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At least 109 records · Page 6Linked to original sources
PubMed2000

Yeti--a degenerate gypsy-like LTR retrotransposon in the filamentous ascomycete Podospora anserina.

In the filamentous ascomycete Podospora anserina a 6,935-bp retrotransposon, Yeti, has been identified and characterized. It is flanked by a 5-bp target site duplication and contains long terminal repeats (LTRs) 354 bp in length. The LTRs show a high degree of identity to the previously reported repetitive element repa, a sequence suggested to represent a solo-LTR element of an unknown transposon. In the investigated Podospora strains, the number of complete Yeti copies is significantly lower than the number of repa elements, with up to 25 copies. Yeti appears to be inactive: it is highly degenerate and no transcripts of the element have been detected even in Podospora cultures grown under elevated stress conditions. The amino acid sequences deduced from Yeti display significant homology, particularly in the reverse transcriptase region, to those of other fungal retrotransposons, indicating that it is a member of the gypsy family. As suggested by the unusual dinucleotide content, degeneration of Yeti appears to be the result of a molecular mechanism resembling repeat-induced point mutation in Neurospora crassa.

Amino Acid Sequence↗
PubMed1998

Small insertions at a shared position in the SSU rDNA of lecanorales (lichen-forming ascomycetes).

Small insertions are reported from the SSU rDNA of the genera Cladonia, Cladina, Stereocaulon, Pertusaria and Physcia (lichen-forming Lecanorales, Ascomycetes). The insertions range in length from 56 to 81 nucleotides, and occur at a shared position, 330 (relative to Escherichia coli), in a semi-conserved region of the SSU rDNA. These small insertions have a simple secondary structure with two stem-loops, and may represent degenerate group-I introns. Species of the same genus often have small insertions of similar lengths, secondary structures and sequences. These similarities suggest that the insertions are homologous and can provide phylogenetic information to support current classifications. Variable sequences of rDNA, such as the small insertions and group-I introns, may be powerful tools for resolving evolutionary relationships among genera and species.

Ascomycota↗
PubMed1999

Phylogenetic relationships between mating-type sequences from homothallic and heterothallic ascomycetes.

To gain a deeper insight into the evolution of mating-type genes from filamentous ascomycetes, a comprehensive sequence analysis of PCR-amplified sequences corresponding to A- and a-specific mating-type sequences was undertaken. The study included nine homothallic (compatible) and eight heterothallic (incompatible) members of the genera Neurospora and Sordaria. Distance and parsimony trees based on gene fragments from the mat a-1 and mat A-1 genes were compared with trees derived from partial DNA sequences of the gpd glyceraldehyde-3-phosphate dehydrogenase gene. In contrast to the sequences from the gpd gene, mating-type genes show striking sequence differences, suggesting that these genes evolve very rapidly. Strong inter-relationships were found among homothallic, as well as among heterothallic, members of both genera, indicating that in each genus a change from one reproductive strategy to another might result from one single event.

Fungal Proteins↗
PubMed2006

Molecular and enzymatic characterisation of extra- and intracellular laccases from the acidophilic ascomycete Hortaea acidophila.

The pigmented ascomycete Hortaea acidophila is able to grow at a pH as low as 0.6 and produces laccases that are involved in melanin synthesis. We now present data on an extracellular and an intracellular laccase which exhibit a high stability at low pH. Furthermore, the optimum for enzyme acitivity is extraordinarily low with pH 1.5 for the intracellular laccase with 2,6-dimethoxyphenol (DMOP) as substrate. Two complete laccase gene sequences of H. acidophila were amplified by inverse polymerase chain reaction (PCR). Whereas the deduced protein laccase I contains an predicted N-terminal signal sequence for protein export, laccase II does not and thus may represent the intracellular laccase. The acidophilic character of both laccases seems to be reflected in their primary structure.

Amino Acid Sequence↗
PubMed2004

Lipids stimulate spore germination in the entomopathogenic ascomycete Ascosphaera aggregata.

The alfalfa leafcutting bee (Megachile rotundata) is solitary and managed on a large scale for pollination of alfalfa seed crops. The bees nest in holes drilled in wood or polystyrene blocks, and their larvae are highly prone to a fungal disease called chalkbrood. The most prevalent form of chalkbrood is caused by Ascosphaera aggregata, but this ascomycete is difficult to culture. Hyphae will grow on standard fungal media, but spore germination is difficult to achieve and highly variable. We found that germination can be enhanced with oils. Lipids derived from plants and bee larvae increased germination from 50% (without oil) to 75-85% (with oil). Percent germination was significantly greater in the presence of lipids but germination was not significantly different when different oils, including mineral oil, were used. A. aggregata spores oriented along the oil-aqueous interface in the broth in a polar fashion, with swelling and germ tube formation always occurring into the aqueous portion of the broth. The other half of the spore tended to attach to a lipid droplet, where it remained, without swelling, during germ tube formation. The physical attachment of spores to the oil-aqueous interface is what most probably stimulates spore germination, as opposed to some nutritional stimulation. However, further research is needed to determine if and where the spores encounter such an interface when germinating in the host gut, where germination normally occurs.

