Toxicity data relevant for hazard characterization

Individual and combined occurrences of the prevalent mycotoxins in commercial feline and canine food

Mycotoxins, such as aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisins (FBs), ochratoxin A (OTA), T-2 toxin (T-2), and zearalenone (ZEN), can contaminate animal feeds and pose risks to animal health and production performance. These mycotoxins are commonly found in cereals and grains, with the increased use of cereals in pet food, there is a rising concern about mycotoxin contamination among pet owners. To address this, we analyzed imported brands of feline and canine food from the Chinese market produced in 2021-2022. Ninety-three samples were analyzed, comprising 45 feline food and 48 canine food samples. Among them, 14 were canned food and 79 were dry food. The results indicate that AFB1, DON, FBs, OTA, T-2, and ZEN occurred in 32.26%, 98.92%, 22.58%, 73.12%, 55.91%, and 7.53% of the samples, respectively. The most prevalent mycotoxin was DON, followed by OTA, T-2, AFB1, and FBs, whereas ZEN was less frequently detected. The mean concentrations of the six mycotoxins in pet feed samples were 3.17 μg/kg for AFB1, 0.65 mg/kg for DON, 2.15 mg/kg for FBs, 6.27 μg/kg for OTA, 20.00 μg/kg for T-2, and 30.00 μg/kg for ZEN. The levels of mycotoxins were generally below the limits of the Pet Feed Hygiene Regulations of China and the EU. Notably, a substantial majority of the pet food samples (88 out of 93) were contaminated by two or more mycotoxins. AFB1, FBs, OTA, and ZEN occurred slightly more often in feline food than in canine food. Except for OTA, the contamination rates for the other five mycotoxins in canned food were lower than those in dry food. Moreover, except for AFB1, the levels of the other five mycotoxins in canned foods were lower than those in dry foods. This study highlights the widespread contamination of pet foods with mycotoxins, which poses a significant risk to pets from continuous exposure to multiple mycotoxins.

Rapid prediction of deoxynivalenol contamination in wheat bran by MOS-based electronic nose and characterization of the relevant pattern of volatile compounds

BACKGROUND

Deoxynivalenol (DON) is a mycotoxin, mainly produced by Fusarium sp., most frequently occurring in cereals and cereal-based products. Wheat bran refers to the outer layers of the kernel, which has a high risk of damage due to chemical hazards, including mycotoxins. Rapid methods for DON detection in wheat bran are required.

RESULTS

A rapid screening method using an electronic nose (e-nose), based on metal oxide semiconductor sensors, has been developed to distinguish wheat bran samples with different levels of DON contamination. A total of 470 naturally contaminated wheat bran samples were analyzed by e-nose analysis. Wheat bran samples were divided in two contamination classes: class A ([DON] ≤ 400 µg kg^-1 , 225 samples) and class B ([DON] > 400 µg kg^-1 , 245 samples). Discriminant function analysis (DFA) classified wheat bran samples with good mean recognizability in terms of both calibration (92%) and validation (89%). A pattern of 17 volatile compounds of wheat bran samples that were associated (positively or negatively) with DON content was also characterized by HS-SPME/GC-MS.

CONCLUSIONS

These results indicate that the e-nose method could be a useful tool for high-throughput screening of DON-contaminated wheat bran samples for their classification as acceptable / rejectable at contamination levels close to the EU maximum limit for DON, reducing the number of samples to be analyzed with a confirmatory method. © 2018 Society of Chemical Industry.

Comparison of Anorectic Potencies of Type A Trichothecenes T-2 Toxin, HT-2 Toxin, Diacetoxyscirpenol, and Neosolaniol

Trichothecene mycotoxins are common contaminants in cereal grains and negatively impact human and animal health. Although anorexia is a common hallmark of type B trichothecenes-induced toxicity, less is known about the anorectic potencies of type A trichothecenes. The purpose of this study was to compare the anorectic potencies of four type A trichothecenes (T-2 toxin (T-2), HT-2 toxin (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO)) in mice. Following oral exposure to T-2, HT-2, DAS, and NEO, the no observed adverse effect levels (NOAELs) and lowest observed adverse effect levels (LOAELs) were 0.01, 0.01, 0.1, and 0.01 mg/kg body weight (BW), and 0.1, 0.1, 0.5, and 0.1 mg/kg BW, respectively. Following intraperitoneal (IP) exposure to T-2, HT-2, DAS, and NEO, the NOAELs were 0.01 mg/kg BW, except for DAS (less than 0.01 mg/kg BW), and the LOAELs were 0.1, 0.1, 0.01, and 0.1 mg/kg BW, respectively. Taken together, the results suggest that (1) type A trichothecenes could dose-dependently elicit anorectic responses following both oral gavage and IP exposure in mice; (2) the anorectic responses follow an approximate rank order of T-2 = HT-2 = NEO > DAS for oral exposure, and DAS > T-2 = HT-2 = NEO for IP administration; (3) IP exposure to T-2, HT-2, DAS, and NEO evoked stronger anorectic effects than oral exposure. From a public health perspective, comparative anorectic potency data should be useful for establishing toxic equivalency factors for type A trichothecenes.

