Fusaric acid in Fusarium moniliforme cultures, corn, and feeds toxic to livestock and the neurochemical effects in the brain and pineal gland of rats

Repression of autocrine pheromone signaling leads to fusaric acid over-production

Fusaric acid (FA), a picolinic acid derivative, is a natural substance produced by a wide variety of fungal plant pathogens belonging to the Fusarium genus. As a metabolite, fusaric acid exerts several biological activities including metal chelation, electrolyte leakage, repression of ATP synthesis, and direct toxicity on plants, animals and bacteria. Prior studies on the structure of fusaric acid revealed a co-crystal dimeric adduct between FA and 9,10-dehydrofusaric acid. During an ongoing search for signaling genes differentially regulating FA production in the fungal pathogen Fusarium oxysporum (Fo), we found that mutants lacking pheromone expression have an increased production of FA compared to the wild type strain. Noteworthy, crystallographic analysis of FA extracted from Fo culture supernatants showed that crystals are formed by a dimeric form of two FA molecules (1:1 molar stoichiometry). Overall, our results suggest that pheromone signaling in Fo is required to regulate the synthesis of fusaric acid.

Fusaric acid inhibits proliferation and induces apoptosis through triggering endoplasmic reticulum stress in MCF-7 human breast cancer cells

Breast cancer has replaced lung cancer to be the leading cancer in the world. Currently, chemotherapy is still the major method for breast cancer therapy, but its overall effect remains unsatisfactory. Fusaric acid (FSA), a mycotoxin derived from fusarium species, has shown potency against the proliferation of several types of cancer cells, but its effect on breast cancer cells has not been examined. Therefore, we explored the possible effect of FSA on the proliferation of MCF-7 human breast cancer cells and uncovered the underlying mechanism in the present study. Our results showed that FSA has a strong anti-proliferative effect on MCF-7 cells through inducing ROS production, apoptosis and arresting cell cycle at G2/M transition phase. Additionally, FSA triggers endoplasmic reticulum (ER) stress in the cells. Notably, the cell cycle arrest and apoptosis inducing effect of FSA can be attenuated by ER stress inhibitor, tauroursodeoxycholic acid. Our study provide evidence that FSA is a potent proliferation inhibition and apoptosis inducing agent against human breast cancer cells, and the possible mechanism involves the activation of ER stress signaling pathways. Our study may highlight that FSA is promising for the future in vivo study and development of potential agent for breast cancer therapy.

Effect of Abiotic Conditions on Growth, Mycotoxin Production, and Gene Expression by Fusarium fujikuroi Species Complex Strains from Maize

Fusarium fujikuroi species complex (FFSC) strains are a major concern for food quantity and quality due to their strong ability to synthesize mycotoxins. The effects of interacting conditions of water activity, temperature, and incubation time on the growth rate, toxin production, and expression level of biosynthetic genes were examined. High temperature and water availability increased fungal growth. Higher water activity was in favor of toxin accumulation. The maximum amounts of fusaric acid (FA) and fumonisin B1 (FB1) were usually observed at 20–25 °C. F. andiyazi could produce a higher content of moniliformin (MON) in the cool environment than F. fujikuroi. The expression profile of biosynthetic genes under environmental conditions varied wildly; it was suggested that these genes might be expressed in a strain-dependent manner. FB1 concentration was positively related to the expression of FUM1, while a similar correlation of FUB8 and FUB12 with FA production could be observed in F. andiyazi, F. fujikuroi, and F. subglutinans. This study provides useful information in the monitoring and prevention of such toxins entering the maize production chain.

β-Carboline Alkaloids from Peganum harmala Inhibit Fusarium oxysporum from Codonopsis radix through Damaging the Cell Membrane and Inducing ROS Accumulation

Fusarium oxysporum is a widely distributed soil-borne pathogenic fungus that can cause medicinal herbs and crops to wither or die, resulting in great losses and threat to public health. Due to the emergence of drug-resistance and the decline of the efficacy of antifungal pesticides, there is an urgent need for safe, environmentally friendly, and effective fungicides to control this fungus. Plant-derived natural products are such potential pesticides. Extracts from seeds of Peganum harmala have shown antifungal effects on F. oxysporum but their antifungal mechanism is unclear. In vitro antifungal experiments showed that the total alkaloids extract and all five β-carboline alkaloids (βCs), harmine, harmaline, harmane, harmalol, and harmol, from P. harmala seeds inhibited the growth of F. oxysporum. Among these βCs, harmane had the best antifungal activity with IC₅₀ of 0.050 mg/mL and MIC of 40 μg/mL. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results revealed that the mycelia and spores of F. oxysporum were morphologically deformed and the integrity of cell membranes was disrupted after exposure to harmane. In addition, fluorescence microscopy results suggested that harmane induced the accumulation of ROS and increased the cell death rate. Transcriptomic analysis showed that the most differentially expressed genes (DEGs) of F. oxysporum treated with harmane were enriched in catalytic activity, integral component of membrane, intrinsic component of membrane, and peroxisome, indicating that harmane inhibits F. oxysporum growth possibly through damaging cell membrane and ROS accumulation via regulating steroid biosynthesis and the peroxisome pathway. The findings provide useful insights into the molecular mechanisms of βCs of P. harmala seeds against F. oxysporum and a reference for understanding the application of βCs against F. oxysporum in medicinal herbs and crops.

Biosensor approach for electrochemical quantitative assessment and qualitative characterization of the effect of fusaric acid on a culture-receptor

Fusaric acid (FA) is a secondary fungal metabolite, which is widespread on corn and corn-based feed and food; FA has non-specific toxicity. Biosensor method is an express and easy-to-use method for quantitative and qualitative assessment of FA effect. Search for cultures has been performed for the formation of laboratory models of FA biosensor with the Clark-type oxygen electrode as transducer: respiration intensity of chosen cultures changed in the presence of FA. Resting cells of Fusarium oxysporum f. sp. vasinfectum and Bacillus subtilis were used as receptors of the amperometric biosensor for FA determination in aqueous solution. To enhance the sensitivity of detection, induction by substrate was performed for Bacillus subtilis. Response-concentration linear dependencies were obtained in a range of 0.5-500 FA mg/L. Biosensor models were applied to characterize influence of FA on microbial cells and investigate some features of FA transport. The dependences of the cells' response to FA on FA concentration were obtained; the kinetic parameters S_0.5 and V_max were determined for each culture. Inhibition-threshold FA (S^it) concentrations were similar for both studied cultures. At concentrations lower than S^it, the process of simple diffusion governed FA transport into cells and caused the cells' response to FA for non-induced culture.

Defence response in plants and animals against a common fungal pathogen, Fusarium oxysporum

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Fusarium oxysporum species complex (FOSC) is considered one of the most devastating plant pathogen.

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FOSC is an emerging pathogen of immunocompromised individuals.

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Mycotoxins produced by FOSC predisposes the host to other pathogens.

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Comparative immune reactions in plant and invertebrate show that several antimicrobial peptides (AMPs) and secondary metabolites maybe used as control against Fusarium infection.

Plant pathogens emerging as threat to human and animal health has been a matter of concern within the scientific community. Fusarium oxysporum, predominantly a phytopathogen, can infect both plants and animals. As a plant pathogen, F. oxysporum is one of the most economically damaging pathogen. In humans, F. oxysporum can infect immunocompromised individuals and is increasingly being considered as a problematic pathogen. Mycotoxins produced by F. oxysporum supress the innate immune pathways in both plants and animals. Hence, F. oxysporum is the perfect example for studying similarities and differences between defence strategies adopted by plants and animals. In this review we will discuss the innate immune response of plant and animal hosts for protecting against F. oxysporum infection. Such studies will be helpful for identifying genes, protein and metabolites with antifungal properties suitable for protecting humans.

