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PubMed2001

Natural occurrence of entomophthoralean fungi pathogenic to collembolans.

The aim of this study was to assess the natural occurrence of fungi from the order Entomophthorales (Zygomycetes) pathogenic to a range of collembolan species. A total of 11,709 collembolans representing a total of 15 species from all three subclasses within Collembola were collected and incubated. Infection with Neozygites-like spp. (Entomophthorales) was recorded in the two subclasses, Arthropleona and Symphypleona. The morphology of the primary conidia of the Neozygites-like fungi infecting collembolans showed a high degree of variation in shape and size, and the fungi were divisible into five groups. One group consisted of Neozygites sminthuri, while the other four groups, while still closely resembling the genus Neozygites, did not fit within the description of any known species and were preliminarily designated Neozygites sp. nov. 1 to 4. Neozygites sp. nov. 1, infecting Sphaeridia pumilis, was observed to form globular secondary conidia, which have not been observed before within the genus Neozygites. A formal species description needs, however, yet to be performed. The infection was mainly found in species from the subclass Symphypleona, where two new host genera for Neozygites, Deuterosminthurus and Sphaeridia, were recorded. However, the prevalence of Neozygites spp. was low, up to 10% in S. pumilis, 6% in Sminthurus viridis, and below 1% in Deuterosminthurus sulphureus. Infection with an obligatory entomopathogenic fungus was for the first time well documented within the subclass Arthropleona, where specimens of Orchesella cincta and Orchesella villosa sporulated with a N. sminthuri-like fungus. Additionally, infection with the facultative pathogen Conidiobolus coronatus was recorded from several hosts representing both the subclass Arthropleona (Isotoma anglicana and O. cincta) and the subclass Symphypleona (Dicyrtoma sp. and S. viridis). For most species the prevalence of C. coronatus resembled that of Neozygites spp. and did not exceed 8.8%. The only exception was Dicyrtoma sp., for which the only associated entomophthoralean fungus was C. coronatus, where the prevalence reached 17.8% infection.

Animals↗
PubMed1992

Regulatory sequences for expressing genes in oomycete fungi.

Promoter and terminator sequences from a range of species were tested for activity in the oomycetes, a group of lower fungi that bear an uncertain taxonomic affinity to other organisms and in which little is known of the sequences required for transcription. Transient assays, using the reporter gene beta-glucuronidase (GUS), were used to examine the function of these promoters and terminators in the plant pathogens Phytophthora infestans and P. megasperma f. sp. glycinea, and in the saprophytic water mold, Achlya ambisexualis. Oomycete promoters, isolated from the ham34 and hsp70 genes of Bremia lactucae and the actin gene of P. megasperma f. sp. glycinea, resulted in high levels of GUS accumulation in each of the three oomycetes. In contrast, little or no activity was detected when promoters from higher fungi (four ascomycetes and one basidiomycete), plants, and animals were tested. The terminator from the ham34 gene resulted in much higher levels of GUS accumulation than did others, although an oomycete terminator was not absolutely required for expression. Transcript mapping of RNA from stable transformants confirmed accurate initiation from the B. lactucae hsp70 promoter and termination within 3' ham34 sequences in P. infestans. Our results indicate that the transcriptional machinery of the oomycetes differs significantly from that of the higher fungi, but that enough conservation exists within the class to allow vectors developed from one oomycete species to be used for others.

Base Sequence↗
PubMed1991

Differentiation of species and strains among filamentous fungi by DNA fingerprinting.

We have analyzed 11 strains and clones, representing five species (Penicillium janthinellum, P. citrioviridae, P. chrysogenum, Aspergillus niger, Trichoderma harzianum) and three genera of filamentous fungi, for the presence of hypervariable loci in their genomes by hybridization with simple repeat oligonucleotides and the DNA of phage M13. The oligonucleotide probes (CT)8, (GTG)5 and (GACA)4, as well as M13 DNA, are informative probes for fingerprinting in all genera and species tested. The probe (GATA)4 produced informative fingerprints only with the genomic DNA of A. niger. There was no similarity between the fingerprints originating from fungi of different genera and also little similarity between the fingerprints of different species belonging to the same genus. Fingerprints of strains of the same species differed only slightly from each other. Fingerprints of clones originating from one strain were identical. The results indicate that DNA fingerprinting is a powerful method to differentiate species and strains of filamentous fungi.

