Showing papers on "Mycelium published in 1989"

Evidence for three differentially regulated catalase genes in Neurospora crassa: effects of oxidative stress, heat shock, and development.

Abstract: Genetic and biochemical studies demonstrated that Neurospora crassa possesses three catalases encoded by three separate structural genes. The specific activities of the three enzymes varied in response to superoxide-mediated stress, heat shock, and development. The three loci, which we designated cat-1, cat-2, and cat-3, map to the right arms of chromosomes III, VII, and III, respectively. The cat-1-encoded enzyme (designated Cat-1; estimated molecular weight, 315,000; pI 5.2) was the predominant catalase in rapid-growth mycelium, and its activity was substantially increased in paraquat-treated and heat-shocked mycelium. Cat-2 (Mw, 165,000; pI 5.4) was absent from rapid-growth mycelium but present at low levels in conidia and stationary-phase mycelium. It was the predominant catalase in extracts derived from mycelium that had been heat shocked for 2 h. Cat-3 (Mw, 340,000; pI 5.5) was the predominant catalase in extracts from mature conidia.

Functional aspects of phosphorus uptake and carbon translocation in incompatible ectomycorrhizal associations between Pinus sylvestris and Suillus grevillei and Boletinus cauipes

Abstract: summary Pinus sylvestris L. and Larix eurolepis Henry seedlings were grown together in non–sterile laboratory microcosms containing functional mycelial networks of one of three different ectomyeorrhizal Fungi. The fungi used were Suillus bovinus (Fr.) O. Kuntze, and two Fungi which are commonly considered to be specific to Larix spp., Suillus grevillei (Klotzsch) Sing, and Boletirms cavipes (Opat.) Kalchbr. Patterns of mycorrhizal infection, transport of labelled assimilate and phosphorus uptake within the microcosms were studied in order to evaluate tine functional attributes of associations formed between P. sylvestris and the two‘larch specific’fungi. Fungal colonization of lateral roots and accumulation of labelled assimilate from adjacent plants fed with 14CO2 was significantly greater in the roots of Pinus plants when the ectomycorrhizal fungus was S. bovinu, and significantly greater in Larix roots when the fungus was V. grevillei or li. cavipes. Kctomycorrhizas formed between P. sylvestris and Ii, cavipes were fully functional in terms of transfer of labelled assimilate to the fungal mycelium. In mixed communities infected by B. caripes, myeclial uptake and translocation of 32P-labelled orthophosphate was significantly greater to Larix plants than to Pinus plants. Formation of sheathed lateral roots on the Pinus plants was low. There was some autoradiographic evidence of phosphorus translocation from mycorrhizal pine roots to stem and leaf tissue hut levels of activity in the shoots were low, indicating limited translocation across the host-fungus interface.

Effects of forest soil acidification on ectomycorrhizal and vesicular—arbuscular mycorrhizal development

Abstract: SUMMARY Seedlings of Pinus contorta Dougl. and Phleum pratense L. were grown in the greenhouse in forest floor (F/H horizons) and mineral soil from a P. contorla stand which had been acidified (pH 1.6 5.2) with S° dust over a 5-year period. Although S° dust was the primary treatment it was assumed that acidification accounted for the major effects on the plants and mycorrhizas. Pinus contorla failed to grow below pH 2.8 and ectomycorrhizas were absent below pH 3.3. Pheleum pratense ceased growth at pH 3.3 and no vesicular-arbuscular (VA) mycorrhizas were formd below pH 4.0. There did not appear to be any relationship between the relative abundance of coarse and fine VA mycorrhizal endophytes and soil acidity. Cenococcum geophilum L. was a common ectomycorrhizal associate of pine seedlings grown in the F/H soil, and E-strain fungi (Complexipes), Mycelium radicis atrovirens Melin, Tomentella sp. and Suillus sp. were all more common in the mineral soi than in the F/H soil. Piloderma bicolor (Peck) Julich was observed to occur in large, discrete patches in the undisturbed natural stand but did not form ectomycorrhizas in the greenhouse. Both P. pratense and P. contorla were capable of good growth in extremely acid soils in a non-mycorrhizal state.

