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  • Trichoderma reesei  (7)
  • phosphorus  (2)
  • 62F15  (1)
  • 1
    ISSN: 1432-0983
    Schlagwort(e): Trichoderma reesei ; Homologous transformation ; pyrG ; Vector integration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The Trichoderma reesei orotidine-5′-phosphate decarboxylase gene was isolated by heterologous hybridization with the corresponding Neurospora gene as a probe. A 2.7 kb SalI fragment, which exclusively hybridized to the Neurospora gene, was subcloned in pGEM-5Zf(+). This subclone was termed pFG1 and was used to transform a Trichoderma reesei pyrG- negative mutant to PYR+. The transformation frequency in this homologous system was up to 12000 transformants per μg DNA. About one-fifth of the transformants tested were abortive. Perfect mitotic stability was found in half of the non-abortive transformants, correlating with vector integration at homologous and ectopic loci. In the unstable transformants the transforming DNA appears to be present in the form of extrachromosomal elements.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1432-0983
    Schlagwort(e): Trichoderma reesei ; Cellobiohydrolase genes ; Cellulase formation ; Trichoderma sp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Eight different species of Trichoderma (T. virgatum, T. longibrachiatum, T. harzianum, T. pseudokoningii, T. polysporum, T. koningii, T. todica, T. saturnisporum), and three strains of T. reesei [QM 6a (wildtype), QM 9123 and QM 9414 (derived mutants)] were found to contain single copies of the cellobiohydrolase genes cbh1 and cbh2 in their genome. This was demonstrated by hybridization of the respective chromosomal DNAs with the corresponding gene fragments of T. reesei QM 9414. According to the relative position of cbh1 and cbh2 in Southern blots, T. harzianum, T. virgatum and T. saturnisporum were clearly distinguishable as unique species. Despite the presence of both cbh genes, these species did not form detectable cellobiohydrolase (CBH) I or II, or exhibit any cellulase activity. All other taxa were identical with respect to the genomic position of cbh1, formed two groups with respect to the position of cbh2, and produced varying amounts of CBH I and II. In all cases CBH I and II production correlated with the relative amount of cbh1- and cbh2-mRNA found. This was particularly true for the three strains of T. reesei, which secreted different amounts of CBH I and II, their efficiency to transcribe cbh1 and cbh2 having been increased as a result of mutation for higher cellulase production.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1432-0983
    Schlagwort(e): Trichoderma reesei ; Transformation ; Hygromycin B ; Hygromycin B phosphotransferase ; Pyruvate Kinase ; Promoter ; Terminator ; Dominant selection marker
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Trichoderma reesei was transformed to hygromycin B resistance using a novel vector, which contains the E. coli hygromycin B phosphotransferase gene (hph) fused between promoter and terminator elements of the homologous Trichoderma pkil (coding for pyruvate kinase) and cbh2 (coding for cellobiohydrolase II) genes, respectively. Transformation frequencies of over 1800–2500 transformants/μg DNA were obtained, which is a 15–20-fold increase over that with pAN7-1, which contains hph between A. nidulans expression signals. Mitotically-stable transformants contained the hph gene and the regulatory sequences of the pkil promoter and the cbh2 terminator integrated into the genome. Evidence for preferentially ectopic integration is given.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1432-0983
    Schlagwort(e): DNA fingerprinting of Trichoderma ; Trichoderma reesei ; RFLP ; Strain classification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have analyzed nine different species of the filamentous fungus Trichoderma and three strains of T. reesei for the presence of hypervariable loci in their genomes by hybridization with simple repeat oligonucleotides [(CT)8, (GTG)5, and (GACA)4]. On the basis of the DNA-fingerprints obtained, the Trichoderma aggregate is re-classified into five groups: I (T. reesei, T. todica), II (T. polysporum, T. longibrachiatum, T. koningii, and T. pseudokoningii), III (T. virgatum), IV (T. saturnisporum) and V (T. harzianum). These results contradict the claim that T. reesei is a subspecies of T. longibrachiatum. Furthermore, hybridization with (CA)8 allowed a subdivision of group II, wherein T. pseudokoningii formed a subgroup, IIb, which is highly homologous with, but distinct from subgroup IIa. The results show that RFLP analysis may be used to re-classify the Trichoderma aggregate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 154 (1990), S. 150-155 
    ISSN: 1432-072X
