Developmental effects of fumonisin B1 in mice

Developmental and toxic effects of aqueous extracts of F. moniliforme culture material containing known levels of fumonisin B₁ were recently reported in mice and included maternal hepatotoxicity and lethality, maternal body weight gain reduction, increased embryonic resorptions, reduced offspring body weights, and fetal malformations including cleft palate, hydrocephalus, malformed ribs and incomplete digital and sternal ossification. These studies also suggested that the effects of the fungal extract on the mouse offspring may be mediated via maternal effects. The contribution of fumonisin B₁ (FB₁), a major toxic metabolite of F moniliforme, in the induction of these effects was evaluated in this study by administering 0 to 100 mg pure FB₁/kg of body weight on gestational days (GD) 7 through 15 to pregnant Charles River CD1 mice and assessing maternal health and fetal development till the end of gestation. Doses of 25 mg/kg or higher of pure FB₁ induced maternal liver lesions (mostly necrotic changes), associated with ascites and increased hepatocytic nuclear diameter. Fumonisin doses of 50 mg/kg or higher also resulted in significantly increased maternal ALT on GD12, and reduced offspring bodyweights on GD 18. Increased resorptions and decreased numbers of live offspring were only evident at 100 mg FB₁/kg body weight. Offspring exhibited dose-dependent increase in the incidence and severity of hydrocephalus of both the lateral and third ventricles at doses of 25 mg/kg or higher. Doses of 25 mg/kg or higher also increased the sphinganine/sphingosine (Sa/So) ratios in maternal but not fetal livers. These results suggest that FB₁ may be a developmental toxicant accounting for most but not all earlier reported effects of F. moniliforme culture extract. Association of FB₁ effects on the offspring with maternal hepatoxicity and with alteration of Sa/So ratio in maternal but not fetal liver supported the earlier claim that FB₁ effects on the mouse offspring are mediated by maternal hepatotoxicity.     

Increased cytotoxicity of food-borne mycotoxins toward human cell lines in vitro via enhanced cytochrome p450 expression using the MTT bioassay

Eight food-borne mycotoxins epidemiologically implicated in human disease were tested for their cytotoxic effects on human cells previously immortalised and transfected to introduce human cytochrome p450(CYP 450) genes. Such cells retain many characteristics of normal cell growth and differentiation while simultaneously having the potential of either increasing or decreasing the metabolic activity (cytotoxicity) of the challenging mycotoxins. The MTT assay provided an indication of cytotoxicity. Of the nine CYP 450s introduced CYP1A2 was most effective,rendering the cells 540 times more sensitive than the control cells to aflatoxin B₁, 28 times more sensitive to aflatoxin G₁ and 8-fold more sensitive to ochratoxin A. CYP3A4 resulted in the cells being 211 times more toxic to aflatoxin B₁ and 8-fold more toxic to aflatoxin G₁ while CYP 2A6, CYP 3A5 and CYP 2E1 also produced observable effects. No increase in metabolic activity was found using cyclopiazonic acid, deoxynivalenol,fumonisin B₁, patulin or T-2 toxin. CD5Os were calculated for the mycotoxins against the non-CYP-introduced control cells. There was almost a five order of magnitude difference between the most toxic,T-2 toxin (CD50 0.0057 g/ml) and the least toxic, fumonisin ₁(CD50 476.2 g/ml). In vitro biological assays thus provide an excellent system for quantifying the often low CD50s expressed bymycotoxins in foods.This revised version was published online in October 2005 with corrections to the Cover Date.     