Early stages in colonization of Allium porrwn (leek) roots by the vesicular—arbuscular mycorrhizal fungus, Glomus versiforme

Abstract: SUMMARY Leek (Allium porrum L. cv. Titan) roots wore colonized by the vesicular arbuscular (VA) mycorrhizal fungus Glomus versiforme (Daniels and Trappe) Berch. External hyphae were of varying sizes and had a single-layered wall surrounding a vacuolate cytoplasm. Intra-hyphal hyphae were frequent in the extraradical mycelium. Some external hyphae formed small branches which initiated simple appressoria over the outer tangential wall of epidermal cells. Appressoria were multinucleate and possessed many structures which we have interpreted to be bacterium-like organclles (BLOs). Infection hyphae formed by appressoria penetrated the radial cell walls of epidermal cells and were surrounded by an electron dense substance and host cell wall. Epidermal and cortical cells reacted frequently by forming cell wall thickenings. Hyphae in the exodermis formed coils which were surrounded by host plasma membrane but not host cell wall, and had many nuclei and BLOs.

Spatial dynamics and interactions of the woodland fairy ring fungus, Clitocybe nebularis

Abstract: summary The extension rates of Clitocybe nebularis (Batsch ex Fr.) Kummer strains on 2% malt agar were only 30–40%, of those, up to 3.4 mm d−1, observed in woodland at equivalent exponential mean temperatures. Extension of mature field systems was accomplished by mycelial annuli or arcs 30-40 cm wide, differentiated into a leading edge of mycelial cords followed by a zone of dense, diffuse mycelium which bleached litter components, and a trailing edge of greyish, Used mycelium. Disruption of mature annuli by natural obstacles or experimental re-orientation within the mycelial band resulted in regression of the affected segment of mycelium. Localized lysis following encounter with an obstacle by immature patches of mycelium with a diameter of 30–50 cm, led to polarized development of the residual mycelium. Strains from different fruit bodies were somatically compatible when paired on 2% malt agar if sampled from the same ring, but incompatible if from different rings, resulting in mutual antagonism and formation of a persistent demarcation zone. By contrast, collision between adjacent systems in woodland culminated in mutual obliteration of the interaction fronts. C nebularis was non-combative when paired against other decomposer basidiomycetes on 2% malt agar, being either replaced or deadlocked but not replacing mycelia of these fungi. The implications of these observations are discussed in terms of emerging concepts of ecological strategies, foraging theory and polarity in mycelial collectives.

Production of beauveria bassiana [Deuteromycotina. Hyphomycetes] sympoduloconidia in submerged culture

Abstract: Submerged conidiation of the entomogenous HyphomyceteBeauveria bassiana is reported Conidiogenous cells produce sympoduloconidia on conidiogenous cells in liquid shaker culture; hyphal bodies and mycelium fragments are also produced The morphology of these fungal structures is discussed and illustrated Several simple liquid media are tested for the production of conidia and hyphal bodies Maximum yields of conidia (170×106 conidia/ml) are produced in a medium consisting of sucrose (2%) — yeast extract (05%) and basal salts, and maximum yields of hyphal bodies (740×106 hyphal bodies/ml) in a sucrose (25%) — yeast extract (25%) medium

Growth responses and lignin production in cell suspensions of Pinus elliottii ‘elicited’ by chitin, chitosan or mycelium of Cronartium quercum f.sp. fusiforme

Abstract: Incubation of suspension-cultured slash pine (Pinus elliotti Engelm.) cells with living mycelial plugs or homogenized, washed and autoclaved mycelium of Cronartium quercum f.sp. fusiforme led to rapid clouding of the medium and visible inhibition of cell growth with only a slight increase in cell mortality. Purified chitin elicited similar changes in cloudiness and growth. Chitin treatment concentrations of up to 1 mg ml-1 showed only slight changes in viability over several days (as with the mycelium and mycelial extract). In contrast, chitosan concentrations of as low as 60 μgml-1 showed cell mortality and browning, with a complete ‘hypersensitive’ response and over 90% cell death occurring within 48 h at between 180 and 270 μ ml-1 chitosan amendment. Phloroglucinol staining showed the presence of lignin-like compounds in the medium and lignin-like compounds were elevated in the cell walls of the chitin, chitosan and mycelium elicited suspension cultures as compared to controls.

Method of protecting useful plants from diseases caused by soil-borne and seed-borne pathogens by treating seeds with cultures of microorganisms

Abstract: Useful plants can be protected against soil-borne and seed-borne diseases by coating the seeds of said plants with fungus spores, in particular ascospores of Chaetomium globosum, mycelium, bacteria or culture extracts thereof. The protection is in some cases superior to that afforded by sugar beet and cotton seeds which are coated with commercially available fungicides.

Calcium ion regulates aerial mycelium formation in actinomycetes.