Antifungal activity of volatile compounds generated by endophytic fungi Sarocladium brachiariae HND5 against Fusarium oxysporum f. sp. cubense

The soil-born filamentous fungal pathogen Fusarium oxysporum f. sp. cubense (FOC), which causes vascular wilt disease in banana plants, is one of the most economically important Fusarium species. Biocontrol using endophytic microorganisms is among the most effective methods for controlling banana Fusarium wilt. In this study, volatile organic compounds (VOCs) showed strong antifungal activity against FOC. Seventeen compounds were identified from the VOCs produced by endophytic fungi Sarocladium brachiariae HND5, and three (2-methoxy-4-vinylphenol, 3,4-dimethoxystyrol and caryophyllene) showed antifungal activity against FOC with 50% effective concentrations of 36, 60 and 2900 μL/L headspace, respectively. Transmission electron microscopy (TEM) and double fluorescence staining revealed that 2-methoxy-4-vinylphenol and 3,4-dimethoxystyrol damaged the plasma membranes, resulting in cell death. 3,4-dimethoxystyrol also could induce expression of chitin synthases genes and altered the cell walls of FOC hyphae. Dichloro-dihydro-fluorescein diacetate staining indicated the caryophyllene induced accumulation of reactive oxygen species (ROS) in FOC hyphae. FOC secondary metabolism also responded to active VOC challenge by producing less fusaric acid and expressions of genes related to fusaric acid production were interrupted at sublethal concentrations. These findings indicate the potential of S. brachiariae HND5 as a biocontrol agent against FOC and the antifungal VOCs as fumigants.

Fusaric acid decreases p53 expression by altering promoter methylation and m6A RNA methylation in human hepatocellular carcinoma (HepG2) cells

Fusaric acid (FA) is a food-borne mycotoxin that mediates toxicity with limited information on its epigenetic properties. p53 is a tumour suppressor protein that regulates cell cycle arrest and apoptotic cell death. The expression of p53 is regulated transcriptionally by promoter methylation and post-transcriptionally by N-6-methyladenosine (m6A) RNA methylation. We investigated the effect of FA on p53 expression and its epigenetic regulation via promoter methylation and m6A RNA methylation in human hepatocellular carcinoma (HepG2) cells. HepG2 cells were treated with FA [0, 25, 50, 104, and 150 µg/ml; 24 h] and thereafter, DNA, RNA, and protein was isolated. Promoter methylation and expression of p53 was measured using qPCR and Western blot. RNA immuno-precipitation was used to determine m6A-p53 levels. The expression of m6A methyltransferases (METTL3 and METTL14), demethylases (FTO and ALKBH5), and readers (YTHDF1-3 and YTHDC2) were measured using qPCR. FA induced p53 promoter hypermethylation (p < 0.0001) and decreased p53 expression (p < 0.0001). FA decreased m6A-p53 levels (p < 0.0001) by decreasing METTL3 (p < 0.0001) and METTL14 (p < 0.0001); and suppressed expression of YTHDF1 (p < 0.0001), YTHDF3 (p < 0.0001), and YTHDC2 (p < 0.0001) that ultimately reduced p53 translation (p < 0.0001). Taken together, the data shows that FA epigenetically decreased p53 expression by altering its promoter methylation and m6A RNA methylation in HepG2 cells. This study reveals a mechanism for p53 regulation by FA and provides insight into future therapeutic interventions.

Methanolic Extracts from Cultivated Mushrooms Affect the Production of Fumonisins B and Fusaric Acid by Fusarium verticillioides

The maize pathogen Fusarium verticillioides and their mycotoxins cause damage to plants, animals, and human health. This work aimed to evaluate the effect of crude extracts (CEs) from Agaricus subrufescens, Lentinula edodes, and Pleurotus ostreatus fruiting bodies on in vitro production of biomass and mycotoxins by two strains of F. verticillioides. Stipes and pilei were separated before extraction for A. subrufescens and L. edodes. Comparative metabolomics and dereplication of phenolic compounds were used to analyze all CEs. Mushroom CEs did not significantly inhibit the production of mycelial biomass at concentrations of 2 mg mL⁻1. CEs from A. subrufescens (stipes and pilei) and L. edodes pilei inhibited the production of fumonisins B1 + B2 + B3 by 54% to 80%, whereas CE from P. ostreatus had no effect. In contrast, CE from L. edodes stipes dramatically increased the concentration of fumonisins in culture media. Fusaric acid concentration was decreased in cultures by all CEs except L. edodes stipes. Differences in phenolic composition of the extracts may explain the different effects of the CE treatments on the production of mycotoxins. The opposing activities of stipes and pilei from L. edodes offer an opportunity to search for active compounds to control the mycotoxin production by F. verticillioides.

Effect of interacting conditions of water activity, temperature and incubation time on Fusarium thapsinum and Fusarium andiyazi growth and toxin production on sorghum grains

This study examined the effect of interacting conditions of water activity (a_W, 0.995, 0.98 and 0.95) and temperature (15, 25 and 30 °C) on growth rate of two Fusarium thapsinum and one F. andiyazi strains isolated from sorghum in Argentina. In addition, the effect of interacting conditions (a_W × temperature × incubation time (7, 14, 21 and 28 days)) on mycotoxin production (moniliformin (MON), fusaric acid (FA) and fusarin C (FUS C)) on a sorghum grain substrate was evaluated. Statistical analysis showed that a_W and temperature significantly affected growth of both species, mainly the a_W. Incubation time significantly influenced mycotoxin production by both species as well, mostly for FA. Maximum growth rates of the F. thapsinum strains were obtained at the highest a_W (0.995) and 25 °C and growth rate decreased as a_W and temperature were reduced. The same growth profile was observed for F. andiyazi RCFA09 (maximum growth rates at 0.995-25 °C). Mycotoxin production by both species was detected at the highest a_W levels whereas at 0.95 a_W only low amounts of MON were produced by F. thapsinum. Maximum MON and FUS C production by both F. thapsinum strains was observed at 0.995 a_W and 25-30 °C after 28 days of incubation. Also, F. thapsinum strains showed maximum FA production at the highest a_W and temperature but after 14 days; after this incubation time toxin levels significantly decreased. The responses to a_W and temperature of F. andiyazi were similar to that of F. thapsinum strains in relation to FA and FUS C production. Maximum levels of FA were detected at the highest a_W after 14 days of incubation at 25-30 °C. Fusarin C was produced at all assayed temperatures but maximum levels were detected at 30 °C and 0.995 a_W after 28 days of incubation. Two-dimensional profiles on the interactions of a_W by temperature were developed from these data to identify conditions that indicate a significant risk from MON, FA and FUS C accumulation on sorghum grains. The results of this study suggest that sorghum grains could be colonized by these species and toxin production can occur, especially during development stages under field conditions at high water activity of grains or during grain storage if the drying process is slow or deficient. To our knowledge, this study described for the first time FUS C production by F. thapsinum and F. andiyazi under interacting conditions of a_W, temperature and incubation time on sorghum grains.

Dose-dependent neuroprotective effect of oriental phyto-derived glycyrrhizin on experimental neuroterminal norepinephrine depletion in a rat brain model

The dose-dependent neuroprotective role of licorice-derived glycyrrhizin during subacute neuroterminal norepinephrine (NE) depletion was studied in rat brain. Experimental design included thirty 5-week-old male rats randomly divided into five groups. Compared to the saline-injected control group, the group receiving daily intraperitoneal injection of fusaric acid (FA; 5 mg/kg/b.w.) for 30 days showed pharmacological depletion of NE. The neuroprotective effects of three successively increasing oral doses of glycyrrhizin were examined in FA-treated rats. Neurochemical parameters and histo-/immunohistopathological changes in the hippocampus were examined. FA generated global hippocampal stress with altered neurobiochemical parameters, accompanied by immune-confirmed inflammatory tissue damage, and noticeable behavioral changes. Although glycyrrhizin after FA-induced intoxication did not correct the recorded drop in the NE level, it decreased the dopamine levels to control levels. Similarly, glycyrrhizin at a high dose restored the serotonin level to its normal value and blocked the FA-induced increase in the level of its metabolite, 5-hydroxyindoleacetic acid. The FA-induced rise in γ-aminobutyric acid (GABA) and histamine was alleviated after administration of a high dose of glycyrrhizin. This was accompanied by improvements in the bioenergetic status and neuronal regenerative capacity through recovery of ATP and brain-derived neurotrophic factor levels to the pre-intoxicated values. High doses of glycyrrhizin also ameliorated the FA-generated behavioral changes and oxidative damage, manifested by the reduction in the expression of cortical pro-apoptotic caspase 3 in the same group. This study suggests that glycyrrhizin can potentially mend most of the previously evoked neuronal damage induced by FA intoxication in the brain of an experimental rat model.

