Fum3p, a 2-ketoglutarate-dependent dioxygenase required for C-5 hydroxylation of fumonisins in Fusarium verticillioides

Fumonisins are polyketide-derived mycotoxins produced by several agriculturally important Fusarium species. The B series fumonisins, FB(1), FB(2), FB(3), and FB(4), are fumonisins produced by wild-type Fusarium verticillioides strains, differing in the number and location of hydroxyl groups attached to the carbon backbone. We characterized the protein encoded by FUM3, a gene in the fumonisin biosynthetic gene cluster. The 33-kDa FUM3 protein (Fum3p) was heterologously expressed and purified from Saccharomyces cerevisiae. Yeast cells expressing the Fum3p converted FB(3) to FB(1), indicating that Fum3p catalyzes the C-5 hydroxylation of fumonisins. This result was verified by assaying the activity of Fum3p purified from yeast cells. The C-5 hydroxylase activity of purified Fum3p required 2-ketoglutarate, Fe(2+), ascorbic acid, and catalase, all of which are required for 2-ketoglutarate-dependent dioxygenases. The protein also contains two His motifs that are highly conserved in this family of dioxygenases. Thus, Fum3p is a 2-ketoglutarate-dependent dioxygenase required for the addition of the C-5 hydroxyl group of fumonisins.     

FUM9 Is Required for C-5 Hydroxylation of Fumonisins and Complements the Meitotically Defined Fum3 Locus in Gibberella moniliformis

Deletion of the Gibberella moniliformis FUM9 gene resulted in mutants that produce only fumonisins that lack a C-5 hydroxyl group. This phenotype is identical to that of previously described mutants with defective alleles at the meiotically defined Fum3 locus. Transformation with a wild-type FUM9 gene into a Fum3-defective mutant restored wild-type fumonisin production. These results indicate that the FUM9 protein catalyzes the C-5 hydroxylation of fumonisins and that FUM9 and the Fum3 locus are the same gene.     

FUM9 is required for C-5 hydroxylation of fumonisins and complements the meitotically defined Fum3 locus in Gibberella moniliformis

Deletion of the Gibberella moniliformis FUM9 gene resulted in mutants that produce only fumonisins that lack a C-5 hydroxyl group. This phenotype is identical to that of previously described mutants with defective alleles at the meiotically defined Fum3 locus. Transformation with a wild-type FUM9 gene into a Fum3-defective mutant restored wild-type fumonisin production. These results indicate that the FUM9 protein catalyzes the C-5 hydroxylation of fumonisins and that FUM9 and the Fum3 locus are the same gene.     

A bidomain nonribosomal peptide synthetase encoded by FUM14 catalyzes the formation of tricarballylic esters in the biosynthesis of fumonisins

Fumonisins are a group of polyketide-derived mycotoxins produced by Fusarium verticillioides, a filamentous fungus infecting corn and contaminating food and feeds. Fumonisins contain two tricarballylic esters that are critical for toxicity. Here, we present genetic and biochemical data for the esterification mechanism. FUM14 in F. verticillioides has been deleted by homologous recombination, and the resultant mutant lost the ability to produce fumonisins. Two new metabolites, HFB(3) and HFB(4), which are biosynthetic precursors of fumonisins lacking the tricarballylic esters, were detected in the mutant. The results suggest that FUM14 is required for the esterification of fumonisins. FUM14 was predicted to encode a nonribosomal peptide synthetase (NRPS) containing two domains, peptidyl carrier protein and condensation domain. Both the intact Fum14p and the condensation domain have been expressed in Escherichia coli and purified for activity assays. Fum14p was able to convert HFB(3) and HFB(4) to the tricarballylic esters-containing fumonisins, FB(3) and FB(4), respectively, when incubated with tricarballylic thioester of N-acetylcysteamine. In addition, the condensation domain was able to convert HFB(1) to FB(1). These data provide direct evidence for the role of Fum14p in the esterification of fumonisins. More interestingly, the results are the first example of an NRPS condensation domain catalyzing a C-O bond (ester) formation, instead of the typical C-N bond (amide) formation in nonribosomal peptides. The understanding of the esterification mechanism provides useful knowledge for mycotoxin reduction and elimination. The study also provides new insight into the reactions catalyzed by NRPS.     

