IDENTIFICATION OF HAZARDOUS FUSARIUM SECONDARY METABOLITES OCCURRING IN FOOD RAW MATERIALS

Hazardous secondary metabolites produced by Fusarium molds were identified in the first step of a risk assessment procedure, the hazard identification. These mycotoxins are excreted, often simultaneously, by the fungus into plant tissue. A literature survey revealed the occurrence of 61 Fusarium species in agricultural produce (cereals, vegetables, fruits) of which 35 species were reported to produce a total of 137 secondary metabolites in laboratory experiments. This literature review shows that 41 (30%) of these secondary metabolites have been tested and found toxic in various assays and should be considered hazardous if present in food. Six of these were reported to be related to human intoxications. Four metabolites belonged to the trichothecenes (T-2 toxin, nivalenol, deoxynivalenol and acetyldeoxynivalenol), the others were zearalenone and fumonisin B₁. Twelve metabolites, including the previously mentioned six, were reported to have been tested in feeding trials using vertebrates. These twelve secondary metabolites should be regarded as most important and need to be evaluated in each risk assessment procedure for mycotoxins in food commodities .     

ALTERATION OF GLUCOSINOLATE CONTENT, PATTERN, AND MUTAGENICITY OF CABBAGE (BRASSICA OLERACEA) GROWN ON MUNICIPAL SEWAGE SLUDGE—AMENDED SOIL

Cabbage (Brassica oleracea var. capitata) was grown on soil (control) or municipal sewage sludge-treated plots. The cabbage was freeze-dried and analyzed for glucosinolate content and pattern. Results showed that cabbage grown on sludge-amended soil contained only half the glucosinolate content of cabbage grown on the control plot. The pattern of individual glucosinolates present was also altered. The sludge-grown cabbage glucosinolate extract was shown to be mutagenic in the non-activated test system of S. typhimurium TA 100. Extracts of both sludge-grown and control cabbage were shown to enhance the mutagenicity on a dose-response basis of aflatoxin B₁, benzo(a)pyrene, and captan.     

TOXICITY OF 1, 2-DIMETHYLHYDRAZINE IN MICE: EFFECT OF DIET AND DEVELOPMENT OF TOLERANCE

The effect of diet on the lethality of 1, 2-dimethylhydrazine (DMH) injections was investigated using Swiss mice. Mortality was highest when mice were fed a nutrient-diluted/high-fat diet, was intermediate with a nutrient-diluted/low-fat diet and was lowest with laboratory chow. Wheat bran was not protective. Mice developed tolerance to DMH after receiving several injections of progressively increasing dose.     

EFFECT OF GAMMA RADIATION ON TOXICITY AND IMMUNOGENICITY OF SALMONELLA TYPHIMURIUM

Salmonella typhimurium H391 neurotoxin was sensitive to gamma radiation under in vivo conditions but resistant under in vitro conditions. Cells were detoxified after exposure to a radiation dose of 500 krad while isolated neurotoxin retained toxicity up to a dose of 3,000 krad. Detoxification of S. typhimurium H391 cells after exposure to 500 krad was accompanied by loss of antigenic properties which may be attributed to changes in the physico-chemical behavior of the neurotoxin moiety after in vivo radiation.     

GAS CHROMATOGRAPHIC DETERMINATION OF VOLATILE METABOLITES FORMED BY OBESUMBACTERIUM PROTEUS AND HAFNIA SPECIES

The taxonomic relationships between 19 ‘Hafnia protea’ strains, the Obesumbacterium proteus type strain, a ‘Flavobacterium proteus’ strain, 27 H. alvei strains, an unidentified Hafnia strain, two Enterobacter cloacae strains and the type strains of Yersinia enterocolitica, ‘Y. philomiragia’, Y. pseudotuberculosis and Y. ruckeri, were determined by numerical analysis of the metabolic end products . The numerical data revealed three definite fermentation groups at a 75% similarity level. The ‘H. protea’ (14), O. proteus, ‘F. Proteus’, four Yersinia as well as six H. alvei strains in fermentation group A followed the mixed acid fermentation. Twenty one H. alvei strains, six strains received as ‘H. protea’ the Hafnia sp. and the two E. cloacae strains followed the 2,3-butanediol fermentation (fermentation groups B and C). The strains in fermentation group B formed more acid and less 2,3-butanediol than strains in fermentation group C .     

ANTTNUTRITIONAL FACTORS AND TOXICITY IN RAW DRY BEANS (Phaseolus vulgaris, L.) OF 12 BRAZILIAN CULTTVARS

In the present work, the relative toxicity of 12 cultivars of raw dry beans was studied. When raw dry bean flours were given in the diets as the only source of protein the Wistar rats died within 3.8 (Goiano Precoce) to 8.4 days (Aroana). When whole seed flour was mixed with casein, strong impairment to ration utilization and animal development was observed, which was measured as loss of weigh:, decreased protein digestibility, decreased biological value and net protein utilization. A positive and significant correlation between toxicity and hemagglutination activity was established. On the other hand, antitryptic activity and tannin content did not show any correlation with the toxic effect. The deterimental effect of the lectins was evident by their interaction with the intestinal mucosa, which resulted in rupture of intestinal villii thus causing interference with absorption. These effects, when strong and prolonged, can cause the rat's death, in spite of the rat's adaptive and recovering capacity.     

氨基酸突变及其对蛋白质二级结构的影响

本文由分子进化数据从氨基酸的突变频率求出每一对氨基酸的相似指标,并讨论氨基酸突变对蛋白质二级结构的影响.     

EFFECT OF ADDITION OF α-, β-, AND κ-CASEIN, AND Na-CASEINATE ON VISCOELASTIC PROPERTIES OF SKIM MILK CURD

Creep compliance was used to determine the effects of the addition of α-, β-, and κ-casein, and Na-caseinate on the viscoelastic properties of skim milk curd. The results of all measurements can be represented by a six-element mechanical model. Addition of α- and β-casein, and Na-caseinate (1.80g/L) to raw skim milk reduced the instantaneous modulus of rigidity and final viscosity of the curd, while κ-casein addition at the same level increased both viscoelastic parameters. Shielding of κ-casein and depletion of serum Ca⁺⁺ ions by α- and β-casein is thought to have caused the reduction of curd rigidity and viscosity. Subsequent experiments indicated that the addition of β-casein before and after rennet hydrolysis produced different curd strength with the latter producing a stronger curd.