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At least 253 records · Page 14Linked to original sources
PubMed2002

Measuring diversity of endophytic fungi in leaf fragments: does size matter?

Endophytic fungi inhabit living plant tissues without causing disease symptoms. Although abundant, the extent of their contribution to fungal biodiversity remains unclear. Since endophytic fungi are poorly known, especially in the tropics, current estimates of fungal species are probably conservative. Here we tested strategies for sampling endophytic fungi in tropical plants. We compared the number of fungi isolated from 400 mm2 leaf pieces that were divided into increasingly small fragments. Leaf pieces were surface-sterilized, cut into fragments and plated on culture media. For a given area, cutting leaf pieces into smaller fragments significantly increased the number of fungal morphospecies recovered. There was a strong linear relationship between size of fragments and number of fungi isolated. By extrapolation, an estimated 16 +/- 3 fungi could be recovered from a 2 x 2 cm leaf piece, using infinitely small fragments. This represents a large part of the fungal diversity estimated to exist in leaf endophytes in a population. We conclude that reducing the size and increasing the number of leaf fragments will increase the number of fungal species isolated. This strategy will help to estimate real values of endophytic fungal diversity.

Ascomycota↗
PubMedDate not supplied

Dendritic cells and fungi.

Fungi comprise a group of microorganisms that in the past 20 years has become increasingly important as a cause of human disease. Few fungi are professional but instead opportunistic pathogens, and some fungi can even act as allergens. Dendritic antigen-presenting cells function as a link between innate and adaptive immunity and are therefore important in recognition of pathogens. Effective defense requires the host to discriminate between different pathogens to induce an appropriate response. Signaling from different groups of microbes can be mediated via the Toll-like receptors (TLRs), leading to activation of conserved host defense signaling pathways that control the expression of a variety of immune response genes. Different dendritic cells (DCs) express different patterns of recognition molecules, which indicate that they are more or less efficient when responding to certain pathogens. DCs have an important role in the induction of cell-mediated immune responses to fungi, and the studies reviewed here show that fungi, or possibly fungi-derived factors, provide a powerful activation stimulus to DCs, resulting in DC maturation with upregulation of co-stimulatory molecules and production of cytokine patterns leading to different T cell responses. The possibility of using ex vivo-generated DCs as therapeutic tools for restoring anti-fungal immunity is a challenge for the future.

Antigen Presentation↗
PubMed1975

Species richness of the parasitic fungi of british trees.

The species richness of fungi associated with British trees is described by a significant species/area curve (r = 0.53, 0.01 > P > 0.001). Introduced tree species cannot be shown to have fewer fungal species than natives, per unit distributional range about Britain. Also, among natives and among introductions, older host taxa do not have more fungal species than do younger ones. This indicates the species richness of fungi to rapidly reach the limit set by host range, within ecological time. The slope of the species/area relationship for fungi is one-fourth that for insects; we propose that this is due to the inherently greater dispersability of fungi. Finally, the species/area regression residuals for fungi are correlated with those for insects (r = 0.65, 0.001 > P), suggesting plant defense mechanisms may be generally effective to plant parasites, be they insects or fungi.

Journal Article↗
PubMed1987

Extensive genetic divergence associated with speciation in filamentous fungi.

Little is known about genetic differentiation during speciation in fungi. The Collybia dryophila complex (Basidiomycetes: Tricholomataceae) contains several closely related groups of fungi at various levels of evolutionary divergence. Mating compatibility studies show there are several intersterile groups within the complex, three of which are distributed over two or more continents. Genetic relationships among five intersterility groups were compared by the method of DNA.DNA hybridization. Clustering techniques were used to reconstruct phylogenetic relationships of these fungi. Genic identity based on DNA.DNA hybridization corresponds well with mating compatibility. Reduced genic identity was observed between geographically isolated populations of a single mating group. This evidence suggests an allopatric mode of evolution for the C. dryophila group. These results indicate extensive genic divergence is associated with the appearance of intersterility barriers in basidiomycetous fungi. The levels of divergence observed in these and in other fungi are significantly higher than that observed in many other eukaryotes, and this suggests that the rate of molecular or morphological evolution in fungi may differ from that found in other organisms.

Journal Article↗
PubMed1991

Fungi in megakaryocytes. An unusual manifestation of fungal infection of the bone marrow.

