Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ASCOMYCETES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
PubMed1985

Light-regulated protein and poly(A)+ mRNA synthesis in Neurospora crassa.

We have examined the effect of illumination upon the patterns of protein synthesis in the filamentous ascomycete Neurospora crassa by pulse labelling and two-dimensional gel electrophoresis. Light did not affect overall rates of protein synthesis but did induce the synthesis of six novel polypeptides whose appearance followed a temporally regulated pattern. When translation products of mRNA from illuminated cultures and dark control cultures were compared it was found that the synthesis of five out of six of the polypeptides specific to illuminated cultures could be seen in vitro. We believe that this is consistent with the hypothesis that light regulates the transcription of some genes in N. crassa, although we cannot exclude effects on mRNA stability or the control of precursor splicing.

Electrophoresis, Polyacrylamide Gel↗
PubMed1991

Poisoning by Gyromitra esculenta--a review.

Gyromitra esculenta (Pers.: Fr.) Fr. and a few other mushrooms have caused severe poisonings and even deaths in humans. Clinical data are characterized primarily by vomiting and diarrhoea, followed by jaundice, convulsions and coma. Gastrointestinal disorders distinguish this poisoning. Frequent consumption can cause hepatitis and neurological diseases. The species of concern are mainly G. esculenta and G. gigas (Kromb.) Cooke (non Phill.). Nevertheless, recent advances in chromatography, biochemistry and toxicology have established that other Ascomycetes species also may prove toxic. Gyromitrin (acetaldehyde methylformylhydrazone, G) and its homologues are toxic compounds that convert in vivo into N-methyl-N-formylhydrazine (MFH), and then into N-methylhydrazine (MH). The toxicity of these chemicals, which are chiefly hepatotoxic and even carcinogenic, has been established through in vivo and in vitro experiments using animals, cell cultures and biochemical systems. When we consider the chemical nature and the reactivity of these natural compounds, we suggest that chemical and biochemical mechanisms may explain their intrinsic biological activity.

Animals↗
PubMed2003

The effect of carbohydrate carbon sources on the production of constitutive and inducible laccases by Botryosphaeria sp.

The influence of carbohydrates: glucose, fructose, galactose, galacturonic acid, xylose, lactose, sucrose, pectin and inulin, were evaluated as sole carbon source for the production of laccases by the ascomycete, Botryosphaeria sp. Veratryl alcohol, a laccase inducer, was added to culture media to study inducible laccase production on the same carbon sources. Inulinase and pectinase were also produced when Botryosphaeria sp. was grown on inulin, and galacturonic acid and pectin, respectively, and their levels were less in the presence of veratryl alcohol. Botryosphaeria sp. produced constitutive laccases on all carbon sources examined, and veratryl alcohol increased the laccase production on most of carbon sources studied except for inulin and galacturonic acid. Evidence is presented that Botryosphaeria sp. is also pectinolytic.

Ascomycota↗
PubMed2005

Soilborne filamentous fungi in Brazil.

The Atlantic Rainforest is a Brazilian ecosystem that is being rapidly being destroyed, along with the abiotic and biotic factors present in it. Among the biotic factors, the fungi are found in the soil which, besides being of major importance in terms of ecological niches, also have broad and significant applications in biotechnology. In order to assess the biodiversity of these microorganisms in this type of ecosystem, the Banhado Grande region was chosen at the Jureia-Itatins Ecology Station, in the state of Sao Paulo, Brazil. Within this region, two areas were delimited for study, one covered with natural (primary) vegetation and the other containing vegetation that regenerated following the planting of rice crops, referred to here as secondary. Collection of compound soil samples were taken (depth 0-15 cm) over a period of two and a half years, with the litter first being removed, during dry/cold and humid/hot periods. After sifting the samples, they were appropriately processed using the serial dilution technique to isolate the fungi from the soil. Six different culture media were used, having pHs of 4.5, 7.0 and 9.0. Altogether, 1,211 strains were isolated, divided into the following groups: Hyphomycetes, the most abundant followed by Ascomycetes, Zygomycetes, Coelomycetes, and Oomycetes. From these, 112 species were identified, 8 down to the genus level, and those that did not produce conidia were grouped as Mycelia sterilia. Among the strains, 67 were cellulolytic, 32 originated solely in soil under natural vegetation, and 26 originated solely in soil under secondary vegetation.

