Fumonisin B1 Concentrations Research Articles

ORIGINAL ARTICLE: Brain and hypophyseal acetylcholinesterase activity of pubertal boars fed dietary fumonisin B1

The effects of dietary fumonisin B1 (FB1) on regional brain and hypophyseal activities of AChE (EC 3117), the enzyme which catalyses the hydrolysis of acetylcholine, were studied using 24 male Large White weanling pigs divided into four groups. Each group received one of the four diets containing 0.2, 5.0, 10.0 and 15.0 mg FB1/kg in a 6-month feeding trial. All animals were slaughtered at the end of the feeding trial; the brains and the hypophyses obtained were carefully dissected out. Significant (p < 0.05) influence of dietary FB1 on regional brain and hypophyseal AChE activities were observed. The AChE activities in the pons, amygdala, hypothalamus and the medulla oblongata declined significantly (p < 0.05) with increased dietary FB1 concentrations. The findings of this study suggest that diets containing 5.0 mg FB1/kg and above significantly (p < 0.05) altered regional brain and hypophyseal AChE activities in the animals. Dietary exposure to FB1 at a concentration of approximately 5.0 mg/kg or more for a 6-month period is a potential health risk that may induce adverse physiological response resulting from altered brain neurochemistry in growing pigs.

Effects of aflatoxin B(1) and fumonisin B(1) on the viability and induction of apoptosis in rat primary hepatocytes.

The present study evaluated the effect of aflatoxin B1 (AFB1) and fumonisin B1 (FB1) either alone, or in association, on rat primary hepatocyte cultures. Cell viability was assessed by flow cytometry after propidium iodine intercalation. DNA fragmentation and apoptosis were assessed by agarose gel electrophoresis and acridine orange and ethidium bromide staining. At the concentrations of AFB1 and FB1 used, the toxins did not decrease cell viability, but did induce apoptosis in a concentration and time-dependent manner.

Simultaneous occurrence of mycotoxins in human food commodities from Cameroon

Eighty-two samples of dried food commodities from Cameroon were screened and quantified for different mycotoxins, including fumonisin B1 (FB1), zearalenone (ZEA), deoxynivalenol (DON), aflatoxin (AF) and ochratoxin A (OTA), by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), respectively. The percentage of positive samples was as follows: FB1 41%, AF 51%, ZEA 57%, DON 65% and OTA 3%. High FB1 contents were found in maize, averaging 3,684µg/kg (range: 37-24,225µg/kg), whereas the highest average ZEA level was found in peanuts (70µg/kg), followed by maize (69µg/kg), rice (67µg/kg) and beans (48µg/kg) with no ZEA was detected in soybeans. DON contents were low, ranging from 13 to 273µg/kg, and for AF the average content was 2.6µg/kg with peanuts and maize as principal substrates. The incidence of OTA was low, with a mean level of 6.4µg/kg recorded. The majority (79%) of samples contained more than one mycotoxin and the most frequent co-occurrence found was FB1 + ZEA + DON, detected in 21% of samples (mainly maize) analysed. Co-contamination with FB1 + ZEA + DON + AF was found in 11% of the samples. Although a large proportion of samples had fairly low levels of individual mycotoxins, this should be of concern as the co-occurrence of mycotoxins may generate additive or synergistic effect in humans, especially if the respective commodities are consumed almost on a daily basis.

In vitro production of fumonisin B1 and B2 byFusarium moniliforme and the biocontrol activity ofTrichoderma harzianum

Fumonisin B1 (FB1) and B2 (FB2) production ofFusarium moniliforme isolates (Fm8, Fm22, Fm29, Fm31) on corn kernels and liquid culture and biocontrol activity of twoTrichoderma harzianum strains (T16, T23) against mycelial growth and FB1 and FB2 production was evaluated. Fm31 was determined as the highest yielding isolate for fumonisins production (FB1:118.00 μg/g; FB2:71.67 μg/g) on corn kernels. It was then incubated in five different liquid culture and the highest concentration of FB1 was obtained from corn meal medium (CMM), with 3.7 initial pH. FB1 amount was as much as on the solid culture, but FB2 amount was noticeably lower. T16 and T23 decreased radial extension of Fm31 about 70% after 13 days. The colony diameter ofF. moniliforme was less at 13 days than at 7 days, possibly due to mycelial lysis of Fm31. On corn kernels, T23 performed better with an inhibinoculation rate of 92.96% (FB1) and 92.68% (FB2) at same-day inoculation. In CMM, treatments at 0, 3 and 5 days after inoculation (DAI) of Fm31 rapidly inhibited FB1 and FB2 production. The inhibitory effect of T16 and T23 isolates on fumonisin production could be measured with inoculations at 7 DAI and T23 was again found more effective.