Intestinal toxicity of the type B trichothecene mycotoxin fusarenon-X: whole transcriptome profiling reveals new signaling pathways

The few data available on fusarenon-X (FX) do not support the derivation of health-based guidance values, although preliminary results suggest higher toxicity than other regulated trichothecenes. Using histo-morphological analysis and whole transcriptome profiling, this study was designed to obtain a global view of the intestinal alterations induced by FX. Deoxynivalenol (DON) served as a benchmark. FX induced more severe histological alterations than DON. Inflammation was the hallmark of the molecular toxicity of both mycotoxins. The benchmark doses for the up-regulation of key inflammatory genes by FX were 4- to 45-fold higher than the previously reported values for DON. The transcriptome analysis revealed that both mycotoxins down-regulated the peroxisome proliferator-activated receptor (PPAR) and liver X receptor - retinoid X receptor (LXR-RXR) signaling pathways that control lipid metabolism. Interestingly, several pathways, including VDR/RXR activation, ephrin receptor signaling, and GNRH signaling, were specific to FX and thus discriminated the transcriptomic fingerprints of the two mycotoxins. These results demonstrate that FX induces more potent intestinal inflammation than DON. Moreover, although the mechanisms of toxicity of both mycotoxins are similar in many ways, this study emphasize specific pathways targeted by each mycotoxin, highlighting the need for specific mechanism-based risk assessments of Fusarium mycotoxins.

Cellular responses to T-2 toxin and/or deoxynivalenol that induce cartilage damage are not specific to chondrocytes

The relationship between T-2 toxin and deoxynivalenol (DON) and the risk of Kashin-Beck disease is still controversial since it is poorly known about their selectivity in cartilage damage. We aimed to compare the cytotoxicity of T-2 toxin and DON on cell lines representative of cell types encountered in vivo, including human chondrocytes (C28/I2), human hepatic epithelial cells (L-02) and human tubular epithelial cells (HK-2). In addition, we determined the distribution of T-2 toxin and DON in Sprague-Dawley (SD) rats after a single dose exposure. T-2 toxin or DON decreased proliferation in a time- and concentration-dependent manner and their combination showed a similar antagonistic effect in C28/I2, L-02 and HK-2 cells. Moreover, we observed cell cycle arrest and apoptosis, associated with increased oxidative stress and decline in mitochondrial membrane potential induced by T-2 toxin and/or DON. In vivo study showed that T-2 toxin and DON did not accumulate preferentially in the knee joint compared to liver and kidney after an acute exposure in SD rats. These results suggest that T-2 toxin and/or DON inhibit proliferation and induce apoptosis through a possible mechanism involving reactive oxygen species-mediated mitochondrial pathway that is not specific for chondrocytes in vitro or joint tissues in vivo.

Individual and combined effects of feed artificially contaminated with with fumonisin B1 and T-2 toxin in weaned rabbits

Co-contamination of feed and feed raw materials with two or more mycotoxins is frequently reported, however, only a few studies have investigated the combined effects of low doses of multiple mycotoxins. In the present study the individual and combined effects of 10 mg/kg fumonisin B1 and 2 mg/kg T-2 toxin (n=12/group) were investigated in weaned rabbits. Mycotoxin contaminated feed was produced by adding fungal cultures of Fusarium verticillioides and Fusarium sporotrichioides, and fed to 40 days old rabbits during 28 days. Feed intake and body weight were measured weekly, serum biochemistry and antioxidant parameters on day 0, 14 and 28, while histopathological examination and comet assay were performed at the end of the experiment. T-2 exposure both alone and in combination resulted in 15-18% less final body weight compared to the control and FB1 treatment. There was a significant increase in the concentration of plasma total protein, albumin, fructosamine and creatinine in the group treated with FB1 compared to the control. The liver and the kidney of most animals treated with T-2 toxin, FB1 and their combination showed pathological changes, occurring more frequent in animals exposed to both toxins. T-2 resulted in depletion of lymphocytes in the spleen. FB1 and T-2 exerted synergistic effect on the antioxidant/oxidative parameters after 2 weeks of exposure, manifesting in less glutathione and glutathione peroxidase, while more malondialdehyde was produced. Both toxins caused DNA damage in the lymphocytes, which was more pronounced in the group fed T-2 toxin and T-2 combined with FB1, without additive or synergistic effects.

The Effect of Low Monotonic Doses of Zearalenone on Selected Reproductive Tissues in Pre-Pubertal Female Dogs--A Review

The growing interest in toxic substances combined with advancements in biological sciences has shed a new light on the problem of mycotoxins contaminating feeds and foods. An interdisciplinary approach was developed by identifying dose-response relationships in key research concepts, including the low dose theory of estrogen-like compounds, hormesis, NOAEL dose, compensatory response and/or food tolerance, and effects of exposure to undesirable substances. The above considerations increased the researchers’ interest in risk evaluation, namely: (i) clinical symptoms associated with long-term, daily exposure to low doses of a toxic compound; and (ii) dysfunctions at cellular or tissue level that do not produce clinical symptoms. Research advancements facilitate the extrapolation of results and promote the use of novel tools for evaluating the risk of exposure, for example exposure to zearalenone in pre-pubertal female dogs. The arguments presented in this paper suggest that low doses of zearalenone in commercial feeds stimulate metabolic processes and increase weight gains. Those processes are accompanied by lower proliferation rates in the ovaries, neoangiogenesis and vasodilation in the ovaries and the uterus, changes in the steroid hormone profile, and changes in the activity of hydroxysteroid dehydrogenases. All of the above changes result from exogenous hyperestrogenizm.