AAL Toxins,funionisms (biology and chemistry) and host-specificity concepts

The AAL toxins and the fumonisins (FB₁ and FB₂) are structurally related and produced respectively by Alternaria alternata f.sp. lycopersici and Fusarium moniliforme. AAL toxin is characterized as a hostspecific toxin, toxic to tomato, whereas fumonisin B₁ causes equine leukoencephalomalacia. FB₁ and FB₂ were biologically active in susceptible tomato tissue (Earlypak-7) and animal tissue culture (rat hepatoma H4TG and dog kidney MDCK). Conversely, AAL toxin was also active in the rat and dog tissue culture cells. Both fungi produce toxin/s in culture that cause death in rats; these toxins are other than AAL and fumonisin. The peracetylated derivatives of AAL and FB₁ are biologically inactive in both the tomato bioassay and the animal tissue culture systems. Acetylation of the amine renders AAL inactive. The hydrolysis product of AAL (pentolamine) is toxic to the susceptible tomato line whereas the pentolamine of fumonisin is not.AAL and FB₁ can be analyzed by Continuous Flow Fast Atom Bombardment (CFFAB) and Ionspray Mass Spectrometry (ISM), both sensitive to the picomole range. The N-acetyl of the TFA hydrolysis product of AAL and FB₁ is determined by comparing the fragment ions at m/z 86 and 140 for FB₁ and 72 and 126 for AAL.Published as paper No. 19,598 of the contribution series of the Minnesota Agricultural Experiment Station based on research conducted under Project 22–34H, supported by HATCH funds.     

Alterations of the glutathione redox cycle status in fumonisin B1-treated pig kidney cells

Fumonisin B₁ (FB₁) causes equine leukoencephalomalacia, porcine pulmonary edema, and liver tumors and chronic nephritis in rats. To investigate mechanisms by which FB₁ induces toxicity, effects of FB₁ on cellular glutathione (GSH) redox status and GSH depletion on FB₁ toxicity in pig kidney (LLC-PK₁) cells were studied. Treatment of LLC-PK₁ cells with 50 μM FB₁ for 24 hours significantly decreased cellular GSH contents from 56 ± 3.2 to 42.7 ± 4.4 nmol/mg protein (p < 0.05) and increased the activities of glutathione reductase (GR) from 25.7 ± 2.4 to 35.7 ± 5.0 μmol NADPH/mg protein (p < 0.05). The activities of glutathione peroxidase (GSHpx), catalase, and Cu,Zn-superoxide dismutase (SOD) were not changed by this treatment. Treatment of LLC-PK₁ cells for 12 hours with 0.1. mM buthionine sulfoximine (BSO), a selective inhibitor of the enzyme γ-glutamylcysteine synthetase that catalyzes the rate-limiting reaction in de novo GSH synthesis, decreased cellular GSH levels to about 20% of that found in the control cells. The cells pretreated with 0.1 mM BSO for 12 hours were significantly sensitized to the FB₁ cytotoxicity as determined by a long-term survival assay (p < 0.05). The results demonstrate that FB₁ changes GSH redox cycle status in LLC-PK₁ cells, and GSH may play a role in cytoprotection against FB₁ toxicity. © 1997 John Wiley & Sons, Inc.     

In vivo effects of fumonisin B1-producing and fumonisin B1-nonproducing Fusarium moniliforme isolates are similar: Fumonisins B2 and B3 cause hepato- and nephrotoxicity in rats

Fumonisins are mycotoxins produced by Fusarium moniliforme, F. proliferatum, and related Fusarium species found on corn. They occur naturally in corn-based feeds and foods and are suspected human esophageal carcinogens. Fumonisin B₁ (FB₁), the most common homologue, causes the animal diseases associated with F. moniliforme. Hepato- and nephrotoxicities, disrupted sphingolipid metabolism, and liver cancer have been found in rats fed FB₁. To determine the in vivo effects of diets containing fumonisins B₂ (FB₂) or B₃ (FB₃), male rats were fed culture materials (CM) of FB₁ non-producing F. moniliforme isolates to provide low (4.6–6.7 ppm), mid (32–49 ppm) or high (219–295 ppm) dietary levels of either FB₂ (FB₂CM) or FB₃ (FB₃CM). Other groups were fed culture material of an FB₁ producing isolate (FB₁CM) providing 6.9, 53 or 303~ppm total fumonisins (FB₁ : FB₂ : FB₃ = 1.0 : 0.38 : 0.15) and a tenth group was fed a control diet having no detectable fumonisins. One-half (n = 5/group) the animals were killed after three weeks, at which time the toxicological and histopathological effects of the three culture materials were similar, mimicked the effects of FB₁, and included decreased body weight gains, serum chemical indicators of hepatotoxicity, decreased kidney weights, and apoptosis of hepatocytes and kidney tubular epithelium. FB₁CM, FB₂CM, and FB₃CM affected sphingolipids, causing increased sphinganine to sphingosine ratios (Sa/So) in both liver and kidneys. The remaining animals (n = 5/group) were fed a control diet for three additional weeks. All body weight and tissue specific effects, including increased Sa/So, induced by the FB₂CM, FB₃CM and low level FB₁CM diets were absent following the recovery period. Except for mild biliary lesions found in the high dose FB₁CM group and a few apoptotic hepatocytes present in one mid- and two high-dose FB₁CM rats, no evidence of toxicity remained in these groups following the recovery period.This revised version was published online in October 2005 with corrections to the Cover Date.     