Reduction of fumonisin B1 in extruded corn breakfast cereals with salt, malt and sugar in their formulation

The objective was to determine the effect of added sodium chloride, barley malt and sucrose on the stability of fumonisin B1 (FB1) present in corn flour. Two levels of both sodium chloride (0.4% and 2%) and barley malt (0.8% and 5%) were added to the unextruded corn flour, and six levels of sucrose (3–10%) were used. The addition of sucrose at the lowest salt content (0.4%) as well as salt, either at 0.4% or at 2%, led to a significant decrease of FB1 levels in extruded samples, whereas malt, either at 0.8% or at 5%, did not significantly affect FB1 stability. Decontamination rates depended on the concentrations of added ingredients and ranged from 2% to 92%. The greatest reductions in FB1 content were achieved with extrusion cooking with a high salt content, whilst the lowest reductions were the result of processing corn flour with low contents of both salt and sucrose. Salt at 2% was the most effective ingredient in reducing FB1 content of the final extruded food.

Incomplete Recoveries of Fumonisins Present in Naturally Contaminated Corn Foods from an Immunoaffinity Column

Following previous observations of apparent instability of fumonisin B1 in corn starch and corn meal, immunoaffinity column (IAC) cleanup, of the type used in the analysis of commercial starch-containing corn foods for fumonisins, was investigated. Foods analyzed for naturally occurring fumonisins B1, B2, and B3 included corn flour (3 different products), corn meal, and corn flakes. In 2 series of experiments, fractions were eluted by gravity or vacuum from narrow- or wide-bore Fumonitest IACs either with 2 x 2 mL methanol, followed by 2 mL methanol-water (8 + 2, v/v), or with 2 mL methanol, then 2 mL methanol-water (8 + 2, v/v). The ratio (%) of fumonisin B1 concentration in the first methanol eluate to the total concentration measured from all eluates in most cases varied from 25-70%. Incomplete recoveries were also observed for fumonisins B2 and B3. It is concluded that there can be a major underestimation of naturally occurring fumonisins in methods using only methanol elution for IAC cleanup, as in AOAC INTERNATIONAL Official Method 2001.04 (accuracy of these methods had been determined only by spiking the food with fumonisins). Elution with 2 x 2 mL methanol-water (8 + 2, v/v) was chosen as a practical procedure; means of 81-98% of the total fumonisin B1 concentration were found in the first eluate, except for corn flakes and 2 experiments with corn meal.

Real-Time PCR and Agar Plating Method to Predict Fusarium Verticillioides and Fumonisin B1 Content in Nigerian Maize

Eighty maize grain samples collected in Nigeria were investigated for fumonisin B 1 (FB 1 ) content and Fusarium verticillioides colonization. F. verticillioides DNA was quantified by species-specific real-time PCR and living propagules of the fungus were counted by agar-plating method. FB 1 was detected in 55 (68.7%) of the total samples (mean: 98.5 µg/kg, range: 10 to 714 µg/kg) at 10 µg/kg detection limit. The mean amount of F. verticillioides DNA determined by real-time PCR was 49.7 µg/kg (range: 10-126.7 µg/kg), while agar plate method showed the presence of F. verticillioides in 45 samples (mean incidence: 21.0%, range: 6.7-60.0%). There was cor- relation ties between F. verticillioides DNA by real time PCR and fungal colonization by agar plate method (R = 0.71, p = 00001 at 95% confidence level), and means of FB 1 and F. verticillioides DNA in the yellow and white maize were significantly different. Despite the high consumption of maize in Nigeria, the amount of FB 1 ingested by consumers appears to be low. The estimated daily intake of fumonisins was 0.21 µg/kg body weight per day.