Crop Diseases and Mycotoxin Accumulation in Temperate Agroforestry Systems

Background: Temperate agroforestry is regarded as a sustainable alternative to monoculture agriculture due to enhanced provisioning of ecosystem services. Plant health and food safety are crucial requirements for sustainable agriculture; however, studies of fungal diseases and mycotoxin contamination of crops grown under temperate agroforestry are lacking. This study therefore aimed to compare fungal colonization and mycotoxin contamination of crops grown in temperate agroforestry against conventional monoculture. Methods: The biomass of plant pathogenic fungi in oilseed rape plants and barley and wheat grain harvested in 2016 to 2018 at four paired agroforestry and monoculture sites was quantified using species-specific real-time PCR. Mycotoxin content of barley and wheat grain was determined by HPLC-MS/MS. Results: The colonization of oilseed rape plants with the vascular pathogen Verticillium longisporum and wheat grain with the head blight pathogen Fusarium tricinctum was lower in agroforestry than in conventional monoculture. Mycotoxin content of barley and wheat grain did not differ between agroforestry and monoculture systems and did not exceed the legal limits of the EU. Remarkably, fumonisin B1 was detected in wheat grains at two sites in two years, yet the low levels found do not raise food safety concerns. No differences were found between the two production systems with regard to infection of wheat and barley grain with five Fusarium species (F. avenaceum, F. culmorum, F. graminearum, F. poae, and F. proliferatum) and oilseed rape with fungal pathogens Leptosphaeria biglobosa, Leptosphaeria maculans, and Sclerotinia sclerotiorum. Conclusions: Temperate agroforestry does not negatively affect the infection of wheat, barley and oilseed rape with major fungal pathogens though it may suppress the infection of oilseed rape with V. longisporum and wheat grain with F. tricinctum. Furthermore, temperate agroforestry does not increase mycotoxin contamination of barley and wheat. Therefore, temperate agroforestry does not negatively affect food safety.

Mycotoxins in Conversation With Bacteria and Fungi

An important goal of the mycotoxin research community is to develop comprehensive strategies for mycotoxin control and detoxification. Although significant progress has been made in devising such strategies, yet, there are barriers to overcome and gaps to fill in order to design effective mycotoxin management techniques. This is in part due to a lack of understanding of why fungi produce these toxic metabolites. Here we present cumulative evidence from the literature that indicates an important ecological role for mycotoxins, with particular focus on Fusarium mycotoxins. Further, we suggest that understanding how mycotoxin levels are regulated by microbial encounters can offer novel insights for mycotoxin control in food and feed. Microbial degradation of mycotoxins provides a wealth of chemical information that can be harnessed for large-scale mycotoxin detoxification efforts.

Evaluation of the cytotoxic and genotoxic effects of mycotoxin fusaric acid

Fusaric acid (FA) is produced by several Fusarium species and is commonly found in grains. This investigation was performed to evaluate the cytotoxic and genotoxic effects of FA either in human cervix carcinoma (HeLa) cell line using 3-(4,5-dimethylthiazolyl-2)-2,5 diphenyltetrazolium bromide (MTT) assay and in human lymphocytes using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), micronuclei (MN) as well as comet assay in vitro. The cells were treated with 0.78, 1.56, 3.125, 6.25, 12.50, 25, 50, 100, 200, and 400 µg/mL concentrations of FA. It has potent cytotoxic effect on HeLa cell line measured by MTT assay especially at higher concentrations (200, 400 µg/mL). The half of inhibitory concentration (IC₅₀) evidenced by FA in the HeLa cells was 200 μg/mL at 24 h and between 200 and 400 μg/mL at 48 h. It was also observed that FA produced a significant decrease in mitotic index (MI) at 12.50 µg/mL compared to solvent control. Furthermore, it indicated a cytotoxic effect at the concentrations ranging from 25 to 400 μg/mL in human lymphocytes. The results of this research point out that being exposed to FA at high concentrations show cytotoxicity. Besides FA induced comet tail intensity at 3.125, 6.25, and 12.50 µg/mL concentrations in isolated human lymphocytes. On the other hand, no genotoxic effects were seen in human lymphocytes in vitro using CA, SCE and MN assays.

Fusaric acid contributes to virulence of Fusarium oxysporum on plant and mammalian hosts

Fusaric acid (FA) is amongst the oldest identified secondary metabolites produced by Fusarium species, known for a long time to display strong phytotoxicity and moderate toxicity to animal cells; however, the cellular targets of FA and its function in fungal pathogenicity remain unknown. Here, we investigated the role of FA in Fusarium oxysporum, a soil-borne cross-kingdom pathogen that causes vascular wilt on more than 100 plant species and opportunistic infections in humans. Targeted deletion of fub1, encoding a predicted orthologue of the polyketide synthase involved in FA biosynthesis in F. verticillioides and F. fujikuroi, abolished the production of FA and its derivatives in F. oxysporum. We further showed that the expression of fub1 was positively controlled by the master regulator of secondary metabolism LaeA and the alkaline pH regulator PacC through the modulation of chromatin accessibility at the fub1 locus. FA exhibited strong phytotoxicity on tomato plants, which was rescued by the exogenous supply of copper, iron or zinc, suggesting a possible function of FA as a chelating agent of these metal ions. Importantly, the severity of vascular wilt symptoms on tomato plants and the mortality of immunosuppressed mice were significantly reduced in fub1Δ mutants and fully restored in the complemented strains. Collectively, these results provide new insights into the regulation and mode of action of FA, as well as on the function of this phytotoxin during the infection process of F. oxysporum.

Emerging Mycotoxins: Beyond Traditionally Determined Food Contaminants

Modern analytical techniques can determine a multitude of fungal metabolites contaminating food and feed. In addition to known mycotoxins, for which maximum levels in food are enforced, also currently unregulated, so-called "emerging mycotoxins" were shown to occur frequently in agricultural products. The aim of this review is to critically discuss the relevance of selected emerging mycotoxins to food and feed safety. Acute and chronic toxicity as well as occurrence data are presented for enniatins, beauvericin, moniliformin, fusaproliferin, fusaric acid, culmorin, butenolide, sterigmatocystin, emodin, mycophenolic acid, alternariol, alternariol monomethyl ether, and tenuazonic acid. By far not all of the detected compounds are toxicologically relevant at their naturally occurring levels and are therefore of little or no health concern to consumers. Still, gaps in knowledge have been identified for several compounds. These gaps should be closed by the scientific community in the coming years to allow a proper risk assessment.

A Rapid Method with UPLC for the Determination of Fusaric Acid in Fusarium Strains and Commercial Food and Feed Products

A rapid, sensitive and validated method for the determination of fusaric acid (FA) in several Fusarium strains and different commercial food and feed products is reported based on ultra-performance liquid chromatography. This method requires only crude sample by a simple extraction with methanol, and requires a very short time of 8 min for completion. Separation of FA was performed at injection volume of 1 μl with a 20:80 (v/v) water/acetonitrile mobile phase containing 0.1 % formic acid at a flow rate of 0.05 ml/min and detected with UV at 220 nm. Nice linearity and good correlation coefficient (R² > 0.99) were obtained in the concentration range of 1-200 μg/ml. Validation was demonstrated using blank samples spiked at three different concentrations with standard solution, and the method yielded more than 98.2 % recovery efficiencies and below 2.56 % R.S.D. when applied in the analysis of FA produced by Fusarium verticillioides and a set of transgenic strains of this fungus. Satisfactory recoveries in the range of 79.1-105.8 % and R.S.D lower than 10 % were also obtained for the tested commercial food and feed products. The concentration FA detection in the transgenic strains ranged from 9.65 to 135 μg/kg (0.29-4.05 μg per gram of biomass). However, FA was not detected in most of the commercial products with the exception of niblet, oatmeal, red kidney bean and soybean, for which the concentrations of FA ranged from 2.5 to 18 μg/kg (below the permitted maximum). These results show that the proposed method has a great potential application to analyze FA from different sources rapidly.