Reducing production of fumonisin mycotoxins in <Emphasis Type="Italic">Fusarium verticillioides</Emphasis> by RNA interference

The fungus Fusarium verticillioides is a maize pathogen that can produce fumonisin mycotoxins in ears under certain environmental conditions. Because fumonisins pose health risks to humans and livestock, control strategies with minimal risk to the environment are needed to reduce fumonisin contamination. Host-induced gene silencing is a promising technique in which double-stranded RNA expressed in the plant host is absorbed by an invading fungus and down-regulates genes critical for pathogenicity or mycotoxin production in the fungus. A key preliminary step of this technique is identification of DNA segments within the targeted fungal gene that can effectively silence the gene. Here, we used segments of the fumonisin biosynthetic gene FUM1 to generate double-stranded RNA in F. verticillioides. Several of the resulting transformants exhibited reduced FUM1 gene expression and fumonisin production (24- to 3675-fold reduction in fumonisin FB₁). Similar reductions in fumonisin production resulted from double-stranded RNA constructs with segments of FUM8, another fumonisin biosynthetic gene (3.5- to 2240-fold reduction in fumonisin FB₁). FUM1 or FUM8 silencing constructs were transformed into three isolates of F. verticillioides. Whole genome sequence analysis of seven transformants revealed that reductions in fumonisin production were not due to mutation of the fumonisin biosynthetic gene cluster and revealed a complex pattern of plasmid integration. These results suggest the cloned FUM1 or FUM8 gene segments could be expressed in maize for host-induced gene silencing of fumonisin production.     

Fumonisin production by <Emphasis Type="Italic">Fusarium</Emphasis> species isolated from freshly harvested corn in Iran

Fifty-one strains of Fusarium verticillioides and F. proliferatum isolated from corn collected from four different geographic areas in Iran, namely Fars, Khuzestan, Kermanshah and Mazandaran (an endemic oesophageal cancer (OC) area) were evaluated for their ability to produce fumonisins B₁ (FB₁), B₂ (FB₂) and B₃ (FB₃) in corn culture. Fumonisin levels were determined by high-performance liquid chromatography. All tested strains of F. verticillioides and F. proliferatumproduced fumonisins within a wide range of concentrations, 197–9661 g/g, 18–1974 g/g, and 21–1725 g/g for FB₁, FB₂, and FB₃, respectively. The highest mean concentrations of FB₁, FB₂, and FB₃ were 3897, 806 and 827 g/g, respectively. Overall, 61% of the F. verticillioides and F. proliferatum strains produced higher levels of FB₃ than FB₂. The mean ratios of FB₁:FB₂, FB₁:FB₃ and FB₁:total fumonisins were 8, 7 and 0.7 for F. verticillioides and 5.7, 10.7 and 0.7 for F. proliferatum, respectively. Significant differences in some of the meteorological data (rainfall, relative humidity and minimum temperature) from the four provinces were observed. Fumonisin levels produced by F. verticillioides strains isolated from Khuzestan province (tropical zone) were significantly (P < 0.01) higher than the other three provinces. This is the first report of the fumonisin-producing ability of F.verticillioides and F. proliferatum strains isolated from corn harvested from different geographic areas in Iran.     

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.     

Natural occurrence of fumonisins in corn puff in Argentina

Maize presents a substantial contamination by fumonisins (FB) throughout the world. In particular, Argentina presents a high frequency of positive samples and levels of up to 10,000 μg/kg of total FB, depending on the harvest campaign studied. Corn puff, an extruded product of high consumption among children and adolescent populations, was analyzed with the aim of determining the presence and levels of fumonisins B₁, B₂ and B₃. In the present study, 20 samples of different brands were collected from commercial stores. Two solvent systems, two types of agitation, and the number of extractions were tested in order to find the most suitable method to establish the level of fumonisins in corn puff. Extracts were analyzed by high performance liquid chromatography (HPLC) with fluorescence detection. A C18 column and precolumn derivatization with orthophtalaldialdehyde were utilized. The average of fumonisins found in 20 samples was 257.5 μg/kg (n?=?19), 70.4 μg/kg (n??=?14) and 73.3 μg/kg (n??=?6) for FB₁, FB₂ and FB₃, on positive samples, respectively. These are the first analyses in Argentina of this type of product, highlighting the need to continue the studies in the processing industries because, despite the extrusion process that the raw material suffers, a sample was found with a contamination of 1,649 μg/kg total fumonisins.     