    Schlagwort(e): Trichoderma reesei ; β-Glucosidase ; Polyheteroglycan ; Cell wall ; Enzyme activation ; Reassociation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The extracellular β-glucosidase from the filamentous fungus Trichoderma reesei QM 9414 is mainly bound to the cell wall of the fungus and only partially released into the medium. Isolation of the cell walls and its hydrolysis by enzymatic treatment with Aspergillus niger cellulase released β-glucosidase, which appeared tightly associated with a cell wall polysaccharide. This polysaccharide was purified by gel filtration and ion exchange chromatography and was shown to consist of mannose, galactose, glucose, galacturonic acid and glucuronic acid. It was devoid of protein and phosphate. It reassociated both with extracellular β-glucosidase as well as β-glucosidase released from the fungus' cell wall. Addition of the polysaccharide to the β-glucosidase in vitro increased the enzyme's activity against 4-nitrophenyl-β-glucoside twofold. These findings suggest, that the isolated polysaccharide functions as an “anchor glycan” for the β-glucosidase in Trichoderma reesei.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1432-072X
    Schlagwort(e): Trichoderma reesei ; Cellobiohydrolase ; Monoclonal antibodies ; Conidial bound enzymes ; Recombinant fungal cellulase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Monoclonal antibodies have been used to determine the presence of cellobiohydrolases I and II (CBH I and II), and endoglucanase I (EG I) on the surface of conidia from Trichoderma reesei QM 9414 and RUT C-30, and 8 other Trichoderma species. For this purpose, proteins were released from the conidial surface by treatment with a non-ionic detergent (Triton X-100 and β-octylglucoside), followed by SDS-PAGE/Western blotting and immunostaining. Both CBH I and II were clearly present, but — unlike in extracellular culture fluids from Trichoderma — CBH II was the predominant cellulase. In T. reesei EG I could not be detected. The higher producer strain T. reesei RUT C-30 exhibited a higher conidial level of CBH II than T. reesei QM 9414. In order to assess the importance of the conidial CBH II level for cellulase induction by cellulose, multiple copies of the chb2 gene were introduced into the T. reesei genome by cotransformation using PyrG as a marker. Stable multicopy transformants secreted the 2- to 4-fold level of CBH II into the culture medium when grown on lactose as a carbon source, but their CBH I secretion was unaltered. Upon growth on cellulose, both CBH I and CBH II secretion was enhanced. Those strain showing highest cellulase activity on cellulose also appeared to contain the highest level of conidial bound CBH II. CBH II was also the predominant conidial cellulase in various other Trichoderma sp. However, roughly the same amount of conidial bound CBH II was detected in all strains, although their cellulase production differed considerably.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1617-4623
    Schlagwort(e): Trichoderma reesei ; Aspergillus niger ; Protein kinase C gene ; Signal transduction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Oligonucleotides, designed on the basis of conserved flanking amino acid sequence segments within the catalytic domain of eukaryotic protein kinase C (PKC) proteins, were used as primers for polymerase chain reactions to amplify a 427-bp chromosomal DNA fragment from the filamentous fungusTrichoderma reesei. This fragment was then used to isolate genes encoding PKC homologues ofT. reesei andAspergillus niger (pkcl andpkcA, respectively). The genes contain six (T. reesei) and eight (A. niger) introns, which exhibit notable conservation in position with those found in the correspondingSchizosaccharomyces pombe pkc1 + andDrosophila melanogaster dPKC53Ebr genes. A single 4.2-kb transcript was detected in Northern analyses. The deduced PKC1 (T. reesei, 126 kDa) andPKCA (A. niger, 122 kDa) amino acid sequences reveal domains homologous to the Cl and C3/C4 domains of PKC-related proteins, but lack typical Ca2+-binding (C2) domains. Both contain a large, extended N-terminus, which shares a high degree of similarity with the corresponding regions ofSaccharomyces cerevisiae PKC1 andS. pombe pkc1+ and pkc2+ proteins, but which is not present in PKCs ofDictyostelium or higher eukaryotes. This extended region can be divided into three subdomains; the N-terminal one contains a hydrophobic helix-turn-helix motif, whereas the C-terminal one contains potential targets for proteolytic processing. A polyclonal antiserum raised against the pseudosubstrate-binding domain of PKC1 recognizes inT. reesei a 115–120 kDa protein in Western blots. Expression ofpkc1 cDNA in insect cells directs the synthesis of a PKC1 protein of similar size. TheT. reesei PKC1 protein was partially purified and some of its properties examined: it is stimulated about twofold by phospholipids or phorbol esters but is not stimulated by Ca2+. We conclude that these PKC proteins from filamentous fungi represent the Ca2+-insensitive fungal homologues of the nPKC family.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1573-5036
    Schlagwort(e): cations ; fire ; nitrogen ; nutrients ; phosphorus ; slash-and-burn ; soil ; tropical forests
