Mycotoxin determinations on animal feedstuffs and tissues in Western Canada.
Results of examination of specimens of plant or animal origin for various mycotoxins are presented. Analyses for aflatoxins and ochratoxins were most frequently requested, usually on the basis of visible mouldiness. Aflatoxin B1 was found in one of 100 specimens at a level of 50 ppb in a sample of alfalfa brome hay. Ochratoxin A was detected in seven of 95 specimens comprising six samples of wheat at levels between 30 and 6000 ppb and one sample of hay at a level of 30 ppb. An overall detection rate of 4.2% involving significant levels of potent mycotoxins suggests that acute or chronic mycotoxicoses may occur in farm livestock or poultry more frequently than presently diagnosied. (+info)
Prepubertal exposure to zearalenone or genistein reduces mammary tumorigenesis.
Prepubertal exposure to a pharmacological dose (500 mg kg(-1)) of the phyto-oestrogen genistein can reduce the incidence and multiplicity of carcinogen-induced mammary tumours in rats. However, such an exposure also disrupts the function of the hypothalamic-pituitary-gonadal axis, making it unsuitable for breast cancer prevention. We studied whether prepubertal exposure to genistein at a total body dose broadly comparable to the level typical of Oriental countries, approximately 1 mg kg(-1) body weight, affects mammary tumorigenesis. We also studied whether prepubertal exposure to zearalenone, a major source for phyto-oestrogens in the USA, influences breast cancer risk. Prepubertal rats were treated between postnatal days 7 and 20, with 20 microg (approximately 1 mg kg(-1) body weight) of either genistein or zearalenone. Zearalenone exposure significantly reduced both the incidence and multiplicity of mammary tumours induced by 7,12-dimethylbenz(a)anthracene (DMBA). Genistein exposure significantly reduced tumour multiplicity, but not tumour incidence, when compared with vehicle-treated animals. Furthermore, 60% of the tumours in the genistein group were not malignant, while all the tumours analysed for histopathology in the vehicle and zearalenone groups were adenocarcinomas. A higher number of differentiated alveolar buds, and lower number of terminal ducts, were present in the DMBA-treated mammary glands of the phyto-oestrogen exposed rats. The concentration of oestrogen receptor (ER) binding sites after the DMBA treatment was low in the mammary glands of all groups but a significantly higher proportion of the glands in the zearalenone exposed rats were ER-positive (i.e. ER levels > or = 5 fmol mg(-1) protein) than the glands of the vehicle controls. Our data suggest that a prepubertal exposure to a low dose of either zearalenone or genistein may protect the mammary gland from carcinogen-induced malignant transformation, possibly by increasing differentiation of the mammary epithelial tree. (+info)
Toxic effects of mycotoxins in humans.
Mycotoxicoses are diseases caused by mycotoxins, i.e. secondary metabolites of moulds. Although they occur more frequently in areas with a hot and humid climate, favourable for the growth of moulds, they can also be found in temperate zones. Exposure to mycotoxins is mostly by ingestion, but also occurs by the dermal and inhalation routes. Mycotoxicoses often remain unrecognized by medical professionals, except when large numbers of people are involved. The present article reviews outbreaks of mycotoxicoses where the mycotoxic etiology of the disease is supported by mycotoxin analysis or identification of mycotoxin-producing fungi. Epidemiological, clinical and histological findings (when available) in outbreaks of mycotoxicoses resulting from exposure to aflatoxins, ergot, trichothecenes, ochratoxins, 3-nitropropionic acid, zearalenone and fumonisins are discussed. (+info)
Expression of a functional antizearalenone single-chain Fv antibody in transgenic Arabidopsis plants.
The efficacy of cloning a recombinant mycotoxin antibody in plants was tested using Arabidopsis as a model. An antizearalenone single-chain Fv (scFv) DNA fragment was first cloned in the newly constructed phage display vector (pEY.5) and then recloned in the plant transformation vector pKYLX71::35S(2). After transformation, constructs of antizearalenone scFv were introduced into immature Arabidopsis seeds via Agrobacterium tumefaciens mediation by vacuum infiltration. Only plants transformed with the construct containing a PR-1b signal peptide sequence produced transgenic offspring. The antizearalenone scFv "plantibody" from these transgenic plants bound zearalenone with a high affinity (50% inhibitory concentration, 11.2 ng/ml) that was comparable to that of bacterially produced scFv antibody and the parent monoclonal antibody (MAb). By electron microscopic immunogold labeling, the presence of antizearalenone scFv was detected mainly in the cytoplasm and only occasionally outside the cell. Like bacterially produced scFv antibody, antizearalenone scFv plantibody exhibited greater sensitivity to methanol destabilization than did the parent MAb. The sensitivity of antizearalenone scFv plantibody to acidic disassociation was similar to the sensitivities of bacterially produced scFv antibody and MAb. Expression of specific plantibodies in crops might be useful for neutralizing mycotoxins in animal feeds and for reducing mycotoxin-associated plant diseases. (+info)
A novel lactonohydrolase responsible for the detoxification of zearalenone: enzyme purification and gene cloning.