Abstract: Ca2+ induced the formation of aerial mycelia in Streptomyces ambofaciens. Its effect was inhibited by ethylene glycol bis(β-aminoethyl ether)-N, N, N', N'-tetraacetic acid, a Ca2+ specific chelating agent. A survey of 36 strains of actinomycetes showed that Ca2+ regulated aerial mycelium formation in 21 (58%) of them. The Ca2+ concentration required for aerial mycelium formation in the culture medium ranged from 0.1 to 1.5 mM.

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

Abstract: 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.

Itaconic acid production by immobilizedAspergillus terreus on sucrose medium

Abstract: The itaconic acid production by immobilizedAspergillus terreus TTK 200-5-3 mycelium was optimized in shake flask fermentations using statistical experimental design and empirical modelling. The maximum itaconic acid concentration was calculated to be 13.3 g/l in the investigated experimental area when initial sucrose concentration was 10%, ammonium nitrate concentration 0.275% and initial pH 3. The itaconic acid product concentration using immobilized mycelium was about double of that obtained with the free mycelium.

Quantification of three vesicular-arbuscular mycorrhizal fungi (Glomus spp) in roots of leek (Allium porrum) on the basis of activity of diagnostic enzymes after polyacrylamide gel electrophoresis

Abstract: Leek ( Allium porrum L.) roots separately colonized by the vesicular-arbuscular mycorrhizal fungi Glomus caledonium, G. mosseae and Glomus sp. type E3 were mixed with nonmycorrhizal roots to give samples of different infection levels. Extracts of these samples were subjected to electrophoretic separation on polyacrylamide gels and stained for specific enzyme activity (esterase or glutamate oxaloacetate transaminase or peptidase). The staining intensity of the diagnostic fungal isozymes (measured as peak height on a densitometer trace) was correlated with the biomass of the fungus in the root sample and so this offers a method of quantifying the contribution of a single fungus to a mixed infection and of estimating the viability of the intraradical mycelium.

Fungi invading roots of perennial ryegrass (Lolium perenne L.) in pasture

Abstract: Fungal invasion of roots in perennial ryegrass turf samples taken during Autumn, from 18 sites in New Zealand, was investigated by microscopy and plate culture isolation techniques. The most frequently encountered fungi were Phialophora radicicola Cain and sterile fungi with dark or hyaline mycelium. Other deuteromycetes, particularly Codinaea fertitis Hughes … Kendrick, Fusarium oxysporum Schlecht., Periconia macrospinosa Lefebvre … A.G. Johnson, Penicillium spp., and Trichoderma spp., basidiomycetes, and vesicular-arbuscular mycorrhizal spp., were also common. Two additional sites were sampled over a 7-month period to examine the effects of root age, season, and fungicide treatment. Fungi were not affected by season or fungicide treatment (benomyl or triadimefon plus iprodione), but brown (old) roots were colonised more by fungi than white (young) roots. Fifty of 51 isolates of fungi commonly found in ryegrass roots invaded roots of ryegrass seedlings grown axenica1ly on water agar. Gaeumannomy...

Histochemical localization of desoxyhemigossypol, a phytoalexin in Verticillium dahliae‐infected cotton stems

Abstract: SUMMARY The terpenoid phytoalexin desoxyhemigossypol (dHG) was detected histochemically in the stem xylem of Verticillium dahliae Kleb-infected, wilt-resistant Seabrook Sea Island cotton as a green product on V. dahliae mycelium within vessel lumens and in specialized, often solitary, paravascular parenchyma cells. The SbCl3-HCIO4 histochemical reagent yielded a green-coloured Sb-dHG product specific for dHG when used as a spray on chromatograms of extracts from Verticillium-infected stele tissue. Both dHG and related terpenoid aldehyde derivatives occurred together in parenchyma cells and on V. dahliae mycelium. The presence of dHG on Verticillium mycelium reinforces previous studies that identified dHG as the most toxic and possibly most important phytoalexin in the resistance of cotton to V. dahliae.

Polyamines and Ornithine Decarboxylase Activity during Growth and Differentiation in Sclerotium rolfsii