Evaluation of the extraction and purification procedures of the maleyl derivatization HPLC technique for the quantification of the fumonisin B mycotoxins in corn cultures

The extraction and purification methods used in the maleyl derivatization HPLC technique was evaluated with respect to the pH of the extraction mixture, the extraction solvent and the purification methods used in order to determine optimum conditions for quantification of fumonisins B₁, B₂, and B₃ in corn cultures. The highest recovery of the three compounds was obtained by extraction at pH 3.5 with CH₃OH–H₂0 (3∶1), whilst the subsequent solvent partitioning and reversedphase C₁₈ Sep-pak purification have been shown to be very important in the quantification of the fumonisins in the corn cultures. The percentage recovery of the improved technique, utilizing a gradient HPLC solvent system for the simultaneous determination of the fumonisins, was 93.4% for FB₁, 68.0% for FB₂, and 82.6% for FB₃. The study indicates that the polarity of the fumonisins and consequently their solubility during extraction as well as their behavior during the subsequent purification step play an important role in quantification of these mycotoxins in corn cultures.     

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.     

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: 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.     

Mycotoxin Production by Fusarium proliferatum isolates from rice with Fusarium sheath rot disease

Twenty samples of unpolished (rough) rice collected in Arkansas and Texas during the 1995 harvesting season from fields exhibiting Fusarium sheath rot disease or panicle blight were previously shown to include 8 samples positive for fumonisin B₁(FB₁) in the range 2.2–5.2 ppm, and moniliformin (MON), but no beauvericin (BEA), deoxynivalenol, its derivatives or zearalenone were detected. Fifteen cultures of F. proliferatum were established from the 20 rough rice samples. Single spore isolates of each culture were grown on rice and tested for the production of fumonisins (FB₁, FB₂, FB₃, etc.), MON and BEA. All 15 isolates produced FB₁, FB₂, MON and BEA in culture on rice. No deoxynivalenol, its derivatives orzearalenone were detected. Seven cultures produced FB₁ at >50ppm (range 80–230 ppm), with therest producing FB₁ in the range 14–43 ppm.FB₂ was produced in the range 5–47 ppm, and those cultures which produced the most FB₁ also produced the most FB₂. Of the 15 cultures producing MON, 11 produced it at >100 ppm in the range 188–6018 ppm, with the rest producing in the range 7–64 ppm. BEA was produced in the range 109–1350 ppm. Other derivatives of fumonisins, including FA₁, FA₂ and partially hydrolyzed FB₁, as well asseveral unknown metabolites including a compound with MW 414, were identified in culture extracts by continuous flow fast atom bombardment with ion spraymass spectrometry (CF/FAB/MS). Further study is needed to identify the factors that control production of FB₁, MON and BEA by F.proliferatu in culture and in field samples. This revised version was published online in June 2006 with corrections to the Cover Date.     

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.     

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     

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.     

Functional replacement of the ketosynthase domain of FUM1 for the biosynthesis of fumonisins, a group of fungal reduced polyketides

The genetic manipulation of the biosynthesis of fungal reduced polyketides has been challenging due to the lack of knowledge on the biosynthetic mechanism, the difficulties in the detection of the acyclic, non-aromatic metabolites, and the complexity in genetically manipulating filamentous fungi. Fumonisins are a group of economically important mycotoxins that contaminate maize-based food and feed products worldwide. Fumonisins contain a linear dimethylated C₁₈ chain that is synthesized by Fum1p, which is a single module polyketide synthase (PKS). Using a genetic system that allows the specific manipulation of PKS domains in filamentous fungus Fusarium verticillioides, we replaced the KS domain of fumonisin FUM1 with the KS domain of T-toxin PKS1 from Cochliobolus heterostrophus. Although PKS1 synthesizes different polyketides, the F. verticillioides strain carrying the chimeric PKS produced fumonisins. This represents the first successful domain swapping in PKSs for fungal reduced polyketides and suggests that KS domain alone may not be sufficient to control the product’s structure. To further test if the whole fumonisin PKS could be functionally replaced by a PKS that has a similar domain architecture, we replaced entire FUM1 with PKS1. This strain did not produce any fumonisin or new metabolites, suggesting that the intrinsic interactions between the intact PKS and downstream enzymes in the biosynthetic pathway may play a role in the control of fungal reduced polyketides.     