Animals↗
PubMed2001

A new trihydroxy fatty acid from the ascomycete, Chinese truffle Tuber indicum.

From the chloroform/methanol extract of the fruiting bodies of the ascomycete Chinese truffle Tuber indicum Cooke et Massee, a new trihydroxylated monounsaturated fatty acid (1) has been isolated. The structure of this new linoleic acid-derived metabolite was established as 9,10,11-trihydroxy-(12Z)-12-octadecenoic acid by means of spectroscopic and chemical methods. The fatty acid composition of the chloroform-soluble fraction of this fungus was analyzed by gas chromatography-mass spectrometry. The content of the predominant unsaturated fatty acids (oleic and linoleic acids) is as high as 68%. The use of dimethyl disulfide adduct was effective in the determination of the position of the double bond, and the glycol oxidation fission reaction with sodium metaperiodate supported on silica gel was helpful in establishing the location of the trihydroxylic groups in the new fatty acid.

Ascomycota↗
PubMed1975

The phenoloxidases of the ascomycete Podospora anserina. XI. The state of copper of laccases I, II and III.

1. Laccases I, II and III were (EC 1.14.18.1) prepared from the mycelium of the ascomycete Podospora anserina. The tetrameric laccase I(mol. wt 340 000, 16 copper atoms) and the monomeric laccases II and II (mol. wt 80 000, 4 copper atoms) have been studied by optical absorption-, circular dichroism-(CD)and electron paramagnetic resonance spectroscopy (EPR). 2. The visible and near ultraviolet difference absorption spectrum, which is apparently identical for all three laccases, shows two maxima at 330 and 610 nm and a shoulder at about 725 nm. The molar extinction coefficients of these bands are 4 times larger for the tetrameric laccase I compared to the monomeric laccases II and III which show values similar to other blue copper-containing oxidases. 3. CD spectra between 300 and 730 nm of the tree laccases are similar and contain at least 5-bands in the oxidized enzyme. If the enzyme is reduced, only a band at 307 nm remains. The molar ellipticity values of these bands are 4 times larger for laccase I than the corresponding bands of laccases II and III. It is inferred that the reducible bands are associated with the Type 1 Cu-2+. 4. In all three laccases the EPR-detectable copper accounts for only about 50% of the total copper content. The 9-GHz and 35-GHz spectra, which are identical for all three laccases, consist of two components of equal intensity. One component shows a rather small copper hyperfine coupling and a small deviation from axial symmetry. It is suggested that this copper is associated with the blue chromophore in analogy to Type 1 Cu-2+ in other blue copper proteins. The other component has a broader hyperfine coupling similar to Type 2 Cu-2+ as found in other copper proteins. The assumption that the experimental spectra result from a superposition of the spectra of equal amounts of Type 1 and Type 2 Cu-2+ has been verified by computer simulation. 5. It is suggested that the copper ions which are not detected by EPR are connected to the absorption band at 330 nm and that these ions are also essential for the function of these laccases.

Ascomycota↗
PubMed1981

"Mycococcus" of the ascomycete mold and carcinogenesis.

There is a time in history when it becomes necessary to coin a term to describe a newly discovered identity. According to our research findings there is now the need to add a new term to medical microbiology. Our studies indicate that there is consistently present, determined though revised culturing procedures of aseptic freshly collected cancerous tissue, a micro-organism which resembles and/or is identified as staphylococci, micrococci, enterococci, etc. Our work indicates that these microbes are the absent outside cell wall, enzyme and hormone-deficient aberrant form of the ascomycete mold. They could be listed as the asexual conidial bodies. However, because they multiply in cancerous tissue, as a separate entity, with absolutely no evidences of phialedes or hyphal elements being present, and because they are predominantly cocci in appearance, I wish to suggest that we use the term "mycococcus". On occasions some cultures will reveal microbes which give an alternating rod to oval-like movement and appearance. Sometimes the rods may be small and chain-like. These ultimately turn out to be the altered microbes such as aspergillus of the branching type fungus. The term in this instance may be considered as "mycomicrobe" or "mycobacillus".

Ascomycota↗
PubMed1989

The ura5 gene of the ascomycete Sordaria macrospora: molecular cloning, characterization and expression in Escherichia coli.

