Twenty-three barley samples harvested in 1987 and 34 barley samples harvested in 1989 were analyzed for deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEN). Out of 23 samples in 1987 crop, 22, 22 and 9 were positive for DON, NIV and ZEN, respectively. Of 34 samples in 1989 crop, 13, 24 and 9 were positive for DON, NIV and ZEN, respectively. Frequencies and levels of Fusarium mycotoxins in 1987 crop were higher than those in 1989 crop. It seems that higher humidity and lower temperature during the heading through harvest season in 1987 resulted in higher levels of Fusarium contamination and mycotoxins as compared to those in 1989.
Six mycotoxins, aflatoxins (AFB1, AFB2, AFG1, AFG2), cyclopiazonic acid (CA) and kojic acid (KA) which produced by Aspergillus flavus group species were analyzed by GC without chemical derivatization. The GC system contains fused silica capillary column (DB-5, 0.25mm i.d.×10m) and capillary on-column injector. Either FID or MS could be used as a detector. The analysis was highly reproducible and the detection limit of these mycotoxins by GC-FID were 1 ng for AFB1 and AFB2, 2 ng for AFG1 and AFG2, 0.5 ng for CA and 1 ng for KA.
Development of fungal mycelia and citrinin or aflatoxin production in each steamed rice inoculated and cultured with Penicillium citrinum or Aspergillus flavus, after cross sectioning the kernels (30 μm thick) by using a cryotome, were observed by an optical microscopic method (fluorescence and ordinal, respectively). In the P. citrinum-inoculated rice, fluorescence due to citrinin production was observed only in the surface layer of the kernel even after 14 days' culture at 28°C. It was not found in the central part of the kernel. In the same section, the fungus digested the cell walls, as well as starch, in the surface layer only. In the A. flavus-inoculated rice, fluorescence due to the aflatoxin production was found in the entire part of the section of the kernel after 7 to 8 days' culture at 28°C. The same section was shown that most of the walls of starchy cells disappeared by fungal digestion. These results showed that mycelial invasion and mycotoxin production, viz. citrinin or aflatoxins, are almost concurrent in the inoculated rice kernels. The modes of the invasion and the digestion were somewhat different between those of P. citrinum and A. flavus.
Effects of repeated administrations (i.p. and p.o.) of emestrin on male ICR mice were examined. Mice injected i.p. showed a high mortality (about 70%) with severe peritonitis fibrosa, while those administered orally showed no peritonitis. Lymphatic leukemia and lung tumor (papillary adenoma) were seen in 3 and 2 mice, respectively, out of 18 survived mice during 25 months. There were no significant differences between the administration routes in the incidence and duration of the tumor development. There were neither tumor nor hyperplastic nodules in the liver, although an increase in volume and marked pleomorphism of nuclei of hepatocytes were seen in the central area of hepatic lobules.