Effect of mycotoxin-containing diets on epigenetic modifications of mouse oocytes by fluorescence microscopy analysis

Mycotoxins, such as aflatoxin (AF), fumonisin B1, zearalenone (ZEA), and deoxynivalenol (DON), are commonly found in many food commodities. Mycotoxins have been shown to increase DNA methylation levels in a human intestinal cell line. We previously showed that the developmental competence of oocytes was affected in mice that had been fed a mycotoxin-containing diet. In this study, we explored possible mechanisms of low mouse oocyte developmental competence after mycotoxin treatment in an epigenetic modification perspective. Mycotoxin-contaminated maize (DON at 3,875 μg/kg, ZEA at 1,897 μg/kg, and AF at 806 μg/kg) was included in diets at three different doses (mass percentage: 0, 15, and 30%) and fed to mice for 4 weeks. The fluorescence intensity analysis showed that the general DNA methylation levels increased in oocytes from high dose mycotoxin-fed mice. Mouse oocyte histone methylation was also altered. H3K9me3 and H4K20me3 level increased in oocytes from mycotoxin-fed mice, whereas H3K27me3 and H4K20me2 level decreased in oocytes from mycotoxin-fed mice. Thus, our results indicate that naturally occurring mycotoxins have effects on epigenetic modifications in mouse oocytes, which may be one of the reasons for reduced oocyte developmental competence.

The effect of experimental fusarium mycotoxicosis on microbiota diversity in porcine ascending colon contents

The objective of the study was to determine the effect of exposure of pigs to the Fusarium mycotoxins zearalenone (ZEN) and deoxynivalenol (DON), administered together and separately, on the colon microbiota. An experiment was conducted for 42 days on gilts, randomly assigned to four groups and administered either ZEN, DON, ZEN+DON, or a placebo. The number of aerobic mesophilic bacteria, yeasts, molds, anaerobic Clostridium perfringens, fecal streptococci, Enterobacteriaceae, Escherichia coli, and lactic acid bacteria (LAB) were determined in the contents of the ascending colon. The influence of mycotoxins on the functional diversity of the colonic microbiota was assessed using EcoPlate tests (Biolog). Analysis revealed the predominance of LAB in all groups of pigs. Zearalenone, administered separately and together with DON, was found to have an adverse effect on mesophilic aerobic bacteria, but only after long exposure to this mycotoxin. During the six weeks of the experiment, the concentration of C. perfringens, E. coli, and other bacteria in the family Enterobacteriaceae was most considerably reduced in the experimental groups exposed to zearalenone, both separately and together with DON. Mycotoxins also affected the functional biodiversity of microorganisms. Both Shannon’s diversity index and the number of catabolized substrates in Biolog plate (the R index) were much higher in the group subjected to mixed mycotoxicosis.

Toxicokinetics and tissue depletion of Fusarenon-X and its metabolite nivalenol in piglets

Fusarenon-X (FX) is one of the trichothecene mycotoxins mainly produced by Fusarium crookwellense, which naturally occurs in agricultural commodities such as wheat and barley. To investigate the toxicokinetics of FX and its metabolite nivalenol (NIV), FX was then administered intravenously or orally to piglets at a dosage of 1mg/kg body weight. The concentrations of FX and NIV in the plasma and various tissues were measured using LC-MS/MS. The plasma concentrations of FX in the piglets were determined up to 24h and 48h after iv and po administration, respectively, and the concentration of NIV was detected up to 12h after both types of administration. The Cp(0) of FX was 580.28 ± 140.81 ng/ml after iv administration. The values of t1/2β, Vss and Foral were 1.71 ± 0.74 h, 0.009 ± 0.002 ml and 74.40 ± 18.96%, respectively. FX and NIV were detectable in the vital organs up to 24h after po administration. The peak level of FX in the liver, the kidney, and the spleen, respectively, were 165.95 ± 9.68 ng/g, 66.29 ± 8.48 and 7.35 ± 0.69 ng/g at 3h following po administration. In vitro of liver postmitochondrial fractions with FX demonstrated that the liver and kidney are capable of FX-to-NIV metabolism.

Lipid metabolism disorders, lymphocytes cells death, and renal toxicity induced by very low levels of deoxynivalenol and fumonisin b1 alone or in combination following 7 days oral administration to mice

SCOPE

In our previous study focused on in vitro interactive effect of Fusarium mycotoxins deoxynivalenol (DON) and fumonisin B1 (FB1), we reported that these toxins tested at low level and in association could lead to additive or synergistic cytotoxic effect. The aim of the present study is to confirm those findings by in vivo study.

