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At least 55 records · Page 3Linked to original sources
PubMed2000

Inhibitory effects of water extracts from fruiting bodies of cultured Cordyceps sinensis on raised serum lipid peroxide levels and aortic cholesterol deposition in atherosclerotic mice.

We investigated the effects of the water extracts of the fruiting bodies of cultured Cordyceps sinensis (WECS) on lipid metabolism in mice fed an atherogenic diet. WECS was orally administered at doses of 50, 100 and 200 mg/kg/day for 12 weeks. WECS showed no toxic effects on the growth rate, liver or kidney weights of the mice. Mice fed the atherogenic diet showed marked increases in serum lipid and lipid peroxide levels and also aortic cholesterol levels, particularly cholesteryl ester level, a major lipid constituent in atherosclerotic lesions. WECS significantly suppressed the increased serum lipid peroxide level but not other lipid levels in a dose-dependent manner. WECS also suppressed the increased aortic cholesteryl ester level in a dose-dependent manner. These results suggest that WECS prevents cholesterol deposition in the aorta by inhibition of LDL oxidation mediated by free radicals rather than by reduction in serum lipid level. WECS may exert beneficial effects on the formation of the atherosclerotic lesion induced by oxidative stress with few side effects.

Animals↗
PubMed2001

Determination of nucleosides in natural Cordyceps sinensis and cultured Cordyceps mycelia by capillary electrophoresis.

Cordyceps sinensis is a well-known traditional Chinese medicine, and some of the active components are nucleosides. The analysis of nucleosides in Cordyceps material has been performed by reversed-phase high-performance liquid chromatography (HPLC) with gradient elution or by spectrometry. Here, we have explored the possibility of using capillary electrophoresis to determine the content of three major nucleosides (adenosine, guanosine and uridine) in Cordyceps. Capillary electrophoresis needs no gradients, and it provides a better separation due to its higher efficiency. In order to optimize the resolution, the separation of adenosine, guanosine and uridine was determined in Cordyceps with respect to the variation of buffer concentration, pH, temperature, and voltage. By using the calibrated electrophoresis system, the separation was achieved for the three nucleosides in less than 10 min with a background electrolyte consisting of 0.2 M boric acid-sodium hydroxide buffer, pH 8.5. The nucleoside contents of various types of natural Cordyceps and cultured Cordyceps mycelia were determined and compared. There was a great variation of nucleoside content in different sources of Cordyceps; the cultured Cordyceps mycelia, however, contains a much higher concentration than the natural Cordyceps.

Adenosine↗
PubMed2007

Effect of temperature on the extraction kinetics and diffusivity of Cyclosporin A in the fungus Tolypocladium inflatum.

The influence of temperature on the extraction kinetics of Cyclosporin A (CyA) from the mycelia of Tolypocladium inflatum was examined in this study. The extraction of CyA from mycelia was performed in a 2-L stirred, baffled vessel using 30% v/v aqueous methanol. The temperature range used was from 5 to 45 degrees C. A linear relationship was found between the extraction yield of CyA and temperature. As the temperature increased, the yield of CyA increased with a maximum CyA yield of 18.3% obtained at 45 degrees C, which is 21.3% higher than the yield at 25 degrees C. The activation energy for the extraction of CyA from T. inflatum was found to be 36.7 kJ/mol, which indicates that the extraction of CyA from T. inflatum is controlled by both solubilization of CyA and diffusion of CyA through the solid phase of mycelia. The overall mass transfer coefficient, k(L)a(S), was found to increase from 1.02 x 10(-3) to 1.34 x 10(-2) s(-1) as the temperature increased from 5 to 45 degrees C. The effective diffusivity of CyA in the solid matrix of mycelia was found to increase from 1.05 x 10(-15) to 1.43 x 10(-14) m(2)/s as the temperature increased from 5 to 45 degrees C. A mathematical diffusion model was developed and was used to fit the experimental kinetic data of CyA extraction and determination of CyA effective diffusivities at different temperatures. This is the first time CyA diffusivities as a function of extraction temperature are reported in the literature.

