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  • 1
    ISSN: 1573-0832
    Keywords: cell wall extract ; trichothecene ; mycotoxin ; host-parasite interaction ; Cucumis melo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Addition of fruit cell wall extracts from two muskmelon cultivars into liquid media affected mycotoxin production by a strain of Myrothecium roridum pathogenic to muskmelon. Cell wall extracts from a susceptible cultivar (‘Iroquois’) significantly increased toxin production while cell wall extracts from a resistant cultivar (‘Hales Best’) significantly inhibited toxin production. Media containing 0.1 or 1.0 mg ml−1 stimulated toxin production more than media containing 10 or 100 mg ml−1 of cell wall extracts. Previous studies in our laboratory suggest that roridin E may be involved in virulence or pathogenicity of M. roridum; the present study indicates that cell wall polysaccharides as well as other materials present in cell wall preparations from susceptible host tissue provide a better substrate for toxin production than cell wall preparation from resistant host tissue.
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  • 2
    ISSN: 1573-0832
    Keywords: Emestrin ; mycotoxin ; mycotoxicosis ; Emericella striata ; mouse liver ; mouse lymphoid tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effects of emestrin (EMS), a secondary metabolite of the Emericella species, on male ICR mice were examined. The intraperitoneal LD50 values of EMS were 17.7 and 13.0 mg/kg at 24 and 48 hr, respectively. The target organs of EMS were the heart, liver and thymus. In doses over 30 mg/kg the experimental animals died from cardiac failure shortly after the injections. Several survivors that were given EMS in doses under 20 mg/kg showed severe centrilobular necrosis in the liver at 24 hr. Marked degeneration of mitochondria was seen in electron micrographs of both cardiac muscle cells and hepatocytes. In the degenerated hepatocytes, prominent proliferation of RER, membrane-limited inclusions containing both ribosome-like granules and RER, and fenestrated lamella-like structures were observed. Massive necrosis of lymphocytes was always observed in the cortical layer of the thymus of the survivors within 24 hr, while bilateral adrenalectomized mice showed no discernible pathomorphological changes in the lymphoid tissues. Pretreatment of mice with diethyl maleate increased the incidence and severity of hepatic necrosis, whereas that with either cysteine or CoCl2 reduced the severity of centrilobular necrosis of the liver. Pretreatment with phenobarbital had no significant effect on EMS-induced hepatic lesions.
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  • 3
    ISSN: 1573-0832
    Keywords: Fusarium ; trichothecene ; cytotoxicity ; bioassay ; mycotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Twenty-six trichothecene mycotoxins produced by Fusarium sporotrichioides (MC-72083) and Fusarium sambucinum were screened for relative cytotoxicity in cultured baby hamster kidney (BHK-21) cells. The relative cytotoxicity was measured as LC100. The most cytotoxic trichothecenes were T-2 toxin (5 ng/ml) and the recently isolated 4-propanoyl HT-2 (5 ng/ml) and 3′-hydroxy T-2 toxin (5 ng/ml). T-2 tetraol (1 × 104 ng/ml), 8-β-hydroxytrichothecene (1 × 104 ng/ml), sporotrichiol (2 × 104 ng/ml), 8-oxodiacetoxyscirpenol (6 × 104 ng/ml) and 8-acetyl T-2 tetraol (1 × 105 ng/ml) were the least toxic of the regular trichothecenes. None of the modified trichothecenes or the apotrichothecene were very cytotoxic: 8-β-hydroxysambucoin (2 × 103 ng/ml), FS-1 (5 × 103 ng/ml), 8-α-hydroxysambucoin (8 × 104 ng/ml) and trichotriol (1 × 105 ng/ml). The modified trichothecenes, FS-2 and FS-3, were not toxic even at 1 × 105 ng/ml. The baby hamster kidney cell bioassay proved to be a very sensitive and reproducible means of screening new trichothecene mycotoxins for relative cytotoxicity.
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  • 4
    ISSN: 1573-0832
    Keywords: Antibiotic ; dothistromin ; haemolysis ; mycotoxin ; phototoxicity ; phytotoxicity ; tautomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The toxicity of the fungal phytotoxin dothistromin (l) to microorganisms, its lysis of human red blood corpuscles and beetroot tissue, and its unexpectedly selective inhibition of radicle elongation for Trigonella foenum-graecum were strongly light-dependent. Dothistromin was also toxic to Artemia salina but without requiring light activation. It was not active as a wilt or necrosis toxin, possible because of its ready adsorption onto external plant tissue.
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  • 5
    ISSN: 1573-0832
    Keywords: acidic soil ; Aspergillus caelatus ; Aspergillus tamarii ; DNA sequence ; mycotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fungi in Aspergillus section Flavi include both aflatoxin producers and non-producers. Aspergillus caelatus is a recently described non-aflatoxigenic species in this section, which has some common characteristics with A. tamarii, such as yellowish brown color and double walled spores. In contrast to the morphological similarities, all of the A. caelatus isolates tested produced no cyclopiazonic acid whereas most isolates of A. tamarii produce this compound. There are six nucleotide differences that distinguish the DNA sequences of these two species in the regions of ITS1, ITS2, 5.8S rDNA and 28S rDNA and this is a consistent difference. Both species were isolated from acidified field soils, but A. tamarii isolates were more common than A. caelatus in highly acidic soils.