Development of simple sequence repeat (SSR) markers for discrimination among isolates of Fusarium proliferatum

The plant pathogen Fusarium proliferatum has a wide host range and occurs worldwide. Many isolates of the fungus produce mycotoxins in plant tissues, which, if ingested, can cause harm to animals and humans. In 2008, an outbreak of salmon blotch of onions, caused by F. proliferatum, was detected in southern Israel. The source and distribution of the fungus in Israel were unknown. Inter-simple sequence repeats (ISSR) were used to identify repetitive motifs present in seven isolates of F. proliferatum from Israel, Germany and Austria. ISSR repeat motifs were, used to develop 17 simple sequence repeat (SSR) loci. Six of these SSR markers were polymorphic in and consistently amplified from ten isolates collected in Israel, Germany, Austria and North America, from cucumber, onion, garlic, maize, and asparagus. These six polymorphic SSR alleles included 5 to 12 copies of di-, tri, and pentanucleotide motifs and yielded six to 9 alleles each. Sixteen of the SSR loci were amplified at least one of the seven Fusarium species, F. verticillioides, F. thapsinum, F. subglutinans, F. andiyazi, F. globosum, F. fujikoroi and F. oxysporum. The data demonstrate that these SSRs can be used for characterization of F. proliferatum isolates from diverse hosts and geographic locations and that they are transferable to other species of Fusarium.

Production of Fusaric Acid by Fusarium spp. in Pure Culture and in Solid Medium Co-Cultures

The ability of fungi isolated from nails of patients suffering from onychomycosis to induce de novo production of bioactive compounds in co-culture was examined. Comparison between the metabolite profiles produced by Sarocladium strictum, by Fusarium oxysporum, and by these two species in co-culture revealed de novo induction of fusaric acid based on HRMS. Structure confirmation of this toxin, using sensitive microflow NMR, required only three 9-cm Petri dishes of fungal culture. A targeted metabolomics study based on UHPLC-HRMS confirmed that the production of fusaric acid was strain-dependent. Furthermore, the detected toxin levels suggested that onychomycosis-associated fungal strains of the F. oxysporum and F. fujikuroi species complexes are much more frequently producing fusaric acid, and in higher amount, than strains of the F. solani species complex. Fusarium strains producing no significant amounts of this compound in pure culture, were shown to de novo produce that compound when grown in co-culture. The role of fusaric acid in fungal virulence and defense is discussed.

Determination of oral bioavailability of fusaric acid in male Sprague-Dawley rats

Head and neck squamous cell cancer accounts for 3 % of new cancer cases and 2 % of cancer mortality annually in the United States. Current treatment options for most head and neck cancers continue to be surgical excision with or without radiation, radiation alone, or chemotherapy with radiation depending on location, stage of disease, and patient preference. Fusaric acid (FA) is a novel compound from a novel class of nicotinic acid derivatives that have activity against head and neck squamous cell carcinoma (HNSCC). Although its exact mechanism is still unknown, FA is thought to be active by increasing damage to DNA and preventing its synthesis and repair. The novel mechanism of FA provides an alternative to present therapies, as a single agent whether given parenterally or orally. It has synergy with conventional agents taxol, carboplatin, and erlotinib. In order to determine if FA has reasonable oral bioavailability, we have determined the pharmacokinetics of FA in male Sprague Dawley rats following administration by gavage and by intravenous injection. The bioavailability of FA was sufficient (58 %) to suggest that FA may be viable as an orally administered medication. Despite the encouraging bioavailability of FA, the intravenous (IV) pharmacokinetics suggested non-linear behavior within the IV dose range of 10, 25, and 75 mg/kg. These results demonstrate that further pharmacokinetic and toxicity studies in larger animals such as dogs and non-human primates are warranted.

Screening survey of co-production of fusaric acid, fusarin C, and fumonisins B₁, B₂ and B₃ by Fusarium strains grown in maize grains

Fusarium species isolated from Belgian maize were screened for their ability to produce fusarin C, fusaric acid, fumonisins B1 (FB1), FB2 and FB3 in maize grains. First, cultivation of Fusarium species in Myro liquid medium allowed overcoming the shortage of the standard of fusarin C on the market. All Fusarium verticillioides produced much higher contents of mycotoxins in Myro compared to Fusarium graminearum or Fusarium venenatum. The optimization of the LC-MS/MS method resulted in low limits of detection and quantification for fusarin C, fusaric acid, FB1, FB2 and FB3 determination in maize grains. Its application for screening the potential toxin production ability evidenced that the concentrations of the analytes were significantly increased at various levels when F. verticillioides strains were cultivated in maize grains and reached 441 mg kg(-1) for fusaric acid, 74 mg kg(-1) for fusarin C, 1,301 mg kg(-1) for FB1, 367 mg kg(-1) for FB2 and 753 mg kg(-1) for FB3.

Characterization of the fusaric acid gene cluster in Fusarium fujikuroi

The "bakanae" fungus Fusarium fujikuroi is a common pathogen of rice and produces a variety of mycotoxins, pigments, and phytohormones. Fusaric acid is one of the oldest known secondary metabolites produced by F. fujikuroi and some other Fusarium species. Investigation of its biosynthesis and regulation is of great interest due to its occurrence in cereal-based food and feed. This study describes the identification and characterization of the fusaric acid gene cluster in F. fujikuroi consisting of the PKS-encoding core gene and four co-regulated genes, FUB1-FUB5. Besides fusaric acid, F. fujikuroi produces two fusaric acid-like derivatives: fusarinolic acid and 9,10-dehydrofusaric acid. We provide evidence that these derivatives are not intermediates of the fusaric acid biosynthetic pathway, and that their formation is catalyzed by genes outside of the fusaric acid gene cluster. Target gene deletions of all five cluster genes revealed that not all of them are involved in fusaric acid biosynthesis. We suggest that only two genes, FUB1 and FUB4, are necessary for the biosynthesis. Expression of the FUB genes and production of fusaric acid and the two derivatives are favored under high nitrogen. We show that nitrogen-dependent expression of fusaric acid genes is positively regulated by the nitrogen-responsive GATA transcription factor AreB, and that pH-dependent regulation is mediated by the transcription factor PacC. In addition, fusaric acid production is regulated by two members of the fungal-specific velvet complex: Vel1 and Lae1. In planta expression studies show a higher expression in the favorite host plant rice compared to maize.

Fusaric acid, a mycotoxin, and its influence on blood coagulation and platelet function

The current study intended to explore the effect of fusaric acid on blood coagulation including plasma coagulation and platelet aggregation. Fusaric acid exhibited biphasic effects on citrated human plasma recalcification time. At concentrations below 50 ng, fusaric acid decreased the clotting time of plasma dose-dependently from 130 ± 3s control value to 32 ± 3s; however, above 50 ng, fusaric acid increased the clotting time from 32 ± 3s and reached a maximum of 152 s at 100 ng and remained unaltered thereafter for the increased dose of fusaric acid. Fusaric acid without damaging red blood cells and platelets, inhibited agonists such as collagen, ADP, thrombin, and epinephrine-induced aggregation of both platelet-rich plasma (PRP) and washed platelets preparations of human. Interestingly, fusaric acid showed biphasic effects only in thrombin-induced platelet aggregation of washed platelets, and at lower concentration (below 900 ng) it activated platelet aggregation; however, in increased concentration (above 900 ng) it inhibited the platelet aggregation of washed platelets. In addition, fusaric acid also inhibited the agonist ADP-induced platelet aggregation of washed platelet suspension but did not show biphasic effect. Further, fusaric acid did not induce the platelets to generate reactive oxygen species (ROS) that clearly suggests that the induction of platelet function could be the result of the fusaric acid-mediated receptor interaction but not through the morphological shape change.

