Effect of dietary β-1,3 glucan on immune responses and disease resistance of healthy and aflatoxin B1-induced immunocompromised rohu (Labeo rohita Hamilton)

The immunostimulant β-1,3 glucan was fed at 0·1% in feed for 7 days to healthy and aflatoxin B₁(AFB₁)-induced immunocompromised fish, Labeo rohita (one of the major tropical carp species), in a 60 day trial. The effects of AFB₁, glucan and their interactions on non-specific and specific immunity levels and disease resistance of fish were studied. A single intraperitoneal injection of AFB₁at 1·25 mg kg⁻¹body weight) caused a significant (P< 0·05) reduction in non-specific immunity as measured through neutrophil phagocytic indices, serum bactericidal activity, and specific immunity as measured through bacterial agglutination titre against Edwardsiella tarda, as well as reduced protection against Aeromonas hydrophila challenge in comparison to control fish which were exposed neither to aflatoxin nor to glucan. Feeding of glucan to healthy fish raised the non-specific and specific immunity level and protection against bacterial infection compared with the control. Feeding of glucan to AFB₁-induced immunocompromised fish for 7 days significantly raised the degree of resistance against A. hydrophila challenge and the non-specific immunity level in comparison to non-treated AFB₁exposed fish. Although feeding of glucan was able to increase specific immunity, al measured through haemagglutination titre against sheep red blood cells, and bacterial (E. tarda) agglutination titre in healthy fish in comparison to all other groups, no significant increase in specific immunity to the aflatoxin-exposed group was seen.     

Immunosuppressive effects of aflatoxin in growing rats

The immunosuppressive potential of aflatoxin B₁ (AFB₁), the carcinogenic metabolite ofAspergillus flavus, was evaluated in growing rats. The weanling rats were subchronically exposed to 60, 300 and 600 µg AFB₁/kg body weight for four weeks on alternate days by oral feeding. Various parameters of cell mediated immunity (CMI) and humoral immunity were assessed in control and treated animals. CMI was evaluated by measuring delayed type of hypersensitivity (DTH) response and humoral by plaque forming cell (PFC) assay. The lymphoproliferative response assay for T- and B-cells was also performed. It was observed that AFB₁ selectively suppressed cell mediated immunity in growing rats. AFB₁ suppressed CMI at the 300 and 600 µg dose levels only as measured by DTH response assay. It is concluded that continuous low level exposure of aflatoxin to growing host may enhance its susceptibility to infection and tumorigenesis.Abbreviations AF Aflatoxin - AFB₁ Aflatoxin B₁ - CMI Cell mediated immunity - CPM Counts per minute - DTH Delayed type of hypersensitivity - GST Glutathione-S-transferase - LPS Lipopolysaccharide - PFC Plaque forming cell - PHA Phytohemagglutinin - SRBC Sheep red blood cells     

Evaluation of glucomannan for its adsorbing ability of Aflatoxin B<Subscript>1</Subscript> and T-2 Toxin in the Gastrointestinal Tract of Broiler Chickens

A biological experiment was conducted to evaluate the ability of glucomannan to adsorb aflatoxin B₁(AFB₁ and T-2 toxin in gut conditions of broiler chickens. Glucomannan (GM) was tested at 0.1 percent (1kg / ton) on a total of two hundred uniformly weighing five-week-old commercial broiler birds, which were randomly assigned to one of the ten dietary treatments with four replicates each. Four birds were sacrificed at 30 minutes intervals i.e., 0, 30, 60, 90 and 120 minutes from each treatment, and the gut contents were collected. The toxin concentrations in the dried gut samples were estimated and percent of AFB₁ and T-2 toxin recovered was measured. Thein vivo results revealed that glucomannan had the ability to adsorb Aflatoxin upto 75–90% and T-2 toxin upto 30–35% in gastrointestinal tract of broilers.     