Clinical Laboratory Techniques↗
PubMed2003

Beauveria bassiana isolated from engorged females and tested against eggs and larvae of Boophilus microplus (Acari: Ixodidae).

The purpose of this work was to evaluate the in vitro virulence of three isolates of Beauveria bassiana to eggs and larvae of the tick Boophilus microplus. The fungus tested were isolated from engorged females of B. microplus collected on the field, and identified as Bb28, Bb29 and Bb30. These isolates were evaluated by immersion of eggs and larvae in suspensions with different conidial concentrations: 10(8), 10(7), 10(6) and 10(5) conidia/ml and compared to the control groups. In the treated eggs, there was a percentage much smaller of hatching than that observed in the controls. The egg hatch was inversely proportional to the conidial concentration. In larval bioassays, all isolates resulted in a higher mortality of larvae compared to the control according to the conidial concentrations/ml, 10 days after treatment inoculation.

Animals↗
PubMed2004

Entomopathogenic potential of Metarhizium anisopliae isolated from engorged females and tested in eggs and larvae of Boophilus microplus (Acari: Ixodidae).

The purpose of this work was to evaluate the in vitro virulence of three isolates of Metarhizium anisopliae var. anisopliae to eggs and larvae of the tick Boophilus microplus. The fungus tested was isolated from engorged females of B. microplus collected in the field, and identified as Ma01, Ma02 e Ma04. These isolates were evaluated by immersion of eggs and larvae in suspension with different conidial concentrations: 10(5), 10(6), 10(7) e 10(8) conidia/ml. In each isolate there was a treatment group for each spore concentration and a control group with 10 repetitions. It was observed in the treated egg groups that there was a hatching percentage that was much less than that observed in the control groups. This was in inverse proportion to the conidia concentration/ml. Larval bioassays of all the tested isolates resulted in a high mortality of larvae in direct proportion to the spore concentration/ml, 10 days after the conidia suspensions were inoculated. To consolidate the infection, the fungus used in bioassays was re-isolated.

Animals↗
PubMed2004

Screening for antibacterial activity in 72 species of wood-colonizing fungi by the Vibrio fisheri bioluminescence method.

Resistance of pathogenic bacteria to antibiotics leads scientists to discover new antibacterial drugs. Ninety samples of wood-colonizing fungi were cultivated on agar plates, and their extracts tested for antibacterial activity using the Vibrio fischeri bioluminescence test. Two fungi species, Serpula lacrymans and Nectria vilior, were found to be a potential new source of thermostable antibiotics. Vibrio fischeri bioluminescence test was found to be a useful method for antibacterial activity screening from the samples of natural origin.

Aliivibrio fischeri↗
PubMed1979

[Course and modification of Hypomyces ochraceus m 359 autolysis].

Growth and natural autolysis of the ascomycete Hypomyces ochraceus were investigated in shake cultures by measuring dry weight, pH value, and uptake of carbohydrate. The alkaline autolysis resulted in maximum loss of 53% of dry weight during an incubation period of 35 days. Early autolysis was induced by limitation of oxygen, increasing temperature, addition of peracetic acid, and sodiumacide. Autolysis is discussed to be derived from deficiency of energy.

Azides↗
PubMed2006

Fungicide control of mushroom cobweb disease caused by Cladobotryum strains with different benzimidazole resistance profiles.

The benzimidazole fungicides thiabendazole and carbendazim, and the imidazole fungicide prochloraz-Mn, were tested for their efficacy in controlling cobweb disease of mushrooms caused by two Cladobotryum isolates. Isolate 202A was benzimidazole-sensitive in vitro and cobweb growth on the casing was well controlled by both benzimidazole fungicides in cropping experiments. Carbendazim also controlled the development of spotting symptoms much more effectively than thiabendazole. A second isolate (192B1) was benzimidazole-resistant and was highly resistant to thiabendazole in vitro but it showed some sensitivity to carbendazim in vitro at moderate to high concentrations. Despite this, carbendazim did not control disease symptoms in cropping experiments, confirming that isolate 192B1 is cross-resistant to other benzimidazole fungicides. Both isolates showed some sensitivity to prochloraz-Mn in vitro. This fungicide gave between 45% and 65% control of cobweb growth on the casing caused by either 202A or 192B1 but gave no control of spotting symptoms. Reducing the fungicide application volume did not give enhanced disease control. The emergence of benzimidazole resistance reduces the value of benzimidazoles in the control of mushroom pathogens. However, the lack of effective alternatives means they continue to have utility in cases where pathogens are still sensitive but this requires regular monitoring of pathogen populations for resistance.