Agar↗
PubMed2005

Growth and production of laccases by the ligninolytic fungi, Pleurotus ostreatus and Botryosphaeria rhodina , cultured on basal medium containing the herbicide, Scepter (imazaquin).

The herbicide, Scepter, whose active principle is imazaquin, is commonly used in soybean farming to combat wide-leaf weeds. The basidiomycete, Pleurotus ostreatus , and the ascomycete, Botryosphaeria rhodina , were evaluated for their growth and laccase production when cultured on basal media containing Scepter. Both fungi could grow on the herbicide when cultivated in solid and submerged liquid culture in the presence of Scepter at concentrations of 0-6% (v/v) for P. ostreatus , and up to 0-50% (v/v) for B. rhodina , and in each case produced laccases when assayed against ABTS [2,2(1)-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)] and 2,6-dimethoxyphenol. P . ostreatus could tolerate up to 6% of Scepter before it became toxic to the fungus, while in the case of B. rhodina , 50% (v/v) Scepter was the highest amount that supported grow, and laccase activity was detectable up to 25% (v/v). An inverse relationship existed between the level of Scepter in the culture medium that supported fungal growth and laccase production. Analysis of the results showed that the fungi studied presented different behaviour towards Scepter in the culture environment.

Ascomycota↗
PubMed2006

Metal tolerance of yeasts isolated from water, soil and plant environments.

The tolerance of seventy yeast strains belonging to 15 species, isolated from water and soil environments as well as from tree leaves, to four heavy metals--copper, zinc, nickel and cadmium were studied. We have found that the interspecific and intraspecific variations in metal tolerance among studied strains were considerable. The highest interspecific variations were observed toward copper and cadmium. The strains of the species Sporobolomyces salmonicolor, Cryptococcus albidus, Cystofilobasidium capitatum, Saccharomyces cerevisiae, and Candida maltosa belonged to the most sensitive ones. In general ascomycetous yeasts were more tolerant to heavy metals than basidiomycetous ones. The differences among strains that came from various natural sources were also found. The most sensitive yeast population originated from untilled soil whereas the most tolerant population was isolated from tree leaves.

Basidiomycota↗
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↗
PubMed1992

Systematics, distribution, and host specificity of grass endophytes.

Clavicipitaceous endophytes (Ascomycetes) are distributed worldwide in many grasses and sedges forming a perennial and often mutualistic association with their hosts. Most endophytes appear to produce alkaloid toxins in infected plants. The high frequency of infection in many grasses and in certain grassland communities may indicate a selective advantage of infected over non-infected host plants due to their toxic effects on grazing animals and insects. Field observations and artificial inoculations of seedlings have demonstrated a high degree of specificity of most endophytes to their host plant, particularly in asexual, seed-borne endophytes. Specific isozyme genotypes found on several host species suggest that host-specific physiological races may occur. Knowledge of host range and host specificity is vital for potential applications of endophytes in pest control.

Acremonium↗
PubMedDate not supplied

A nonribosomal peptide synthetase involved in the biosynthesis of ampullosporins in Sepedonium ampullosporum.

Recently, the saprophytic ascomycete Sepedonium ampullosporum strain HKI-0053 was isolated from a basidiomycete on account of its premature induction of pigment formation in Phoma destructiva, a process often related to the neuroleptic activity of the inducing compound. The active substance was identified as the 15-membered peptaibol type peptide Ampullosporin. Although to date more than 300 peptaibols have been discovered, their biosynthetic machinery has not been characterized yet. By improving the culture conditions it was possible to grow S. ampullosporum in a submerged culture and to increase Ampullosporin production by more than three times to 33 mg/l at reduced fermentation times. The appearance of two high molecular weight proteins, HMWP1 (1.5 MDa) and HMWP2 (350 kDa) was closely related to the production of Ampullosporin during the course of fermentation. Both proteins showed a cross-reaction with antibodies against a core fragment of nonribosomal peptide synthetases (NRPSs). Biochemical characterization of the partially purified enzymes exhibited selectivity for the substrate amino acid alpha-aminoisobutyric acid (Aib). substantiating their involvement in Ampullosporin biosynthesis. Our data suggest that Ampullosporin synthetase has been isolated, and provides the basis for the characterization of the entire biosynthetic gene cluster. Furthermore, this knowledge will enable the manipulation of its NRPS template, in order to engineer mutant strains of Sepedonium ampullosporum which could produce more potent analogues of Ampullosporin.