MATERIALS AND METHODS

Swiss mice were orally administered with low doses of DON (45 μg/kg bw/day), FB1 (110 μg/kg bw/day), and their mixture (DON + FB1) for 7 days.

RESULTS

As results, no death or abnormal symptoms were observed in all groups. The significant of loss of weight was observed in females group treated with FB1 and its association with DON. Serum chemistry examinations revealed that disorders in lipid metabolism, renal filtration perturb and a rhabdomyolysis. DON has been found as particular inducer of kidney cell deoxyribonucleic acid (DNA) methylation and blood lymphocytes cell death as measured by lymphocytes DNA fragmentation. Female mice were more sensitive and the mixture of DON and FB1 led to additive or more than additive effect particularly for their target kidney which showed different pattern of toxicity.

CONCLUSION

Based on the results of this study, the no-observed-adverse effect level (NOAEL) o both DON and FB1 should be low than 45 μg/kg bw/day and 110 μg/kg bw/day, respectively in mice.

T-2 toxin and its metabolite HT-2 toxin combined with insulin-like growth factor-I modify progesterone secretion by porcine ovarian granulosa cells

The aim of this study was to examine the effect of A-trichothecenes T-2 and HT-2 toxins combined with insulin-like growth factor I (IGF-I) on the release of steroid hormone progesterone (P4) by porcine ovarian granulosa cells (GCs). The cells were incubated without (control) or with treatments of A-trichothecenes T-2 (100 and 1000 ng/mL)/ HT-2 (100 and 1000 ng/mL) combined with IGF-I (1, 10 and 100 ng/mL) for 24 h. Progesterone secretion was determined by RIA. The release of P4 by GCs after addition of T-2 toxin (at 100 ng/mL) combined with IGF-I (at 10 but not at 1 and 100 ng/mL) and HT-2 toxin (at 100 ng/mL) combined with IGF-I (at all doses) was significantly (P < 0.05) inhibited. On the other hand the release of P4 after addition of T-2/ HT-2 toxin (at 1000 ng/mL) combined with IGF-I (at all doses) was significantly (P < 0.05) stimulated. Alone IGF-I addition (at 10, 100 but not at 1 ng/mL) significantly (P < 0.05) stimulated P4 release by GCs. The results of our in vitro study indicate the T-2 and HT-2 toxins combined with IGF-I could modify progesterone secretion by porcine ovarian granulosa cells and potentially regulate process of steroidogenesis in the ovaries. Currently, occurrence of mycotoxins in food and feed is a worldwide problem and therefore study of these toxins as well as their interaction with different substances such as growth factors could be beneficial for better understanding of mechanism of their toxic effects in organism.

Comparative hematoxicity of fusirium mycotoxin in experimental sprague-dawley rats

Mycotoxins are fungal toxin and contaminated to human through food-stuffs. Hematological abnormality, mainly thrombocytopenia and leukopenia are induced after consumption of mycotoxin. Experiments were conducted to evaluate the hematotoxicity of trichothecenes mycotoxins in Sprague-Dawley rats. Hematological parameters viz. Hemoglobin, hematocrit, erythrocyte count (RBC), white blood cell count (WBC), lymphocytes, monocytes, neutrophils, eosinophils, basophils, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, mean platelet volume, plateletcrit and platelet distribution width were determined at 0, 6, 12 and 24 h after injection of 0.5 ml of T-2, Deoxynivalenol (DON), nivalenol, zearalenone, neosolaniol, ochratoxin-B mycotoxin equivalent to 1 × 10(-3) μg/μl to Sprague-Dawley rats. Experiments showed that trichothecenes toxin produces severe hematological alternation. The reductions of RBC and WBC were observed in all Fusarium mycotoxins treated group. T-2 toxin group shows severe toxicity as compared to other mycotoxin treated group. DON is the least hematotoxicity and T-2 the most.

Modeling deoxynivalenol contamination of wheat in northwestern Europe for climate change assessments

Climate change will affect mycotoxin contamination of feed and food. Mathematical models for predicting mycotoxin concentrations in cereal grains are useful for estimating the impact of climate change on these toxins. The objective of the current study was to construct a descriptive model to estimate climate change impacts on deoxynivalenol (DON) contamination of mature wheat grown in northwestern Europe. Observational data from 717 wheat fields in Norway, Sweden, Finland, and The Netherlands were analyzed, including the DON concentrations in mature wheat, agronomical practices, and local weather. Multiple regression analyses were conducted, and the best set of explanatory variables, mainly including weather factors, was selected. The final model included the following variables: flowering date, length of time between flowering and harvest, wheat resistance to Fusarium infection, and several climatic variables related to relative humidity, temperature, and rainfall during critical stages of wheat cultivation. The model accounted for 50 % of the variance, which was sufficient to make this model useful for estimating the trends of climate change on DON contamination of wheat in northwestern Europe. Application of the model in possible climate change scenarios is illustrated.