Reduced Toxicity of Fumonisin B1 in Corn Grits by Single-Screw Extrusion

Corn grits spiked with 30 μg/g fumonisin B1 and two batches of grits fermented with Fusarium verticillioides (batch 1 contained 33 μg/g, and batch 2 contained 48 μg/g fumonisin B1), which were extruded by a single-screw extruder with and without glucose (10%, dry weight basis) supplementation were fed to rats. Control groups were fed uncontaminated grits. Extrusion with glucose more effectively reduced fumonisin B1 concentrations of the grits (75 to 85%) than did extrusion alone (10 to 28%). With one exception, the fumonisin B1–spiked and fermented extrusion products caused moderately severe kidney lesions and reduced kidney weights, effects typically found in fumonisin-exposed rats. Lesions in rats fed the least contaminated grits (batch 1) after extrusion with 10% glucose were, however, significantly less severe and not accompanied by kidney weight changes. Therefore, extrusion with glucose supplementation is potentially useful for safely reducing the toxicity of fumonisins in corn-based products and studies to determine the optimal conditions for its use are warranted.

Toxicokinetics of fumonisin B1 in turkey poults and tissue persistence after exposure to a diet containing the maximum European tolerance for fumonisins in avian feeds

The kinetic of fumonisin B1 (FB1) after a single IV and oral dose, and FB1 persistence in tissue were investigated in turkey poults by HPLC after purification of samples on columns. After IV administration (single-dose: 10 mg FB1/kg bw), serum concentration–time curves were best described by a three-compartment open model. Elimination half-life and mean residence time of FB1 were 85 and 52 min, respectively. After oral administration (single-dose: 100 mg FB1/kg bw) bioavailability was 3.2%; elimination half-life and mean residence time were 214 and 408 min, respectively. Clearance of FB1 was 7.6 and 7.5 ml/min/kg for IV and oral administration, respectively. Twenty-four hours after the administration of FB1 by the intravenous route, liver and kidney contained the highest levels of FB1 in tissues, level in muscle was low or below the limit of detection (LD, 13 μg/kg). The persistence of FB1 in tissue was also studied after administration for 9 weeks of a feed that contained 5, 10 and 20 mg FB1 + FB2/kg diet. Eight hours after the last intake of 20 mg FB1+FB2/kg feed (maximum recommended concentration of fumonisins established by the EU for avian feed), hepatic and renal FB1 concentrations were 119 and 22 μg/kg, level in muscles was below the LD.

Effect of Maize Hybrid Maturity and Grain Hardness on Fumonisin and Zearalenone Contamination

The level of resistance in commercial hybrids for Fusarium ear rot is still not in general adequate to prevent unacceptable toxin concentrations in field. The purpose of this experiment was to verify the behaviour of commercial dent maize hybrids for fumonisin and zearalenone contamination and to identify the variety traits that influence the production of these toxins. Field experiments were carried out in 2000, 2001 and 2002 to evaluate the effect of maize hybrid maturity and endosperm hardness on European Corn Borer (ECB) incidence, fungal ear rot incidence and severity and on fumonisin B1 and zearalenone contents. Nineteen yellow soft commercial hybrids, from the 500, 600 and 700 FAO maturity groups, were compared in 4 sites in NW Italy. Hybrid were grouped in 3 endosperm hardness categories (hard, intermediate, soft) in function of Hard/Soft (H/S) endosperm ratio. No effect due to endosperm hardness or hybrid maturity on the ECB infestation or fungal ear rot incidence and severity was observed. Grain hardness significant influenced fumonisin B1 content: hard endosperm hybrids showed 50% lower contamination than soft hybrids. The presence of fumonisin B1 in the grain of different maturity hybrids only resulted to be significantly different in 2001 experiment, with a mean concentration 2 times higher in the later hybrids (FAO rating 700) compared to the medium and medium-late hybrids. The zearalenone content never resulted to be significantly different in function of the endosperm hardness, while, late maturing hybrids, in which grain moisture content decreases slowly below 30%, are more susceptible to zearalenone contamination. This research has highlighted the presence of variety traits that can influence mycotoxin contamination. An accurate choice of hybrid, considering the territorial and cultivation context, could contribute to achieve products, that contain mycotoxins, which do not exceed the maximum international and UE regulation levels.