Lymphocyte cytotoxicity and erythrocytic abnormalities induced in broiler chicks by fumonisins B1 and B2 and moniliformin fromFusarium proliferatum

Peripheral blood lymphocytes were isolated from broiler chicks that had ingested feed amended with autoclavedFusarium proliferatum culture material containing fumonisin B₁ (FB₁), fumonisin B₂ (FB₂) and moniliformin. Lymphocyte viability was determined for birds that were placed on amended rations at day 1 or day 7 of age at three different levels of mycotoxins, ranging from 61–546 ppm FB₁, 14–94 ppm FB₂ and 66–367 ppm moniliformin. Reduction of the tetrazolium salt, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide], to yield MTT formazan, based on mitochondrial metabolic activity, was used to assess cell viability. Lymphocyte cytotoxic effects were observed in all treatment groups on day 21; chicks that started on amended feed at day 1 of age were affected more than those that started at day 7. Abnormal erythrocytes resembling early stages of erythroblasts were observed in peripheral blood from test chicks. Abnormally shaped red cells (poikilocytes) having a spindle-shape with one or both ends pointed were present. Some red cells appeared to be undergoing mitosis. Both reduced lymphocyte viability and abnormal erythrogenesis occurred in chicks given feed amended withF. proliferatum culture material containing FB₁, FB₂ and moniliformin.     

Comparative cytotoxicity of fumonisin B1 and moniliformin in chicken primary cell cultures

Two water-solubleFusarium metabolites, fumonisin B₁ (FB₁) and moniliformin (MN) were compared for their cytotoxicity in a variety of chicken primary cell cultures. Cardiac and skeletal myocytes and hepatocytes derived from embryos, and splenocytes, macrophages, and chondrocytes derived from 3-to 4-week old chickens were cultured in media containing either FB₁ or MN (0 to 1 mM) for 48 hr. The colorimetric tetrazolium cleavage assay was then used for measuring cell survival. FB₁ was not toxic to macrophages, hepatocytes, cardiac and skeletal myocytes but toxic to splenocytes and chondrocytes. MN was not toxic to chondrocytes and macrophages, but toxic to splenocytes, cardiac and skeletal myocytes. Median effective concentration (EC₅₀) of MN in skeletal myocytes was 42 µM (fiducial limits: 33 to 50 µM) and in cardiac myocytes was 95 µM (fiducial limits: 84 to 122 µM). Estimated EC₅₀ of FB₁ in chondrocytes and splenocytes and EC₅₀ of MN in splenocytes were all greater than 200 µM.     

In vivo and in vitro electrophysiological monitoring of rat neocortical activity after dietary fumonisin exposure

Corn pellets, containing 30 mg/kg bw/day fumonisin B₁ (FB₁) or containing no FB₁ were fed in two series of experiments to rats. Spontaneous and evoked potentials were measured in the neocortex both in vivo and in vitro in “corn fed control” rats and in rats after a five day dietary exposure to FB₁. The FB₁ content of corn was quantitated by HPLC. Auditory evoked potentials recorded in vivo on freely moving animals after feeding a corn diet containing FB₁ for 5 days revealed a highly significant 20–60% decrease in the primary and mid-latency components; cortex slices in vitro showed a reduced excitability both in standard artificial cerebrospinal fluid (ACSF) solution and in a 4-aminopyridine induced epilepsy model. Spontaneous epileptic discharges after FB₁ exposure had an increased latency, decreased frequency, longer duration and modified signal forms. Altered excitability and seizure susceptibility of the neocortex after fumonisin exposure are suspected to be associated with modified signal transmission. These changes may be due to concurrent effects of possible liver and renal toxicity or partly of nutritional deficiencies. This revised version was published online in June 2006 with corrections to the Cover Date.     