Mycological analysis and multimycotoxins in maize from rural subsistence farmers in the former Transkei, South Africa

Maize harvested in the Centane region of the former Transkei, Eastern Cape Province, South Africa, by subsistence farmers has been shown over many seasons to be contaminated with fumonisin mycotoxins. However, there are limited data on the presence of other mycotoxins. Two multimycotoxin LC-MS/MS methods were applied to good and moldy maize samples, as separated by the farmers themselves from the 2011 harvest. One method involved extract cleanup on multitoxin immunoaffinity columns before LC-MS/MS analysis for aflatoxins, fumonisins, deoxynivalenol (DON), zearalenone (ZEN), and T-2 and HT-2 toxins. The other method was based on a "dilute-and-shoot" approach for the above mycotoxins and a wide range of other fungal secondary metabolites. Both methods showed high incidences of fumonisins B1 and B2 (FB1 and FB2) in good maize (100% for both by the first method, means were 2083 and 927 μg/kg for the two analogues; 93% for both by the second method, positive means of 2764 and 1050 μg/kg, respectively). All samples of moldy maize were contaminated (mean FB1 of 27.64 and 35.98 mg/kg, respectively; mean FB2 of 10.58 and 14.14 mg/kg, respectively). Comparison of the two methods for FB1 and FB2 over the entire range of samples gave R(2) values 0.9144 and 0.8859, respectively. Low levels of DON were found by both methods (positive means of 12 and 4.7 μg/kg in good maize, respectively, and of 14 and 5.8 μg/kg in moldy maize, respectively). ZEN was determined with positive means of 108 and 25 μg/kg in good maize, respectively, and of 111 and 135 μg/kg in moldy maize, respectively. No aflatoxins, OTA, or T-2 or HT-2 toxins were detected. A wide range of other Fusarium , Aspergillus , Alternaria , and Penicillium mycotoxins and secondary metabolites were determined.

Mycotoxins in corn and wheat silage in Israel

Silage is an important feed source for intensive dairy herds worldwide. Fungal growth and mycotoxin production before and during silage storage is a well-known phenomenon, resulting in reduced nutritional value and a possible risk factor for animal health. With this in mind, a survey was conducted to determine for the first time the occurrence of mycotoxins in corn and wheat silage in Israel. A total of 30 corn and wheat silage samples were collected from many sources and analysed using a multi-mycotoxin method based on LC-MS/MS. Most mycotoxins recorded in the present study have not been reported before in Israel. Overall, 23 mycotoxins were found in corn silage; while wheat silage showed a similar pattern of mycotoxin occurrence comprising 20 mycotoxins. The most common post-harvest mycotoxins produced by the Penicillium roqueforti complex were not found in any tested samples, indicative of high-quality preparation and use of silage. Moreover, none of the European Union-regulated mycotoxins--aflatoxin B1, ochratoxin, T-2 toxin, diacetoxyscirpenol and deoxynivalenol--were found above their limits of detection (LODs). The Alternaria mycotoxins--macrosporin, tentoxin and alternariol methyl ether--were highly prevalent in both corn and wheat silage (>80%), but at low concentrations. The most prominent (>80%) Fusarium mycotoxins in corn silage were fusaric acid, fumonisins, beauvericin, monilifomin, equisetin, zearalenone and enniatins, whereas in wheat silage only beauvericin, zearalenone and enniatins occurred in more than 80% of the samples. The high prevalence and concentration of fusaric acid (mean = 765 µg kg⁻¹) in Israeli corn silage indicates that this may be the toxin of highest potential concern to dairy cow performance. However, more data from different harvest years and seasons are needed in order to establish a more precise evaluation of the mycotoxin burden in Israeli silage.

Masked mycotoxins: a review

The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.

Nuclear magnetic resonance (NMR) studies on the biosynthesis of fusaric acid from Fusarium oxysporum f. sp. vasinfectum

Fusarium oxysporum is a fungal pathogen that attacks many important plants. Uniquely pathogenic strains of F. oxysporum f. sp. vasinfectum were inadvertently imported into the United States on live cottonseed for dairy cattle feed. These strains produce exceptionally high concentrations of the phytotoxin fusaric acid. Thus, fusaric acid may be a critical component in the pathogenicity of these biotypes. This study investigated the biosynthesis of fusaric acid using (13)C-labeled substrates including [1,2-(13)C(2)]acetate as well as (13)C- and (15)N-labeled aspartate and [(15)N]glutamine. The incorporation of labeled substrates is consistent with the biosynthesis of fusaric acid from three acetate units at C5-C6, C7-C8, and C9-C10, with the remaining carbons being derived from aspartate via oxaloacetate and the TCA cycle; the oxaloacetate originates in part by transamination of aspartate, but most of the oxaloacetate is derived by deamination of aspartate to fumarate by aspartase. The nitrogen from glutamine is more readily incorporated into fusaric acid than that from aspartate.

Effects of feeding diets naturally contaminated with Fusarium mycotoxins on protein metabolism in late gestation and lactation of first-parity sows

A study was conducted to assess the effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins to sows on the capacity for protein synthesis in skeletal muscle, the protein content per cellular unit, and the efficacy of a polymeric glucomannan adsorbent (GMA) to prevent these effects in late gestation and in lactation. Thirty-two Yorkshire sows were assigned to 4 treatment groups (8 per treatment) from 91 +/- 3 d of gestation up to weaning on d 21 after farrowing. Diets included 1) control, 2) contaminated grains, and 3) contaminated grains + 0.2% GMA. A fourth treatment of feeding sows the control diet at a restricted feed allowance was also included. The variables measured include ADFI, average daily BW change, serum total protein, urea, and ammonia, and skeletal muscle DNA, RNA, and protein. To assess the capacity for protein synthesis, ratios of RNA:DNA, and RNA:protein were compared among dietary treatments. To assess the degree of muscle protein mobilization in gestation and lactation, ratios of protein:DNA were compared among dietary treatments. Muscle samples were obtained from the triceps brachii. Blood and muscle samples were obtained 3 times: the first was obtained 1 d before the sows began to receive the experimental diets (90 +/- 3 d of gestation), a second sample was obtained 14 d later (104 +/- 3 d of gestation), and the third sample was obtained 10 d after farrowing. Serum ammonia concentrations were similar in sows fed the contaminated feed and sows fed the restricted feed compared with controls, but serum ammonia concentrations were greater in sows fed contaminated feed (P = 0.02) and restricted-fed sows (P = 0.008) compared with sows fed the contaminated grains plus GMA on 104 +/- 3 d of gestation. There were no reductions in the capacity for protein synthesis caused by mycotoxins or restricted feeding compared with controls. A reduction in ADFI (P = 0.003) was observed in sows fed the 2 contaminated diets in lactation. Muscle protein mobilization was not affected by diet, but a reduction (P = 0.04) in the content of protein per cellular unit was observed in lactation compared with gestation. Reduction in protein:DNA could be caused by the catabolic state in lactation, which was augmented by a low ADFI. The rate of muscle mobilization could be the result of the indirect effect of the reduction in ADFI in lactation rather than a direct effect of Fusarium mycotoxins in the capacity for protein synthesis.

What about the 'other' Fusarium mycotoxins?

Most Fusarium species are capable of producing mycotoxins that may cause adverse effects on human or animal health. The most commonly studied Fusarium mycotoxins include trichothecenes, zearalenone and fumonisins. However, it seems that nearly all of the most prevalent Fusarium species infecting grains are also capable of producing other toxic metabolites. The existing studies, although exiguous, have clearly demonstrated that other toxic metabolites of Fusarium spp. are also present in our foods and feeds, occasionally at very high levels. It is apparent that since mycotoxins, including these 'other' metabolites, are natural toxins, they cannot be completely eliminated from food and feed chains. However, scientific studies are needed to determine their true significance. Thus, the mechanism and level of toxicity as well as presence and concentration levels will have to be fully clarified. In this paper, we briefly review the prevalence of the dominant Fusarium species contaminating maize and small-grain cereals worldwide, and the current knowledge on the biological activity as well as the natural occurrence of their selected less-known toxic metabolites. Additionally, the significance of these 'other' Fusarium mycotoxins is discussed.