Cytotoxicity of Fumonisin B1 in Spheroid and Monolayer Cultures of Rat Hepatocytes

Fumonisin B1 (FB1), the most prevalent member of toxins produced by several species of Fusarium molds, which occur mainly in maize, causes several fatal hepatopathies and nephropathies of animals. The current study was scrutinized to ascertain different cytotoxic and morphological transformations in rat hepatocytes induced by the treatments of diverse concentrations (300, 500, or 1000 μM) of fumonisin B1 in vitro, using both monolayer and spheroid cultures. In each hepatocyte culture, the cytotoxicity of FB1 was augmented in dose- and time-response manners. Morphological transformations among FB1-treated groups integrated accumulation of lipid droplets, cytoplasmic vacuolation in hepatocyte monolayers, and bleb formation in the hepatocyte spheroids. Additionally, electron microscopy revealed the loss of microvilli, mitochondrial swelling, and formation of lamellar membranous whorl in the vacuoles and bile canaliculi-like structures. Appearance of electron dense bodies in the monolayers, and loss of cell-to-cell contact in spheroids were depicted in 1000 μM FB1-treated hepatocytes. These outcomes insinuate different vital events in explaining morphological transformations in the cell membrane and organelles, induced by fumonisins in rat hepatocytes.

Effect ofin vitro digestion on fumonisin B1 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.

Survey of maize from south-western Nigeria for zearalenone, α - and β -zearalenols, fumonisin B1 and enniatins produced by Fusarium species

A survey for the natural occurrence of Fusarium mycotoxins in maize for human consumption in four south-western states of Nigeria using High Performance Liquid Chromatography coupled with Mass Spectroscopy (HPLC/MS) showed that 93.4% of the samples were contaminated with zearalenone (ZON), α- and β-zearalenols (α- and β-ZOL), fumonisin B1 (FB1) or enniatins (ENNs). The fractions of contaminated samples were 73% for FB1 (mean:117 µg kg−1, range:10–760 µg kg−1); 57% for ZON (mean:49 µg kg−1, range:115–779 µg kg−1) and 13% for α-ZOL (mean: 63.6 µg kg−1, range:32–181 µg kg−1), while ENNs A1, B and B1 were present in 3, 7 and 3% of the samples respectively. There was no β-ZOL present above the quantification limits of 50 µg kg−1. Only the FB1 content was significantly different at the 95% confidence level among the four states. The Fusarium species most frequently isolated from maize seeds were F. verticillioides (70%), followed by F. sporotrichioides (42%), F. graminearum (30%), F. pallidoroseum (15%), F. compactum (12%), F. proliferatum (12%), F. equiseti (9%), F. acuminatum (8%) and F. subglutinans (4%). This is the first report of the occurrence of α-zearalenol and enniatins in Nigerian maize.

Protein Kinase C-induced Activation of a Ceramide/Protein Phosphatase 1 Pathway Leading to Dephosphorylation of p38 MAPK

Recently we showed that, in human breast cancer cells, activation of protein kinase C by 4beta-phorbol 12-myristate 13-acetate (PMA) produced ceramide formed from the salvage pathway (Becker, K. P., Kitatani, K., Idkowiak-Baldys, J., Bielawski, J., and Hannun, Y. A. (2005) J. Biol. Chem. 280, 2606-2612). In this study, we investigated intracellular signaling events mediated by this novel activated pathway of ceramide generation. PMA treatment resulted in transient activation of mitogen-activated protein kinases (ERK1/2, JNK1/2, and p38) followed by dephosphorylation/inactivation. Interestingly, fumonisin B1 (FB1), an inhibitor of the salvage pathway, attenuated loss of phosphorylation of p38, suggesting a role for ceramide in p38 dephosphorylation. This was confirmed by knock-down of longevity-assurance homologue 5, which partially suppressed the formation of C(16)-ceramide induced by PMA and increased the phosphorylation of p38. These results demonstrate a role for the salvage pathway in feedback inhibition of p38. To determine which protein phosphatases act in this pathway, specific knock-down of serine/threonine protein phosphatases was performed, and it was observed that knock-down of protein phosphatase 1 (PP1) catalytic subunits significantly increased p38 phosphorylation, suggesting activation of PP1 results in an inhibitory effect on p38. Moreover, PMA recruited PP1 catalytic subunits to mitochondria, and this was significantly suppressed by FB1. In addition, phospho-p38 resided in PMA-stimulated mitochondria. Upon PMA treatment, a mitochondria-enriched/purified fraction exhibited significant increases in C(16)-ceramide, a major ceramide specie, which was suppressed by FB1. Taken together, these data suggest that accumulation of C(16)-ceramide in mitochondria formed from the protein kinase C-dependent salvage pathway results at least in part from the action of longevity-assurance homologue 5, and the generated ceramide modulates the p38 cascade via PP1.