When fungi infect the bone marrow, typically they are associated with granuloma formation and/or necrosis, and the fungi are found within histiocytes or admixed with necrotic debris. Recently two bone marrow biopsy specimens were encountered in which fungi were confined to the cytoplasm of megakaryocytes, a finding not previously reported in the literature. The first case was that of a 46-year-old man with pulmonary histoplasmosis and no known immunodeficiency. The second was that of a 38-year-old man with the acquired immune deficiency syndrome and cryptococcal meningitis. In the first case, many megakaryocytes contained fungal forms consistent with Histoplasma. In the second, one small cluster of megakaryocytes contained several budding yeast consistent with Cryptococcus. Neither marrow biopsy specimen had necrosis, granulomas, or histiocytic infiltration. In both cases, because of the unusual localization of the fungi, they were initially overlooked. The bone marrow may contain fungi even in the absence of abnormalities suggesting fungal infection on routinely stained sections. A silver stain or a periodic acid--Schiff stain should be performed on all marrow biopsy specimens in cases of known or suspected fungal infection outside the marrow. The phenomenon of megakaryocyte emperipolesis is well known, and this process may be responsible for the apparent ability of megakaryocytes to internalize fungi.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

The a and b loci of Ustilago maydis hybridize with DNA sequences from other smut fungi.

The smut fungi are obligately parasitic during the sexual phase of their life cycle, and the mating-type genes of these fungi play key roles in both sexual development and pathogenicity. Among species of smut fungi it is common to find a bipolar mating system in which one locus with two alternate alleles is believed to control cell fusion and establishment of the infectious cell type. Alternatively, several species have a tetrapolar mating system in which two different genetic loci, one of which has multiple alleles, control fusion and subsequent development of the infection hyphae. Cloned sequences from the a and b mating-type loci of the tetrapolar smut fungus Ustilago maydis were used as hybridization probes to DNAs from 23 different fungal strains, including smut fungi with both tetrapolar and bipolar mating systems. In general, all of the smut fungi hybridized with the mating-type genes from U. maydis, suggesting conservation of the sequences involved in mating interactions. A selection of DNAs from other ascomycete and basidiomycete fungi failed to hybridize with the U. maydis mating-type sequences. Exceptions to this finding include hybridization of DNA from the a1 idiomorph of U. maydis to DNA from one strain of U. violacea and hybridization of both a idiomorphs to DNA from Saccharomyces cerevisiae.

Genes, Fungal↗
PubMed2004

Prevalence of fungi in the vagina, rectum and oral cavity in pregnant diabetic women: relation to gestational age and symptoms.

OBJECTIVES: To estimate the prevalence of fungi in the vagina, rectum and oral cavity in pregnant women with diabetes mellitus (DM) type I or gestational diabetes mellitus (GDM) and in healthy controls; to assess the influence of gestational age on the prevalence of fungi; to compare the vaginal symptoms within the groups; and to analyze the multifocality of fungal invasions. METHODS: A total of 251 women were examined: 47 with DM, 72 with GDM and 132 controls. Samples were collected from the vagina, rectum and oral cavity of all women and cultured on Sabouraud media. RESULTS: Fungi were found in 59.8% in at least one of the three locations in all women. Vaginal mycosis was diagnosed more often (p < 0.001) in pregnancies with DM [40.4%, odds ratio (OR) 4.3, confidence interval (CI) 2.41-4.85] than with GDM (22.2%, OR 1.84, CI 0.99-2.12) and nondiabetics (13.6%, OR 1.0). The risk of trifocal mycosis was higher in DM women (OR 2.7, CI 1.72-4.45), than in the controls. Only in 27.6% of symptomatic women were fungi detected in vagina. However, 60.4% of women with vaginal mycosis had symptoms. Among women without mycosis, 42.4% were symptomatic, and discharge was more common in the DM group (50%) than in the GDM group (21.4%) and the controls (28.1%; p < 0.002). The prevalence of fungi in the groups was not influenced by gestational age. CONCLUSIONS: The risk of vaginal mycoses in DM women is more that four times higher and in pregnancies with GDM nearly two times higher than in controls. The risk of trifocal mycosis in DM women is nearly three times higher than in nondiabetics. There is a poor correlation between symptoms of vaginitis and fungal infection. We did not confirm the influence of the gestational age on the prevalence of fungi.