Human and animal health risk assessments of chemicals in the food chain: comparative aspects and future perspectives

Chemicals from anthropogenic and natural origins enter animal feed, human food and water either as undesirable contaminants or as part of the components of a diet. Over the last five decades, considerable efforts and progress to develop methodologies to protect humans and animals against potential risks associated with exposure to such potentially toxic chemicals have been made. This special issue presents relevant methodological developments and examples of risk assessments of undesirable substances in the food chain integrating the animal health and the human health perspective and refers to recent Opinions of the Scientific Panel on Contaminants in the Food Chain (CONTAM) of the European Food Safety Authority (EFSA). This introductory review aims to give a comparative account of the risk assessment steps used in human health and animal health risk assessments for chemicals in the food chain and provides a critical view of the data gaps and future perspectives for this cross-disciplinary field.

(-)-Epigallocatechin gallate suppresses the cytotoxicity induced by trichothecene mycotoxins in mouse cultural macrophages

Trichothecene mycotoxins are toxic secondary metabolites produced by a number of fungi including Fusarium species, which adversely affect lymphocytes. Deoxynivalenol (DON) and HT-2 toxin (HT-2) belong to the trichothecene group of mycotoxins and the occurrence of cereals and foodstuffs with these compounds are serious health problems. The aim of this study was to examine the effect of (-)-epigallocatechin gallate (EGCG), one of the main components in green tea catechins, on DON- or HT-2-induced cytotoxicity in mouse macrophages. EGCG had protective effects against the trichothecene-induced cytotoxicities of both mycotoxins. Additionally, EGCG suppressed the DON-induced activation of caspase-3/7, which is an indicator of apoptosis. These results indicate that EGCG might be useful in protection against DON- or HT-2-induced cell death, suggesting that EGCG could contribute to reducing the toxicities of trichothecenes.

Poor elimination rates in waste water treatment plants lead to continuous emission of deoxynivalenol into the aquatic environment

Deoxynivalenol (DON) is one of the most prominent mycotoxins generated by fungi of the generus Fusarium on crops. Its presence in surface waters was recently demonstrated. Here, we elucidate the occurrence and behaviour of DON in three Swiss waste water treatment plants (WWTP) as a result of human consumption and excretion. DON was shown to be omnipresent in the primary effluent samples of these WWTP in concentrations from 32 to 118 ng/L. Corresponding loads were a factor of 1.3-2.3 higher than predicted based on human excretion data from the literature. DON elimination rates in WWTP ranged from 33 to 57%. These rather low percentages were confirmed with a further, more detailled study conducted at WWTP Kloten/Opfikon (average elimination rate 32%). The relative importance of WWTP as a source of DON in surface waters was compared with agricultural emissions due to runoff from Fusarium infected crops. Both sources seem to contribute equally to the total DON exposure of surface waters of a few ng/L, however, their input dynamics vary considerably in space and time.

Rapid and non-invasive analysis of deoxynivalenol in durum and common wheat by Fourier-Transform Near Infrared (FT-NIR) spectroscopy

Fourier transform near-infrared spectroscopy (FT-NIR) was used for rapid and non-invasive analysis of deoxynivalenol (DON) in durum and common wheat. The relevance of using ground wheat samples with a homogeneous particle size distribution to minimize measurement variations and avoid DON segregation among particles of different sizes was established. Calibration models for durum wheat, common wheat and durum + common wheat samples, with particle size <500 microm, were obtained by using partial least squares (PLS) regression with an external validation technique. Values of root mean square error of prediction (RMSEP, 306-379 microg kg(-1)) were comparable and not too far from values of root mean square error of cross-validation (RMSECV, 470-555 microg kg(-1)). Coefficients of determination (r(2)) indicated an "approximate to good" level of prediction of the DON content by FT-NIR spectroscopy in the PLS calibration models (r(2) = 0.71-0.83), and a "good" discrimination between low and high DON contents in the PLS validation models (r(2) = 0.58-0.63). A "limited to good" practical utility of the models was ascertained by range error ratio (RER) values higher than 6. A qualitative model, based on 197 calibration samples, was developed to discriminate between blank and naturally contaminated wheat samples by setting a cut-off at 300 microg kg(-1) DON to separate the two classes. The model correctly classified 69% of the 65 validation samples with most misclassified samples (16 of 20) showing DON contamination levels quite close to the cut-off level. These findings suggest that FT-NIR analysis is suitable for the determination of DON in unprocessed wheat at levels far below the maximum permitted limits set by the European Commission.

Fusarium spp. contamination of wheat, maize, soybean, and pea grain in Croatia

From 2002 to 2008, 203 samples of wheat, maize, soybean, and pea were analysed for the presence of Fusarium species. Contamination with Fusarium spp., expressed as the percentage of seeds with Fusarium colonies, ranged from 5 % to 69 % for wheat, from 25 % to 100 % for maize, from 4 % to 17 % for soybean, and from 3 % to 17 % for pea. 187 isolates were collected and the following 19 species determined: F. graminearum, F. poae, F. avenaceum, F. verticillioides, F. sporotrichioides, F. heterosporum, F. crookwellense, F. tricinctum, F. semitectum, F. oxysporum, F. proliferatum, F. solani, F. equiseti, F. pseudograminearum, F. chlamydosporum, F. sambucinum, F. compactum, F. scirpi, and F. culmorum. Dominant species were F. graminearum on wheat (27 % of isolates), F. verticillioides on maize (83 % of isolates), F. sporotrichioides on soybean (34 % of isolates), and F. proliferatum on pea (29 % of isolates). Among species identified, F. heterosporum, F. crookwellense, F. pseudograminearum, F. sambucinum, and F. compactum have been reported for the first time in Croatia.

