotrophic/parasitic fungi in the microcosms were not labeled, suggesting a direct water transfer from plants to their mycorrhizal mutualists and not to other fungi in the soil. Even after prolonged drought (70-80 days), mycorrhizal hyphae persisted in soils with water potential values as low as -20 MPa. Maintaining mycorrhizal activity through direct water translocation could potentially improve the nutrient status of deep-rooted plants during periods when the fertile upper soil is dry.

Disasters↗
PubMed2002

Ectomycorrhizae between Alnus acuminata H.B.K. and Naucoria escharoides (Fr.:Fr.) Kummer from Argentina.

Field ectomycorrhizae of Naucoria escharoides on Alnus acuminata ("andean alder", "aliso del cerro") are described in detail for the first time. Naturally occurring ectomycorrhizal roots were sampled beneath sporocarps of N. escharoides. The samples were taken from four natural forest plots at two homogeneous A. acuminata sites (Tucumán and Catamarca Provinces, Argentina). The ectomycorrhizae were characterized morphologically and compared by means of PCR/RFLP analysis of the internal transcribed spacer region of the nuclear rDNA. The most important morphological features of the ectomycorrhizae are a white to pale yellow mantle, simple to monopodial branches, hyaline emanating hyphae, abundant hyphal bundles emerging more or less perpendicularly from a plectenchymatous mantle, and an acute or rounded apex with or without a mantle. N. escharoides fruitbodies have white basal mycelium with emanating hyphae similar to those of andean alder ectomycorrhizae. The RFLP profiles of sporocarps and mycorrhizae were the same.

Agaricales↗
PubMed2002

Colonization of roots by arbuscular mycorrhizal fungi using different sources of inoculum.

Arbuscular mycorrhizal fungi (AMF) form a number of different infective propagules that are used to form new mycorrhizal associations. These are spores, extraradical hyphae and infected roots. However, not all fungi are equally capable of colonizing roots with all of the above-mentioned propagules and there is conflicting evidence of major differences in colonization strategy between members of the Glomineae and Gigasporineae. In this study, we tested the abilities of eight fungal species from four different genera to colonize roots using three different types of inoculum. Glomus and Acaulospora isolates colonized from all inoculum types, whereas Gigaspora and Scutellospora isolates colonized mainly from spores and to a limited degree from root fragments. Extraradical hyphae were not suitable propagules for the species of Gigaspora and Scutellospora tested. This indicates that AMF have different colonization strategies and that this is largely differentiated at the suborder level. It is unclear why there is such a difference among the fungi in inoculum types. Future research should examine differences in the anatomy and physiology to discern a mechanism for such differences in life-history strategies.

Ascomycota↗
PubMed2002

Influence of liming, inoculum level and inoculum placement on root colonization of subterranean clover.

Arbuscular mycorrhizal (AM) fungi differ in their response to soil pH. Thus, change in soil pH may influence the relative abundance of mycorrhizal fungi inside roots. Root colonization by two AM fungi was studied in relation to addition of lime (CaCO3), quantity of inoculum and inoculum placement. Addition of CaCO3 to an acid soil decreased the colonization of roots by Acaulospora laevis but increased colonization by Glomus invermaium when both fungi were present. In acid soil (pH 4.7), almost all roots were colonized by A. laevis, while G. invermaium was dominant when soil pH was increased to pH 7.3. This occurred regardless of whether the inoculum was banded or mixed throughout the soil. There was no effect of CaCO3 on the relative abundance of fungi inside roots at intermediate rates of CaCO3 application (pH 5.3-6.3) when both fungi were inoculated together. In this experiment, both fungi colonized roots at all levels of CaCO3 when inoculated alone, except for A. laevis at the highest level of CaCO3. We conclude that soil pH affects the competitive ability of these two AM fungi during mycorrhiza formation primarily by affecting hyphae growth in soil and thus the relative abundance of hyphae at the root surface and subsequently inside the root.

Calcium Compounds↗
PubMed2002

Phosphorus efficiencies and responses of barley (Hordeum vulgare L.) to arbuscular mycorrhizal fungi grown in highly calcareous soil.