Necessary Role for the Lag1p Motif in (Dihydro)ceramide Synthase Activity

Lag1 (longevity assurance gene 1) homologues, a family of transmembrane proteins found in all eukaryotes, have been shown to be necessary for (dihydro)ceramide synthesis. All Lag1 homologues contain a highly conserved stretch of 52 amino acids known as the Lag1p motif. However, the functional significance of the conserved Lag1p motif for (dihydro)ceramide synthesis is currently unknown. In this work, we have investigated the function of the motif by introducing eight point mutations in the Lag1p motif of the mouse LASS1 (longevity assurance homologue 1 of yeast Lag1). The (dihydro)ceramide synthase activity of the mutants was tested using microsomes in HeLa cells and in vitro. Six of the mutations resulted in loss of activity in cells and in vitro. In addition, our results showed that C18:0 fatty acid CoA (but not cis-C18:1 fatty acid CoAs) are substrates for LASS1 and that LASS1 in HeLa cells is sensitive to fumonisin B1, an in vitro inhibitor of (dihydro)ceramide synthase. Moreover, we mutated the Lag1p motif of another Lag homologue, human LASS5. The amino acid substitutions in the human LASS5 were the same as in mouse LASS1, and had the same effect on the in vitro activity of LASS5, suggesting the Lag1p motif appears to be essential for the enzyme activity of all Lag1 homologues.

Interactive effects of fumonisin B1 and α-zearalenol on proliferation and cytokine expression in Jurkat T cells

Mycotoxins are secondary metabolites of fungi that grow on various food and feed. These compounds elicit a wide spectrum of toxicological effects, including the capacity to alter normal immune function. Feed commodities are usually contaminated with more than one mycotoxin; however, extensive information on the interaction between concomitantly occurring mycotoxins and the consequence for their toxicity is lacking. In the present study, we examined the effects in vitro of fumonisin B1 (FB1) and α-zearalenol (α-ZEA), alone or in combination, on the immune function in the human lymphoblastoid Jurkat T cell line. Treatment of cells with increasing concentrations of FB1 resulted in a dose-dependent induction of proliferation. In contrast, α-ZEA showed a marked inhibitory effect on cell proliferation, even at very low doses, essentially mediated by apoptosis. In stimulated cells pre-incubated with FB1, the levels of IL-2 and IFN γ mRNAs were similar to control whereas a reduction of cytokine transcripts was reported following α-ZEA treatment. Interestingly, co-administration of mycotoxins resulted in further inhibition of both proliferation and IFN γ mRNA expression when compared with α-ZEA alone. In conclusion, FB1 and α-ZEA showed different immunomodulation abilities when individually administered. Combination of mycotoxins resulted instead in interactive effects.

Mycotoxin fumonisin B1 stimulates nitric oxide production in a murine macrophage cell line.

Fumonisin B1 (FB1), a mycotoxin, is a common fungal contaminant of corn and corn products. This sphingolipid-like compound causes a variety of animal diseases and is a suspected human carcinogen. Cellular targets of FB1 include hepatocytes and renal and immune cells. The effects of FB1 on nitric oxide (NO) production induced by lipopolysaccharide (LPS) were investigated in the present study by using a murine macrophage cell line as a model system. Stimulation of NO production was observed for increasing concentrations of FB1 (1, 10, and 100 microM) and either 0.005 or 0.01 microgram/ml LPS. Although with an increasing dose of FB1 the total protein content decreased for the stimulated and the unstimulated cells, the NO production remained elevated for the stimulated cells. It can be hypothesized that the potentiation of the LPS-dependent NO production by FB1 treatment could be due to direct interaction between FB1 and NO synthases and LPS receptors or to a disrupted sphingolipid metabolism.

Rapid Detection of Kernel Rots and Mycotoxins in Maize by Near-Infrared Reflectance Spectroscopy