Developmental effects of fumonisin B1-containingFusarium moniliforme culture extract in CD1 mice

Pregnant Charles River CD1 mice were treated with a semipurified extract ofFusarium moniliforme culture containing 0, 12.5, 25, 50 or 100 mg FB₁/kg each day orally (diluted in distilled water) between gestational days (GD) 7 and 15 to evaluate the developmental toxicity of FB₁. Following sacrifice of dams on GD 18, litters were examined for gross abnormalities and divided equally for skeletal or visceral examination by routine techniques. Significant maternal mortality was observed at doses of 50 and 100 mg FB₁/kg. Dose-dependant decreases in maternal body weight gains, number of live offsprings per litter, and mean body weight of the offspring were produced at FB₁ doses of 25 mg/kg or higher. The percentage of implants resorbed increased at all doses in a dose-dependant manner. A dose-dependant increase, except at the lowest dose tested, in the incidence of ossification deficits involving digits and sternum, short and wavy ribs, and hydrocephalus of lateral and third ventricles was also evident. Cleft palate was seen only at the highest FB₁ dose. Maternal intoxication manifested as a dose-dependant increase in the severity of ascites associated mainly with increased histopathologic scores reflecting hepatocellular damage at day 18. Concommittant increases in serum alanine amino transferase (ALT) on GD 12, reflecting parenchymal liver cell damage, was also observed at all doses above 12.5 mg of FB₁/kg. These results suggest that FB₁-containingF. moniliforme culture extract is developmentally toxic in mice, and that this toxicity may be mediated by maternal hepatotoxicity.     

Effects of fumonisin B1 alone and combined with deoxynivalenol or zearalenone on porcine granulosa cell proliferation and steroid production

Fumonisin B₁ (FB₁) is a Fusarium mycotoxin frequently occurring in corn in combination with deoxynivalenol (DON) and zearalenone. The aim of this study was to determine if FB₁, alone and combined with DON or α-zearalenol (ZEA), zearalenone major active metabolite, can affect granulosa cell proliferation, steroid production, and gene expression in swine. Porcine granulosa cells were cultured for 2 days in serum-containing medium followed by 1 or 2 days in serum-free medium with or without added treatments. Fumonisin B₁ had inhibitory effects on granulosa cell proliferation. Deoxynivalenol strongly inhibited cell growth, and no significant difference was detected in combination with FB₁. α-Zearalenol showed a stimulatory effect on granulosa cell numbers even in combination with FB₁. Regarding steroid production, FB₁ increased progesterone production, and FB₁ had no effect on estradiol production. Deoxynivalenol strongly inhibited progesterone and estradiol production, and FB₁ had no significant effect on this response. α-Zearalenol increased progesterone production, and its combination with FB₁ produced additive effects. α-Zearalenol had no effect on estradiol production, whereas it decreased estradiol production when co-treated with FB₁. Fumonisin B₁ was found to decrease CYP11A1 messenger RNA abundance, and the stimulatory effect of FB₁ on progesterone production was found to be not dependent on 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity suggesting that FB₁ increases progesterone production through a different mechanism. The results show that these Fusarium mycotoxins can influence porcine granulosa cell proliferation and steroid production, thereby demonstrating their potential reproductive effects on swine.     

Fumonisins: Isolation,chemical characterization and biological effects

The fumonisin B mycotoxins (FB₁ and FB₂) have been purified and characterized from corn cultures of Fusarium moniliforme strain MRC 826. Fumonisin B₁ (FB₁, the major fumonisin produced in culture, has been shown to be responsible for the major toxicological effects of the fungus in rats, horses and pigs. Recent investigations on the purification of compounds with chromatographic characteristics similar to FB₁ have led to the identification of two new fumonisins, FB₃ and FB₄. Fumonisins A₁ and A₂, the N-acetyl derivatives of FB₁ and FB₂ respectively, were also purified and shown to be secondary metabolites of the fungus. Short-term carcinogenesis studies in a rat liver bioassay indicated that over a period of 15 to 20 days, at dietary levels of 0.05–0.1%, FB₂ and FB₃ closely mimic the toxicological and cancer initiating activity of FB₁ and thus could contribute to the toxicological effects of the fungus in animals. In contrast, no biological activity could be detected for FA₁ under identical experimental conditions. These studies and others have indicated that the fumonisin B mycotoxins, although lacking mutagenicity in the Salmonella test or genotoxicity in the DNA repair assays in primary hepatocytes, appear to induce resistant hepatocytes similar to many known hepatocarcinogens.     