Aspergillus niger↗
PubMed1996

Isolation of keratinophilic fungi from the floors of private veterinary clinics in Italy.

To evaluate the presence of keratinophilic fungi in the environment, 400 samples were collected from the floors of 50 private veterinary clinics using 55-mm-diameter 'contact plates', containing mycobiotic agar. After incubation for 15 days at 25 degrees C, the following species were isolated: Microsporum canis, Trichophyton terrestre, Chrysosporium keratinophilum, Chrysosporium sp., Microsporum gypseum, Trichophyton ajelloi, Chrysosporium tropicum, Trichophyton mentagrophytes, Chrysosporium state of Arthroderma tuberculatum and Chrysosporium pannorum. It is concluded that the keratinic material shed by infected pets may contribute to the development and propagation of dermatophytes and related fungi in veterinary clinics. Therefore, such veterinary clinics may represent sites where pets and humans are exposed to risk of infection with keratinophilic fungi from the environment.

Animals↗
PubMed1982

Antigens from Histoplasma capsulatum and Blastomyces dermatitidis. I. Immunological comparative studies from polysaccharide-protein complexes of both fungi.

Certain groups of fungi share chemical structures which makes difficult isolation and differentiation of specific antigens by the usual methods of extraction and purification. Therefore, we have oriented our studies to the immunological and biochemical characterization of differences and similarities of molecular structures from fungi, etiologic agents of systemic mycoses, hoping to establish criteria for the utilization and handling of these antigens. A deproteinized polysaccharide-protein complex (D-PPC) was isolated from Histoplasma capsulatum and Blastomyces dermatitidis. The immunological studies with humoral tests indicate a variable cross reaction between antigens of both species. In immunodiffussion systems, the reaction was specific for each species using saline solution of phosphate butter solution, while using an agarose veronal system, the cross reactions were very evident. In addition, differences in cross reactions were obtained with immunoelectrophoresis, haemagglutination and complement fixation microtest. This variation to cross reaction responses suggest that these antigens (D-PPC) share common structures but at the same time must have some different component owned by each one of the fungi which makes them more specific than crude antigens.

Antigens, Fungal↗
PubMed1996

Effects of the infection of toxigenic fungi and an antagonistic Streptomyces strain on wheat spikes.

The objective of the present study was to determine the effect on infection of wheat spikes by toxigenic fungi (Aspergillus parasiticus NRRL 2999, Fusarium tricinctum NRRL 3299, Fusarium graminearum CEREMIC 136/92) and a strain of Streptomyces sp. that is antagonistic to the above-mentioned fungi. Wheat grains (variety GRANERO INTA) were sown in 8 pots containing natural soil and kept in a greenhouse chamber. In the period of the early anthesis the wheat spikes were inoculated with conidial suspensions of each of the fungi in the presence or absence of Streptomyces. Each pot was assigned a different treatment. After an incubation of 100 days and when the wheat plants had attained maturity, the spikes were separated and the following items were determined: (a) number of grains obtained with each treatment, (b) weight of the grains, (c) average weight of the grains/treatment, (d) average number and weight of the grains/spike, and (e) invasion of the caryopses by the microorganisms determined by the analysis of the caryopses in seriate histological sections. There was a significant decrease (p < 0.01) in the average weight of the caryopses and in the weight and number of grains/spike in the presence F. graminearum. The wheat grains were invaded by of F. graminearum and A. parasiticus, an effect which was partially attenuated by the presence of antagonist Streptomyces sp. Nevertheless, the effect was not strong enough to prevent the degenerative consequences on the size and weight of the grains produced by F. graminearum.

Aspergillus↗
PubMed1987

Keratinophilic fungi from Nigerian soil.

During a survey of keratinophilic fungi in Nigerian soil samples, twelve species of fungi were isolated. These included Chrysosporium keratinophilum, C. tropicum, Curvularia lunata, Microsporum audouinii, M. canis, M. fulvum, M. gypseum, M. vanbreuseghemii, Trichophyton ajelloi, T. mentagrophytes, T. soudanense and T. yaoundei. These keratinophilic fungi had a higher incidence by occurrence of individual species during the rainy season (May-October) than the dry season (November-April).

Arthrodermataceae↗
PubMed1988

Keratinophilic fungi on the hair of goats from the West Bank of Jordan.

