Acute toxicity of 12,13-epoxytrichothecenes in one-day-old broiler chicks.

Acute toxic effects of several 12,13-epoxytrichothecenes were investigated in 1-day-old broiler chicks by single oral doses. The 7-day median lethal dose values of purified 8-acetylneosolaniol, diacetoxyscirpenol, T-2 toxin, HT-2 toxin, neosolaniol, deacetyl-HT-2 toxin, and T-2 tetraol were 3.22 +/- 0.26, 3.82 +/- 0.40, 4.97 +/- 0.44, 7.22 +/- 0.39, 24.87 +/- 2.64, 30.18 +/- 7.53 (incomplete value), and 33.79 +/- 5.39 mg/kg of body weight, respectively. Deaths occurred during the 8- to 60-h period after dosing with the tested trichothecenes. Within 4 to 10 h after dosing, inappetence, asthenia, diarrhea, and coma generally developed. Sublethal doses of each toxin decreased feed consumption and weight gain proportionally with the amounts of toxins administered. These results demonstrate that the toxic potency of 12,13-epoxytrichothecenes varies depending on the modification of side chains in the molecule.     

Acute toxicity of 12,13-epoxytrichothecenes in one-day-old broiler chicks

Acute toxic effects of several 12,13-epoxytrichothecenes were investigated in 1-day-old broiler chicks by single oral doses. The 7-day median lethal dose values of purified 8-acetylneosolaniol, diacetoxyscirpenol, T-2 toxin, HT-2 toxin, neosolaniol, deacetyl-HT-2 toxin, and T-2 tetraol were 3.22 +/- 0.26, 3.82 +/- 0.40, 4.97 +/- 0.44, 7.22 +/- 0.39, 24.87 +/- 2.64, 30.18 +/- 7.53 (incomplete value), and 33.79 +/- 5.39 mg/kg of body weight, respectively. Deaths occurred during the 8- to 60-h period after dosing with the tested trichothecenes. Within 4 to 10 h after dosing, inappetence, asthenia, diarrhea, and coma generally developed. Sublethal doses of each toxin decreased feed consumption and weight gain proportionally with the amounts of toxins administered. These results demonstrate that the toxic potency of 12,13-epoxytrichothecenes varies depending on the modification of side chains in the molecule.     

Growth, zearalenone production and some metabolic activities of Fusarium moniliforme under salt stress

With a increasing salinity, a decrease in the growth rate of Fusarium moniliforme was observed. The percentage of germinated conidia decreased with increasing salinity (% germination ranged from 80.3% at 0.0% NaCl to 0.0% at 15% NaCl). Concentration of 12.5% NaCl produced the highest chlamydospore-like structures. Concentration of 5% NaCl increased zearalenone production which decreased with increasing salt stress. Escherichia coli was more tolerant to the toxin than Bacillus subtilis. The total amount of lipids produced by F. moniliforme changed with increasing the concentration of NaCl in the growth medium. The genomic DNA of the control and treated samples showed a common band of more than 20 kilobases. Similar RAPD-PCR patterns were also produced.     

Use of PCR for detection of maize seeds infected with the fungus Fusarium moniliforme Sheldon var.lactis

The procedure of the PCR for the detection of Fusarium moniliforme Sheldon var. lactis on the maize seeds has been elaborated. The based on a highly sensitive molecular genetics technology method of fungal pathogen detection allows to reveal its presence before the visual symptoms of seed damage.     

Structural requirements for the inhibitory action of 12,13-epoxytrichothecenes on protein synthesis in eukaryotes

1. The inhibitory actions of ten trichothecene antibiotics were investigated, in reticulocyte cell-free systems synthesizing protein in vitro, by studying polyribosome profiles and kinetics of amino acid incorporation in the presence or absence of the drugs. 2. The modes of action observed were critically dependent on the drug concentrations used, but the antibiotics tested could be divided into four distinct groups, each exerting a characteristic inhibitory response. 3. The inhibitory action observed in every case was controlled by the chemical structure of the individual trichothecene and in particular was closely related to the nature of the substituent groups present on C-3, C-4, C-8 and C-15 of the molecule.     