Adult↗
PubMed2006

Transport of radiocaesium by arbuscular mycorrhizal fungi to Medicago truncatula under in vitro conditions.

The capacity of arbuscular mycorrhizal (AM) fungi to take up and translocate radiocaesium (Cs) to their host has been shown using the root-organ culture (ROC) system. However, the absence of photosynthetic tissues, lack of a normal root hormonal balance and incomplete source-sink relationships may bias the bidirectional transfer of elements at the symbiotic interface and complicate transport studies. Accordingly, we developed a novel culture system [i.e. the Arbuscular Mycorrhizal-Plant (AM-P) in vitro culture system], where AM fungi and an autotrophic host plant develop under strict in vitro conditions. With this system, we unambiguously demonstrated the capacity of AM fungi to transport Cs. The extraradical fungal hyphae took up 21.0% of the initial supply of 134Cs. Translocation to the plant represented 83.6% of the 134Cs taken up. Distribution of 134Cs in the host plant was 89.8% in the mycorrhizal roots and 10.2% in the shoot. These results confirm that AM fungi can take up, translocate and accumulate Cs. They further demonstrate unambiguously and for the first time that Cs can be transferred from AM fungi to host tissues. These results suggest a potential involvement of AM fungi in Cs biogeochemical cycle and in plant Cs accumulation.

Biological Transport↗
PubMed2006

[Isolation rate and antifungal drug susceptibility of yeast like fungi isolated from blood or vascular catheter].

Increased resistance of strains to antifungal drugs has gained increasing attention. We studied the status of fungal isolation from blood and vascular catheters at Juntendo University Hospital from 1994 to 2002. The major fungi isolated were Candida albicans, Candida parapsilosis, Candida glabrata and Candida trophicalis, or 86% yeast-like fungi. Isolation of these fungi from vascular catheters is increasing. The effectiveness of 6 anti-fungal agents against 116 yeast-like fungi was measured by microdilution. In antifungal activity of micafungin (MCFG), MIC90, was < or = 0.03 g/mL for C. albicans, C. glabrata and C. tropicalis. MCFG showed the strongest antifungal activity among the drugs tested for above Candida spp.. Five of 37 strains of C. albicans were resistant to fluconazole (FLCZ) showing MIC > or =64 g/mL. These strains were also resistant to itraconazole (ITCZ) but MICs of MGFG, flurocytosine (5-FC) and amphotericin B (AMPH-B). Two of 38 strains of C. parapsilosis are resistant to flurocytosine (5-FC) showing MIC > or =64 g/mL. There is no resistant strain of fungi (yeast-like organisms) tested against AMPH-B. Six patients from whom resistant fungi were isolated from blood and vascular catheters have severe diseases and/or are have just undergone a major surgical operation. These results indicate that it is vital for deep mycosis to start early treatment with appropriate drugs selected based on rapid detection and identification of organisms and the drug susceptibility of organisms.

Antifungal Agents↗
PubMed1982

Actinomycetes and fungi in surface waters and in potable water.

In Finnish lakes and rivers used as water supplies, mesophilic fungi and actinomycetes were common, whereas thermophilic fungi and actinomycetes were present only in low concentrations. Fungi and actinomycetes were more abundant in eutrophic and mesotrophic lakes than in oligotrophic lakes. River water contained more thermophilic actinomycetes and fungi and mesophilic actinomycetes than did lake water. Runoff from soil seemed to be an important factor contributing to the incidence of these microbes in water. Chemical coagulation removed actinomycetes and fungi efficiently, but sand filtration allowed their passage. Disinfection could not prevent actinomycetes and fungi from reaching the distribution system. During infiltration in the production of recharged groundwater, mesophilic actinomycetes could even multiply appreciably.

Journal Article↗
PubMed1982

Degradation of Coal by the Fungi Polyporus versicolor and Poria monticola.

We report that two species of basidiomycete fungi (Polyporus versicolor and Poria monticola) grow in minimal liquid or solid medium when supplemented with crushed lignite coal. The fungi also grow directly on crushed lignite coal. The growth of both fungi was observed qualitatively as the production and extension of hyphae. No fungal growth occurred in minimal agar medium without coal. The fungi degraded solid lignite coal to a black liquid product which never appeared in cultures unless fungi and coal were present together. Apparently, lignite coal can serve as the principal substrate for the growth of the fungi. Infrared analyses of the liquid products of lignite degradation showed both similarities to and differences from the original lignite.