Two experiments were carried out to investigate phosphorus efficiencies and mycorrhizal responsiveness in an improved cultivar (Clipper) and a landrace (Sahara) of barley (Hordeum vulgare L.). In experiment 1, two pot sizes were used to evaluate the effect of soil volume on P uptake and mycorrhizal responsiveness. In experiment 2, a compartmented ("cross-pot") system was used to monitor (32)P delivery by external hyphae of arbuscular mycorrhizal fungi (AMF) to the host plant. Results showed that, irrespective of growth conditions, Sahara had much larger root biomass than Clipper and consequently substantially more P was allocated to roots in Sahara than in Clipper. Specific root length in Clipper was much longer than in Sahara. Increase in soil volume enhanced percentage root length colonised by AMF, plant growth and P uptake, and Sahara was more sensitive to changes in soil volume than Clipper. Pot size (soil volume) used to assess responsiveness to AMF by different plant species or genotypes with different root/shoot ratios might be a confounding factor. Clipper was more responsive to AMF than Sahara in terms of tissue P concentrations, which is partly related to their differences in root/shoot ratios. However, increases in SPU [specific P uptake, mg P (g root biomass)(-1)] caused by AMF were bigger in Clipper, suggesting that AMF played a larger role in P uptake. In accordance with the larger increase in SPU, Clipper took up more (32)P via AMF hyphae than Sahara. The compartmented system using radioactive P might be an alternative approach to directly investigate mycorrhizal responsiveness of different plant species or varieties than conventional pot experiments, provided that the same AM fungus is used.

Biomass↗
PubMed2003

Two genetically related strains of Tuber borchii produce Tilia mycorrhizas with different morphological traits.

Two genetically related strains of Tuber borchii Vittad. (1BO and 43BO) produce mycorrhizas with Tilia platyphyllos Scop. with a different degree of efficiency. The aim of this work was to characterize the morphology of the fungal symbiotic structures in order to examine potential relationships between the anatomical traits of the mycorrhiza, the mycorrhizal capacities of the fungal strains and their effect on the host plants. Some morphological features of mantle hyphae (small size, intense staining, vacuolization, abundance of mitochondria) led to a mantle with morphological features that were isolate-specific. There were unexpected differences, at least under our experimental conditions: 1BO strain mantle cells were larger, less reactive to staining, more highly vacuolated and poorer in mitochondria than those of 43BO. These features were found throughout the mantle in 1BO, while the inner mantle hyphae of 43BO were significantly smaller and more intensely stained than the outer cells. In the 43BO strain there was a positive relation between these features and higher infectivity (evaluated as percentage of mycorrhizal tips) as well as a slightly more effective stimulation of plant growth. These observations suggest that genetically related truffle strains produce mycorrhizas with different morphologies, which may be related to a more efficient response of the host plant to inoculation.

Ascomycota↗
PubMed2005

Accumulation of reactive oxygen species in arbuscular mycorrhizal roots.

We investigated the accumulation of reactive oxygen species (ROS) in arbuscular mycorrhizal (AM) roots from Medicago truncatula, Zea mays and Nicotiana tabacum using three independent staining techniques. Colonized root cortical cells and the symbiotic fungal partner were observed to be involved in the production of ROS. Extraradical hyphae and spores from Glomus intraradices accumulated small levels of ROS within their cell wall and produced ROS within the cytoplasm in response to stress. Within AM roots, we observed a certain correlation of arbuscular senescence and H2O2 accumulation after staining by diaminobenzidine (DAB) and a more general accumulation of ROS close to fungal structures when using dihydrorhodamine 123 (DHR 123) for staining. According to electron microscopical analysis of AM roots from Z. mays after staining by CeCl3, intracellular accumulation of H2O2 was observed in the plant cytoplasm close to intact and collapsing fungal structures, whereas intercellular H2O2 was located on the surface of fungal hyphae. These characteristics of ROS accumulation in AM roots suggest similarities to ROS accumulation during the senescence of legume root nodules.

Fungi↗
PubMed2006

Functional expression of the green fluorescent protein in the ectomycorrhizal model fungus Hebeloma cylindrosporum.

Hebeloma cylindrosporum is a model fungus for mycorrhizal studies because of its fast growth rate, simple nutritional requirements, and completion of its life cycle in vitro, and because it is amenable to transformation. To advance cell biological research during establishment of symbiosis, a tool that would enable the direct visualisation of fusion proteins in the different symbiotic tissues [namely, the expression of reporter genes such as Green Fluorescent Protein (GFP)] was still a missing tool. In the present study, H. cylindrosporum was transformed using Agrobacterium carrying the binary plasmid pBGgHg containing the Escherichia coli hygromycin B phosphotransferase (hph) and the EGFP genes, both under the control of the Agaricus bisporus glyceraldehyde-3-phosphate dehydrogenase promoter. EGFP expression was successfully detected in transformants. The fluorescence was uniformly distributed in the hyphae, while no significant background signal was detected in control hyphae. The suitability of EGFP for reporter gene studies in Hebeloma cylindrosporum was demonstrated opening up new perspectives in the Hebeloma genetics.