We cloned the ura5 gene coding for the orotate phosphoribosyl transferase from the ascomycete Sordaria macrospora by heterologous probing of a Sordaria genomic DNA library with the corresponding Podospora anserina sequence. The Sordaria gene was expressed in an Escherichia coli pyrE mutant strain defective for the same enzyme, and expression was shown to be promoted by plasmid sequences. The nucleotide sequence of the 1246-bp DNA fragment encompassing the region of homology with the Podospora gene has been determined. This sequence contains an open reading frame of 699 nucleotides. The deduced amino acid sequence shows 72% similarity with the corresponding Podospora protein.

Amino Acid Sequence↗
PubMed2005

Evidence for functional laccases in the acidophilic ascomycete Hortaea acidophila and isolation of laccase-specific gene fragments.

Hortaea acidophila is a pigmented, yeast-like ascomycete that is able to grow at a pH as low as 0.6. This study presents evidence that H. acidophila possesses at least two functional laccases that seem to be involved in melanin synthesis. This evidence is supported by PCR amplification of laccase-specific gene fragments by using primers derived from conserved copper-binding-regions and by Southern Blot analysis. Due to their low pH optimum the laccases may be of special interest for biotechnological use.

Amino Acid Sequence↗
PubMed2006

Gene expression profiling of the nitrogen starvation stress response in the mycorrhizal ascomycete Tuber borchii.

The focus of this work is on the nitrogen starvation stress responses operating in a plant symbiotic fungus. A cDNA array profiling analysis was conducted on N-limited mycelia of the mycorrhizal ascomycete Tuber borchii. Fifty-one unique transcripts, out of 2062 redundant arrayed cDNAs, were differentially expressed by at least 1.5-fold in response to N deprivation. Only two N assimilation components-a nitrate transporter and a high-affinity ammonium transporter-were found among differentially expressed genes. All the other N status responsive genes code for as yet unidentified hypothetical proteins or components not directly involved in N assimilation or metabolism, especially carbohydrate binding proteins and oligosaccharide as well as lipid modifying enzymes. A subset of cDNA array data were confirmed and extended by Northern blot analysis, which showed that most of the latter components respond not only to nitrogen, but also to carbon source depletion.

Amino Acid Sequence↗
PubMed2006

Hexose uptake in the plant symbiotic ascomycete Tuber borchii Vittadini: biochemical features and expression pattern of the transporter TBHXT1.

Here, we report the first evidence of a hexose transporter gene, Tbhxt1, in the ectomycorrhizal ascomycete Tuber borchii Vittadini. The protein encoded by Tbhxt1 functionally complements the hxt-null mutant Saccharomyces cerevisiae EBYVW.4000. TBHXT1 has a strong preference for d-glucose (K(m)=38+/-10 microM) over d-fructose (K(m)=16+/-5mM) and uncoupling experiments indicate that TBHXT1 catalyzes the transport via a proton-symport mechanism. The investigations on the substrate specificity reveal that TBHXT1 also imports d-mannose, and the use of deoxyglucose analogues shows that the hydroxyl groups at C1, C3 and C4 are important for substrate recognition. Tbhxt1 is not regulated by fructose, but it reaches its highest level of expression at 3mM glucose and is repressed by very high glucose concentration. Prolonged carbon starvation condition upregulates Tbhxt1, while its expression remains at basal level in the ectomycorrhizal tissue. The mode of regulation of Tbhxt1 is consistent with its role as a high-affinity d-glucose transporter.

Amino Acid Sequence↗
PubMed2006

Occurrence of laccases in lichenized ascomycetes of the Peltigerineae.

Following our previous findings of high extracellular redox activity in lichens, the results of the work presented here identify the enzymes involved as laccases. Despite numerous data on laccases in fungi and flowering plants, this is the first report of the occurrence of laccases in lichenized ascomycetes. Extracellular laccase activity was measured in 40 species of lichens from different taxonomic groupings and contrasting habitats. Out of 20 species tested from suborder Peltigerineae, 18 displayed laccase activity, while activity was absent in species tested from other lichen groups. Identification of the enzymes as laccases was confirmed by the ability of lichen leachates to readily metabolize substrates such as 2,2'-azino(bis-3-ethylbenzthiazoline-6-sulfonate) (ABTS), syringaldazine and o-tolidine in the absence of hydrogen peroxide, sensitivity of the enzymes to cyanide and azide, the enzymes having typical laccase pH and temperature optima, and an absorption spectrum with a peak at 614nm. Desiccation and wounding stimulated laccase activity. Laccase activity was not increased after treatment with normal inducers of laccase synthesis, suggesting that they are constitutively expressed. Electrophoresis showed that the active form of laccase from Peltigera malacea was a tetramer with an unusually high molecular mass of 340kDa and an isoelectric point (pI) of 4.7. The finding of abundant extracellular redox enzymes known to actively produce reactive oxygen species suggest that their roles may include increasing nutrient supply to lichens by delignification, and deterring pathogens by contributing to the oxidative burst. Furthermore, once released into the environment, they may participate in the carbon cycle by facilitating the breakdown or formation of humic substances.

