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  • Aspergillus  (10)
  • 1990-1994  (10)
  • 1
    ISSN: 1573-0832
    Keywords: Versicolorin A ; hemiacetal ; reductase ; Aspergillus ; versicolorin C ; dihydrosterigmatocystin ; aflatoxin G2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Versicolorin A hemiacetal was converted to versicolorin C in cell-free systems fromAspergillus parasiticus. The rate of reaction catalyzed by the 35–70% ammonium sulfate fraction was 0.43 nmol min−1 mg−1 with NADPH as cosubstrate and 0.17 nmol. min−1 mg−1 with NADH at 25°C at pH 7.4. The product from incubation of 17-hdyroxy-16,17-dihydrosterigmatocystin with the 35–70% ammonium sulfate fraction and NADPH was a polar compound which was converted to dihydrosterigmatocystin by 0.4 M HCl. The olar comound is proposed to be the 14,17-hydrated open-chain derivative of dihydrosterigmatocystin. Aflatoxin G2a was also reduced in this system to a polar product tentatively identified as the 13,16-hydrated open-chain derivative of AFG2. The reductase activity may be involved in the formation of reduced intermediates and aflatoxins in cultures ofA. parasiticus.
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  • 2
    ISSN: 1573-0832
    Keywords: Aspergillus ; immunogold staining ; biotin-avidin linked immunosorbent assay ; double immunodiffusion ; aspergillosis ; aspergilloma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An immunogold assay (IGA) was developed to detect IgG and IgE antibodies to Aspergillus fumigatus. Sixteen sera from patients with allergic bronchopulmonary aspergillosis (ABPA), aspergilloma, and normal controls were studied. All sera were also evaluated for antibodies against A. fumigatus by biotin-avidin linked enzyme immunosorbent assay (BALISA) and by agar gel double diffusion method. A. fumigatus specific IgG and IgE antibodies could be detected by IGA in all the patients' sera but not in the sera of normal controls. Both IgG and IgE antibodies to A. fumigatus could be demonstrated in all the sera by BALISA and normal controls showed only low levels of these antibodies. There was a positive correlation between the degree of reactivity detected by IGA, the BALISA titer and the precipitins by agar gel diffusion. It can be concluded that IGA is a reliable, sensitive and simple method capable of detecting both IgG and IgE antibodies against A. fumigatus in patient serum.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 112 (1990), S. 93-104 
    ISSN: 1573-0832
    Keywords: Aspergillus ; fungal elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have attempted to elucidate the natural history of pulmonary aspergillus intracavitary colonization (PAIC) based on more than 350 cases of the disease observed in the last 11 years and on data collected from the literature. The data indicate that PAIC is a dynamic process consequent to the continual growth and death of fungal elements and also with their relationships to the anatomic features of the cavity (valvular mechanisms, vascular alteration). The clinical presentations reflect immunological changes in the host. Metabolites produced by the species of Aspergillus involved affect the clinical presentation of the syndrome.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 116 (1991), S. 149-150 
    ISSN: 1573-0832
    Keywords: Fungal taxonomy ; new techniques ; ubiquinone systems ; Emmonsiella ; Ajellomyces ; Penicillium ; Aspergillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract An array of new techniques including biochemical, physiological and molecular biological methods are being introduced to modify or improve the systematics of fungi of biotechnological, medical and industrial importance. In some genera e.g. Penicillium and Aspergillus such a multidisciplinary approach has shown to be useful and has resolved confusing species concepts. However, in other cases the significance of new techniques is still unclear and results drawn from such studies may even increase nomenclatural instability. Taxonomists should be careful and users aware and whenever possible a pragmatic approach should be welcomed.
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  • 5
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus ; Versicolorin B ; Versiconal hemiacetal acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The sequence of steps versiconal hemiacetal acetate (VHA) to versiconal (VL) catalyzed by an esterase and VL to versicolorin B (VB) catalyzed by VL cyclase has been previously demonstrated in cell-free systems fromAspergillus parasiticus. VHA esterase and VL cyclase activities were estimated by determining the amounts of VL and VB after incubation of VHA in cell-free extracts from mycelia that were either synthesizing or not synthesizing aflatoxins. VHA esterase activity but not VL cyclase activity was present in extracts from cells grown in a nonaflatoxin-producing medium. VHA esterase activity was present in extracts from mycelia grown in aflatoxin-producing medium harvested after one to six days of incubation. VL cyclase activity was absent at one day, low at two days, maximal at three to five days, and lower at six days. VL cyclase activity appears in the later part of the growth period which is also the period of aflatoxin biosynthesis. This supports a role for VL cyclase in the aflatoxin biosynthetic pathway.