Abstract: Changes in polyamine content and in the activity of ornithine decarboxylase (ODC) were followed during growth and differentiation of the plant pathogenic fungus Sclerotium rolfsii, in submerged mycelium liquid cultures and on solid agar cultures. Mycelial growth in submerged cultures was characterized by high putrescine content and ODC activity. Growth cessation, resulting from glucose exhaustion in the medium, was accompanied by a sharp decrease in putrescine content and ODC activity. Spermine, the level of which was initially low, was detected in high amounts after all of the glucose was consumed and when the fungus developed the potential for sclerotium formation. A decrease in spermidine, and especially putrescine content, and an increase in spermine content, were observed during the transition from mycelium to mature sclerotia on solid agar medium. Addition of spermine to solid agar medium increased the number of sclerotia by 40%. The changes in the content of the three polyamines were reversed when sclerotia were allowed to germinate. Moreover, α-difluoromethylornithine, the enzyme-activated inhibitor of ODC, greatly inhibited mycelium growth, sclerotium germination and ODC activity, and this inhibition was completely reversed by the addition of putrescine. Cycloheximide delayed sclerotium germination and initially inhibited ODC activity, but ODC inhibition was relieved as soon as sclerotia began to germinate. The data indicate that specific changes in polyamines are linked with two distinct developmental events in S. rolfsii. Mycelial growth and sclerotium germination are positively correlated, and possibly causally linked, with a marked increase in putrescine content and biosynthesis (while spermine cannot be detected). Differentiation (sclerotium formation), however, is accompanied by a major increase in spermine content.

Effect of phosphate on the toxicity of phosphite in Phytophthora palmivora

Abstract: The concentration of Pi in the growth medium had a marked effect on the amount of the fungicide phosphite accumulated by Phytophthora palmivora The mass of mycelium, produced after 7 days growth in a medium containing excess Pi, was not markedly inhibited until phosphite concentrations of 10 mM or greater were supplied In contrast, in a Pi-deficient medium, growth was inhibited by 01 mM phosphite In the latter medium, the fungus took up significantly more phosphite once Pi had been depleted from the medium (from day 4 to 6) When 7 day old mycelium was presented with either 1 mM Pi or phosphite, the Pi-deficient mycelium transported either anion at almost eight times the rate found in the Pi-excess mycelium The level of alkaline phosphatase present in the Pi-deficient mycelium was also significantly elevated

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

Abstract: 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 β-oxidation pathway and further metabolized to support growth of new vegetative hyphae.

Production and Localization of Proteinases in Colonies of Timber-decaying Basidiomycete Fungi

Abstract: Proteinase activity was detected in culture filtrates of eight wood-decaying basidiomycete fungi and compared in terms of ability to clear skimmed milk agar. All the fungi were proteolytic, but to differing extents. Five were compared using azocasein hydrolysis as a measure of proteolytic activity at the centres and margins of agar-grown colonies and it was found that in Coriolus versicolor the marginal mycelium was the more strongly proteolytic, while in all the other fungi proteolysis by central mycelium was greater. The time course of changes in proteolytic activity in culture filtrates of C. versicolor and Serpula lacrimans grown on the surface of liquid media was compared over 4 weeks, and differences were found which suggested that C. versicolor mycelium inactivates its proteinases after secreting them, but that S. lacrimans does not. The results are interpreted in terms of the likely role of proteinases in the nitrogen economy of these fungi when growing on their wood substrates.

Conidia of Heterobasidion annosum from Tsuga heterophylla forests in western Washington

Abstract: Heterobasidion annosum produces conidia abundantly in culture; however, since conidiophores are rare in nature, conidia are usually considered to have little or no role in dispersal. Heterokaryotic mycelia of H. annosum produce both heterokaryotic and homokaryotic conidia, whereas basidiospores are homokaryotic. This difference was exploited to assess the relative prevalence of these spore types in western hemlock forests of western Washington state. Two out of 10 spores trapped on selective media were found to give rise to heterokaryotic mycelia identified by the presence of clamp connections. However, homokaryotic conidia could not be distinguished from basidiospores by this method, so two approaches were taken in the laboratory: examining conidia for number of nuclei and determining frequency of clamp connections in conidial cultures. Both methods indicated that from a single heterokaryotic mycelium, half of the conidial progeny were homokaryotic and the other half heterokaryotic. Thus the presence of ...

Structural analysis of water-soluble fractions obtained from Aspergillus fumigatus mycelium.

Abstract: Fractions were prepared from the water-soluble components ofAspergillus fumigatus mycelium either by lectin-affinity chromatography or salt precipitation. While they varied considerably in their amino-acid composition, each contained a preponderance of aspartic and glutamic acids.13C-NMR spectroscopy of these fractions, compared with that of polysaccharide obtained by alkaline extraction, indicated the presence of glycoproteins, the polysaccharide components of which contained β-d-Galf units that are part of structures chemically different from those obtained by alkali treatment. In two of the three fractions examined, gas-liquid chromatography-mass spectrometry showed marked differences in the contents of non-reducing end-units of α-d-Manp and β-d-Galf. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of the preparations revealed an array of components, which stained to differing extents with silver stain and with Coomassie Blue and many of which were bound by lectins with specificity for different sugars.