Amino Acid Sequence↗
PubMed2003

Mycosporine-glutamicol-glucoside: a natural UV-absorbing secondary metabolite of rock-inhabiting microcolonial fungi.

Microcolonial ascomycetes are known to inhabit bare rock surfaces in cold and hot deserts and thus are habitually exposed to high levels of solar radiation. Several of these stress-tolerant fungal isolates, cultivated in the laboratory under daylight illumination, were studied for the presence of effective UV-radiation protection substances. Liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analyses allowed for efficient separation and structure clarification of two mycosporines. It was demonstrated that both mycosporine-glutamicol-glucoside and mycosporine-glutaminol-glucoside are natural and constitutive secondary metabolites of microcolonial fungi. The function and relation of these substances in the fungal cell are discussed.

Ascomycota↗
PubMed2004

Cloning and expression analysis of the ornithine decarboxylase gene (PbrODC) of the pathogenic fungus Paracoccidioides brasiliensis.

We describe the isolation and sequencing of PbrODC, the gene encoding ornithine decarboxylase (ODC) in Paracoccidioides brasiliensis. The gene contains a single open reading frame made of 1413 bp with a single intron (72 bp), and encodes a 447 amino acid polypeptide with a predicted molecular weight of 50.0 kDa, an isoelectric point of 4.9 and a high similarity to other fungal ornithine decarboxylases. Functionality of the gene was demonstrated by transformation into a Saccharomyces cerevisiae odc null mutant. A phylogenetic tree generated with several fungal ODCs provided additional evidence to favour a taxonomic position for P. brasiliensis as an ascomycetous fungus, belonging to the order Onygenales. Expression of the PbrODC gene was determined by Northern analyses during growth of the mycelial and yeast forms, and through the temperature-regulated dimorphic transition between these two extreme phases. Expression of PbrODC remained constant at all stages of the fungal growth, and did not correlate with a previously observed increase in the activity of ornithine decarboxylase at the onset of the budding process in both yeast growth and mycelium-to-yeast transition. Accordingly, post-transcriptional regulation for the product of PbrODC is suggested.

Amino Acid Sequence↗
PubMed1992

Cloning and disruption of a gene required for growth on acetate but not on ethanol: the acetyl-coenzyme A synthetase gene of Saccharomyces cerevisiae.

A DNA fragment of Saccharomyces cerevisiae with high homology to the acetyl-coenzyme A (acetyl-CoA) synthetase genes of Aspergillus nidulans and Neurospora crassa has been cloned, sequenced and mapped to chromosome I. It contains an open reading frame of 2139 nucleotides, encoding a predicted gene product of 79.2 kDa. In contrast to its ascomycete homologs, there are no introns in the coding sequence. The first ATG codon of the open reading frame is in an unusual context for a translational start site, while the next ATG, 24 codons downstream, is in a more conventional context. Possible implications of two alternative translational start sites for the cellular localization of the enzyme are discussed. A stable mutant of this gene, obtained by the gene disruption technique, had the same low basal activity of acetyl-CoA synthetase as wild-type cells when grown on glucose but completely lacked the strong increase in activity upon entering the stationary phase, providing direct proof that the gene encodes an inducible acetyl-CoA synthetase (ACS1) of yeast. As expected, the mutant was unable to grow on acetate as sole carbon source. Nevertheless, it showed normal induction of isocitrate lyase on acetate media, indicating that activity of acetyl-CoA synthetase is dispensable for induction of the glyoxylate cycle in S. cerevisiae. Surprisingly, disruption of the ACS1 gene did not affect growth on media containing ethanol as the sole carbon source, demonstrating that there are alternative pathways leading to acetyl-CoA under these conditions.