Einfluß des Rohproteinniveaus in Maisfutterrationen bei verschiedenen Harnstoffgaben in der Jungbullenmast

Mycotoxins are fungal secondary metabolites that elicit a wide spectrum of toxicological effects, including the alteration of normal immune function. In the present study we investigated the independent effect of four mycotoxins, aflatoxin B₁ (AFB₁), fumonisin B₁ (FB₁), deoxynivalenol (DON) and nivalenol (NIV), on lymphocyte proliferation using human and porcine lymphocytes. Human and porcine peripheral blood mononuclear cells and porcine splenocytes were cultured with increasing concentrations of mycotoxins for 72 hours and labelled in the last 24 hours with [methyl-³H]-thymidine. The results showed that increased concentrations of AFB₁, DON and NIV affected the [methyl-³H]-thymidine cellular proliferation following mitogen stimulation in both species and cell types. Lower concentrations of mycotoxins enhanced cellular proliferation, which was more pronounced in human than in porcine cells, while higher concentrations caused a dose-dependent decrease. DON and NIV were the most potent mycotoxin in both species and both cell types. Based on the results of this in vitro study, high correlations were found between proliferation of human and porcine lymphocytes after mycotoxin exposure, especially for DON and NIV.     

Fumonisin B1 alters sphingolipid metabolism and immune function in BALB/c mice: Immunological responses to fumonisin B1

Fumonisins have been reported to have diverse effects on animals, including immunosuppression in chickens and feeder calves; therefore, the effects of fumonisin B₁ (FB₁) on immune function in BALB/c mice was investigated. When administered i.p. with sheep red blood cells (SRBC), 5 to 100 µg of FB₁ reduced the number of plaque-forming cells (PFC) produced against SRBC; however, when administered daily, 1 to 50 µg of FB₁ caused a 4 to 12-fold increase in the number of PFC after SRBC injection. Therefore, FB₁ is not only immunosuppressive; but also, immunostimulatory. To test the possibility that there may have been an immune response to FB₁ as an antigen, FB₁ was injected into mice and the number of splenic cells forming rosettes on FB₁-treated SRBC was determined. There were dose-dependent increases in the antigen-binding cells, with up to 4.9- and 4.6-fold increases, respectively, upon primary and secondary immunization. FB₁-binding immunoglobulins could be detected in sera from some treated mice, but this response was not obtained in every experiment. In summary, these results show that FB₁ has diverse effects on the immune system, causing both stimulation and suppression of the response to foreign antigens, and apparently inducing an antigenic response to FB₁.Abbreviations DMEM Dulbecco's Modified Eagle's Medium - FB₁ fumonisin B₁ - FCS fetal calf serum - PBS phosphate buffered saline - PFC plaque forming cells - RFC rosette forming cells - SRBC sheep red blood cells     

Natural occurrence of Fusarium species and fumonisin-production by toxigenic strains isolated from poultry feeds in Argentina

Fusarium species and fumonisin production by toxigenic strains were investigated. During 1996–1998, 158 samples of poultry feeds were collected from a factory located in the department of Río Cuarto Córdoba province, Argentina. The most common species of Fusarium were F. moniliforme (60.7%) and F. nygamai (35.4%) followed by F. semitectum, F. subglutinans, F. proliferatum, F. dlamini, F. solani, F. oxysporum and F. napiforme. Fungal counts ranged from 1 × 10³ to 8 × 10⁵ CFU/g with mean values from 1.5 × 10³ to 2.3 × 10⁵ CFU/g. The highest counts were for F. dlamini, F. subglutinans, F. moniliforme and F. nygamai. Strains of F. moniliforme, F. nygamai, and F. proliferatum were screened for their potential to produce fumonisin B₁ (FB₁), fumonisin B₂ (FB₂) and fumonisin B₃ (FB₃) in corn grain. The samples were analysed using a modified high performance liquid chromatography method. The strains assayed, 43 strains, produced three fumonisins. There was a high degree of variability in the quantities of FB₁, FB₂, and FB₃ produced. The toxin produced in highest levels by the majority of the strains was FB₁. The range of concentration varied from 5.4 to 3,991, 1.01 to 189 and 0.4 to 765 ppm per gram of corn for FB₁, FB₂ and FB₃ respectively. The toxigenic pattern of strains was normal, although two strains of F. moniliforme produced exceptionally high concentrations of FB₃ and minor concentrations of FB₂ and FB₁. This is the first report from Argentina on Fusarium species in poultry feeds and fumonisin production by these strains.This revised version was published online in October 2005 with corrections to the Cover Date.     