Agaricus↗
PubMed2004

Growth and pathogenicity of isolates of the fungus Metarhizium anisopliae against the parasitic mite, Psoroptes ovis: effects of temperature and formulation.

Psoroptes mites (Acari: Psoroptidae) are important ectoparasites of mammals, and are of particular economic significance as the agents of mange in sheep. To be effective against mites, putative fungal biocontrol agents must be able to operate at the relatively high temperatures and humidities found at the sheep skin surface. To consider this, the growth rates of different isolates of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin (Deuteromycotina: Hyphomycetes) were compared and the pathogenicity of these isolates against Psoroptes derived from rabbits (Psoroptes ovis Hering, syn P cuniculi) were evaluated at temperatures between 28 degrees C and 40 degrees C, and when formulated in either Tween 80 or silicone oil. For this study four multi-conidia, arthropod-derived, isolates of M anisopliae were used: from the USA, France, Denmark and Brazil. One single-conidia culture derived from the US isolate was also included in the investigation. Fungal growth was higher at the lower temperatures and none of the isolates grew at 40 degrees C. The growth of the US and single-conidia isolate declined markedly with temperature. In contrast, the Danish, French and Brazilian isolates grew almost as well at 32 degrees C and 35 degrees C as at 28 degrees C and 30 degrees C. The French and Brazilian isolates showed some growth at 37.5 degrees C but the Danish and US isolates did not. The number of fatal infections which resulted from exposure of mites to the fungal isolates was also strongly influenced by temperature. At 30 degrees C all isolates gave between 70 and 90% infection. The number of infections declined with increasing temperature and no infections were seen at 40 degrees C. However, the French and Danish isolates of M anisopliae gave higher numbers of infections than the other isolates at elevated temperatures. When formulated in silicone oil, significantly higher levels of infection were obtained than when formulated in Tween 80, even at the relatively high temperature of 37.5 degrees C. It is suggested that high-temperature adapted isolates of M anisopliae formulated in silicone oil offer good candidates as control agents under the conditions found at the sheep skin surface.

Animals↗
PubMed2001

Sequences of polypeptide antibiotics stilboflavins, natural peptaibol libraries of the mold Stilbella flavipes.

From the culture broths of the mold Stilbella flavipes CBS 146.81, a mixture of polypeptides could be isolated by adsorption on XAD polystyrene resin and purified by Sephadex LH-20 chromatography. Using preparative thin-layer chromatography (TLC) three groups of peptides, named stilboflavins (SF) A, B, and C could be separated. Each of the groups showed microheterogeneity when investigated by high-performance liquid chromatography (HPLC). Employing on-line HPLC-electrospray ionization tandem mass spectrometry in the positive and negative ionization mode, together with gas chromatography-selected ion monitoring mass spectrometry, enantioselective GC and quantitative amino acid analysis, the sequences of stilboflavins A and B could be determined. Exchange of Glu in stilboflavins A peptides (acidic) against Gln in stilboflavins B peptides (neutral) is the rational for different polarity of the peptide groups and their separatability by TLC. Since SF A and B are bioactive N-acetylated 20-residue peptides with a high proportion of alpha-aminoisobutyric acid and C-terminal bonded amino alcohols (either leucinol, isoleucinol or valinol) the peptides belong to the group of peptaibol antibiotics.

Amino Acid Sequence↗
PubMedDate not supplied

Preparation of site-specific isotopically labelled zervamicins, the antibiotic peptaibols produced by Emericellopsis salmosynnemata.