Fumonisins--novel mycotoxins with cancer-promoting activity produced by Fusarium moniliforme.

Cultures on corn of Fusarium moniliforme MRC 826 are known to cause leukoencephalomalacia in horses and to be toxic and hepatocarcinogenic in rats. Culture material of this F. moniliforme isolate has also been shown to exhibit cancer-promoting activity in a short-term cancer initiation-promotion bioassay with diethylnitrosamine-initiated rats and the induction of gamma-glutamyl-transpeptidase-positive (GGT+) foci as an endpoint after 4 weeks of promotion. This bioassay was used as a monitoring system to isolate cancer-promoting compounds from cultures of F. moniliforme MRC 826. Culture material was successively extracted with ethyl acetate and CH3OH-H2O (3:1). Most of the cancer-promoting activity was recovered in the CH3OH-H2O extract and remained in the aqueous phase following partitioning of this extract between CH3OH-H2O (1:3) and CHCl3. The CH3OH-H2O fraction was chromatographed on an Amberlite XAD-2 column, and the active fraction was eluted with CH3OH. This fraction was chromatographed on a silica gel column with CHCl3-CH3OH-CH3COOH (6:3:1) as eluent and further purified on a C18 reverse-phase column. Two pure compounds were isolated, and these have been chemically characterized and given the trivial names fumonisin B1 and B2. At least 2 g of the major compound fumonisin B1 was purified from 1 kg of culture material. Fumonisin B1 in the diet (0.1%) significantly (P less than 0.001) induced the formation of GGT+ foci in the livers of initiated as well as noninitiated rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fusaric acid accelerates the senescence of leaf in banana when infected by Fusarium

Fusarium oxysporum f.sp. cubense (FOC) is a causal agent of vascular wilt and leaf chlorosis of banana plants. Chloroses resulting from FOC occur first in the lowest leaves of banana seedlings and gradually progress upward. To investigate the responses of different leaf positions to FOC infection, hydroponic experiments with FOC inoculation were conducted in a greenhouse. Fusarium-infected seedlings exhibited a decrease in net photosynthesis rate, stomatal conductance, and transpiration rate of all leaves. The wilting process in Fusarium-infected seedlings varied with leaf position. Measurements of the maximum photochemical efficiency of photosystem II (F _V/F _max) and visualization with transmission electron microscopy showed a positive correlation between chloroplast impairment and severity of disease symptoms. Furthermore, results of malondialdehyde content and relative membrane conductivity measurements demonstrated that the membrane system was damaged in infected leaves. Additionally, the activities of phenylalanine ammonia-lyase, peroxidase and polyphenol oxidase were increased and total soluble phenolic compounds were significantly accumulated in the leaves of infected plants. The structural and biochemical changes of infected plants was consistent with plant senescence. As the FOC was not detected in infected leaves, we proposed that the chloroplast and membrane could be damaged by fusaric acid produced by Fusarium. During the infection, fusaric acid was first accumulated in the lower leaves and water-soluble substances in the lower leaves could dramatically enhance fusaric acid production. Taken together, the senescence of infected banana plants was induced by Fusarium infection with fusaric acid production and the composition of different leaf positions largely contribute to the particular senescence process.     

Occurrence of zearalenone in maize

The occurrence of zearalenone in whole plants and parts of maize usually used for silage making was investigated during the cultivation period of the crop. Zearalenone was detected upto several hundreds of μg/kg DM, that mainly accumulated at the end of the ripening process thus contaminating the silages subsequently. The highest concentrations of zearalenone were observed in the leaves especially at the bottom of the plant, which may correlate with leaf necrosis increasing towards harvest. Further research is needed to clarify health risks for farm animals due to uptake of contaminated feed and possible carry-over of zearalenone and its metabolites into the food chain of man.     