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  • 6
    ISSN: 1573-0832
    Keywords: Aflatoxin ; soya-bean root ; leucine ; mycotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present work reports a portion of our continuing effort to determine the mechanism(s) whereby aflatoxins cause toxic responses in in vitro cultured plant tissues. Few investigations have dealt with the mode of action of aflatoxin B1 (AFB1) in excised plant tissues. Here is detailed AFB1 influence on growth, uptake and incorporation of 14C-leucine by excised, incubated soya-bean roots. Pure AFB1 was added to culture medium prior to autoclaving. One gram fresh weight portions of roots from three-day old soya-bean seedlings were excised and incubated for 4, 8, 12 and 24 hours. Growth was assayed by following changes in root dry weight. Aflatoxin B1 inhibited root dry weight at both 20 and 30 μg/ml. Uptake of 14C-leucine was checked by following its depletion from the medium. Reduced 14C-leucine uptake by roots exposed to 20 μg/ml AFB1 suggests that the toxin may alter the plasmalemma. A possible role for AFB1 in modification of membrane-associated amino acid transport mechanisms is discussed. Incorporation of 14C-leucine into trichloroacetic acid-precipitable cytoplasm was assayed. Inhibition of this incorporation at 20 μg/ml AFB1 was most apparent at 12 hours. Thus, AFB1 may also impair the ability of excised soya-bean roots to carry out protein synthesis.
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  • 7
    ISSN: 1573-0832
    Keywords: New Zealand ; Fusarium ; mycotoxin ; deoxynivalenol ; acetyldeoxynivalenol ; fusarenon-X ; zearalenone ; wortmannin ; moniliformin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sixty-two isolates of Fusarium were obtained from pasture grass and soil from various areas of New Zealand and identified as F. anthophilum [2], F. avenaceum [17], F. crookwellense [8], F. culmorum [4], F. graminearum [1], F. nivale [3], F. oxysporum [3], F. sambucinum [17], F. semitectum [1], F. tricinctum [1] and an unidentified Fusarium spp. [5]. These isolates were grown on autoclaved rice and tested for toxicity to rats in feeding tests. Eighty two percent of the isolates were toxic, of which twenty-four percent were severely toxic and caused hemorrhages of stomach and intestine, hematuria, and finally death. Cultures of the most toxic isolates contained 0.1 to 104 ppm of deoxynivalenol, 0.7 and 7 ppm of 15- and 3-acetyldeoxynivalenol respectively, 0.2 to 4 ppm of fusarenon- X, 11 to 1021 ppm zearalenone, 40 to 272 ppm of the hemorrhagic factor (wortmannin), 2,100 to 7,200 ppm of moniliformin, 565 ppm of the cytotoxic factor (HM-8) and enniatin in substantial concentrations. F. sambucinum is reported as a moniliformin producer for the first time.
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  • 8
    ISSN: 1573-0832
    Keywords: mycotoxin ; trichothecene ; immunosuppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract T-2 toxin and other trichothecene mycotoxins experimentally impair normal immune function and may predispose humans and animals to infectious disease. In this study, the histopathologic effects of Salmonella typhimurium challenge concurrently with sublethal T-2 toxin exposure were examined in the Salmonella-resistant C3H/HeN mouse. Oral administration of T-2 toxin (1 mg/kg) every other day for 10 d had little effect on the tissues examined when compared to control animals. Mice challenged with S. typhimurium and then treated with T-2 toxin every other day for 10 d had markedly larger and more bacterial-related lesions in the spleens, kidneys, and livers than animals challenged with S. typhimurium alone. Differences in bone marrow, Peyer's patches and ileal tissues were less discernable between S. typhimurium and S. typhimurium plus T-2 toxin treated groups. These results were consistent with previous findings that T-2 toxin compromised murine resistance to S. typhimurium infection and ultimately caused death in animals challenged with a sublethal dose of the organism.
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  • 9
    ISSN: 1573-0832
    Keywords: mycotoxin ; ochratoxin ; Penicillium ; storage ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Eleven-kilogram parcels of HY-320 wheat, a cultivar of the new Canada Prairie Spring class, were kept at 15 and 19% initial moisture contents (IMC) in simulated storage in a Manitoba farm granary for 60 weeks to determine biotic and abiotic changes and mycotoxin production. Ochratoxin A reached a maximum of 0.24 ppm by week 20 in the 19% IMC wheat, but was absent in the 15% IMC wheat; no other mycotoxins were detected. Temperature, moisture content, O2 and CO2 levels, fat acidity values, seed germination, microfloral incidence and abundance, and the presence of other mycotoxins were monitored. Principal component analysis of all variables showed that the first principal components accounted for 32–41% of the system variability, and contained the ochratoxin A variable. Ochratoxin A was produced in moist grain that had decreased seed germination andAltermaria activity, and high fungal activity byPenicillium andAspergillus versicolor. Compared to other stored cereals previously studied, HY-320 wheat would be ranked in a low-risk category for mycotoxin formation, based on the ochratoxin A levels observed.
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  • 10
    ISSN: 1573-0832
    Keywords: Balkan Endemic Nephropathy ; nephropathy ; mycotoxin ; Penicillium aurantiogriseum ; Penicillium commune ; mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Seven out of nine Penicillium isolates from mouldy maize in Yugoslavia have been differentiated into the adjacent species P. aurantiogriseum and P. commune. Nephrotoxicity of cultured mycelia in the rat has been demonstrated for all isolates of both species and was correlated usefully, though indirectly, with the production of benzodiazepine secondary metabolites, notably auranthine. Shredded wheat (22 g) moulded by an example of each species and fed to a rat over 4 days elicited renal pathology in the P3 segment of proximal tubules, involving frequent pyknosis and extensive mitosis typical of this as yet uncharacterised toxin. The effect was attributed in P. aurantiogriseum at least partly to the spores. Prominent pathology was elicited by only lg of spores given over 4 days.
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