The mycoflora of the hair in 178 goats from the West Bank of Jordan was analysed and the frequency of occurrence and the relative importance value for the different keratinophilic fungi found were calculated. One hundred and seven species which belong to 38 genera were isolated. Thirty six of these species were either well recognised agents of mycoses (Trichophyton mentagrophytes, T. verrucosum, and M. nanum), or have been frequently isolated from human and animal lesions (Arthroderma spp., Acremonium kiliense, Alternaria alternata, Aspergillus flavus, Cladosporium carionii, and several other species). These potentially pathogenic fungal species comprised 66.9% of all keratinophilic fungi found on the hair of goats. The role of this animal as a reservoir for dermatophytes and other potentially pathogenic fungi is discussed.

Animals↗
PubMed1988

A comparison of the highly selective fluorescence staining of fungi in tissue sections with Uvitex 2B and Calcofluor White M2R.

The selective fluorescence staining of two fungi, Candida albicans and Blastomyces dermatitides, with Uvitex 2B and Calcofluor White M2R was studied in deparaffinized and frozen sections of mouse kidney and lung. Both fluorochromes emitted maximally at about 430 nm, independent of the mounting media (Kaiser's gelatin or Entellan). In addition to fungi, both fluorochromes also stained elastic fibres. The fluorescence intensity remained unchanged after storage of sections for more than 6 months in conventional slide boxes. The two fluorochromes showed the following differences: Calcofluor faded 1.25 times faster than Uvitex when illuminated with ultraviolet light. Calcofluor showed a greater affinity for tissues in general, and red cells and renal tubular casts in particular. Counterstaining of deparaffinized sections with Hemalum and Eosin reduced the fungi fluorescence and suppressed the general background fluorescence. However, it led to an intensification of Eosin staining and the fluorescence of red cells in Calcofluor-stained sections but not in Uvitex-stained ones. Similarly, the background fluorescence in frozen sections was reduced by Evans Blue, although elastic fibres still fluoresced after staining with Calcofluor. The degree of staining selectivity, and thus the contrast produced within a histological specimen, was greater with Uvitex 2B than with Calcofluor White M2R.

Animals↗
PubMed1988

Visualization of fungi in histological sections.

Deparaffinized kidney sections from mice infected with Candida albicans and lung sections from mice infected with Blastomyces dermatitides were stained with the stilbene derivative, Uvitex 2B (1%), and counterstained with haemalum and eosin. Fungi selectively stained with Uvitex 2B are visualized by blue fluorescence under incident illumination with ultraviolet light. Simultaneous or consecutive illumination with transmitted light permits the assignment of fluorescent fungi to haemalum-eosin-stained structures in the section. The most practical means of achieving a high optical contrast with Uvitex 2B in sections and good haemalum-eosin staining is to use the established haemalum-eosin technique, but with a solution containing both 1% eosin and 1% Uvitex 2B in place of eosin alone. Since Uvitex 2B stains all fungi investigated so far, it affords a simple, sensitive and inexpensive method of selectively detecting opportunistic fungal infections in conventional histopathology.

Animals↗
PubMed2003

Detection of aflatoxigenic fungi in feeds using the PCR method.

The possibility of using the polymerase chain reaction (PCR) to speed up and specify the detection of aflatoxigenic fungi isolated from feed was investigated. The method, applied to 2 genes encoding the biosynthesis of aflatoxins (apa-2 and ver-1), was optimized on two collection cultures (Aspergillus flavus CCM F-108 and A. parasiticus CCM F-550). The specificity of the optimized PCR method was proved on collection cultures of different kinds of fungi. Fifty feed samples out of which 18 showed positive findings of aflatoxigenic fungi on an Aspergillus Flavus and Parasiticus Agar (AFPA) medium were tested. Isolated strains of Aspergillus strains were verified using the PCR method; its reaction products were detected in 1% agarose gel by electrophoresis. The results almost exclusively matched those gained from the AFPA medium.

Aflatoxins↗
PubMed2001

Screening of basidiomycete fungi for the quinone-dependent sugar C-2/C-3 oxidoreductase, pyranose dehydrogenase, and properties of the enzyme from Macrolepiota rhacodes.