Near-infrared (NIR) spectroscopy is a practical spectroscopic procedure for the detection of organic compounds in matter. It is particularly useful because of its nondestructiveness, accuracy, rapid response, and easy operation. This work assesses the applicability of NIR for the rapid identification of micotoxigenic fungi and their toxic metabolites produced in naturally and artificially contaminated products. Two hundred and eighty maize samples were collected both from naturally contaminated maize crops grown in 16 areas in north-central Italy and from ears artificially inoculated with Fusarium verticillioides. All samples were analyzed for fungi infection, ergosterol, and fumonisin B1 content. The results obtained indicated that NIR could accurately predict the incidence of kernels infected by fungi, and by F. verticillioides in particular, as well as the quantity of ergosterol and fumonisin B1 in the meal. The statistics of the calibration and of the cross-validation for mold infection and for ergosterol and fumonisin B1 contents were significant. The best predictive ability for the percentage of global fungal infection and F. verticillioides was obtained using a calibration model utilizing maize kernels (r2 = 0.75 and SECV = 7.43) and maize meals (r2 = 0.79 and SECV = 10.95), respectively. This predictive performance was confirmed by the scatter plot of measured F. verticillioides infection versus NIR-predicted values in maize kernel samples (r2 = 0.80). The NIR methodology can be applied for monitoring mold contamination in postharvest maize, in particular F. verticilliodes and fumonisin presence, to distinguish contaminated lots from clean ones, and to avoid cross-contamination with other material during storage and may become a powerful tool for monitoring the safety of the food supply.

Agronomic and environmental impacts on concentrations of deoxynivalenol and fumonisin B1 in corn across Ontario

Relative effects of year, weather, and cultural practices on concentrations of deoxynivalenol (DON) and fumonisin B1 (FB1) were compared in grain that was harvested from corn fields across Ontario, Canada, from 1993 to 2000. Overall, between 59% and 88% of grain samples were contaminated with DON ≥ 0.2 μg g−1 in each year of the survey. From 1997 to 2000, between 17% and 56% of samples were contaminated with FB1 = 1.0 μg g−1, which is higher than first reported for fumonisins in 1993 in Ontario (9%). Deoxynivalenol and FB1 were mostly associated with corn hybrid and year-to-year effects caused by weather or geographical differences in the 8-year study. Among all cultural practices, corn hybrid was the most influential for both DON and FB1 accumulation, accounting for 25% (P < 0.0001) of the variation in both toxins across years. The effect due to year (or to weather, perhaps) accounted for 12% (P < 0.0001) of the variation in concentration of DON and 19% of the variation in FB1. When the effects of hybrid and year were considered in the same model, 42% of the variability of both toxins was accounted for in the model. A higher incidence of DON and fumonisin was detected for corn grown after wheat than for corn after corn. These results demonstrate that predictive models for DON in corn need to include the sensitivity of corn hybrids to infection by Fusarium spp. or mycotoxin accumulation, in addition to the response caused by weather. In practice, the best chance for corn growers to reduce DON and FB1 in harvested grain, when comparing cultural practices, is to select hybrids that are known to have more resistance to fusarium ear rots or mycotoxin accumulation than others.

Effect of Bt corn on broiler growth performance and fate of feed-derived DNA in the digestive tract

The aim of the study was to evaluate the effect on broiler performance of transgenic Bacillus thuringiensis (Bt) corn containing the Cry1A(b) protein compared with the corresponding near isogenic corn and to analyze the degradation of the Cry1A(b) gene in the digestive tract. Ross male broilers (432) were fed for 42 consecutive days with diets containing Bt or isogenic corn. Diet, Bt corn, and the isogenic form of the Bt corn were analyzed for composition and aflatoxin B1, fumonisin B1, and deoxynivalenol contents. Broiler body weight and feed intake were recorded at regular intervals (d 0, 21, and 42). The presence of the Cry1A(b) gene and plant-specific genes Zein and Sh-2 in gut contents of crop, gizzard, jejunum, cecum, and samples of blood was determined in 10 animals per treatment at the end of the trial using a PCR technique. Chemical composition was not different between Bt and its isogenic form, whereas the fumonisin B1 content for Bt was lower than for isogenic corn (2,039 vs. 1,1034 ppb; P < 0.05). The results of the growth study showed no difference for average daily weight gain (129.4 vs. 126.0 g/d), feed intake (63.4 vs. 61.8 g/d), and feed conversion ratio (1.95 vs. 2.02) among the groups. No significant relationship was observed between mycotoxins content and growth performances. Feed-derived DNA is progressively degraded along the digestive tract. Detection frequency of short fragments of maize-specific high copy number Zein gene was high but significantly decreased in distal sectors. An 1,800-bp fragment of the Cry1A(b) gene, corresponding to the minimal functional unit, was detected only in crop and gizzard of birds fed Bt corn. Sh-2 showed the same detection frequency of Cry1A(b) and was also found in birds fed isogenic corn. Blood samples were positive with low frequency only for the Zein gene fragment. No significant difference in DNA detection was observed between birds fed Bt and isogenic corn, indicating that DNA derived from transgenic feed undergoes the same fate as isogenic feed.