A simple procedure for the preparation of the specifically labelled peptide antibiotic zervamicins IC, IIA and IIB has been developed. The zervamicin molecules are labelled with stable isotopes by culturing the Emericellopsis salmosynnemata on a well-defined synthetic medium containing the highly isotopically enriched amino acid. To obtain the peptide with the specifically and highly enriched amino acid residue, precautions have been taken to prevent any de novo biosynthesis of the particular amino acid from unlabelled precursors. The enrichment of the labelled peptide is determined by mass spectrometric analysis. Following this method we have incorporated [2',4',5',6',7'-2H5]-L-Trp-1, [1'-15N]-L-Trp-1 and [2',3',4',5',6'-2H5]-L-Phl-16 into zervamicins IC, IIA and IIB on the preparative scale and without scrambling of the label. Thus, using the procedures described, isotopically labelled zervamicins can be prepared, allowing them to be studied by solid-state NMR.

Anti-Bacterial Agents↗
PubMed2002

A refined method for the determination of Saccharomyces cerevisiae cell wall composition and beta-1,6-glucan fine structure.

In yeast and other fungi, cell division, cell shape, and growth depend on the coordinated synthesis and degradation of cell wall polymers. We have developed a reliable and efficient micro method to determine Saccharomyces cerevisiae cell wall composition that distinguishes between beta1,3- and beta1,6-glucan. The method is based on the sequential treatment of cell walls with specific hydrolytic enzymes followed by dialysis. The low molecular weight (MW) products thus separated account for each particular cell wall polymer. The method can be applied to as little as 50-100 mg (wet wt) of radioactively labeled cells. A combination of chitinase and recombinant beta-1,3-glucanase is initially used, releasing all of the chitin and 60-65% of the beta1,3-glucan from the cell walls. Next, recombinant endo-beta-1,6-glucanase from Trichoderma harzianum is utilized to release all the beta-1,6-glucan present in the wall. The chromatographic pattern of endoglucanase digested beta-1,6-glucan provides a characteristic "fingerprint" of beta-1,6-glucan and the fine structure of the oligosaccharides in this pattern was determined by 1H NMR and electrospray ionization mass spectroscopy. The final enzymatic step uses laminarinase and beta-glucosidase to release the remaining beta-1,3-glucan. The cell wall mannan remains as a high MW fraction at the end of the fractionation procedure. Good sensitivity and correlation with cell wall composition determined by traditional methods were observed for wild-type and several cell wall mutants.

Cell Wall↗
PubMed2000

Molecular characterization of a cellulase-negative mutant of Hypocrea jecorina.

The "cbh2 activating element," CAE, consisting of two separate boxes (ATTGG = CCAAT and GTAATA, respectively) is essential for cellobiohydrolase II gene expression in the filamentous fungus Hypcrea jecorina. Here we report that cell-free extracts from a cellulase-negative mutant form CAE-protein complexes with higher mobility and lower binding-strength compared to the wild type. EMSA analysis demonstrated an increased mobility of the GTAATA-binding protein complex and, supported by in vivo footprinting, a lowered binding strength of the HAP2/3/5 proteins. However, the hap2/hap3/hap5 genes of the mutant are unaltered and transcribed normally. A nucleotide fragment of the cbh1 promoter containing a (GG)CTAATA motif without an adjacent CCAAT box is also bound by cell-free extracts of H. jecorina, and the protein-DNA complex of the mutant shows the characteristic increase in mobility. We conclude that this mutant is defective in the functional formation of the CAE-protein complexes but not in their binding to the target sequences itself.

Base Sequence↗
PubMed1996

Cellulase formation by species of Trichoderma sect. Longibrachiatum and of Hypocrea spp. with anamorphs referable to Trichoderma sect. Longibrachiatum.