Journal Article↗
PubMed2000

Detection and identification of decay fungi in spruce wood by restriction fragment length polymorphism analysis of amplified genes encoding rRNA.

We have developed a DNA-based assay to reliably detect brown rot and white rot fungi in wood at different stages of decay. DNA, isolated by a series of CTAB (cetyltrimethylammonium bromide) and organic extractions, was amplified by the PCR using published universal primers and basidiomycete-specific primers derived from ribosomal DNA sequences. We surveyed 14 species of wood-decaying basidiomycetes (brown-rot and white-rot fungi), as well as 25 species of wood-inhabiting ascomycetes (pathogens, endophytes, and saprophytes). DNA was isolated from pure cultures of these fungi and also from spruce wood blocks colonized by individual isolates of wood decay basidiomycetes or wood-inhabiting ascomycetes. The primer pair ITS1-F (specific for higher fungi) and ITS4 (universal primer) amplified the internal transcribed spacer region from both ascomycetes and basidiomycetes from both pure culture and wood, as expected. The primer pair ITS1-F (specific for higher fungi) and ITS4-B (specific for basidiomycetes) was shown to reliably detect the presence of wood decay basidiomycetes in both pure culture and wood; ascomycetes were not detected by this primer pair. We detected the presence of decay fungi in wood by PCR before measurable weight loss had occurred to the wood. Basidiomycetes were identified to the species level by restriction fragment length polymorphisms of the internal transcribed spacer region.

Ascomycota↗
PubMed2004

Nonvalue of culturing cerebrospinal fluid for fungi.

No studies have evaluated the efficacy of culturing cerebrospinal fluid (CSF) for fungi. Because of the facts that the most common fungi responsible for meningitis grow well in media utilized for routine bacterial cultures and that cryptococcal antigen tests are commonly ordered, the efficacy of routinely performing fungal cultures specifically to recover fungi has been questioned. We examined data from 1225 samples of CSF which were cultured for both bacteria and fungi. Twelve specimens yielded fungi, 10 from fungal cultures and 8 from bacterial cultures. Cryptococcus neoformans was found in 10 specimens, Candida albicans was found in 1, and a Cladosporium sp. was found in 1. Eight of 12 positive specimens had concordant culture results. The discordant cases were one specimen that was bacterial culture positive but fungal culture negative and three specimens that were fungal culture positive but bacterial culture negative. Of the latter discrepant cultures, one had fungal contamination only and the other two were positive for cryptococcal antigen. Therefore, omitting the fungal cultures on these specimens would not adversely impact patients. When both cryptococcal antigen tests and bacterial cultures are ordered routinely, eliminating fungal cultures on CSF would have had no impact on the patients in this study. All the clinically significant fungi were detected by the cryptococcal antigen test and/or bacterial culture. With a few exceptions, the combined use of cryptococcal antigen test and bacterial cultures of CSF could replace routine fungal cultures of CSF. Exceptions include settings where fungal pathogens other than Cryptococcus and Candida remain important causes of meningitis.

Antigens, Fungal↗
PubMed2006

Filamentous Fungi (Magnaporthe grisea and Fusarium oxysporum).

A better understanding of fungal biology will facilitate judicious use of beneficial fungi and will also advance our efforts to control pathogenic fungi. Molecular studies of fungal biology have been greatly aided by transformation-mediated mutagenesis techniques. Transformation via nonhomologous integration of plasmid DNA bearing a selectable marker (e.g., antibiotic resistance gene) has been widely used for the random insertional mutagenesis of fungi - as an alternative to chemical and radiation mutagens - mainly because the integration of plasmid into the genome provides a convenient tag for subsequent identification and isolation of the mutated gene. Homologous recombination between a target gene on the chromosome and the introduced DNA carrying its mutant allele results in targeted gene knock-out. An important advance in fungal transformation methodology is the development of Agrobacterium tumefaciens-mediated transformation (ATMT) protocols for fungi. ATMT has been successfully applied to a phylogenetically diverse group of fungi and offers a number of advantages over conventional transformation techniques in both the random insertional mutagenesis and targeted gene knock-out. In this chapter, we describe ATMT protocols and vectors for fungal gene manipulation using two plant pathogenic fungi, Magnaporthe grisea and Fusarium oxysporum, as target organisms.