Mycelial cultures of 76 strains of lignocellulose-degrading basidiomycete fungi were screened for the activity of pyranose dehydrogenase, a novel sugar oxidoreductase recently detected in Agaricus bisporus. Of these fungi, 37 strains belonging to seven phylogenetically related genera of mostly litter-decomposing Agaricales were positive for the dehydrogenase, based on activity assays towards D-glucose with 1,4-benzoquinone or ferricenium ion as electron acceptors, and on TLC/HPLC analyses of the reaction products. Lack of activity with O(2) as the oxidant, specificity for C-3 of D-glucose, and active extracellular secretion of the enzyme were used as criteria to differentiate pyranose dehydrogenase from pyranose 2-oxidase (EC 1.1.3.10), known to be produced by numerous wood-rotting fungi. Extracellular pyranose dehydrogenase from Macrolepiota rhacodes was heavily glycosylated. The enzyme was characterized as a 78-kDa flavoprotein under denaturing conditions and a 76-kDa native protein using gel filtration. This enzyme had a maximum extracellular activity of 4.1 U ml(-1) in 39-day liquid cultures. It exhibited broad selectivity for sugar substrates and oxidized D-glucose (K(m)=1.82) exclusively at C-3 to 3-dehydro-D-glucose (D-ribo-hexos-3-ulose), in contrast to pyranose dehydrogenases from Agaricus species, which acted at both C-3 and C-2 of D-glucose. The N-terminal sequence, AVVYRHPDEL, showed significant similarity with that reported for A. bisporus.

Basidiomycota↗
PubMed2006

Evolution and diversification of RNA silencing proteins in fungi.

Comprehensive phylogenetic analyses of fungal Argonaute, Dicer, and RNA-dependent RNA polymerase-like proteins have been performed to gain insights into the diversification of RNA silencing pathways during the evolution of fungi. A wide range of fungi including ascomycetes, basidiomycetyes, and zygomycetes possesses multiple RNA silencing components in the genome, whereas a portion of ascomycete and basidiomycete fungi apparently lacks the whole or most of the components. The number of paralogous silencing proteins in the genome differs considerably among fungal species, suggesting that RNA silencing pathways have diversified significantly during evolution in parallel with developing the complexity of life cycle or in response to environmental conditions. Interestingly, orthologous silencing proteins from different fungal clades are often clustered more closely than paralogous proteins in a fungus, indicating that duplication events occurred before speciation events. Therefore, the origin of multiple RNA silencing pathways seems to be very ancient, likely having occurred prior to the divergence of the major fungal lineages.

Ascomycota↗
PubMed1999

Degradation of Soil Humic Extract by Wood- and Soil-Associated Fungi, Bacteria, and Commercial Enzymes.

> Abstract An alkaline humic extract (HE) of a black calcareous forest mull was exposed to 36 fungal and 9 eubacterial isolates in liquid standing culture. At 21 d in fungi, and 4 d in bacteria, the groups of wood-degrading basidiomycetes, terricolous basidiomycetes, ectomycorrhizal fungi, soil-borne microfungi, and eubacteria had reduced the absorbance (A340) of HE media by 57, 28, 19, 26 and 5%, respectively. Gel permeation chromatography revealed that the large humic acid molecules were more readily degraded than the smaller fulvic acid molecules and served as a sole source of carbon and energy. The more active HE degraders reduced the overall molecular weight of humic and fulvic acids by 0.25 to 0.47 kDa. They also reduced the chemical reactivity of HE to tetrazotized o-dianisidine, indicating the degradation of hydroxylated aromatic molecules (which are responsible for this reaction). Decreases in absorbance, molecular weight, and reactivity were caused by fungal manganese peroxidase, horseradish peroxidase, beta-glucosidase, and abiotic oxidants such as H2O2 and Mn(III) acetate. It is concluded that fungi, some of which are propagated in contaminated soils to control xenobiotics, metabolize HE compounds enzymatically. They use enzymes which are also involved in the degradation of soil xenobiotics. Because of reductions in the molecular weight of HE, which is a potential carrier of heavy metal ions and xenobiotics, solubility and motility of humic substances in soil and surface waters are increased.

Journal Article↗
PubMed2000

Mineralisation of 14C-labelled synthetic lignin and ligninolytic enzyme activities of litter-decomposing basidiomycetous fungi.