The cellulolytic potential of the wild-type strain of Trichoderma reesei was compared to other members of Trichoderma sect. Longibrachiatum and Hypocrea spp. that have anamorphs referable to that section. There was high diversity even within the same species (as defined by morphological and macromolecular characters). Differences, where notable, were more pronounced for carboxymethyl-cellulase activity than for filter paper activity. High cellulase activities were observed for several strains of T. longibrachiatum and T. citrinoviride, whereas T. parceramosum formed only low levels of activity. Among the corresponding teleomorphs, most strains of H. schweinitzii were comparatively poor producers, whereas the highest percentage of high producers was found among H. jecorina isolates, and many strains were even more active than the parent T. reesei QM 6a. Immunoblot analysis of corresponding culture filtrates of various H. jecorina strains showed that the three major cellulase proteins (cellobiohydrolase I, cellobiohydrolase II, and endoglucanase I) were present in culture filtrates and their M(r) was identical to that of the respective T. reesei proteins. ELISA analysis demonstrated that these enzymes were also present in the same relative proportions in culture filtrates from H. jecorina and T. reesei. With the aid of primers, corresponding to conserved sequences in the cellobiohydrolase I-encoding gene cbh1, a fragment of this gene was amplified from selected strains of H. jecorina, T. reesei, T. longibrachiatum, T. citrinoviride, and H. schweinitzii. The fragments had the same size in all fungi. Cleavage of this fragment with Hhal produced a RFLP pattern which was identical in H. jecorina and T. reesei, but different in the other species. In the latter, the RFLP pattern was also species specific. These results provide support for a close genetic similarity of T. reesei and H. jecorina cellulases. In the latter, an ascomycetous model system for cellulase biosynthesis is now available. The results further indicate that other anamorphs of Trichoderma section Longibrachiatum are promising sources of high cellulase production.

Cellulase↗
PubMed2001

Characterization of pisatin-inducible cytochrome p450s in fungal pathogens of pea that detoxify the pea phytoalexin pisatin.

Many fungi that are pathogenic on pea have the ability to demethylate and thus detoxify the pea phytoalexin pisatin. This detoxification reaction has been studied most thoroughly in Nectria haematococca MP VI where it functions as a virulence trait. The enzyme catalyzing this reaction [pisatin demethylase (pda)] is a cytochrome P450. In the current study, the induction of whole-cell pda activity and the biochemical properties of pda in microsomal preparations from the pea pathogens Ascochyta pisi, Mycosphaerella pinodes, and Phoma pinodella are compared to the pda produced by N. haematococca. Based on cofactor requirements and their inhibition by carbon monoxide, cytochrome P450 inhibitors, and antibodies to NADPH:cytochrome P450 reductase, we conclude that the pdas from the other pea pathogens also are cytochrome P450s. All of the enzymes show a rather selective induction by pisatin, have a low K(m) toward pisatin, and have a fairly high degree of specificity toward pisatin as a substrate, suggesting that each pathogen may have a specific cytochrome P450 for detoxifying this plant antibiotic. Since the pdas in these fungi differ in their pattern of sensitivity to P450 inhibitors and display other minor biochemical differences, we suggest that these fungi may have independently evolved a specialized cytochrome P450 as a virulence trait for a common host.

Antibodies↗
PubMed2001

Effects of exogenous nutrients on conidial germination and virulence against the silverleaf whitefly for two hyphomycetes.

Exogenous protein and sugar sources were tested for their impact on conidial germination of two silverleaf whitefly (Bemisia argentifolii) pathogens: Beauveria bassiana and Paecilomyces fumosoroseus. In liquid culture, sugars stimulated only 5-27% germination of B. bassiana and < or =11% germination of P. fumosoroseus, whereas, yeast extract or peptone stimulated 95-100% germination. In the absence of additional nutrients, agar alone stimulated approximately 50% germination. Storing spores for different periods of time did not alter their general response to exogenous nutrients. When spores were germinated before being applied to third instar B. argentifolii, mortality was as much as 2.45 times greater and occurred more rapidly than that for fresh spores. For ungerminated conidia, the mean time to death from infection was 5.45 (SE = 0.16) and 4.74 (SE = 0.08) days for application rates of 37 and 144 conidia x mm(-2), respectively. When conidia were germinated before application, infection times dropped to 4.58 (SE = 0.16) and 4.45 (SE = 0.10) days, respectively. A likely explanation for the greater pathogenicity and virulence of germinated over ungerminated B. bassiana conidia is that only a fraction of the spores applied to whitefly nymphs actually germinate on the cuticle. For some specialized applications, such as greenhouse production systems, it may be beneficial to germinate spores immediately prior to application.

Animals↗