Pathway of deoxynivalenol-induced apoptosis in human colon carcinoma cells

The mycotoxin, deoxynivalenol (DON), is generally detected in cereal grains and grain-based food products worldwide. Therefore, DON has numerous toxicological effects on animals and humans. The present investigation was conducted to determine the molecular aspects of DON toxicity on human colon carcinoma cells (HT 29). To this aim, we have monitored the effects of DON on (i) cell viability, (ii) Heat shock protein expressions as a parameter of protective and adaptive response, (iii) oxidative damage and (iv) cell death signalling pathway. Our results clearly showed that DON treatment inhibits cell proliferation, did not induce Hsp 70 protein expression and reactive oxygen species generation. We have also demonstrated that this toxin induced a DNA fragmentation followed by p53 and caspase-3 activations. Finally, our findings suggested that oxidative damage is not the major contributor to DON toxicity. This mycotoxin induces direct DNA lesions and could be considered by this fact as a genotoxic agent inducing cell death via an apoptotic process.

Development of a pig jejunal explant culture for studying the gastrointestinal toxicity of the mycotoxin deoxynivalenol: histopathological analysis

The digestive tract is a target for the mycotoxin deoxynivalenol (DON), a major cereals grain contaminant of public health concern in Europe and North America. Pig, the most sensitive species to DON toxicity, can be regarded as the most relevant animal model for studying the intestinal effects of DON. A pig jejunal explants culture was developed to assess short-term effects of DON. In a first step, jejunal explants from 9-13 week-old and from 4-5 week-old pigs were cultured in vitro for up to 8h. Explants from younger animals were better preserved after 8h, as assessed by morphological scores and by villi lengths. In a second step, DON dose-related alterations of the jejunal tissue were observed, including shortened and coalescent villi, lysis of enterocytes, oedema. After 4h of DON exposure of explants from 4-5 week-old pigs, a no-effect concentration level of 1 microM was estimated (corresponding to diet contaminated with 0.3mg DON/kg) based on morphological scores, and of 0.2 microM based on villi lengths. In conclusion, our data indicate that pig intestinal explants represent a relevant and sensitive model to investigate the effects of food contaminants.

Transcriptomic-based bioassays for the detection of type A trichothecenes

The type A trichothecenes T-2 toxin (T-2) and HT-2 toxin (HT-2) are hazardous Fusarium products that contaminate many field crops growing in cold to temperate regions across the world. Toxicity studies in laboratory and farm animals have been used to derive a temporary tolerable daily intake (t-TDI) for the sum of T-2 and HT-2 of no more than 60 ng/kg body weight. To protect the consumers, it is now necessary to screen a large number of food samples for the presence of these poisonous fungal metabolites. Towards that goal, we discovered that the transcriptional apparatus of a human carcinoma cell line (MCF7) provides a sensitive biological sensor of type A trichothecenes. In fact, exposure of this easy-to-culture cell line to T-2 or HT-2 results in the regulation of >2,000 different transcripts with expression changes ranging from >5,000-fold gene inductions to >40-fold gene repressions. These transcriptional responses have been exploited to develop practical microchip and reverse transcription-polymerase chain reaction (RT-PCR) assays for the detection of type A trichothecenes at parts per billion levels.

A new PCR-based bioassay strategy for the detection of type A trichothecenes in food

Type A trichothecenes (primarily T-2 and HT-2 toxins) are common fungal metabolites found in a wide range of grains and other field crops grown in temperate climatic zones. By acting as potent inhibitors of protein synthesis, T-2 and HT-2 exert adverse effects particularly against rapidly proliferating tissues, including the bone marrow, the immune system and epithelial cells. Based on toxicity studies in laboratory and farm animals, a temporary tolerable daily intake for the sum of T-2 and HT-2 has been issued in the European Union. However, exposure assessments suggest that the combined intake of these natural compounds exceeds in many cases the proposed threshold. To further protect the consumers, it is therefore necessary to screen a large number of food samples for parts per billion levels of both T-2 and HT-2. Towards that goal, we are the first to report that these two type A trichothecenes induce fast and high-amplitude transcriptional changes in cultured human breast cancer cells. This specific response involving marker gene inductions by more than 1000-fold has been exploited to develop a real-time PCR-based screening method that displays a limit of detection of 5 ng g(-1) for T-2 and 10 ng g(-1) for HT-2. The practicability of this bioassay is demonstrated by its application to the detection of type A trichothecenes in different food matrices.