Occurrence and correlations of nematodes,Fusarium oxysporum and edaphic factors on banana plantations

Problems caused by nematodes and Fusarium wilt (Panama disease) on banana plantations are responsible for yield losses and are limiting to its cultivation. In the state of Goias, there is little information about the nematode occurence on this crop, and its relation with the incidence of Fusarium oxysporum f.sp. cubense (Foc). This research had the purpose to identify the occurrence of plant‐parasitic nematodes on banana plantations and to verify its correlation with the Fusarium wilt and with the soil attributes (pH, texture, nutrients). Twelve banana orchards in the state of Goias were sampled in the municipalities of Anapolis, Caiaponia, Goiatuba, Itaguaru, Itumbiara (two areas), Jatai, Morrinhos, Ouro Verde, Palestina, Taquaral and Uruana. All sampled areas, except Morrinhos, revealed contamination with Foc, and all areas had different genera of nematodes either in the soil or in the roots samples. Meloidogyne sp., Helicotylenchus sp. and Rotylenchus sp. were the main genera of plant‐parasitic nematodes found in the samples, with Meloidogyne sp. and Rotylenchus sp. being the most dominant and abundant genera. The presence of Pratylenchus sp. increases the population levels of F. oxysporum. Helicotylenchus sp. is highly correlated with high concentrations of Mn. High population density of Meloidogyne sp. was found in irrigated areas with low concentrations of P, Ca, Mg and soil pH.     

Occurrence and toxigenicity of shape Fusarium moniliforme from freshly harvested maize ears with special references to fumonisin production in Egypt

Using the seed-plate technique, 18 different isolates of Fusarium moniliforme were isolated on pentachloronitrobenzene (PCNB) agar medium from 18 samples of a local variety of corn collected from locations in Minia Governorate. The isolates of F moniliforme were screened for their ability to produce fumonisins on polished rice grains using the solid state fermentation technique. Based on thin layer chromatographic (TLC) analyses using silica gel plates, 14 of the 18 isolates tested produced FB₁ and FB₂ with R _f (0.17) and (0.24), respectively. Concentration of FB₁ was estimated using high performance liquid chromatography (HPLC). Production of FB₁ by the 14 isolates of F. moniliforme tested ranged from 69 to 4495 ppm indicating that mouldy corn may represent a health hazard to consumers. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phosphodiesterase-phosphomonesterases from Fusarium moniliforme. Separation and properties of four isozymes.

Purified phosphodiesterase-phosphomonoesterase was found to be composed of four isozymes with different isoelectric points. These isozymes, phosphodiesterase-phosphomonoesterases 1-4, were separated from one another by repeated isoelectric focusing. Very little difference in amino acid composition, enzymic properties or circular dichroism spectra was detected among the isozymes. Far-ultraviolet circular dichroism spectra showed that the enzyme contained about 10% alpha-helix and 40% beta-structure. Phosphodiesterase-phosphomonesterase is a glycoprotein, because it was adsorbed on concanavalin A-Sepharose 4B and gave a band of carbohydrate coincident with that of protein or enzymic activity on polyacrylamide disc gel electrophoresis. Carbohydrate analyses revealed that the enzyme contained 37 micron of N-acetylglucosamine and 358 micron of mannose per mg of protein. The carbohydrate contents of the four isozymes were almost the same.     

Protein synthesis by mammalian cells treated with C-3-modified analogs of the 12,13-epoxytrichothecenes T-2 and T-2 tetraol.

Modification at the C-3 position of the trichothecenes T-2 and T-2 tetraol affected their ability to inhibit protein synthesis in African green monkey kidney (Vero) and mouse erythroleukemia cells. Replacement of the 3-hydroxyl of T-2 with hydrogen caused a 24-fold decrease in activity, whereas acetylation resulted in a 500-to 1,000-fold decrease. Protection of the 3-hydroxyl with a tetrahydropyranyl moiety gave an analog that was 37-fold more inhibitory to Vero than to mouse erythroleukemia cells; with the other analogs a similar effect on protein synthesis was found for both types of cells. The analogs obtained after alkaline hydrolysis were much less potent than the parent trichothecenes. The 3-tetrahydropyranyl-modified analog was equivalent in potency to T-2 tetraol, while the deoxygenated species was at least threefold less potent. All T-2 analogs caused some degree of polysome "runoff," thereby demonstrating that these species inhibit protein synthesis at the chain initiation stage when added at their 50% infective dose concentrations or lower. From these results, we suggest that the 3-hydroxyl moiety is essential for T-2 to exhibit such high activity on eucaryotic cell protein synthesis and that modification at the C-3 position decreases but does not eliminate this activity.     