Within a screening program, 27 soil litter-decomposing basidiomycetes were tested for ligninolytic enzyme activities using agar-media containing 2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonate), a humic acid or Mn2+ ions as indicator substrates. Most active species were found within the family Strophariaceae (Agrocybe praecox, Stropharia coronilla, S. rugosoannulata) and used for mineralisation experiments with a 14C-ring-labelled synthetic lignin (14C-DHP). The fungi mineralised around 25% of the lignin to 14CO2 within 12 weeks of incubation in a straw environment; about 20% of the lignin was converted to water-soluble fragments. Mn-peroxidase was found to be the predominant ligninolytic enzyme of all three fungi in liquid culture and its production was strongly enhanced in the presence of Mn2+ ions. The results of this study demonstrate that certain ubiquitous litter-decomposing basidiomycetes possess ligninolytic activities similar to the wood-decaying white-rot fungi, the most efficient lignin degraders in nature.

Basidiomycota↗
PubMed2004

Accumulation of genes for susceptibility to rust fungi for which barley is nearly a nonhost results in two barley lines with extreme multiple susceptibility.

Nonhost resistance is the most common type of resistance in plants. Understanding the factors that make plants susceptible or resistant may help to achieve durably effective resistance in crop plants. Screening of 109 barley (Hordeum vulgare L.) accessions in the seedling stage indicated that barley is a complete nonhost to most of the heterologous rust fungi studied, while it showed an intermediate status with respect to Puccinia triticina, P. hordei-murini, P. hordei-secalini, P. graminis f. sp. lolii and P. coronata ff. spp. avenae and holci. Accessions that were susceptible to a heterologous rust in the seedling stage were much more or completely resistant at adult plant stage. Differential interaction between barley accessions and heterologous rust fungi was found, suggesting the existence of rust-species-specific resistance. In particular, many landrace accessions from Ethiopia and Asia, and naked-seeded accessions, tended to be susceptible to several heterologous rusts, suggesting that some resistance genes in barley are effective against more than one heterologous rust fungal species. Some barley accessions had race-specific resistance against P. hordei-murini. We accumulated genes for susceptibility to P. triticina and P. hordei-murini in two genotypes called SusPtrit and SusPmur, respectively. In the seedling stage, these accessions were as susceptible as the host species to the target rusts. They also showed unusual susceptibility to other heterologous rusts. These two lines are a valuable asset to further experimental work on the genetics of resistance to heterologous rust fungi.

Basidiomycota↗
PubMed1997

Differences in DNA methylation patterns are detectable during the dimorphic transition of fungi by amplification of restriction polymorphisms.

A modification of the amplified fragment length polymorphism technique was developed for the determination of DNA methylation in dimorphic fungi representative of three of the major fungal taxa: Mucor rouxii, a zygomycete; Yarrowia lipolytica, an ascomycete; and Ustilago maydis, a basidiomycete. DNA obtained from the yeast or mycelial stages of the fungi was digested with a mixture of EcoRI, and one of the isoschizomers MspI and HpaII, whose ability to cleave at the sequence CpCpGpG is affected by the methylation state. The resulting fragments were ligated to primers and subjected to a double round of amplification by the polymerase chain reaction, radiolabeled in the second round, and separated by polyacrylamide gel electrophoresis. Comparison of patterns revealed differences indicative of fragments whose methylation state did or did not change during the dimorphic transition. These results indicate the usefulness of the method for the study of DNA methylation, demonstrate the universality of DNA methylation in fungi, and confirm that differential DNA methylation occurs during fungal morphogenesis.

DNA Methylation↗
PubMed2003

Growth and survival of seedlings of native plants in an impoverished and highly disturbed soil following inoculation with arbuscular mycorrhizal fungi.

We investigated whether arbuscular mycorrhizas influenced growth and survival of seedlings in an extremely impoverished and highly disturbed soil. Seedlings of four plants species native to the site were either inoculated with native sporocarpic arbuscular mycorrhizal (AM) fungi or fertilised prior to transplanting, and followed over 86 weeks at the site. One treatment was also irrigated with N-rich leachate from the site. In a laboratory experiment, seedlings were fertilised with excess P for 6 weeks, and location of the P store determined. Growth and survival of AM and fertilised seedlings were similar at the site. Inoculated mycorrhizal fungi and roots appeared to extend into the surrounding soil together. P concentration in leaves of all plants was extremely low. Irrigation with leachate increased growth of seedlings. In the laboratory experiment, significantly more P was stored in roots than shoots. We suggest that successful revegetation of extremely disturbed and impoverished sites requires selection of mycorrhizal fungi and plants to suit the edaphic conditions and methods of out-planting.

Cupressaceae↗