Mycoflora and fumonisin-producing strains ofFusarium moniliforme in mixed poultry feeds and component raw material

In a survey of the mycoflora and mycotoxins in foods and feeds, 66 samples of mixed poultry feeds and some component raw materials were investigated. Fungal counts ranged from < 10² to 1.3 × 10⁶ CFU/g.Fusarium spp. counts ranged from 10² to 1.0 × 10⁶ CFU/g. TheFusarium spp. strains isolated were screened for their potential to produce fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) in maize cultures. Samples and maize cultures were analysed for FB₁ and FB₂ using TLC and fluorescamine-derivative HPLC. No fumonisins were detected in the samples (<6 ppm).Fusarium moniliforme was isolated in 59.1% of samples, and 97.4% of the strains produced FB₁ and 79.4% of strains produced FB₂ in maize cultures. Some isolates produced higher FB₁ and FB₂ levels than the reference strainF. moniliforme MRC 826.     

Occurrence of fumonisin B1 and B2 in corn-based foodstuffs in Taiwan market

Corn-based human foodstuffs purchased in Taiwan were analyzed for fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) using high-performance liquid chromatography. Fifty-two (33.9%) and 32 (20.9%) of 153 samples were found to contain FB₁ (73–2395 ng/g) and FB2 (120–715 ng/g), respectively. The highest frequency of detection and also the highest FB1 concentrations were found in sweetcorn (50%, 1089 ng/g) and cornflour (50%, 608 ng/g), followed by corn snacks (33.3%, 2395 ng/g), miscellaneous corn products (33.3%, 73 ng/g), popcorn (31.8%, 1003 ng/g) and cornflakes (23.5%, 1281 ng/g). 16 corn snacks (= approximately 20.5% of the samples) had an average FB₁ and FB₂ content of 456 and 145 ng/g, respectively, while six sweetcorn (= 25%) samples were contaminated with an average of 400 ng/g of FB₁ and 65 ng/g of FB₂. Of the 22 pop-corn samples examined, 7 had an average of 347 ng/g and 116 ng/g of FB₁ and FB₂, respectively. During an analysis of the distribution pattern for the combined fumonisin levels of FB₁ and FB₂, it became apparent that more than 69% of tested samples had fumonisin concentrations below 100 ng/g, while 11.1% (or 17 samples) contained in excess of 600 ng toxins per g. These results clearly illustrated that commercially available corn-based foodstuffs for human consumption in Taiwan are frequently contaminated with FB₁ and FB₂.This revised version was published online in October 2005 with corrections to the Cover Date.     

Production of fumonisins byFusarium species of Taiwan

Twenty-nineFusarium species isolated from various sources in different districts of Taiwan were tested for their ability to produce fumonisins in corn cultures. OnlyFusarium moniliforme produced fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂). The finding that the other 28Fusarium species produced neither FB₁ nor FB₂ is preliminary because only one strain per species was studied. The detection of FB₁ and FB₂ in cultures ofF. moniliforme was demonstrated by TLC and HPLC, and FB₁ was further confirmed by mass spectrometry. In a separate experiment, in which 38 strains ofF. moniliforme were tested for fumonisins, approximately 66% (25/38) produced FB₁ and/or FB₂. Of the 25 strains, 14 produced only FB₁ and 11 produced both FB₁ and FB₂, and the amounts of FB₁ and FB₂ produced by different strains varied greatly. This is the first report that fumonisins are found in corn cultures experimentally infected withF. moniliforme strains from Taiwan. It is safe to assume that fumonisin producing strains ofF. moniliforme are widely distributed among the economic crops such as corn, rice, sugarcane, and sorghum throughout the Island.Abbreviations FB₁ Fumonisin B₁ - FB₂ Fumonisin B₂ - OPA o-phthalidialdehyde     

Ear-rot fungi and mycotoxins in South African corn of the 1989 crop exported to Taiwan