Fusarium populations on Chinese barley show a dramatic gradient in mycotoxin profiles

We report on a large gene bank of Fusarium isolates established by a broad survey conducted in 2005 in which infected barley ears were collected in 23 counties of seven provinces and two municipalities along the Yangtze River in China. In total, 1,894 single spore isolates were obtained. The isolates were characterized at the species level by a newly developed and robust set of diagnostic primers based on single nucleotide polymorphisms (SNPs) among members of the F. graminearum clade. In addition, we determined their chemotype using previously described polymerase chain reaction (PCR) primers. The results showed that in all regions F. asiaticum was the predominant species causing Fusarium head blight (FHB) on barley in China (N = 1,706), while in the upper valleys of the Yangtze River also F. graminearum sensu stricto, F. meridionale, and F. proliferatum were found. Major differences in the chemotypes were found in the F. asiaticum populations, from very high to exclusive nivalenol (NIV) chemotypes in the mountainous upper valleys of the Yangtze River to predominantly deoxynivalenol (DON) chemotypes in the middle and lower valleys. In contrast to the F. asiaticum isolates from three counties in Sichuan province, which were largely NIV producers (278 of 291), F. graminearum isolates from these sampling sites were for the vast majority (27 of 28) DON producers, indicating that despite sharing the same habitat, these sympatric species apparently have unique mycotoxin chemotypes.

Immunotoxicity of nivalenol after subchronic dietary exposure to rats

Immunobiological effects of nivalenol (NIV), a trichothecene mycotoxin produced by Fusarium nivale, were examined in male F344 rats after 90-day dietary exposure at doses of 0, 0.4, 1.5, and 6.9 mg/kg body weight/day (0, 6.25, 25 and 100 ppm, respectively) in a subchronic toxicity study. With regards to the serum immunoglobulin levels, a slight increase of IgM was observed only at 6.9 mg/kg (26% increase), while levels of IgG and IgA did not fluctuate at any dose. Flow cytometric analysis of splenic cells revealed a dose-dependent decrease of T lymphocyte/B lymphocyte (CD3(+)/B220(+)) ratio from 1.5mg/kg and an elevated CD4(+)helper/CD8(+)cytotoxic T lymphocyte ratio at 6.9 mg/kg. Furthermore, increases of natural killer (NK) activity of splenic lymphocytes against YAC-1 target cells were observed at all doses, while the magnitude of changes was similar between 1.5 and 6.9 mg/kg. At 6.9 mg/kg, the reduction of the ratio of NKR-P1A(+) splenic cells, which is an indicator of NK cells in the spleen, was apparent. As with other previous studies of NIV, decreased body weight was observed from 1.5 mg/kg during the experiment in the present study. In summary, NIV affected immune function in rats after 90-day dietary exposure, the effects being apparent from 0.4 mg/kg judging from the increase of NK activity, although nutritional suppression might have influenced the immunological changes appeared from 1.5mg/kg.

Distribution of toxigenicFusariumspp. and mycotoxin production in milling fractions of durum wheat

A reliable and sensitive PCR assay to specifically detect trichothecene-producing Fusarium spp. in milling fractions and kernel tissue of naturally infected durum wheat is reported. Assays were based on a combination of primers derived from the trichodiene synthase and the beta-tubulin genes. The occurrence of toxigenic Fusarium spp. in semolina and wheat tissue (grain ends, crease, pericarp, aleurone layer, germ and albumen) was detected, even for a weakly contaminated wheat sample. Penetration of toxigenic Fusarium spp. into the interior of durum wheat kernel was demonstrated for the Nefer variety, indicating that none of the tissue structures within the wheat kernel acted as an effective barrier to fungal invasion. Moreover, after inoculation by toxigenic Fusarium strains, semolina was shown to allow high yields of trichothecenes, while bran was demonstrated to contain biochemical inhibitors able to significantly reduce trichothecene production. These results will be useful in improving breeding strategies to control trichothecene contamination of durum wheat kernels.

Selective Sample Cleanup by Reusable Sol−Gel Immunoaffinity Columns for Determination of Deoxynivalenol in Food and Feed Samples

The paper describes the development of a simple and highly selective method for the determination of deoxynivalenol (DON) in food and feed samples. It combines sample cleanup with sol-gel immunoaffinity columns containing monoclonal anti-DON antibodies and quantification of DON by high-performance liquid chromatography with ultraviolet detection. The sol-gel immunoaffinity columns are as selective as commercial DON immunoaffinity columns but superior with regard to production costs, storage stability, and reusability. In applying the method for the analysis of maize, wheat, and spaghetti samples, it offers detection limits (LOD, S/N = 3) of 240, 200, and 207 ng/g, and recoveries of 83, 99, and 97%, respectively.