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The most commonly observed change in soil following slash-and-burn clearing of tropical forest is a short-term increase in nutrient availability. Studies of shifting cultivation commonly cite the incorporation of nutrient-rich ash from consumed aboveground biomass into soil as the reason for this change. The effects of soil heating on nutrient availability have been examined only rarely in field studies of slash-and-burn, and soil heating as a mechanism of nutrient release is most often assumed to be of minor importance in the field. Few budgets for above and belowground nutrient flux have been developed in the tropics, and a survey of results from field and laboratory studies indicates that soils are sufficiently heated during most slash-and-burn events, particularly in dry and monsoonal climates, to cause significant, even substantial release of nutrients from non-plant-available into plant-available forms in soil. Conversely, large aboveground losses of nutrients during and after burning often result in low quantities of nutrients that are released to soil. Assessing the biophysical sustainability of an agricultural practice requires detailed information about nutrient flux and loss incurred during management. To this end, current conceptual models of shifting cultivation should be revised to more accurately describe these fluxes and losses.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 1573-5036
    Schlagwort(e): fire ; nitrogen ; phosphorus ; soil nutrient heterogeneity ; tree effects ; tropical dry forest
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Individual trees are known to influence soil chemical properties, creating spatial patterns that vary with distance from the stem. The influence of trees on soil chemical properties is commonly viewed as the agronomic basis for low-input agroforestry and shifting cultivation practices, and as an important source of spatial heterogeneity in forest soils. Few studies, however, have examined the persistence of the effects of trees on soil after the pathways responsible for the effects are removed. Here, we present evidence from a Mexican dry forest indicating that stem-related patterns of soil nutrients do persist following slash-and-burn removal of trees and two years of cropping. Pre-disturbance concentrations of resin extractable phosphorus (P), bicarbonate extractable P, NaOH extractable P, total P, total nitrogen (N) and carbon (C), KCl extractable nitrate (NO3 -), and net N mineralization and nitrification rates were higher in stem than dripline soils under two canopy dominant species of large-stemmed trees with contrasting morphologies and phenologies (Caesalpinia eriostachys Benth. and Forchhammeria pallida Liebm.). These stem effects persisted through slash burning and a first growing season for labile inorganic and organic P, NaOH inorganic P, and plant-available P, and through a second growing season for labile organic P, NaOH organic P, and plant-available P. While stem effects for extractable NO3 -, net nitrification rates, total N and C disappeared after felling and slash burning, these stem effects returned after the first growing season. These results support the view that tree-influenced patterns of soil nutrients do persist after tree death, and that trees contribute to the long-term spatial heterogeneity of forest soils.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Theory and decision 40 (1996), S. 191-214 
    ISSN: 1573-7187
    Schlagwort(e): 62J99 ; 62F15 ; 62C10 ; 62C15 ; Utility theory ; non-informative prior ; distributional distance ; entropy ; Hellinger distance ; conjugate prior ; Fisher information ; exponential families ; bayes estimator
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Sociologie , Wirtschaftswissenschaften
    Notizen: Abstract Since the choice of a particular loss function strongly influences the resulting inference, it seems necessary to rely on “intrinsic” losses when no information is available about the utility function of the decision-maker, rather than to call for classical losses like the squared error loss. Since this setting is quite similar to the derivation of noninformative priors in Bayesian analysis, we first recall the conditions of this derivation and deduce from these conditions some requirements on the intrinsic losses. It then appears that these loss functions should only depend on the sampling distribution and that they should be independent of the parameterization of the distribution. The resulting estimators are therefore transformation equivariant. We study the properties of two natural intrinsic losses, namely entropy and Hellinger losses, and show that they can be expressed in closed form for exponential families. Moreover, the entropy loss also provides analytic expressions of Bayes estimators under conjugate priors; the derivation of Bayes estimators associated with the Hellinger loss is more cumbersome, as shown in Poisson and Gamma cases, while leading to similar estimators.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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