A shipment of South African corn (1989) exported to Taiwan, was analyzed for various ear-rot fungi andFusarium mycotoxins. Two sets of samples, one from the points of origin in South Africa prior to shipment, and the other from the end-point distributors in Taiwan, were studied. Surface-sterilized kernels were plated onto two different agar media and the fungal colonies identified. High Performance Liquid Chromatography was used to analyze mycotoxin levels. The predominant ear-rot fungi, in decreasing order of isolation frequency, wereFusarium subglutinans, F. moniliforme, Diplodia maydis andF. graminearum. Aspergillus flavus andA. parasiticus were not isolated from samples prior to export, but a small number ofA. flavus isolates were found after shipment. The predominant mycotoxins were fumonisins B₁ (0–865 ng/g) and B₂ (0–250 ng/g). Low levels of moniliformin (390 ng/g) were detected in some samples before shipment. Zearalenone (25 ng/g), and nivalenol (120 ng/g) were detected in two out of 32 samples taken in Taiwan. The samples contained no detectable levels of either aflatoxins (>0.5 ng/g) or deoxynivalenol (>100 ng/g) before or after shipment.Abbreviations RSA South Africa(n) - FB₁ fumonisin B₁ - FB₂ fumonisin B₂ - ETVL eastern Transvaal - WTVL western Transvaal     

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.     

Variability and characterization of mycotoxin-producing Fusarium spp isolates by PCR-RFLP analysis of the IGS-rDNA region

In the present report, a total of 75 Fusarium spp isolates (35 of the Gibberella fujikuroi species complex, 26 of F. oxysporum, 7 of F. graminearum, 5 of F. culmorum, 1 of F. cerealis, and 1 of F. poae) from different hosts were characterized morphologically, physiologically and genetically. Morphological characterization was performed according to macroscopic and microscopic aspects. Physiological characterization was based on their ability to produce fumonisin B₁ (FB₁), fumonisin B₂ (FB₂), zearalenone (ZEA) and type B trichothecenes (deoxynivalenol, nivalenol and 3-acetyldeoxynivalenol). FB₁, FB₂, and ZEA were determined by liquid chromatography and trichothecenes by gas chromatography. Molecular characterization of isolates was carried out using an optimized and simple method for isolation of DNA from filamentous fungi and polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) of the intergenic spacer region (IGS) of the rDNA. The results indicated that G. fujikuroi complex isolates can be␣divided into low and high fumonisin producers. The haplotypes obtained with HhaI, EcoRI, AluI, PstI and XhoI enzymes provided very characteristic groupings of G. fujikuroi isolates as a function of host type and fumonisin producing capacity. F. graminearum, F. culmorum and F. cerealis isolates were high ZEA␣and type B trichothecene producers, while F. oxysporum and the G. fujikuroi complex isolates did not show this ability. The haplotypes obtained with CfoI, AluI, HapII, XhoI, EcoRI and PstI enzymes permitted to discern these five Fusarium species and G. fujikuroi complex isolates but the restriction patterns of the IGS region did not show any relationship with the geographic origin of isolates.     

Developmental toxicity of fumonisin in Syrian hamsters

The effects of fumonisin on development of Syrian hamster fetuses were studied using fumonisin B₁ and B₂ extracted fromFusarium moniliforme corn-culture and purified fumonisin B₁. A significant increase in litters with fetal deaths occurred with the high doses of purified (18 mg FB₁/kg) and culture-extracted (18 mg FB₁ plus 4.5 mg FB₂) fumonisin. It is concluded that prenatal exposure to fumonisin on days 8 and 9 of gestation is detrimental to fetal hamster survivability but does not induce clinical maternal intoxication at these doses. Equivalent doses of fumonisin B₁, whether from culture-extract or pure solution produced similar results.     

Fumonisin and Beauvericin Induce Apoptosis in Turkey Peripheral Blood Lymphocytes

Fumonisins, a family of mycotoxins produced by Fusarium verticillioides (synonym Fusarium moniliforme Sheldon) and F. proliferatum, have been associated with various deleterious effects in different animal species. Serological, hematological and pathological effects and mortality have previously been observed in broiler chicks fed F. proliferatum culture material containing known concentrations of fumonisin, moniliformin and beauvericin. Turkey peripheral blood lymphocytes were exposed in vitro for 72 hours to fumonisin B₁(FB₁), fumonisin B₂(FB₂), hydrolyzed fumonisin B₁ (HFB₁), moniliformin and tricarballylic acid (TCA) (0.01-25 g/ml). A decrease in cell proliferation, as determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] bioassay, occurred in the order: FB₂ > FB₁ > HFB₁, with IC₅₀ = 0.6 M, 1 M and 10 M, respectively. Internucleosomal DNA fragmentation and morphological features characteristic of apoptosis were observed following exposure to fumonisin B₁ and beauvericin; cytoplasmic condensation and membrane blebbing were seen by light microscopy. Tricarballylic acid and moniliformin did not interfere with cell proliferation. Results suggested that fumonisin B₁ and beauvericin may affect immune functions by suppressing proliferation and inducing apoptosis of lymphocytes.     