Ascomycota↗
PubMed2006

Molecular phylogeny of the genus Stereocaulon (Stereocaulaceae, lichenized ascomycetes).

In the present study phylogenetic relationships of the genus Stereocaulon (lichenized ascomycetes) were examined using DNA sequences from the ITS1-5.8 S-ITS2 rDNA gene cluster and from the protein-coding beta-tubulin gene. In addition to the fruticose species traditionally classified in Stereocaulon, representatives of the crustose species that have recently been transferred to the genus were included. Muhria, a monotypic genus that is morphologically similar to Stereocaulon, differing only in apothecia ontogeny, was also incorporated. The analyses included 101 specimens from the ingroup representing 49 taxa. Sequences from both DNA regions were analysed simultaneously using direct optimization under the parsimony optimality criterion. The results support the inclusion of the crustose species and Muhria in Stereocaulon, while the current infrageneric classification is not supported. As Muhria is securely nested within Stereocaulon the new combination Stereocaulon urceolatum comb. nov. (syn. Muhria urceolata) is made. Further, species concepts need to be re-examined, as some species do not appear as monophyletic entities in the phylogeny.

Ascomycota↗
PubMed2004

Cyclic azaphilones daldinins E and F from the ascomycete fungus Hypoxylon fuscum (Xylariaceae).

Phytochemical examination of the methanolic extract of fruit bodies of the Xylariaceous ascomycete fungus Hypoxylon fuscum led to the isolation of two azaphilone derivatives named daldinins E and F together with two known compounds daldinin C and 4,5,4',5'-tetrahydroxy-1:1'-binaphthyl using a combination of reversed phase HPLC and high performance gel permeation chromatography. Their structures were determined by 2D NMR, MS, IR, UV, and CD spectroscopy. Their antioxidative activities were also estimated by an indication of a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging effect. The chemosystematics of Hypoxylon is discussed.

Ascomycota↗
PubMed1977

High-pressure liquid-chromatographic assay of nucleotide-pool concentrations during polysaccharide biosynthesis in four ascomycetes.

High-resolution liquid-chromatographic methods developed for analyzing nucleotide pools at the nanogram level in four representative species of ascomycetes (Penicillium citrinum, Aspergillus niger, Fusarium moniliforme, and Cladosporium herbarum) were used to study polysaccharide biosynthesis. Nucleotides extracted from the mycelial mat were preseparated from interfering polysaccharides, glycoproteins, and nucleic acids on a column of Biogel P-2. Resolution of 18 nucleotides from each fungal species was accomplished on AS-Pellionex-SAX, pellicular anion-exchanger by using a high-pressure liquid chromatograph. Nucleotides were identified by comparing peak retention-times, by differential u.v. absorption with two detectors in series at selected wavelengths, and by acid or enzymic hydrolysis with product identification by liquid chromatography. Pyrimidine bases exceeded purines by at least three fold, and uridine nucleotides often constituted 60-80 mole percent of the total nucleotides; extractable cytidine nucleotides were negligible. Uridine 5'-(2-acetamido-2-deoxy-alpha-D-glucopyranosyl disphosphate) is the preponderant nucleotide throughout the growth cycles of all four species, amounting to 30-60% of all nucleotides present. For all four fungal species, a burst of nucleotide formation was observed after the first 48h (15-30 mumol/g tissue), with fluctuations that eventually fell to 0.1 mumol/g on the tenth day.

Ascomycota↗
PubMed2003

Structural characterization of Botryosphaeran: a (1-->3;1-->6)-beta-D-glucan produced by the ascomyceteous fungus, Botryosphaeria sp.

The exopolysaccharide, Botryosphaeran, produced by the ligninolytic, ascomyceteous fungus Botryosphaeria sp., was isolated from the extracellular fluid by precipitation with ethanol, and purified by gel permeation chromatography to yield a carbohydrate-rich fraction (96%) composed mainly of glucose (98%). Infra-red and 13C NMR spectroscopy showed that all the glucosidic linkages were in the beta-configuration. Data from methylation analysis and Smith degradation indicated that Botryosphaeran was a (1-->3)-beta-D-glucan with approx 22% side branching at C-6. The products obtained from partial acid hydrolysis demonstrated that the side branches consisted of single (1-->6)-beta-linked glucosyl, and (1-->6)-beta-linked gentiobiosyl residues.

Acetylation↗