Optimization of protoplast formation, regeneration, and viability in Microsporum gypseum.

Abstract: Factors affecting high yields, regeneration frequencies, and viability of protoplasts from clonal cultures of Microsporum gypseum were investigated. Maximum yields of protoplasts were obtained after 6 hrs digestion of 2–4 days old mycelium with Novozyme 234 using CaCl2 (0.4 M) as an osmotic stabilizer and glycine + HCl (pH 4.5) as the buffer system. Mercaptoethanol + dithiothreitol (0.01 M) proved to be the best pretreatment of mycelium prior to digestion with enzyme. A regeneration frequency of 94.4% was obtained using the top agar method with complete medium (pH 6.5) containing 0.5% agar and 0.4 M CaCl2 as an osmoticum. Colonies from regenerated protoplasts on medium containing CaCl2 were pigmented and completely powdery with high sporulation. Protoplast viability was studied in osmotic stabilizer supplemented with glucose or glutamine. After 24 hrs, glucose (2%) and glutamine (2%) enhanced protoplast viability by 22% and 23%, respectively. Protein synthesis, as measured by 3H-lysine uptake, matched the viability profile determined by fluorescence microscopy.

Structural and Functional Analysis of Ribosomal Subunits from Vegetative Mycelium and Spores of Streptomyces antibioticus

Abstract: The structure and function of ribosomes from spores and vegetative mycelium of Streptomyces antibioticus were compared. Differences were observed in the sedimentation coefficient of ribosomes from spores (56·86S) and vegetative mycelium (69·77S). Reverse-phase high-performance liquid chromatography of ribosomal proteins of the 30S and 50S subunits revealed differences which included several polypeptides present in the vegetative ribosomes but absent from spore ribosomes. The latter were also defective in their ability to promote polyphenylalanine synthesis, the functional activity of both ribosomal subunits being affected. The soluble fraction of spores also showed decreased protein-synthesizing activity, compared to that of the vegetative mycelium. Recovery of normal ribosomal subunits and soluble fraction activity occurred early in the germination process, reaching activity values approaching those of the vegetative state during initiation of germination. It is suggested that regulation of cellular metabolism at the level of translation may be involved in the establishment of spore dormancy.

Ethylene is synthesized by vegetative mycelium in surface cultures of Penicillium cyclopium Westling

Abstract: Surface cultures of Penicillium cyclopium, grown in a closed aeration system on a semisolid minimal medium with 2-keto-glutarate, glutamate or glucose as carbon source, produced ethylene in two phases. The first was associated with aerial hyphae formation; the second, with conidiation. The maximum rate of ethylene synthesis coincided with intensive oxygen consumption whereas the cessation and reutilization of ethylene occurred together with a low respiration rate. After the removal of the aerial mycelium, vegetative hyphae continued ethylene production up to 50% of the value reached in intact cultures. Neither detached aerial mycelium with penicilli nor pure conidia produced ethylene. The content of ethylene in the medium of a producing culture was four-fold higher than would correspond to its concentration in the atmosphere above the culture. In the upper agar layer (1.25 mm), a high pH (8.8) and 30 mM was found, presumably because of mycelium autolysis. The pH in the layer 3 mm below the surface was 2.4...

Detection and characterization of two antigens specific for cell walls ofCandida albicans mycelial growth phase

Abstract: Antiserum againstCandida albicans ATCC 10231 mycelium growth phase absorbed with yeast cells and intracellular material of mycelium cells showed a positive reaction with mycelium cells in immunofluorescence assay, whereas with yeast cells the reaction was negative. Mycelium and blastospore cell wall were extracted with dithiothreitol (DTTMy- and DTTB-extract). When DTTMy was separated in gel-electrophoresis, two glycoprotein bands of 87 and 67 Kd could be detected. In immunoblot these bands showed a strong reaction with mycelium cell wall-specific antiserum, but also a weak reaction with the blastospore antiserum. Whereas pronase treatment destroyed antigenicity, mannanase treatment did not. After enzymatic digestion with endoglycosidase H, four major enzymatic digestion products were found at 37, 35, 30, and 27 Kd when protein staining was performed. The digestion products at 37 and 35 Kd could be made visible through glycoprotein staining. Antibodies of yeast-phase-immunized animals reacted only with the 37 and 30 Kd bands, whereas the digestion products at 35 and 27 Kd were also detected by mycelium cell wall-specific antiserum. This proves the existence of two mycelium cell wall-specific antigens (35 Kd and 27 Kd) that can be isolated from the DTT-mycelium cell wall extract by endoglycosidase H treatment.