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.     

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.     

Effect of<Emphasis Type="Italic">in vitro</Emphasis> digestion on fumonisin B<Subscript>1</Subscript> in corn flakes

Low levels of fumonisins have been found frequently in corn based breakfast cereals and can occur bound to protein and other matrix components.In vitro digestion of two samples of corn flakes was carried out under "fed conditions." Fumonisins were measured as o-phthaldialdehyde/mercaptoethanol derivatives by LC-fluorescence. One sample of corn flakes (FN12) had high concentrations of fumonisin B₁ (FB) (average 125 ng/g) and total bound FB₁, (TB FB₁) (average 92 ng/g) and the other (FN11) had a low level of free FB₁ (average 29 ng/g) and no detectable TB FB₁. After incubation of the samples with gastrointestinal tract solutions simulating saliva plus stomach and duodenal juices, chyme was analysed for FB₁, hydrolyzed FB₁ (HFB₁) and partially hydrolyzed fumonisin B₁ (PHFB₁). The bioaccessibility (percentage of FB₁ released from corn flakes into chyme) was 38-78% for incurred FB₁ in FN12, 8-54% for incurred plus spiked FB₁ in FN12, and 19-66% for incurred plus spiked FB₁ in FN11. HFB₁ and PHFB₁ were not detected. If free FB₁ was first extracted from sample FN12, no FB1 was detected in the chyme, indicating no contribution from TB FB₁. Concentrations were corrected for method recovery of FB₁ or, for bound FB₁, partial method recovery of HFB₁ Presented at the XIIth IUPAC International Symposium on Mycotoxins and Phycotoxins, Istanbul, Turkey, 21–25 May, 2007     

Zearalenone, deoxynivalenol and fumonisins in mixed-feed for laying hens

Fusarium toxins are secondary metabolites produced byfungi of these genera in many commodities under certain conditions. A study was carried out to investigate the co-occurrence of zearalenone (ZEN), deoxynivalenol (DON) and fumonisins (FB₁ and FB₂) in 52 samples of mixed-feed for poultry contaminated withFusarium verticillioides. The zearalenone and deoxynivalenol were checked using immunoaffinity column and the extraction of fumonisin was performed by strong anion exchange (SAX) solid phase column. Detection and quantification were determined by high performance liquid chromatography (HPLC). The limit of detection was 5 μg/kg for ZEN, 100 μg/kg for DON and 50 and 100 μg/kg for FB₁ and FB₂ respectively.Fusarium toxins were detected in 20 samples. Sixteen samples were positive for ZEN (30.7%) presenting levels that ranged from 7.4 μg/kg to 61.4 μg/kg (mean=27.0 μg/kg). 13.5% of the samples presented contaminations of DON, with levels ranging from 100.0 μg/kg to 253 μg/kg (mean=l18.07 μg/kg). FB₁ was detected in 19.2% of samples, with levels ranging from 50.0 μg/kg to 110.0 μg/kg (mean=73.6 μg/kg). FB2 was not detected in any sample. In positive samples simultaneously contamination with two or three mycotoxins were detected in 9 of them (17.3%).     

Trends of fumonisin contamination and animal intoxication through monitoring 1991 to 1997 corn crop in the State of Paraná, Brazil