Agrobacterium tumefaciens↗
PubMed2006

Identification of heavy metal-induced genes encoding glutathione S-transferases in the arbuscular mycorrhizal fungus Glomus intraradices.

Arbuscular mycorrhizal fungi are able to alleviate the stress for plants caused by heavy metal contamination of soil. To analyze the molecular response of arbuscular mycorrhizal fungi to these pollutants, a subtractive cDNA library was constructed using RNA from Glomus intraradices extraradical hyphae of a root organ culture treated with a mixture of Cd, Zn, and Cu. Screening by reverse Northern blot analysis indicated that, among 308 clones, 17% correspond to genes up-regulated by heavy metals. Sequence analysis of part of the clones resulted, amongst others, in the identification of six genes putatively coding for glutathione S-transferases belonging to two different classes of these enzymes. Expression analyses indicated that the genes are differentially expressed during fungal development and that their RNA accumulation dramatically increases in extraradical hyphae grown in a heavy metal-containing solution.

Daucus carota↗
PubMed2006

Occurrence of arbuscular mycorrhizal fungi in bromeliad species from the tropical Atlantic forest biome in Brazil.

The mycorrhizal status of epiphytic, rupicolous, and terrestrial bromeliad species from the Brazilian Atlantic Rain Forest has been examined. Roots of 13 species of bromeliads were analyzed for the presence of mycorrhizal structures such as arbuscules, hyphae, and vesicles as well as other fungal structures. Rhizosphere soil was sampled to identify arbuscular mycorrhizal fungal (AMF) species associated only with terrestrial bromeliad species. Most specimens collected were epiphytic bromeliads in the genera Aechmea, Bilbergia, Nidularium, Tillandsia, and Vriesea. Differentiating structures of AMF were found in only three species of bromeliads. The pattern of mycorrhizal colonization was mainly internal, and external mycelium and arbuscules were observed only in the terrestrial Nidularium procerum. Root endophytes with dark brown septate mycelium, thin external hyphae, and Rhizoctonia-like sclerotia were also detected in some root segments. A total of ten spore morphotypes were recovered from the rhizosphere of N. procerum, with Acaulospora mellea, A. foveata, and Glomus sp. being the most common species recovered. Our study demonstrated that most of the epiphytic species are not associated with AMF. We attribute this mainly to the exposed bare root conditions found in epiphytic bromeliads.

Brazil↗
PubMed1999

[Clinical and histopathological characterization of oral leukoplakia in patients with HIV infection].

The aim of this study was to assess the prevalence of oral leukoplakia (OL) in HIV-positive patients and to evaluate the clinical and histopathological features and the presence of Candida hyphae and viral infections (HSV 1, 2, HPV, EBV and CMV) by immunocytochemical methods using mono- or polyclonal antibodies. A total of 269 HIV-seropositive patients, (222 men, median age 36.7 years and 47 women, median age 32 years) were registered. OL occurred in 20/269 (7.4%) patients (men, smokers, median age 38 years); the non-homogeneous form was observed in 11%. A lesional biopsy specimen was obtained from 8/20 patients. Specimens did not show signs of epithelial dysplasia. Candida hyphae were evident in 2/8 cases. Two patients tested positive for HPV and CMV; antibodies against EBV, HSV1 and 2 were negative. In conclusion, the prevalence of OL is comparatively high in this group of HIV-seropositive patients (7.4% vs. 0.9-2.2%). Moreover, the mean age of the study group at the time of diagnosis for OL was lower (38 years vs. 60 years).

AIDS-Related Opportunistic Infections↗
PubMed2004

Enhancing of erythromycin production by Saccharopolyspora erythraea with common and uncommon oils.