Effects of feedborne fusarium mycotoxins on brain regional neurochemistry of turkeys

An experiment was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins on brain regional neurochemistry of turkeys. The possible preventative effect of a poly-meric glucomannan mycotoxin adsorbent (GMA) was also determined. Forty-five 1-d-old male turkey poults were fed wheat-, corn-, and soybean meal-based diets up to wk 6, formulated with control grains, contaminated grains, or contaminated grains + 0.2% GMA. Deoxynivalenol was the major contaminant, and the concentrations were 2.2 and 3.3 mg/kg of feed during starter and grower phases, respectively. Concentrations of brain monoamine neurotransmitters and metabolites were measured in discrete regions of the brain including the pons, hypothalamus, and cortex by HPLC with electrochemical detection. Neurotransmitters and metabolites analyzed included norepinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, serotonin (5-hydroxytryptamine, 5-HT), and 5-hydroxyindoleacetic acid (5-HIAA). The concentration of 5-HIAA and the 5-HIAA:5-HT-ratio were significantly decreased in pons after feeding contaminated grains. Dietary supplementation with GMA prevented these effects. In the pons, a significant positive correlation (r = 0.52, P < 0.05) was observed between the concentration of 5-HT and BW gain after feeding contaminated diets. The feeding of contaminated diet had no significant effects on the concentrations of neurotransmitters and metabolites in hypothalamus and cortex. It was concluded that consumption of grains naturally contaminated with Fusarium mycotoxins adversely altered the pons serotonergic system of turkeys. Supplementation with GMA partially inhibited these effects.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on small intestinal morphology of turkeys

An experiment was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins on morphometric indices of duodenum, jejunum, and ileum in turkeys. The possible preventative effect of a polymeric glucomannan mycotoxin adsorbent (GMA) was also determined. Three hundred 1-d-old male turkey poults were fed wheat, corn, and soybean meal-based starter (0 to 3 wk), grower (4 to 6 wk), developer (7 to 9 wk), and finisher (10 to 12 wk) diets formulated with control grains, contaminated grains, and contaminated grains + 0.2% GMA. Morphometric indices were measured at the end of each growth phase and included villus height (VH), crypt depth, villus width, thicknesses of submucosa and muscularis, villus-to-crypt ratio, and apparent villus surface area (AVSA). At the end of the starter phase, feedborne mycotoxins significantly decreased the VH in the duodenum, and supplementation of the contaminated diet with GMA prevented this effect. The feeding of contaminated grains also reduced (P < 0.05) VH and AVSA in jejunum, whereas none of the variables were affected in the ileum. Villus width and AVSA of duodenum, VH, and AVSA of jejunum and submucosa thickness of ileum were significantly reduced when birds were fed contaminated grains at the end of the grower phase, and supplementation with GMA prevented these effects in jejunum and ileum. No effects of diets were seen on morphometric variables at the end of the developer and finisher phases. It was concluded that consumption of grains naturally contaminated with Fusarium mycotoxins results in adverse effects on intestinal morphology during early growth phases of turkeys, and GMA can prevent many of these effects.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on performance, hematology, metabolism, and immunocompetence of turkeys

An experiment was conducted to investigate the effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on performance, hematology, metabolism, and immunological parameters of turkeys. The efficacy of polymeric glucomannan mycotoxin adsorbent (GMA) in preventing these adverse effects was also evaluated. Three hundred 1-d-old male turkey poults were fed wheat-, corn-, and soybean meal-based starter (0 to 3 wk), grower (4 to 6 wk), developer (7 to 9 wk), and finisher (10 to 12 wk) diets formulated with uncontaminated grains, contaminated grains, and contaminated grains + 0.2% GMA. Feeding contaminated grains significantly decreased BW gains during the grower and developer phases, and GMA supplementation prevented these effects. There was no effect of diet, however, on feed intake or feed efficiency. The feeding of contaminated grains reduced total lymphocyte counts at wk 3 (P < 0.05). Dietary supplementation with GMA increased plasma total protein concentrations compared with controls and birds fed the contaminated diet. Plasma uric acid concentrations in birds fed contaminated grains were increased at the end of the experiment compared with controls, and the feeding of GMA prevented this effect. Feeding contaminated grains significantly increased the percentage of CD4(+) lymphocyte populations during wk 6; however, there was no change in the percentage of CD8(+) and B-lymphocyte populations. Contact hypersensitivity to dinitrochlorobenzene, which is a CD8(+) T cell-mediated delayed-type hypersensitivity response, was significantly decreased after 24 and 72 h by feedborne mycotoxins compared with controls. Supplementation of the contaminated diet with GMA prevented the decrease in response after 24 h. Secondary antibody (IgG titer) response against SRBC antigens (CD4(+) T cell-dependent) was significantly decreased after feeding contaminated grains compared with controls. It was concluded that turkey performance and some blood and immunological parameters were adversely affected by feedborne Fusarium mycotoxins, and GMA prevented many of these effects.

Effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on feed intake, metabolism, and indices of athletic performance of exercised horses

An experiment was conducted to determine the effect of feeding blends of grains naturally contaminated with Fusarium mycotoxins to mature, exercised horses, and to test the efficacy of a polymeric glucomannan mycotoxin adsorbent (GM polymer) in preventing Fusarium mycotoxicoses. Six mature, mixed-breed mares with an average BW of 530 kg were assigned to one of three dietary treatments for 21 d in a replicated 3 x 3 Latin square design. Feed consumed each day was a combination of up to 3.5 kg of concentrates and 5.0 kg of mixed timothy/alfalfa hay (as-fed basis). The concentrates fed included 1) manage; 2) blend of contaminated grains; and 3) contaminated grains + 0.2% GM polymer (MTB-100, Alltech Inc., Nicholasville, KY). Concentrates containing contaminated grains averaged 11.0 ppm deoxynivalenol, 0.7 ppm 15-acetyldeoxynivalenol, and 0.8 ppm zearalenone (as-fed basis). Feed intake and BW were monitored over a 21-d period. Horses were maintained on a fixed exercise schedule throughout the experiment. At the end of the experiment, each horse completed a time-to-fatigue treadmill step test. Variables measured during pretest, each step of the test, and 5 and 10 min posttest were as follows: 1) time-to-fatigue, 2) heart rate, 3) hematological variables, and 4) serum lactate concentration. Each step consisted of 2 min of fast trot with a 2% increase in incline after each 2 min. Feed intake by horses fed contaminated grains was decreased compared with controls throughout the experiment (P < 0.05). Supplementation of 0.2% GM polymer to the contaminated diet did not alter feed intake by horses compared with those fed the unsupplemented contaminated diet. All hay was consumed regardless of concentrate fed. Weight loss from 0 to 21 d was observed in horses fed contaminated grains compared with controls (P < 0.05). No effect of diet was seen on variables used to measure athletic ability, although the results showed an expected response to exercise for a fit horse. We conclude that exercised horses are susceptible to Fusarium mycotoxicoses as indicated by appetite suppression and weight loss.

Effects of feed-borne Fusarium mycotoxins on hematology and immunology of turkeys

Feeding grains naturally-contaminated with Fusarium mycotoxins has been shown to alter the metabolism and performance of turkeys. The objectives of the current experiment were to examine the effects of feeding turkeys with grains naturally contaminated with Fusarium mycotoxins on their hematology and immunological indices (including functions), and the possible protective effect of feeding a polymeric glucomannan mycotoxin adsorbent (GMA). Two hundred twenty-five 1-d-old male turkey poults were fed corn, wheat, and soybean meal-based starter (0 to 3 wk), grower (4 to 6 wk), developer (7 to 9 wk), and finisher (10 to 12 wk) diets formulated with uncontaminated grains, contaminated grains, or contaminated grains with 0.2% GMA. The chronic consumption of Fusarium mycotoxins caused minor and transient changes in hematocrit (0.33 L/L) and hemoglobin (10(6) g/L) concentrations as well as in blood basophil (0.13 x 10(9)/L) and monocyte counts (3.42 x 10(9)/L) compared with controls. Supplementation of the contaminated diet with GMA prevented these effects on blood cell counts. Biliary IgA concentrations were significantly increased (4.45-fold) when birds were fed contaminated grains compared with controls, but serum IgA concentrations were not affected. Contact hypersensitivity to dinitrochlorobenzene, which is a CD8+ T-cell-mediated delayed-type hypersensitivity response, was decreased (48%) by feed-borne mycotoxins compared with the control. By contrast, the primary and secondary antibody response to sheep red blood cells, a CD4+ T-cell-mediated response, was not affected. It was concluded that chronic consumption of grains naturally contaminated with Fusarium mycotoxins exerts only minor adverse effects on the hematology and some immunological indices of turkeys. Consumption of grains naturally contaminated with Fusarium mycotoxins may, however, increase the susceptibility of turkeys to infectious agents against which CD8+ T cells play a major role in defense.