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  • 6
    ISSN: 1573-0832
    Keywords: Aflatoxin biosynthesis ; Aspergillus ; Chaetomium ; Defined medium ; Sterigmatocystins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sterigmatocystin (ST) is a secondary metabolite and a principal mycotoxin known to be produced by over 30 species of filamentous fungi. It is also one of the late intermediates in aflatoxin biosynthesis. We have tested the ability of 7 species ofAspergillus, including 4 strains ofA. versicolor, one species ofBipolaris, and two species ofChaetomium, to produce ST on a sucrose-salts-phenylalanine defined medium as well as on three complex substrates. Highest ST production in our survey was by a strain ofA. versicolor grown on wheat, whereas, the highest ST production on defined medium was byC. cellulolyticum. To our knowledge, this is the first report of ST production byC. cellulolyticum on any substrate. In precursor feeding studies, resting cultures of wild typeA. nidulans andA. versicolor were unable to biotransform O-methylsterigmatocystin (OMST), the last known intermediate in aflatoxin biosynthesis. These results suggest that ST is the end product of polyketide metabolism in the strains tested.
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  • 7
    ISSN: 1573-0832
    Keywords: Aspergillus ; biorational control ; fungicide ; Fusarium ; Gerlachia ; Penicillium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bacillus subtilis produces peptidolipid compounds of the iturin group that have been shown to have antifungal properties, but not all fungal species are sensitive to these compounds. In this study, the activity of iturin A, produced by B. subtilis strain B-3, was tested. Paper disks impregnated with various concentrations of iturin A were placed on agar plates seeded with conidia of toxigenic species of Fusarium, Gerlacia, Penicillium or Aspergillus. Most isolates were inhibited at iturin A concentrations as low as 4 μg/disk. Penicillium italicum, P. vindicatum, A. ochraceus and A. versicolor were most strongly inhibited by the iturin whereas P. citrinum and A. parasiticus were least sensitive to iturin A.
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  • 8
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus ; Moisture ; Parboiled rice ; Rice bran ; Storage fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The changes in moisture content, storage mycoflora and aflatoxin B1 (AFB1) in bran from untreated or raw rice (Rr) and parboiled rice (Pbr) stored in small lots in polyethylene bags were studied at 15-day intervals up to 60 days, using five lots of each type of bran. Deterioration was more rapid with reference to all the three parameters, in Rr bran compared to Pbr bran, the former becoming completely overgrown and caked with fungi by the end of 60 days.Aspergillus flavus was the dominant fungus in Pbr bran, whereasA. candidus andTrichoderma viride were abundant in Rr bran. The frequency of incidence as well as concentration of AFB1 increased with storage time in both types of bran, but the rate of increase as well as overall concentration were much higher in Rr bran. Thus raw rice bran is unsuitable for prolonged storage.
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  • 9
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus ; Diplodia ; Fumonisin ; Fusarium ; Mycotoxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A shipment of South African corn (1989) exported to Taiwan, was analyzed for various ear-rot fungi andFusarium mycotoxins. Two sets of samples, one from the points of origin in South Africa prior to shipment, and the other from the end-point distributors in Taiwan, were studied. Surface-sterilized kernels were plated onto two different agar media and the fungal colonies identified. High Performance Liquid Chromatography was used to analyze mycotoxin levels. The predominant ear-rot fungi, in decreasing order of isolation frequency, wereFusarium subglutinans, F. moniliforme, Diplodia maydis andF. graminearum. Aspergillus flavus andA. parasiticus were not isolated from samples prior to export, but a small number ofA. flavus isolates were found after shipment. The predominant mycotoxins were fumonisins B1 (0–865 ng/g) and B2 (0–250 ng/g). Low levels of moniliformin (≤390 ng/g) were detected in some samples before shipment. Zearalenone (25 ng/g), and nivalenol (120 ng/g) were detected in two out of 32 samples taken in Taiwan. The samples contained no detectable levels of either aflatoxins (〉0.5 ng/g) or deoxynivalenol (〉100 ng/g) before or after shipment.
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  • 10
    ISSN: 1573-0832
    Keywords: Aspergillus ; Candida ; incidence ; leukemia ; blood ; urine ; sputum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Twenty-four patients with acute leukemia were investigated for the incidence of opportunistic fungi. Culture isolations of the sputum and urine samples revealed significant levels of Candida in 14 patients; Candida albicans, C. tropicalis and C. pseudotropicalis were the predominant ones isolated. Aspergillus flavus was isolated from blood in two cases and C. albicans and a black yeast from the blood of another two. Serological studies showed fungal antibodies in seven patients; precipitins against Candida were detected in five and Aspergillus in two. Both of the Aspergillus positive cases and two patients who had rising antibodies against Candida died during the course of investigation. In this study 13 of 24 patients developed oral candidiasis.
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