Acetate-CoA Ligase↗
PubMed2002

Involvement of Nst1p/YNL091w and Msl1p, a U2B'' splicing factor, in Saccharomyces cerevisiae salt tolerance.

Cell tolerance to salt stress depends on many physiological functions, including the best characterized of osmotic adjustment, ion transport and sodium-sensitive sulphate metabolism. From a screening designed to identify novel determinants of salt tolerance we have isolated the YNL091w gene, probably an Ascomycete-specific gene encoding a protein of unknown function. This gene negatively affects salt tolerance and therefore has been designated NST1. The salt tolerance mechanism of nst1 mutants is novel because it is not related to osmoregulation, altered cation accumulation or sulphate metabolism. Genome-wide two-hybrid analysis has suggested that Nst1p interacts with the splicing factor Msl1p and, accordingly, the impact of NST1 on salt tolerance is dependent on a functional MSL1 gene. Loss of MSL1 and NST1 function has pleiotropic phenotypes including increased sensitivity to divalent cations (manganese and zinc) and to caffeine (a cell wall-weakening agent). On the other hand, msl1 mutants but not nst1 mutants are sensitive to thiabendazole (a microtubule-destabilizing agent) and to osmotic stress.

Amino Acid Sequence↗
PubMed2003

cDNA cloning, biochemical and phylogenetic characterization of beta- and beta'-subunits of Candida albicans protein kinase CK2.

We have previously reported that Candida albicans protein kinase CK2 is composed of two distinct catalytic (alpha- and alpha'-) and two distinct regulatory (beta- and beta'-) subunits. We report here the isolation of two cDNAs clones, CaCKB1 and CaCKB2, encoding C. albicans beta- and beta'-subunits, respectively. The predicted beta- and beta'-proteins have calculated molecular masses of 34 kDa and 31 kDa and show all major features conserved in beta-subunits of other organisms, including the N-terminal autophosphorylation site, the internal acidic region and a potential metal-binding motif. The deduced amino acid sequence of C. albicans beta-subunit displays 48% identity with that of Saccharomyces cerevisiae and has an unusually long C-terminal acidic region containing a putative autophosphorylation site. C. albicans beta' shows 54% sequence identity with its S. cerevisiae homologue. Semi-quantitative RT-PCR analyses indicate that the mRNAs corresponding to both subunits are present in similar amounts in the yeast and hyphal forms of the fungus. To evaluate the biochemical properties of C. albicans beta- and beta'-subunits, both proteins were expressed in Escherichia coli and purified. Experiments performed in vitro indicate that both recombinant subunits reconstitute a fully functional holoenzyme when incubated with stoichiometric amounts of human recombinant alpha-subunit, as judged by their ability to abolish basal phosphorylation of calmodulin by human recombinant alpha-subunit and the reversion of the inhibitory effect by polylysine. In addition, both regulatory subunits can be phosphorylated by human recombinant alpha subunit. Phylogenetic analysis of beta- and beta'-proteins of C. albicans and other organisms shows that the CKB gene duplication occurred before the split of the ascomycete and basidiomycete lineages.

Amino Acid Sequence↗
PubMed1998

Induction of differentiation in human promyelocytic leukemia cell line HL60 by a new type of polyenes, falconensone A and its derivatives.

Falconensones A and B are new type of yellow pigment isolated from the mycelial extract of ascomycetous fungi, Emericella falconensis or Emericella fruticulosa, whose structures are similar to retinoic acid (RA). To date, biological activities of falconensones have not been reported. Herein, we reported that falconensone A inhibited growth of HL60 human leukemia cells, when used either singly or in combination with RA. Falconensone A alone did not induce differentiation of HL60 cells. However, falconesone A enhanced the differentiation of HL60 cells induced by 10 nM RA, and its effect was synergistic. On the other hand, falconensone B, the 4'-nor-methyl derivative of falconensone A, showed much lower activity than falconensone A on the inhibition of cell growth. In addition, synthetic derivatives of falconensone A, falconensone A p-bromophenylhydrazone and falconensone A dioxime, were more potent on the inhibition of cell growth and the induction of differentiation than natural falconensones A and B. These compounds induced differentiation of HL60 cells into monocyte/macrophage-like cells, different from granulocyte-like cells induced by RA. These results suggest that falconensone A may be a new type of antiproliferative agent, and that the methyl residue at the 4' position of the cyclopentenone ring of falconensone A may be necessary for biological activity. In addition, falconensone A enhanced RA-induced differentiation of HL60 cells, while its derivatives alone showed growth inhibition and induction of differentiation of HL60 cells. Based on these results, falconensone A and its derivatives may have clinical utility in the treatment of leukemia.