Effects of feed-borne Fusarium mycotoxins on hematology and immunology of laying hens

Feeding grains naturally contaminated with Fusarium mycotoxins has been shown to alter metabolism and performance of laying hens. The objectives of the current experiment were to examine the effects of feeding grains naturally contaminated with Fusarium mycotoxins on hematology and immunological indices and functions of laying hens and the possible protective effect of feeding a polymeric glucomannan mycotoxin adsorbent (GMA). One hundred forty-four laying hens were fed for 12 wk with diets formulated with (1) uncontaminated grains, (2) contaminated grains, or (3) contaminated grains + 0.2% GMA. Fusarium mycotoxins such as deoxynivalenol (DON, 12 mg/kg), 15-acetyl-DON (0.5 mg/kg), and zearalenone (0.6 mg/kg) were identified in the contaminated diets arising from contaminated grains grown in Ontario, Canada. The concentrations of DON arising from naturally contaminated grains in this study were similar to purified mycotoxin fed to experimental mice. The chronic feeding of Fusarium mycotoxins induced small decreases in hematocrit values, total numbers of white blood cells, lymphocytes including both CD4+ and CD8+ T lymphocytes and B lymphocytes, and biliary IgA concentration. Supplementation of diets containing feedborne mycotoxins with GMA prevented the reduction in total number of B lymphocytes in the peripheral blood and the reduction in biliary IgA concentration. In addition, the delayed-type hypersensitivity response to dinitrochlorobenzene was increased by feed-borne mycotoxins, whereas IgG and IgM antibody titers to sheep red blood cells were not affected by diet. We concluded that chronic consumption of grains naturally contaminated with Fusarium mycotoxins at levels likely to be encountered in practice were not systemically immunosuppressive or hematotoxic; however, mucosal immunocompetence needs to be explored further.

Growth-inhibiting effects of concentrations of fusaric acid on the growth of Bacillus mojavensis and other biocontrol Bacillus species

AIMS

To determine the effects of concentrations of fusaric acid on the growth of several strains of the biocontrol bacterial endophyte Bacillus mojavensis and other species within the Bacillus subtilis group, as well as the genetic relationships within this small group of Gram-positive bacteria, and their antagonisms to Fusarium verticillioides, which produce fusaric acid.

METHODS AND RESULTS

The growth of 50 Bacillus strains and species were tested at two concentrations of fusaric acid determined in maize infected by an isolate of F. verticillioides. Molecular characterizations of the strains and species of bacteria were determined with an automated ribotyper. The growth of bacteria measured under both concentrations with an automated turbidometer, Bioscreen, indicated that fusaric acid was toxic to most strains of the bacterial endophyte B. mojavensis. However, the effects of these two concentrations on other Bacillus species varied in that fusaric acid was either bacteriocidal or bacteriostatic to most species.

CONCLUSIONS

These data indicate that the concentrations of fusaric acid are inhibitory to the growth of most Bacillus species, some of which are used as biocontrol agents. This suggests that the endophytic and saprophytic states of F. verticillioides and other Fusarium species cannot be controlled by fusaric-acid-sensitive Bacillus species.

SIGNIFICANCE AND IMPACT OF STUDY

Mycotoxic Fusarium species, such as F. verticillioides, are competitive because all produce fusaric acid, which is inhibitory to biocontrol bacteria, and mutants tolerant to fusaric acid must be developed in order to be effective on biocontrol bacteria.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on performance, metabolism, hematology, and immunocompetence of ducklings

Experiments were conducted to determine the effects of feeding grains naturally contaminated with Fusarium mycotoxins on performance, metabolism, hematology, and immune competence of ducklings. Four hundred sixty-four 1-d-old White Pekin male ducklings were fed starter (0 to 2 wk), grower (3 to 4 wk), and finisher (5 to 6 wk) diets formulated with uncontaminated grains, a low level of contaminated grains, a high level of contaminated grains, or the higher level of contaminated grains + 0.2% polymeric glucomannan mycotoxin adsorbent. Body weight gains, feed consumption, and feed efficiency were not affected by diet. However, consumption of contaminated grains decreased plasma calcium concentrations after 2 wk and plasma uric acid concentrations at the 4-wk assessment point. Mean corpuscular hemoglobin concentrations and hematocrit decreased when ducks were fed contaminated grains for 4 or 6 wk, respectively. In contrast, total numbers of white blood cells and lymphocytes increased transiently in birds fed contaminated grains for 4 wk. The antibody response to sheep red blood cells (CD4+ T cell dependent) and the cell-mediated response to phytohemagglutinin-P (also CD4+ T cell dependent) were not affected by diet, but consumption of contaminated grains for 6 wk decreased the duration of peak cell-mediated response to dinitrochlorobenzene (CD8+ T cell dependent) assessed in a skin test. Feeding grains naturally contaminated with Fusarium mycotoxins, even at levels widely regarded as high, exerted only minor adverse effects on plasma chemistry and hematology of ducklings, and production parameters were unaffected in this avian species. Mycotoxin-contaminated feeds may, however, render these animals susceptible to infectious agents such as viruses against which the CD8+ T cell provides necessary defence. Glucomannan mycotoxin adsorbent was not effective in preventing alterations caused by Fusarium mycotoxins.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on performance and metabolism of laying hens

An experiment was conducted to evaluate the effects of feeding laying hens grains naturally contaminated with a combination of Fusarium mycotoxins. Parameters measured included performance, organ weights, and plasma chemistry. One hundred and forty-four, 45-wk-old laying hens were fed diets including: (1) control, (2) contaminated grains, and (3) contaminated grains + 0.2% polymeric glucomannan mycotoxin adsorbent (GMA) for a 12-wk period. The feeding of contaminated grains decreased feed consumption compared with controls in the first 4 wk. Feed consumption increased, however, from 4 to 8 wk and from 8 to 12 wk. The efficiency of feed utilization (feed consumption/egg mass) decreased compared with controls in the periods from 4 to 8 and from 8 to 12 wk when birds were fed contaminated grains. Supplementation with GMA decreased feed consumption and increased the efficiency of feed utilization in the period from 8 to 12 wk. Egg production and egg mass decreased in wk 4 and 8 compared with controls when contaminated grains were fed, whereas egg and eggshell weights decreased in the fourth wk. Plasma uric acid concentrations increased throughout the experiment and relative kidney weights increased at the end of the experiment compared with controls when birds were fed contaminated grains. The feeding of GMA prevented the elevation in uric acid concentrations and relative kidney weights. It was concluded that layer performance and metabolism were adversely affected by chronic feeding of a combination of Fusarium mycotoxins, and that GMA prevented many of these effects.

Fusaric acid, aFusarium verticillioidesmetabolite, antagonistic to the endophytic biocontrol bacteriumBacillus mojavensis

An endophytic bacterium, Bacillus mojavensis Roberts, Nakamura & Cohan, was patented as a nonpathogenic biocontrol for plant diseases. However, before this bacterium can be used as a biocontrol agent, it must be evaluated against homologous competing organisms, some of which are equally successful endophytes, such as species of Fusarium that are symptomless endophytes, especially on maize. Preliminary field trials using this bacterium as a biocontrol agent against production of the fumonisin mycotoxins caused by infection of maize with Fusarium verticillioides (Sacc.) Nirenberg (= Fusarium moniliforme Sheldon) was less than that observed with greenhouse studies. Fusarium verticillioides and other species produce fusaric acid. Fusaric acid at concentrations as low as 22 µmol/L accounted for a 41% reduction in CFU compared with the control group, while concentrations of 223 µmol/L and higher resulted in total toxicity to the bacterium. Mutants of F. verticillioides that produced low concentrations of fusaric acid did not affect the endophytic CFU of the bacterium in seedlings. These results suggest that fusaric acid accounted for the reduction of bacterial colonization and the resulting poor biocontrol activity and suggested its importance to the fungus is as an antibiotic, which assists in the in planta competition for the intercellular niche colonized by F. verticillioides during its endotrophic state.Key words: Fusarium moniliforme, Fusarium verticillioides, bacterial endophyte, fungal endophyte, fumonisin.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on brain regional neurochemistry of starter pigs and broiler chickens1