Eleven feed samples associated with six animal (horse and poultry) intoxication outbreaks (1991) in the state of Paraná, Brazil, were evaluated for fungal and fumonisin contamination. In order to estimate the␣trend of livestock intoxication, fumonisin contamination was monitored in corn produced both at the commercial level (1991, 1995 crop), and in an experimental field at a local Agronomy Institute (1997 crop). The total mould count in the feed samples ranged from 2.9 × 10³ to 1.9 × 10⁷ CFU/g, with Fusarium verticillioides as the predominant species, at a high count of 2.4 × 10⁴–6.5 × 10⁵ CFU/g. Fumonisins (FB₁ + FB₂) were detected in all corn-based feed samples at levels ranging from 2.89 to 14.54 μg/g. All 27 Northern corn samples (1991 crop) were contaminated with fumonisins at levels ranging from 2.32 to 16.64 μg/g. Twenty-six (96.3%) out of 27 corn samples from the Central-Southern region (1995 crop) were positive for fumonisins (FB₁+FB₂), with the range of 0.07–3.66 μg/g, while all 37 Northern samples (1995 crop) were contaminated with fumonisins ranging from 0.57 to 9.97 μg/g. Twenty-one out of 37 corn samples from the Northern region (1997 crop) were positive for fumonisins, but at low level (range of 0.05–2.67 μg/g). The results showed a decreasing trend in fumonisin contamination over the years. Nowadays animal intoxication outbreaks rarely occur in this State, as both animal producers and feed industries have become conscious about monitoring of corn and other raw materials at the quality control level.     

Mortality in broiler chicks on feed amended withFusarium proliferatum culture material or with purified fumonisin B1 and moniliformin

Two hundred twenty-eight male chicks (Columbia × New Hampshire) were given feed amended with autoclaved culture material (CM) ofFusarium proliferatum Containing fumonisin B₁ (FB₁), fumonisin B₂ (FB₂) and moniliformin in 3 separate feeding trials. Purified FB₁ and moniliformin were given separately and in combination in a fourth feeding trial. Birds were given amended rations at day 1 (Trial 1 and 4), day 7 (Trial 2), and day 21 (Trial 3) and their respective ration was given for 28 days (Trial 1), 21 days (Trial 2), 7 days (Trial 3), and 14 days (Trial 4). FB₁ concentrations were 546, 193, and 61 ppm; FB₂ were 98, 38 and 14 ppm; and moniliformin were 367, 193, and 66 ppm in the first 3 feeding trial regimens. Chicks in Trial 4 were given dietary concentrations of purified FB₁ at 274 and 125 ppm, and moniliformin at 154 and 27 ppm. FB₁ and moniliformin, both alone and in combination, produced dose-responsive clinical signs, reduced weight gains and mortality in chicks. Age of birds given amended feeds had little difference in the clinical response; however, those given the rations from days 7 or 21 were slightly less susceptible than those given rations beginning at 1 day of age. Additive effects were noted when the toxins were given in combination. When toxins were given separately, adverse effects took longer to occur. A system to monitor pattern and rate of defecation (RD) was developed for assessing the chicks' approach to feed, water and heat source as illness progressed. Our results indicate that chicks fed corn heavily infected withF. proliferatum under field conditions could suffer acute death similar to that described for spiking mortality syndrome during the first 3 weeks of age.     

A review and update of animal toxicoses associated with fumonisin-contaminated feeds and production of fumonisins by Fusarium isolates

During the 1989 corn harvest season, numerous reports of equine leukoencephalomalacia (ELEM) outbreaks and a pulmonary edema (PPE) syndrome in swine from several regions of the United States were received by the National Veterinary Services Laboratories (NVSL), Ames, Iowa. Previous and concurrent research linked Fusarium moniliforme and fumonisin-contaminated feeds to both diseases. Chemical and mycological investigations revealed fumonisin B₁ (FB₁) concentrations of 20 to 360 ppm in suspect swine feeds and 8 to 117 ppm in suspect equine feeds. Nonproblem feeds contained concentrations below 8 ppm. Fusarium moniliforme and Fusarium proliferatum were isolated from both problem and nonproblem equine and swine feeds. When cultured on autoclaved corn, the F. moniliforme and F. proliferatum isolates produced respective FB₁ and fumonisin B₂ (FB₂) that range from less than 5 to more than 2450 ppm and less than 5 to more than 1000 ppm, respectively. Isolates from both problem and nonproblem feeds produced high levels (greater than 500 ppm) in culture. Reported here is a review of chemical and mycological data resulting from the study of several cases of PPE and ELEM.     

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.     

