Immunosuppressive properties of deoxynivalenol.

The immunosuppressive effect of deoxynivalenol (DON) was investigated in male Balb/c mice. The effect of the route of DON administration to the animals was first studied. The results showed that DON acted efficiently on the immune system per os. The administration of 100 ppm DON in the diet caused the death of all the animals within a few days. After oral administration of DON to mice, liver and kidney weights were not changed while the thymus weight was significantly reduced at concentrations greater than 10 ppm. The spleen weight was reduced less than the thymus weight. Histologically, the structure of the thymus was damaged and the high doses produced an atrophy of this organ. Serum levels of anti-sheep red blood cells (SRBC) antibodies were significantly reduced, this effect was dose-dependent. The stimulation of B and T cells by mitogens was depressed: the mitogenic responses were more reduced for thymic cells than for splenic cells. DON inhibited cellular proliferation in vitro, as estimated by [3H]thymidine incorporation:murine splenocytes were more sensitive (IC50 = 131 ng/ml of culture) than XP human fibroblasts (IC50 = 252 ng/ml of culture).

Protein synthesis inhibition and cardiac lesions associated with deoxynivalenol ingestion in mice.

Deoxynivalenol (DON), an occasional contaminant of foodstuffs, has been implicated in outbreaks of mycotoxicosis. Balb-c mice that had ingested 0.35 mg/kg of DON showed a drastic decrease in food intake and concomitant loss of weight. Severe depletion of the lymphoid organs and liver were also observed. Cardiac lesions, appeared as calcified pericarditis foci in young animals fed a diet contaminated by 10 to 20 ppm of DON for a period of a few weeks. DON inhibited protein synthesis. This inhibition occurred at lower doses for the heart than for the other organs. This preferential effect on cardiac tissue correlated with the cardiotoxicity observed.

Toxigenic potential of some fusarium isolates from southeast Asia.

The isolation and characterization of 10 isolates of six Fusarium spp. from plant and soil samples collected in Southeast Asia is reported. The ability of these isolates to produce trichothecenes both in liquid cultures (CZ, GYEP, and MYRO) and on rice was assessed, and their toxigenic potential was examined by skin assay and gavage studies with culture filtrates. Although culture filtrates of all the isolates caused minor damage to test animals, only that of F. equiseti DAOM 189762 produced trichothecenes.

Decline in deoxynivalenol (vomitoxin) concentrations in 1983 ontario winter wheat before harvest.

Samples of winter wheat were collected in 1983 from five fields in southwestern Ontario that were naturally infected with head blight. The geometric mean concentration of deoxynivalenol (vomitoxin) in the grain declined significantly from 1.56 mug/g on 7 July to 0.21 mug/g on 14 July and 0.11 mug/g on 18 July and did not increase at harvest (20 through 27 July).

Deoxynivalenol, acetyl deoxynivalenol, and zearalenone formation by Canadian isolates of Fusarium graminearum on solid substrates.

Three isolates of Fusarium graminearum (DAOM 180377, 180378, and 180379) were screened for their ability to produce mycotoxins on the solid substrates corn and rice. They all produced deoxynivalenol and zearalenone on corn. On rice, only DAOM 180378 and 180379 produced significant amounts of these mycotoxins, with levels of deoxynivalenol being much higher than those of zearalenone. The effects of the initial moisture content before autoclaving, incubation temperature, and time were studied with isolate DAOM 180378. At 19.5 degrees C the main product was zearalenone, whereas at 25 degrees C both deoxynivalenol and zearalenone were formed. Higher incubation temperatures (28 degrees C) favored deoxynivalenol formation, the maximum amount being 515 ppm (515 micrograms/g) formed after 24 days at an initial moisture content of 40%. The maximum level of zearalenone produced at the same temperature was 399 ppm, but at an initial moisture content of 35%. Other factors, such as pH, oxygen and carbon dioxide concentrations, and size of the culture flask also appeared to affect the production of mycotoxins.

Toxigenic isolates of Fusarium sporotrichioides obtained from hay in Saskatchewan.

An isolate of Fusarium sporotrichioides Sherbakoff obtained from hay from Kindersley, Saskatchewan, and producing metabolites toxic to insect larvae, rats, and mice was cultured on sterile rye grain and extracted with ethyl acetate. The most toxic fraction derived from column chromatography on silica gel was purified by thin-layer chromatography of silica gel and elution of the main band. This compound was identified as T-2 toxin by comparison with the pure chemical by thin-layer chromatography and, after crystallization, by determination of melting point, infrared spectrum, and nuclear magnetic resonance spectrum. This work demonstrates that strains of F. sporotichioides capable of producing T-2 toxin may be present on hay in western Canada.

Fractionation of Saprolegnia diclina (Oomycetes) satelite DNAs by AgNO3/Cs2SO4 density gradient centrifugation.

Saprolegnia diclina DNA has been fractionated using preparative AgNO3/Cs2SO4 and CsCl density gradients. In addition to the previously identified major satellite DNA, there are two minor DNA components banding at 1.682 and 1.701 g - cm(-3) in CsCl. Purified major satellite DNA bands at 1.707 g - cm(-3) giving a base composition of 48% G + C in good agreement with 47% G + C calculated from its Tm value. The nuclear DNA base composition is 58% G + C by both methods. The base composition of the major satellite DNA suggests that it may represent ribosomal DNA cistrons.