Agrobacterium tumefaciens↗
PubMed2003

[Effect of inoculation with AM fungi on DBP-pollution of plant].

In greenhouse, taking DBP as the object and taking Pigna sinensis inoculated respectively with AM fungi Aculospora lavis and Glomus caledonium as the host plants, a pot experiment was carried out to study the effect of inoculated AM fungi on the dynamics of plant DBP-pollution. The experiment lasted 60d. The results indicated that inoculation with AM fungi could restrain plant from absorbing DBP. Although AM fungi were affected by DBP, they played important roles in decreasing the DBP uptake by plant and the translocation of DBP from roots to aboveground part of plant. After inoculation with AM fungi, the final concentrations of DBP in plants inoculated respectively with Aculospora lavis and Glomus caledonium were decreased, to significant level (P < 0.01) with maximum decrease ratios reaching up to 32.7% and 21.7%, respectively when soil-applied DBP concentration was 4 mg.kg-1, and to significant level (P < 0.05) with maximum decrease ratios reaching up to 30.5% and 30.0%, respectively when soil-applied DBP concentration was 100 mg.kg-1. The translocation of DBP from roots to aboveground part of plant was also inhibited by inoculated AM fungi. Therefore, AM was helpful to decrease plant DBP-pollution.

Dibutyl Phthalate↗
PubMed2004

[Ecological function of wood-inhabiting fungi in forest ecosystem].

Wood-inhabiting fungi are one of the most important parts of forest ecosystem, and play an important role in degrading the wood in forest ecosystem. The major species of these fungi include the groups of Aphyllophorales (Basidiomycota), Discomycetes (Ascomycota) and some imperfect fungi. They have the ability to degrade cellulose, hemicelluloses and lignin of wood. Three type of wood decaying have been found, i.e., white rot, brown rot and soft rot. Many other organisms of forest ecosystem have symbiosis relationship with wood-decaying fungi. Wood-inhabiting fungi could offer the nutrition for many insects and birds, and spores of many wood-rotting species are spread by some insects. The high biodiversity of wood-decaying fungi is one of the important factors for the health of forest ecosystem.

Ascomycota↗
PubMed2004

[Effects of arbuscular mycorrhizal fungi on plant growth and osmotic adjustment matter content of trifoliate orange seedling under water stress].

The effects of arbuscular mycorrhizal fungi Glomus mosseae on plant growth and osmotic adjustment matter content of trifoliate orange [Poncirus trifoliata (L.) Raf.] seedlings under water stress were studied in potted culture. The results showed that arbuscular mycorrhizal fungi inoculation could increase plant growth, such as plant height, stem diameter, leaf area, shoot dry weight, root dry weight and plant dry weight, when the water content of soil was 20%, 16% and 12%. Arbuscular mycorrhizal fungi inoculation also promoted active absorbing areas of plant root and absorption of P from plant rhizosphere, enhanced the accumulated quantities of soluble sugar content in leaves and roots, and reduced proline content of leaf. Plant inoculated with arbuscular mycorrhiza had higher plant water use efficiency than non-mycorrhizal plants. Drought tolerance of trifoliate orange seedling inoculated with arbuscular mycorrhiza was enhanced. Effects of arbuscular mycorrhizal fungi inoculation on trifoliate orange seedling under 20% and 16% water content of soil were more significant than under 12% water content of soil. Arbuscular mycorrhizal fungi infection was severely restrained by 12% water content of soil. Thus, effects of arbuscular mycorrhizal fungi on plant probably positively related to the arbuscular mycorrhizal inoculated percentage.

Absorption↗
PubMed2004

[Effect of endophytic fungi on the culture and four enzyme activities of Anoectochillus formosanus].

OBJECTIVE: To study the effect of endophytic fungi. METHOD: A. formosanus, harvested after having been cultured for age, statistics were taken, fresh weight and dry weight were gained, and enzyme activities of chitinase, beta-1,3-glucase, phenylalanine ammonia-lyase and polyphenoloxidase were determined. RESULT: The survial rates of A. formosanus inoculated with endophytic fungi was 100%. The effect of fungi on fresh weight was very significant (P < 0.01). The effect of fungi on dry weight was significant (P > 0.05). The four enzyme activities were enhanced by endophytic fungi, comparision with the controls. CONCLUSION: Survial rates of A. formosanus can be increased by using endophytic fungi in vitro culture.

Catechol Oxidase↗