The enhancing effect of various concentrations of 18 oils and a silicon antifoam agent on erythromycin production by Saccharopolyspora erythraea was evaluated in a complex medium containing soybean flour and dextrin as the main substrates. The oils used consisted of sunflower, pistachio, cottonseed, melon seed, water melon seed, lard, corn, olive, soybean, hazelnut, rapeseed, sesame, shark, safflower, coconut, walnut, black cherry kernel and grape seed oils. The biomass, erythromycin, dextrin and oil concentrations and the pH value were measured. Also, the kinds and frequencies of fatty acids in the oils were determined. The productivity of erythromycin in the oil-containing media was higher than that of the control medium. However, oil was not suitable as a main carbon source for erythromycin production by S. erythraea. The highest titer of erythromycin was produced in medium containing 55 g/l black cherry kernel oil (4.5 g/l). The titers of erythromycin in the other media were also recorded, with this result: black cherry kernel > water melon seed > melon seed > walnut > rapeseed > soybean > (corn = sesame) > (olive = pistachio = lard = sunflower) > (hazelnut = cotton seed) > grape seed > (shark = safflower = coconut). In media containing various oils, the hyphae of S. erythraea were longer and remained in a vegetative form after 8 days, while in the control medium, spores were formed and hyphae were lysed.

Anti-Bacterial Agents↗
PubMed2005

Intestinal canine pythiosis in Venezuela confirmed by serological and sequencing analysis.

An 11-months-old mixed Terrier male originally from Venezuela, was referred to a Veterinary Hospital with signs of depression, anorexia, vomiting and diarrhea. The illness had begun 1 month earlier. Despite antibiotic chemotherapy and vitamins, the disease progressed. Radiological exams showed involvement of the small intestine. Histopathological studies of tissue samples taken during surgical intervention revealed eosinophilic areas in the center of which, abundant eosinophils, histiocytes and giant cells were observed. Silver stained cross-sections of the small intestine showed slender sparsely septate hyphae within the necrotic areas. Attempts to isolate the etiologic agent in pure culture were fruitless. The dog died without a definitive diagnosis. Fixed tissue samples of the small intestine were later investigated using specific fluorescent antibodies for pythiosis and molecular tools. These exams indicated that the hyphae in the infected tissues belong to the straminipilan pathogen Pythium insidiosum. This is the first confirmed case of dog pythiosis in Venezuela.

Animals↗
PubMed2002

Invasive Aspergillosis in Italian AIDS patients.

BACKGROUND: We studied the prevalence, epidemiological features, symptoms, diagnosis, treatment and outcome of invasive aspergillosis in AIDS patients in Italy. PATIENTS AND METHODS: All patients affected by both aspergillosis and AIDS hospitalized between January 1986 and April 1997 (before highly-active antiretroviral therapy, HAART) in four Italian Department of Infectious Disease. Patients were included in the study only if culture, cytology or histology showed firm evidence of Aspergillus infection. Invasive aspergillosis was defined as the presence of characteristic, closely septate hyphae with repeated acute angle branching in either biopsy materials or percutaneous aspirates from tissues other than the lung. Hyphae were identified using hematoxylin-eosin and methenamine silver stain. RESULTS: During the study, 54 out of 2,614 patients admitted with AIDS showed aspergillosis (2.1%). The disease usually occurred in patients with < 50 CD4 cells/mm(3). Aspergillosis was associated with neutropenia and steroid treatment. Nonspecific symptoms were frequently encountered. Fever and cough were both present in > 70% of the cases of pulmonary aspergillosis. Biopsy specimens were analyzed for definitive diagnosis. Invasive aspergillosis is usually treated with amphotericin B, but in 90% of the cases this did not prevent death. CONCLUSION: In AIDS patients with neutropenia and long-term steroid therapy, it is important to consider invasive aspergillosis in the differential diagnosis of opportunistic infections.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Disseminated mucormycosis caused by Absidia corymbifera leading to cerebral vasculitis.

An 18-year-old woman was admitted to hospital because of subcutaneous hematoma and fever of unknown origin. Acute myeloid leukemia was diagnosed and empirical antimicrobial treatment and induction chemotherapy were started. After initial defervescence, fever relapsed 2 days after the onset of neutropenia. The CT scan of the lung was consistent with an invasive fungal infection. Treatment with amphotericin B was started and antimicrobial treatment was continued with liposomal amphotericin B because of an increase in creatinine later. The fever persisted and the patient suddenly developed progressive neurological symptoms. CT scan of the head suggested cerebral infarction and angiography of the extra- and intracranial arteries showed signs of vasculitis. Six days after the onset of neurological symptoms cerebral death was diagnosed. Autopsy revealed non-septate, irregularly branched hyphae in various histologic sections including brain. Absidia corymbifera could be isolated from lung tissue confirming the diagnosis of disseminated mucormycosis. In this case, angiographic findings suggested severe cerebral vasculitis which was in fact caused by thromboembolic dissemination of fungal hyphae. This case underlines the fact that cerebral symptoms in febrile neutropenic patients are highly indicative for fungal infections of the brain.

Absidia↗