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.     

Occurrence of fumonisins in asparagus (asparagus officinalis L.) and garlic (allium sativum L.) from Germany

Fusarium proliferatum is able to produce fumonisins and is considered a pathogen of many economically important plants (e.g. corn, rice, asparagus) [1]. The occurrence of fumonisin FB₁ inF. proliferatum infected asparagus spears from Germany was investigated using a liquid chromatography/electrospray ionization-mass spectrometry (LC-ESI-MS) method with isotopically labeled fumonisin FB₁-d₆ as internal standard. Asparagus samples were harvested in July 2000 and screened forFusarium species. AltogetherF. oxysporum, F. proliferatum and F. sambucinum were isolated from the spears. The samples infected with F.proliferatum were subsequently analyzed for fumonisins. FB₁ was detected in 9 of the 10 samples in amounts ranging from 36.4 ng/g to 4513.7 ng/g (based on dry weight). Fumonisins FB₂ and FB₃ were found in six samples in lower concentrations. In asparagus spears of June 2002 we could findF. proliferatum in 6% of the samples, however no fumonisins were detectable. Furthermore the capability of producing FB₁ by the fungus in garlic bulbs was investigated. Therefore garlic was cultured inF. proliferatum contaminated soil and the bulbs were screened for infection with F.proliferatum and for the occurrence of fumonisins by LC-MS. F.proliferatum was detectable in the garlic tissue and all samples contained FB₁ (26.0 ng/g to 94.6 ng/g). This is the first report of the natural occurrence of FB₁ in German asparagus spears and furthermore our findings suggest a potential for natural contamination of garlic bulbs with fumonisins. For detailed results and methods see Ref. [2].     

Temporal and dose-response features in swine fed corn screenings contaminated with fumonisin mycotoxins

Fumonisin B₁ (FB₁), a mycotoxin produced byFusarium moniliforme andF. proliferatum, induces liver damage and pulmonary edema in swine. We examined the temporal and dose-response features of FB₁ toxicosis in male weanling crossbred pigs fed nutritionally balanced diets, containing corn screenings naturally contaminated with fumonisins, for 14 days. Total fumonisins (FB₁ and FB₂) in diets 1 through 6 were assayed at 175, 101, 39, 23, 5, and <1 ppm (below detectable concentrations), respectively. Clinical signs, serum biochemical alterations, and morphologic changes were evaluated. Pigs were weighed, and bled for hematologic and clinical chemistry evaluation on days 5 and 14. They were euthanized on day 14, or earlier if respiratory distress was observed. Respiratory distress developed in 3/5 pigs fed diet 1 between days 4 and 6 due to severe pulmonary edema and pleural effusion. Histologic evidence of hepatic injury was present in all pigs fed diets 1 and 2, 3/5 on diet 3, and 1/5 on diet 4. Serum bilirubin and cholesterol concentrations, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and arginase (ARG) activities were elevated in pigs fed diets 1 and 2. Based on liver histopathology, the no observed adverse effect level (NOAEL) for fumonisin toxicity in swine was <23 ppm total fumosins for the 14-day period. Based on regression analyses of the clinical chemistry profiles at 14 days, the NOAEL was <12 ppm, with ALP being the most sensitive parameter. In conclusion, pulmonary edema occurred only at the highest fumonisin concentration (175 ppm), while liver damage occurred at much lower concentrations with a NOAEL of <12 ppm.Abbreviations ALP alkaline phosphatase - ALT alanine aminotransferase - ARG arginase - AST aspartate aminotransferase - ELEM equine leukoencephalomalacia - FB₁ fumonisin B₁ - GGT gamma-glutamyl transferase - NOAEL no observed adverse effect level