Genotoxicity assessment of deoxynivalenol in the Caco-2 cell line model using the Comet assay

The genotoxic risk associated with deoxynivalenol (DON), a prevalent trichothecene mycotoxin which contaminates cereal-based products has not yet been deeply explored. In this work, the alkaline version of the Comet assay was used to evaluate DNA damage stemming from DON exposure in both dividing and differentiated Caco-2 cells, an epithelial intestinal cell line. To avoid false positive results, cytotoxic and apoptotic thresholds were firstly established using the MTS and neutral red assays and the Hoestch staining method, respectively. Dividing cells were found to be more sensitive to DON than differentiated cells and the lowest IC(10) (0.5 microM) obtained for dividing cells exposed for 72 h was used as the highest working concentration in the genotoxicity study. Both differentiated and dividing cells responded with a dose-dependent relationship to DON in terms of DNA damage in the 0.01-0.5 microM range. These results demonstrated the existence of a genotoxic potential for DON at low concentrations compatible with actual exposure situations and calls for additional studies to determine the functional consequences which could be taken into account for the risk assessment of this food contaminant.

Fusarium graminearum TRI14 is required for high virulence and DON production on wheat but not for DON synthesis in vitro

Fusarium head blight (FHB) of wheat (Triticum aestivum L.), caused by the fungus Fusarium graminearum, is a major concern worldwide. FHB grain is reduced in yield, may fail to germinate, and is often contaminated with deoxynivalenol, a trichothecene mycotoxin linked to a variety of animal diseases and feed refusals. Annual losses in the tens of millions of dollars due to FHB underscore the need to develop improved methods of disease control and prevention. Previous research has identified deoxynivalenol biosynthesis as a virulence factor on wheat. Recently, we found that the TRI14 gene of F. sporotrichioides, closely related to F. graminearum, was not required for synthesis of a related trichothecene, T-2 toxin. TRI14 does not share similarity with any previously described genes in the databases. In this study, we examined the role that F. graminearum TRI14 may play in both deoxynivalenol synthesis and in virulence on wheat. TRI14 deletion mutants synthesize deoxynivalenol on cracked maize kernel medium and exhibit wild-type colony morphology and growth rate on complex and minimal agar media. However, FHB assays on greenhouse-grown wheat indicate that FgDeltaTri14 mutants cause 50-80% less disease than wild type and do not produce a detectable quantity of deoxynivalenol on plants. We discuss a number of possible roles that TRI14 may play in the disease process.

Comparative study of cytotoxicity and oxidative stress induced by deoxynivalenol, zearalenone or fumonisin B1 in human intestinal cell line Caco-2

Fusarium species infestations of cereals crops occur worldwide. Fusarium toxins such as, deoxynivalenol (DON), zearalenone (ZEN) and fumonisin B1 (FB1) have been shown to cause diverse toxic effects in animals and also suspected of disease causation in humans. From the literature and mechanistic point of view, DON binds to the ribosomal peptidyl-transferase and inhibits protein synthesis specifically and DNA synthesis consequently. ZEN known to be genotoxic, binds to 17-beta-estradiol receptors, induces lipid peroxidation, cell death and inhibits protein and DNA synthesis. FB1 disrupts sphingolipid metabolism, induces lipid peroxidation altering the cell membrane and causing cell death. We intended to compare DON, ZEN and FB1 (1-150 microM) cytotoxic effect and the pathways leading to cell death and related to oxidative stress and macromolecules syntheses in a human intestinal cell line in order to tentatively classify them according to their respective potential toxicity. The comparison reveals that all three mycotoxins bear, at variable degree, the capability of inducing lipid peroxidation (MDA production) and could be classified above 10 microM in decreasing potency order FB1>DON>ZEN. This effect seems to be related to their common target that is the mitochondria as revealed by MTT test and seemingly not related to sphingoids accumulation concerning FB1. DON and ZEN also adversely affect lysosomes in contrast to FB1. The three mycotoxins inhibit protein synthesis with respective IC50 of 5, 8.8 and 19 microM for DON, FB1 and ZEN confirming that protein synthesis is a specific target of DON. DNA synthesis is inhibited by DON, ZEN and FB1 with respective IC50 of 1.7, 10 and 20 microM. However at higher concentrations DNA synthesis seems to be restored for FB1 and DON suggesting a promoter activity. Altogether the potency of the three mycotoxins in macromolecules inhibition is DON>ZEN>FB1 in Caco-2 cells. It appears then that FB1 acts rather through lipid peroxidation while DON affects rather DNA and protein synthesis.

The risk assessment paradigm and its application for trichothecenes

Risk analysis for trichothecene mycotoxins and other food contaminants, which are to a significant extent unavoidable, presents considerable challenges. Risk assessment is constrained by uncertainties associated with the lack of adequate data, and risk management must consider the fact that mycotoxin contamination can have serious impacts on trade and food sufficiency. These factors necessitate good communication between the risk assessors and risk managers in formulating the questions to be addressed by the risk assessment. Risk assessment must be an iterative process, since the problem formulation and the risk assessment may need to be revised to reflect new data and theories. In addition to providing advice to risk managers, risk assessment should provide a blueprint for future research by illustrating what observations will influence a prediction. The international risk assessments completed for deoxynivalenol, T-2 and HT-2 toxins, and nivalenol have noted a number of issues regarding the lack of adequate intake data for exposure assessment and significant gaps in toxicological studies for hazard characterizations. Addressing these uncertainties would provide risk managers with better guidance for control measures.