Two experiments were conducted to compare the effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on brain regional neurochemistry of starter pigs and broiler chickens. A polymeric glucomannan mycotoxin adsorbent (GM polymer) was also tested for its efficacy in preventing Fusarium mycotoxicoses. In Exp. 1, a total of 150 starter pigs (initial weight = 9.3+/-1.1 kg) were fed five diets (six pens of five pigs per diet) for 21 d. Diets (as-fed basis) included control, 17% contaminated grains, 24.5% contaminated grains, 24.5% contaminated grains + 0.2% GM polymer, and a pair-fed control for comparison with pigs receiving 24.5% contaminated grains. In Exp. 2,360 1-d-old male broiler chicks were fed for 56 d one of four diets containing the same source of contaminated grains as was fed to pigs. The diets included control, 37% contaminated grains, 58% contaminated grains, and 58% contaminated grains + 0.2% GM polymer (as fed). Neurotransmitter concentrations in the cortex, hypothalamus, and pons were analyzed by HPLC. The following brain neurotransmitter alterations (P < or = 0.05) were observed. In pigs, inclusion of contaminated grains in the diet 1) linearly increased cortex 5-hydroxytryptamine (5HT, serotonin) concentrations, while linearly decreasing hypothalamic tryptophan concentrations; 2) quadratically increased hypothalamic and pons 5-hydroxyindoleacetic acid (5HIAA):5HT ratios, whereas the ratio decreased linearly in the cortex; and 3) linearly increased the ratio of hypothalamic 3,4-dihydroxyphenylacetic acid:dopamine (DA) concentrations, whereas hypothalamic norepinephrine (NRE) and pons DA and homovanillic acid (HVA) concentrations linearly decreased. In broiler chickens, inclusion of contaminated grains in the diet 1) linearly increased concentrations of 5HT and 5HIAA in the pons and 5HT concentrations in the cortex; 2) linearly decreased 5HIAA:5HT ratio; and 3) linearly increased pons NRE, 3-methoxy-4-hydroxyphenylethylene glycol, DA, and HVA concentrations. Supplementation of GM polymer to the contaminated diet decreased (P < 0.05) 5HT and 5HIAA concentrations in the cortex of pigs. It was concluded that the differences in alterations of brain neurochemistry might explain the species differences in the severity of Fusarium mycotoxin-induced feed refusal.

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on growth and immunological parameters of broiler chickens

An experiment was conducted to investigate the effects of feeding grains naturally contaminated with Fusarium mycotoxins on growth and immunological parameters of broiler chickens. Three hundred sixty, 1-d-old male broiler chicks were fed 1 of 4 diets containing grains naturally contaminated with Fusarium mycotoxins for 56 d. The diets included (1) control; (2) low level of contaminated grains (5.9 mg/kg deoxynivalenol (DON), 19.1 mg/kg fusaric acid (FA), 0.4 mg/kg zearalenone, and 0.3 mg/kg 15-acetyldeoxynivalenol; (3) high level of contaminated grains (9.5 mg/kg DON, 21.4 mg/kg FA, 0.7 mg/kg zearalenone, and 0.5 mg/kg 15-acetyldeoxynivalenol); and (4) high level of contaminated grains + 0.2% polymeric glucomannan mycotoxin adsorbent (GM polymer). Body weight gains and feed consumption of chickens fed contaminated grains decreased linearly with the inclusion of contaminated grains during the grower phase (d 21 to 42). Efficiency of feed utilization, however, was not affected by diet. Production parameters were not significantly affected by the supplementation of GM polymer to the contaminated grains. Peripheral blood monocytes decreased linearly in birds fed contaminated grains. The feeding of contaminated diets linearly reduced the B-cell count at the end of the experiment, whereas the T-cell count on d 28 responded quadratically to the contaminated diets. The feeding of contaminated diets did not significantly alter serum or bile immunoglobulin concentrations, contact hypersensitivity to dinitrochlorobenzene, or antibody response to SRBC. Supplementation with GM polymer in the contaminated diet nonspecifically increased white blood cell count and lymphocyte count, while preventing mycotoxin-induced decreases in B-cell counts. It was concluded that broiler chickens are susceptible during extended feeding of grains naturally contaminated with Fusarium mycotoxins.

Effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on growth and immunological measurements of starter pigs, and the efficacy of a polymeric glucomannan mycotoxin adsorbent1

An experiment was conducted to investigate the effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on growth and immunological parameters of starter pigs. A polymeric glucomannan mycotoxin adsorbent (GM polymer, Alltech Inc., Nicholasville, KY) was also tested for its efficacy in preventing Fusarium mycotoxicoses. A total of 150 starter pigs (initial weight of 9.3 +/- 1.1 kg) were fed one of five treatment diets (six pens of five pigs per diet) for 21 d. Diets included control, low level of contaminated grains, high level of contaminated grains, high level of contaminated grains + 0.20% GM polymer, and pair-fed control for comparison with pigs receiving the high level of contaminated grains. Feed intake and cumulative weight gain of pigs decreased linearly with the inclusion of contaminated grains in the diet throughout the experiment (P < 0.0001). Weight gains recovered, however, during wk 3 (P > 0.05). There was no difference between the pair-fed group and the pigs fed the diet containing the high level of contaminated grains in terms of weight gain or feed efficiency (P > 0.05). Feeding contaminated grains linearly increased the serum albumin:globulin ratio (P = 0.01), whereas serum urea concentrations and gamma-glutamyltransferase activities responded in a quadratic fashion (P = 0.02). When compared with the pair-fed pigs, serum concentrations of total protein (P = 0.01) and globulin (P = 0.02) were decreased in pigs fed the diet containing the high level of contaminated grains. The feeding of contaminated diets did not significantly alter organ weights expressed as a percentage of BW, serum immunoglobulin concentrations, percentages of peripheral blood lymphocyte subsets, contact hypersensitivity to dinitrochlorobenzene, or primary antibody response to sheep red blood cells (P > 0.05). It was concluded that most of the adverse effects of feeding Fusarium mycotoxin-contaminated grains to starter pigs were caused by reduced feed intake. Although supplementation of GM polymer to the contaminated diet prevented some toxin-induced changes in metabolism, it did not prevent the mycotoxin-induced growth depression under the current experimental conditions.

Effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on feed intake, serum chemistry, and hematology of horses, and the efficacy of a polymeric glucomannan mycotoxin adsorbent

The feeding of Fusarium mycotoxin-contaminated grains adversely affects the performance of swine and poultry. Very little information is available, however, on adverse effects associated with feeding these mycotoxin-contaminated grains on the performance of horses. An experiment was conducted to investigate the effects of feeding a blend of grains naturally contaminated with Fusarium mycotoxins on feed intake, serum immunoglobulin (Ig) concentrations, serum chemistry, and hematology of horses. A polymeric glucomannan mycotoxin adsorbent (GM polymer) was also tested for efficacy in preventing Fusarium mycotoxicoses. Nine mature, nonexercising, light, mixed-breed mares were assigned randomly to one of three dietary treatments for 21 d. The horses were randomly reassigned and the experiment was subsequently replicated in time following a 14-d washout interval. Feed consumed each day was a combination of up to 2.8 kg of concentrates and 5 kg of mixed timothy/alfalfa hay. The concentrates fed included the following: 1) control, 2) blend of contaminated grains (36% contaminated wheat and 53% contaminated corn), and 3) blend of contaminated grains + 0.2% GM polymer. Diets containing contaminated grains averaged 15.0 ppm of deoxynivalenol, 0.8 ppm of 15-acetyldeoxynivalenol, 9.7 ppm of fusaric acid, and 2.0 ppm of zearalenone. Feed intake by all horses fed contaminated grains was reduced (P < 0.001) compared with controls throughout the experiment. Supplementation of 0.2% GM polymer to the contaminated diet increased (P = 0.004) feed intake of horses compared with those fed the unsupplemented contaminated diet. Serum activities of gamma-glutamyltransferase were higher (P = 0.047 and 0.027) in horses fed the diet containing contaminated grain compared with those fed the control diet on d 7 and 14, but not on d 21 (P = 0.273). Supplementation of GM polymer to the contaminated diet decreased (P < 0.05) serum gamma-glutamyltransferase activities of horses compared with those fed unsupplemented contaminated diet on d 7 and 14. Other hematology and serum chemistry measurements including serum IgM, IgG, and IgA, were not affected by diet. It was concluded that the feeding of grains naturally contaminated with Fusarium mycotoxins caused a decrease in feed intake and altered serum gamma glutamyltransferase activities. The supplementation of GM polymer prevented these mycotoxin-induced adverse effects.