Transformation of 3-hydroxy-steroids by Fusarium moniliforme 7alpha-hydroxylase.

Transformation of physiologically important 3-hydroxy-steroids by the DHEA-induced 7alpha-hydroxylase of F. moniliforme was investigated. Whereas DHEA was almost totally 7alpha-hydroxylated, PREG, EPIA and ESTR were only partially converted into their 7alpha-hydroxylated derivatives because hydroxylation at other undetermined positions as well as reduction of ketone at C17 or C20 into hydroxyl also occurred. Cholesterol was not transformed by the enzyme. Kinetic parameters of the 7alpha-hydroxylation for these substrates were determined and confirmed that DHEA was the best substrate of the 7alpha-hydroxylase. Inhibition studies of DHEA 7alpha-hydroxylation by the other 3-hydroxy-steroids were also carried out and proved that DHEA, PREG, EPIA and ESTR shared the same active site of the enzyme. Induction effects of these steroids were compared, and DHEA appeared to be the best inducer of the 7alpha-hydroxylase of F. moniliforme.     

Interactions of Fusarium moniliforme,its metabolites and bacteria with corn

Fusarium moniliforme Sheldon is an economically important pathogen of corn (Zea mays L.) which causes stalk, root and ear rot. Several mycotoxins have also been isolated, identified and implicated in both animal and human toxicoses. The fungus can be disseminated in symptomless corn seed and can also survive in crop residues in the soil. Asymptomatic infection may be related to different corn cultivars, fungal strains, and environmental factors. Symptomatic expression of pathogenicity may vary, but usually the result of such infections is death of the plant. The greatest concern is the asymptomatic infection, since it is in this form that fungal toxins may surreptitiously enter animal and human food chains. F. moniliforme produces both fusaric acid, which is phytotoxic to corn and interferes with seed germination, and plant growth regulators that may affect pathogenicity of the fungus or be associated with the production of mycotoxins. Other metabolites, including fusarin C, moniliformin, and the fumonisins, may or may not be phytotoxic, but are associated with animal and human toxicoses. The control of F. moniliforme in corn is therefore quite important. One potential means to accomplish this reduction is biocontrol by the application of antagonistic rhizobacteria to corn kernels at planting. To be effective the bacteria must be able to colonize the corn root system and be able to prevent root infection by successful competing with F. moniliforme which may be accomplished by siderophore and or antibiotic activity.     

Isolation of beauvericin as an insect toxin from Fusarium semitectum and Fusarium moniliforme var. subglutinans

Nonpolar methylene chloride-soluble extracts from the mycelia of Fusarium semitectum and Fusarium moniliforme var. subglutinans were toxic to Colorado potato beetles. The major toxic metabolite was isolated and found to be the cyclodepsipeptide, beauvericin. This is the first report of the isolation of beauvericin from the genus Fusarium.     

Production of fumonisins by Fusarium moniliforme and Fusarium proliferatum isolates associated with equine leukoencephalomalacia and a pulmonary edema syndrome in swine.

Fumonisin B1 (FB1) and FB2 were isolated from corn cultures of both Fusarium moniliforme and Fusarium proliferatum. Respective concentrations in culture materials of FB1 and FB2 ranged from 960 to 2,350 and 120 to 320 micrograms/g for F. moniliforme and from 1,670 to 2,790 and 150 to 320 micrograms/g for F. proliferatum. Thin-layer chromatography, gas chromatography-mass spectroscopy, high-performance liquid chromatography, and liquid secondary ion mass spectroscopy were used for detection. Fumonisins from F. proliferatum have not previously been reported.