DNA Damage in Astrocytes Exposed to Fumonisin B1

Fumonisins are a group of toxic metabolites mainly produced by Fusarium moniliforme and Fusarium proliferatum, fungi that commonly occur on corn throughout the world. Fumonisin B₁ (FB₁), structurally resembling sphingoid bases, is an inhibitor of ceramide synthase, a key enzyme involved in de novo sphingolipid biosynthesis and in the reacylation of free sphingoid bases derived from sphingolipid turnover. This inhibitory effect leads to accumulation of free sphinganine (SA) and sphingosine (SO), inducing cell death. However, little is known on the down stream effectors activated by these sphingolipids in the cell death signaling pathway. We exposed rat astrocytes to FB₁ with the aim of evaluating the involvement of oxygen free radicals and of some other biochemical pathways such as caspase-3 activity and DNA damage. Our results indicate that FB₁ treatment (48, 72 h and 6 days in vitro, DIV, and 10, 50, 100 M) does not affect cell viability. Conversely, after 72 h of treatment, FB₁ (50 and 100 M) induced DNA damage and an enhancement of caspase-3 activity compared to controls. In addition, FB₁ increased the expression of HSP70 at 10 and 50 M at 48, 72 h, and 6 DIV of treatment. We conclude that DNA damage of apoptotic type in rat astrocytes is caused by FB₁ and that the genotoxic potential of FB₁ has probably been underestimated and should be reconsidered.     

Production of fumonisins B1, B2 and B3 byFusarium proliferatum Isolated from rye grains

Using the seed- plate technique, we have isolated a strain ofF. proliferatum from rye grains that produces 3 fumonisins, fumonisin B₁ (FB₁), FB₂ and FB₃ on inoculated rice and corn. Inoculated corn and rice were extracted with an aqueous methanol solution and fumonisin concentrations estimated using high performance liquid chromatography. Production of all 3 fumonisins (FB₁, FB₂ and FB₃) was much higher on rice than corn; ranging from 3816, 1068 and 985 ppm to 1643, 350 and 162 ppm respectively. We conclude that all natural substrates whereF. proliferatum is present as a component of the mycoflora should be monitored for the presence of fumonisins.     

Selective and transient activation of protein kinase C alpha by fumonisin B1, a ceramide synthase inhibitor mycotoxin, in cultured porcine renal cells

Fumonisin B₁ (FB₁), a potent and naturally occurring mycotoxin produced by the fungus Fusarium verticillioides, has been implicated in fatal and debilitating diseases in animals and humans. FB₁ affects a variety of cell signaling proteins including protein kinase C (PKC); a serine/threonine kinase, involved in a number of signal transduction pathways that include cytokine induction, carcinogenesis and apoptosis. The aim of this study was to investigate the short-term temporal and concentration-dependent effects of FB₁ on PKC isoforms present in LLC-PK₁ cells in relation to the FB₁-induced accumulation of sphinganine and sphingosine utilizing various inhibitors and activators. Our studies demonstrated that FB₁ (0.1-1 μM) selectively and transiently activated PKCα at 5 min, without affecting PKC-δ, -ε and -ζ isoforms. At higher FB₁ concentrations and later time points (15-120 min), PKCα membrane concentrations declined to untreated levels. The observed increase in cytosol PKCα protein expression at 15 min was not associated with an increase in its activity or protein biosynthesis. Calphostin C, a PKC inhibitor, abrogated the FB₁-induced translocation of PKCα. Pre-incubation with the PKC activator, phorbol 12-myristate 13-acetate, resulted in an additive effect on membrane translocation of PKCα. Intracellular sphinganine and sphingosine concentrations were unaltered at the time points tested. Myriocin, a specific inhibitor of serine palmitoyltransferase, the first enzyme in de novo sphingolipid biosynthesis, did not prevent the FB₁-induced PKCα cytosol to membrane redistribution. Altering PKCα and its signal transduction pathways may be of importance in the ability of FB₁ to exert its toxicity via apoptosis and/or carcinogenesis.     

