The minimum emetic dose of deoxynivalenol to swine weighing 9 to 10 kg was 0.05 mg/kg of body weight intraperitoneally and 0.1 to 0.2 mg/kg orally. There was no emesis by undosed pigs consuming vomitus from pigs orally dosed with deoxynivalenol or penned with such pigs without access to vomitus. Analysis by gas-liquid chromatography of a sample of Gibberella zeae-infected corn containing about 25% visually damaged kernels indicated 12 ppm of deoxynivalenol. Deoxynivalenol added to feed reduced feed consumption of 20to 45-kg pigs, ranging from a 20% decrease with 3.6 ppm to 90% reduction with 40 ppm. Loss in weight was associated with feed refusal. Feed refusal, however, was much greater for naturally infected corn samples than for feeds with equal concentrations of the pure compound added, indicating the involvement of an additional factor(s) in the swine refusal response.

Deoxynivalenol(DON), 3a,7a,15-trihydroxy-12,13-epoxytrichothec-9-en-8-one, is a toxic metabolite such Fusarium spp. as F.

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Thirty-four samples of domestic wheat and barley grains, collected from eight prefectures of different locations in Japan and previously determined to be positive for deoxynivalenol (DON), nivalenol (NIV) and/or zearalenone (ZEA), were analysed for acetylated derivatives of DON and NIV by gas chromatography-mass spectrometry. In addition to DON and NIV, 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON) and 4-acetylnivalenol (4-ANIV) were found in 25, 4 and 14 samples, respectively. A regional difference in the DON and NIV contamination of Japanese wheat and barley was suggested: DON was the major trichothecene in the northern district and NIV in the central districts, whereas in the southern districts the DON level was similar to or slightly higher than the NIV level. 3-ADON occurred together with DON in almost all prefectures examined, whereas 15-ADON was found only in samples from northern districts. In addition, a high correlation (r = 0.974, n = 23) between levels of DON and its acetates (3-ADON and 15-ADON) was noted. These results may also suggest the possibility of a geographic difference in the distribution of different chemotypes of Fusarium species producing these trichothecenes in Japan.

In vitro production of trichothecene mycotoxins, deoxynivalenol, nivalenol, T-2 toxins, and their derivatives was studied in rice culture using 30 strains from seven Fusarium species. Six strains of three Fusarium species were selected for the evaluation of mycotoxin production and pathogenicity after artificial inoculation to seven wheat lines with different levels of resistance or susceptibility and their eight F1's. Three criteria were used for the evaluation: the reduction of seed set, the reduction of grain weight, and the concentration of mycotoxins in infected grain. Significant variability was observed among Fusarium strains, wheat genotypes, and in the interaction between them. The contribution of Fusarium strains, however, was far greater than that of the other two factors. The kinds and relative amounts of mycotoxins produced in rice culture were consistent with those present in infected grain with some exceptions. Significant correlations were found between the grain weight reduction and the mycotoxin concentration and between the level of resistance of the wheat genotypes under the artificial and natural conditions of infection. The biological role of Fusarium mycotoxins in pathogenicity and wheat resistance to Fusarium head blight is discussed. Key words: Fusarium head blight (scab), Fusarium mycotoxins, Fusarium pathogenicity, wheat resistance to Fusarium head blight.

Attempts were made to elucidate the acetyl transformation of novel trichothecene mycotoxins, 3a,7a,15-trihydroxy-12,13-epoxytrichothec-9-en-8-one (deoxynivalenol) and its derivatives, by trichothecene-producing strains of Fusarium nivale, F. roseum, and F. solani. In the peptone-supplemented Czapek-Dox medium, F. roseum converted 3a-acetoxy-7a,15-dihydroxy-12,13epoxytrichothec-9-en-8-one (3-acetyldeoxynivalenol) to deoxynivalenol. 3-Acetyldeoxynivalenol was also deacetylated by intact mycelia of the three strains in sugar-free Czapek-Dox medium. The growing F. nivale acetylated deoxynivalenol to afford a small amount of 3-acetyldeoxynivalenol. 3a,7a, 15-Triacetoxy-12,13-epoxytrichothec-9-en-8-one (deoxynivalenol triacetate) was transformed by the intact mycelium of F. solani into 7a, 15-diacetoxy-3ahydroxy-12,13-epoxytrichothec-9-en-8-one (7,15-diacetyl-deoxynivalenol), which was then deacetylated to give 7a-acetoxy-3a,15-dihydroxy-12,13-epoxytrichothec-9-en-8-one (7-acetyldeoxynivalenol). It was noted that the ester at C-7 was not hydrolyzed by the fungal mycelium.