Antineoplastic Agents↗
PubMed1999

Regulation of glutamine synthetase from the white button mushroom Agaricus bisporus.

The regulation of glutamine synthetase (GS) from Agaricus bisporus was studied at the posttranscriptional level using a specific antibody fraction directed against purified GS. The cross-reactivity of the antiserum against various Agaricus species and other fungi was tested and low reactivity with the Ascomycetes was found. GS protein and activity levels were measured in cell-free extracts of mycelium grown on different N sources. In mycelium grown on glutamine or ammonium as N source, the biosynthetic GS activity is higher than the transferase activity. Moreover, the results show a correlation between GS biosynthetic activity, GS protein, and previously reported mRNA levels. Also, after addition of ammonium or glutamine to glutamate-utilizing cultures, transferase activity decreased more rapidly than biosynthetic activity and GS protein level. This suggests a conformational modification which only affects transferase activity.

Agaricus↗
PubMed1999

Cloning and characterization of a thermostable cellobiose dehydrogenase from Sporotrichum thermophile.

Cellobiose dehydrogenase (CDH) is an extracellular hemoflavoenzyme produced by several wood-degrading fungi. CDH contains one heme b and one FAD per molecule and oxidizes cellobiose to cellobionolactone in the presence of cytochrome c. In this report, a thermostable CDH from the thermophilic ascomycete Sporotrichum thermophile has been purified, cloned, and characterized. The temperature optimum for this CDH reaction was 60 degrees C, and the activation energy for the reaction was 26.3 kJ/mol. The Km and kcat were temperature-dependent and increased as reaction temperature increased. These kinetic properties prove that this CDH is truly thermophilic. A 2.8-kb cDNA was isolated by screening an expression library of S. thermophile with a polyclonal antisera raised against Phanerochaete chrysosporium CDH. The cDNA encoded an 807-amino-acid protein with a predicted mass of 86,332 Da. S. thermophile CDH is organized into three domains, an N-terminal flavin domain, a middle heme domain, and a C-terminal cellulose-binding domain, which shows sequence similarity with the cellulose-binding domains of endoglucanases and cellobiohydrolases from Trichoderma reesei. Comparison with the CDH sequences of P. chrysosporium and Trametes versicolor identified Met 95 and His 143 as potential heme coordinations. EFIG, LGGPM, and VNSTH motifs in the heme domain and the XRXPXTDXPSXDGXRY motif in the flavin domain were identified as CDH-specific motifs. With regard to the amino acid composition, S. thermophile CDH has more disulfide linkages and acidic and basic amino acids compared to CDHs from P. chrysosporium and T. versicolor.

Amino Acid Sequence↗
PubMed2000

Xenopus allantoicase: molecular cloning, enzymatic activity and developmental expression.

Allantoicase is one of the enzymes of the purine degradation pathway and, interestingly, it appears to be lost, together with uricase and allantoinase, during mammalian evolution. Only allantoicases from the ascomycetes S. pombe, S. cerevisiae, and N. crassa have already been cloned, although the activity has been reported also in fishes and amphibians. By screening a cDNA expression library of Xenopus liver, we have cloned a 1491-bp-length cDNA coding for a 389 amino acid protein that shows an high similarity with the enzyme allantoicase. We have found that allantoicase mRNA is abundantly expressed in kidney and liver, but at much lower level is also present in brain, testis, intestine, and lung. We have detected enzymatic activity in crude extract from kidney, liver, and lung; we have also determined kinetic parameters (K(m) = 8.44 mM, V(max) = 6. 94 micromol min(-1) per mg protein) in kidney. During embryo development, we have detected allantoicase transcript and activity starting from 1 and 5 days after fertilization, respectively.

Amino Acid Sequence↗