Mycotoxin Fumonisin B1 Increases Intestinal Colonization by Pathogenic Escherichia coli in Pigs

Fumonisin B₁ (FB₁) is a mycotoxin that commonly occurs in maize. FB₁ causes a variety of toxic effects in different animal species and has been implicated as a contributing factor of esophageal cancers in humans. In the present study, we examined the effect of dietary exposure to FB₁ on intestinal colonization by pathogenic Escherichia coli associated with extraintestinal infection. Three-week-old weaned pigs were given FB₁ by gavage as a crude extract or as a purified toxin at a dose of 0.5 mg/kg of body weight daily for 6 days. On the last day of the toxin treatment, the pigs were orally inoculated with an extraintestinal pathogenic E. coli strain. All animals were euthanized 24 h later, necropsies were performed, and tissues were taken for bacterial counts and light microscopic examination. Ingestion of FB₁ had only a minimal effect on animal weight gain, did not cause any macroscopic or microscopic lesions, and did not change the plasma biochemical profile. However, colonization of the small and large intestines by an extraintestinal pathogenic E. coli strain was significantly increased. Our results show that FB₁ is a predisposing factor to infectious disease and that the pig can be used as a model for the study of the consequences of ingesting mycotoxin-contaminated food.     

Synthesis and degradation of long-chain base phosphates affect fumonisin B<Subscript>1</Subscript>-induced cell death in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Fumonisin B₁ (FB₁), an inducer of cell death, disrupts sphingolipid metabolism; large accumulations of de novo synthesized free long-chain bases (LCBs) are observed. However, it remains unclear whether tolerance to FB₁ toxicity in plants is connected with preventing the accumulation of free LCBs through their phosphorylation. Here a workflow for the extraction, detection and quantification of LCB phosphates (LCBPs) in Arabidopsis thaliana was developed. We studied the effect of expression of genes for three enzymes involved in the synthesis and degradation of LCBPs, LCB kinase (LCBK1), LCBP phosphatase (SPP1) and lyase (DPL1) on FB₁-induced cell death. As expected, large accumulations of saturated free LCBs, dihydrosphingosine and phytosphingosine, were observed in the FB₁-treated leaves. On the other hand, a high level of sphingenine phosphate was found in the FB₁-treated leaves even though free sphingenine was found in low amounts in these leaves. In comparison of WT and spp1 plants, the LCBP/LCB ratio is likely to be correlated with the degree of FB₁-induced cell death determined by trypan blue staining. The FB₁-treated leaves in dpl1 plants showed severe cell death and the elevation of free LCBs and LCBPs. LCBK1-OX and -KD plants showed resistance and sensitivity to FB₁, respectively, whereas free LCB and LCBP levels in FB₁-treated LCBK1-OX and -KD plants were moderately different to those in FB₁-treated WT plants. Overall, the findings described here suggest that LCBP/LCB homeostasis is an important topic that participates in the tolerance of plant cells to FB₁.     

Fumonisin B1 damages the barrier functions of porcine intestinal epithelial cells in vitro

Fumonisins (Fums) are mycotoxins widely distributed in crops and feed, and ingestion of Fums‐contaminated crops is harmful to animal health. The purpose of this study is to explore the effect of Fum B₁ (FB₁) on barrier functions of porcine intestinal epithelial cells, IPEC‐J2, to clarify the intestinal toxicity of Fums in pigs. The results showed that the persistent treatment of FB₁ significantly decreased the viability of IPEC‐J2. Moreover, the expressions of Claudin 1, Occludin, Zonula Occluden‐1 (ZO‐1) on the messenger RNA (mRNA), and protein levels and MUC1 on the mRNA level were significantly inhibited after FB₁ treatment, while the mRNA relative expression level of MUC2 was clearly increased. FB₁ also enhanced the monolayer cell permeability of IPEC‐J2. Importantly, FB₁ promoted the expression of phosphorylated extracellular regulated protein kinase (p‐ERK_1/2). These data suggest that long‐term treatment of FB₁ can suppress IPEC‐J2 proliferation, damage tight junctions of IPEC‐J2, and regulate expression of mucins to induce the damage of barrier functions of porcine intestinal epithelial cells, which may be associated with the ERK_1/2 phosphorylation pathway.