Effect of climatic conditions on natural mycoflora and fumonisins in freshly harvested corn of the State of Paraná, Brazil

Natural mycoflora associated with fumonisins were analyzed in 150 samples of freshly harvested corn from Central-Southern, Central-Western and Northern regions of the State of Paraná, Brazil and correlated to climatic conditions. The corn samples were frequently contaminated with Fusarium sp.(98.7 to 100%) and Penicillium sp. (93 to 100%), when compared to Aspergillus sp. (not detected to 27.7%). The highest contamination with potentially mycotoxigenic fungi occurred in corn harvested in the Central-Western region, where total mould and yeast counts ranged from 5.5 × 10³ to 5.2 × 10⁶ CFU/g, with 98.7% contaminated byFusarium sp. and 93% by Penicillium sp. In this region F. moniliforme (F. verticillioides) was the predominant Fusariumsp., and was isolated in 85.9% of the samples. Aspergillus sp. was isolated from 27.7% samples. FB₁ was detected in 100% of the samples (mean of 2.39 g/g) and FB₂ in 97.7% (mean of 1.09 g/g). Fumonisins were also detected in all samples from Northern region, with mean of 4.56 g/g (FB₁) and 2.20 g/g (FB₂).Considering 1.0 g/g as the threshold, 72% of the corn samples from the Central-West and 92% from the North were contaminated with concentrations above this value, in contrast to a 18.5% contamination rate from Central-Southern samples. Between corn planting to harvesting season, the average maximum temperature and relative humidity were 26 °C and 77.1%(Central-Southern), 27 °C and 69% (Northern)and 29.9 °C and 89.1% (Central-Western).Therefore, the higher fumonisins contamination of corn from Northern region when compared to the Central-South were due to the differences in rainfall levels (92.8 mm in Central-Southern, 202 mm in Northern) during the month preceding harvest.This revised version was published online in October 2005 with corrections to the Cover Date.     

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     

A limited survey of fumonisins in corn and corn-based products in Asian countries

Natural occurrence of fumonisins B₁ (FB₁) and B₂ (FB₂), a promoter for hepato-carcinogenesis, was investigated in corn and corn — based products sampled in Japan, Nepal, and China by high — performance liquid chromatographic method. From the 9 imported corn kernel and 6 gluten feed samples, FB₁ was detected in 8 corn (0.6 ～ 4.1μg/g) and all gluten feed (0.3 ～ 2.4μg/g) samples, while FB₂ was found in the same corn (0.3 ～ 10μg/g) and 3 gluten feed (0.8 ～ 8.5μg/g) samples. ELISA analysis also revealed the contamination of aflatoxin B₁ in 2 corn and all gluten feed samples along with fumonisins. Of 17 corn grit samples, 14 and 5 samples were contaminated with fumonisin B₁ and B₂, with maximum levels of 2.6 and 2.8μg/g, respectively. As for corn-based foodstuffs marketed in Japan, no significant contamination of fumonisins was observed. Among 24 corn kernel samples in Nepal, 12 and 7 samples were positive for FB₁ and FB₂, and averaged to 0.6 and 1.6μg/g, respectively. One sample showed the highest fumonisin contents as 4.6 and 5.5μg/g, respectively. In corn samples harvested at Shanghai and Beijing, China, FB₁ and FB₂ were detected in various concentrations. Mycological survey has also revealed the presence of a fumonisin — producing fungus in a crop field of Japan. These findings have for the first time demonstrated high levels of contamination of fumonisins in corn and corn — based products in Asian countries. Natural co — occurrence of fumonisins and aflatoxin B₁ was also detected in raw materials for mixed feed.     

Fumonisins in Maize in Relation to Climate,Planting Time and Hybrids in Two Agroecological Zones in Zambia

Field experiments in the high rainfall zone (HRZ) and the medium rainfall zone (MRZ) in Zambia were designed to determine the natural occurrence of fumonisins (FB_1–2) in Zambian maize hybrids, accumulation of FB_1–2 resulting from artificial inoculation with Fusarium verticillioides and effects of climate and planting time on FB_1–2 in maize. Combined FB_1–2 concentrations varied from 0 to 13,050 ng/g, with an overall mean of 666 ng/g. Maize from the HRZ had low incidences of FB_1–2-positive samples (mean 41%) which contained FB_1–2 below 500 ng/g. In the MRZ, higher incidences (mean 97%) and concentrations (40% of samples >1,000 ng/g) were recorded in two out of three years. There was no correlation between mean location FB_1–2 concentrations in individual years and precipitation, number of rain days or monthly precipitation. Postponing the planting time with 10 or 20 days did not significantly affect FB_1–2 concentration, but it reduced the yields in some years.