Zearalenone (ZEN) is converted into a far less oestrogenic product by incubation with Clonostachys rosea IFO 7063. An alkaline hydrolase responsible for the detoxification was purified to homogeneity from the fungus by a combination of salt precipitation and column chromatography methods. The purified enzyme was homodimeric with a subunit molecular mass of 30 kDa and contained an intra-subunit disulphide bridge. On the basis of the internal peptide sequences of the purified protein, we cloned the entire coding region of the gene (designated as zhd101) by PCR techniques. The ZEN degradation activity was detected in heterologous hosts (Schizosaccharomyces pombe and Escherichia coli) carrying the cloned gene. Zhd101 could be a promising genetic resource for in planta detoxification of the mycotoxin in important crops. (+info)
Binding rather than metabolism may explain the interaction of two food-Grade Lactobacillus strains with zearalenone and its derivative (')alpha-earalenol.
The interaction between two Fusarium mycotoxins, zearalenone (ZEN) and its derivative (')alpha-zearalenol ((')alpha-ZOL), with two food-grade strains of Lactobacillus was investigated. The mycotoxins (2 microg ml(-1)) were incubated with either Lactobacillus rhamnosus strain GG or L. rhamnosus strain LC705. A considerable proportion (38 to 46%) of both toxins was recovered from the bacterial pellet, and no degradation products of ZEN and (')alpha-ZOL were detected in the high-performance liquid chromatograms of the supernatant of the culturing media and the methanol extract of the pellet. Both heat-treated and acid-treated bacteria were capable of removing the toxins, indicating that binding, not metabolism, is the mechanism by which the toxins are removed from the media. Binding of ZEN or (')alpha-ZOL by lyophilized L. rhamnosus GG and L. rhamnosus LC705 was a rapid reaction: approximately 55% of the toxins were bound instantly after mixing with the bacteria. Binding was dependent on the bacterial concentration, and coincubation of ZEN with (')alpha-ZOL significantly affected the percentage of the toxin bound, indicating that these toxins may share the same binding site on the bacterial surface. These results can be exploited in developing a new approach for detoxification of mycotoxins from foods and feeds. (+info)
Feed refusal factors in pure cultures of Fusarium roseum 'graminearum'.
Isolations from 1972 Wisconsin feed refusal corn yielded predominantly cultures of Fusarium roseum 'graminearum.' With one possible exception, none of the selected isolates of this fungus induced emesis in pigeons, whereas six of nine isolates produced feed refusal responses in all test animals. A single isolate of F. roseum 'equiseti' also induced a severe refusal response and possibly slight emesis. None of the other fungi isolated from this corn (F. moniliforme, Acremoniella atra) or controls caused either emesis or feed refusal. Zearalenone was detected in all isolates and was shown to be partially responsible for refusal activity. The remaining activity was ascribed to one or more nonvolatile, neutral, relatively polar molecules. T-2 toxin, although not detected in these isolates, was shown to have dramatic refusal activity in rats. (+info)
Sporogen, S14-95, and S-curvularin, three inhibitors of human inducible nitric-oxide synthase expression isolated from fungi.
The induction of human inducible nitric-oxide synthase (iNOS) expression depends (among other factors) on activation of the signal transducer and activator of transcription 1 (STAT1) pathway. Therefore, the STAT1 pathway may be an appropriate target for the development of inhibitors of iNOS expression. HeLa S3 cells transiently transfected with a gamma-activated site (GAS)/interferon-stimulated response element-driven reporter gene construct were used as the primary screening system. Using this system, three novel inhibitors of interferon-gamma-dependent gene expression, namely, sporogen, S14-95, and S-curvularin, were isolated from different Penicillium species. These three compounds also inhibited cytokine-induced, GAS-dependent reporter gene expression in stably transfected human A549/8-pGASLuc cells, confirming the data obtained with the above-mentioned screening system. Furthermore, in A549/8 cells, sporogen, S14-95, and S-curvularin inhibited cytokine-induced activity of the human iNOS promoter [a 16-kilobase (kb) fragment in stably transfected A549/8-pNOS2(16)Luc cells], cytokine-induced iNOS mRNA expression, and cytokine-induced nitric oxide (NO) production in a concentration-dependent manner. The proliferation of A549/8 cells, and the activity of the human eNOS promoter (a 3.5-kb fragment in stably transfected ECV-pNOS III-Hu-3500-Luc cells), were only influenced marginally by the three compounds. Sporogen, S14-95, and S-curvularin also inhibited cytokine-induced activation of STAT1alpha in A549/8 cells. In conclusion, sporogen, S14-95, and S-curvularin represent new transcriptionally based inhibitors of iNOS-dependent NO production, acting on the Janus tyrosine kinase-STAT pathway. These compounds may represent lead structures for the development of drugs inhibiting iNOS-dependent overproduction of NO in pathophysiological situations. (+info)