Interrelationships of dietary protein level,aflatoxin B1 metabolism,and hepatic microsomal epoxide hydrase activity

In a continuation of studies on protein intake and aflatoxin B₁ (AFB₁) metabolism, weanling rats were fed semipurified diets containing either 20% casein or 5% casein for two weeks to determine the effect of dietary protein level on hepatic microsomal epoxide hydrase activity and AFB₁ metabolism in an effort to evaluate the role of protein intake on the formation and degradation of the reactive metabolite of AFB₁. Styrene oxide was used as substrate for epoxide hydrase since the hypothetical AFB₁ 2,3-epoxide (AFB-epox) cannot be synthesized because of its lability. Two groups of animals were fed 20% casein diets; one was fed ad libitum and the second was pair fed to the 5% casein group in order to control the effects of total feed intake. The depression of epoxide hydrase activities caused by the 5% casein diets was approximately equivalent to that previously seen with hepatic microsomal mixed function oxidase (MFO) activities with the identical protocol. Similarly, the metabolism of AFB₁ to AFQ₁ and AFM₁ was depressed by the 5% casein diets, with an increase in the production of chromatographically more polar material. The relationship of the MFO and epoxide hydrase activities to AFB₁ metabolism and formation of macromolecular adducts is discussed.     

The effects of aflatoxin B1 on growth hormone regulated gene-1 and interaction between DNA and aflatoxin B1 in broiler chickens during hatching

Many types of aflatoxin cause problems for both public and animal health. Aflatoxin B₁ (AFB₁) is the most toxic and commonly encountered fungal toxin that appears in poultry feed and in feeds stored under unsuitable conditions. AFB₁ decreases feed quality, egg production and fertility of hatching eggs. Also, AFB₁ alters the development of embryos by infecting eggs. We investigated using sequence analysis the changes caused by different concentrations of AFB₁ on the promoter sequences of the growth hormone regulated gene-1 (GHRG-1) in chick embryo at 13, 17, 19 and 21 days incubation. DNA isolated from the liver of chick embryos treated with different concentrations of AFB₁ was separated using agarose gel electrophoresis to detect apoptosis, and DNA interaction with AFB₁ was investigated using plasmids to detect changes in electrophoretic mobility and their effects on DNA. Base changes of the promoter sequences of GHRG-1 in 5 ng/egg, 15 ng/egg and 40 ng/egg doses of AFB₁ were increased on day 19 compared to base changes of the same AFB₁ doses on day 13. We also found that AFB at different concentrations changed the mobility of DNA by binding to it, and that high doses of AFB1 destroyed DNA. The DNA interaction study using plasmid demonstrated that AFB₁ at high doses was bound to plasmid DNA, slowed its mobility and inhibited restriction cuts.     

Aflatoxin B<Subscript>1</Subscript> Induced Systemic Toxicity in Poultry and Rescue Effects of Selenium and Zinc

Among many challenges, exposure to aflatoxins, particularly aflatoxin B₁ (AFB₁), is one of the major concerns in poultry industry. AFB₁ intoxication results in decreased meat/egg production, hepatotoxicity, nephrotoxicity, disturbance in gastrointestinal tract (GIT) and reproduction, immune suppression, and increased disease susceptibility. Selenium (Se) and zinc (Zn), in dietary supplementation, offer easy, cost-effective, and efficient ways to neutralize the toxic effect of AFB₁. In the current review, we discussed the impact of AFB₁ on poultry industry, its biotransformation, and organ-specific noxious effects, along with the action mechanism of AFB₁-induced toxicity. Moreover, we explained the biological and detoxifying roles of Se and Zn in avian species as well as the protection mechanism of these two trace elements. Ultimately, we discussed the use of Se and Zn supplementation against AFB₁-induced toxicity in poultry birds.     

Effect of aflatoxin B1 on CD3 T cells andalkaline phosphatase in the intestine of mice

The aim of the study was to determine the effect of repeated applications of aflatoxin B₁ (AFB₁) on immunocompetent cells (CD3 T cells) and alkaline phosphatase in the intestinal mucosa. Mice were orally treated with AFB₁ for 24 days. The mucosa of the intestine showed a significant decrease in the number of CD3 T cells and a significantly lower level activity of alkaline phosphatase on day 24 in AFB₁ treated mice. Similarly, with changes in the small intestine, qualitative haematological parameters were modified in systemic immunity as lymphopenia, and neutropenia, monocytopenia. AFB₁ treated animals showed reduction in body weight gain and increased liver weight. We supposed that changes found in the small intestine are secondary to primary systemic haematological lesions. The decrease in CD3 T cells suggests a connection with the decrease in the host's resistance to infectious diseases. This revised version was published online in June 2006 with corrections to the Cover Date.     

Determination of serum aflatoxin B<Subscript>1</Subscript>-lysine to evaluate the efficacy of an aflatoxin-adsorbing feed additive in pigs fed an aflatoxin B<Subscript>1</Subscript>-contaminated diet

In this study, serum aflatoxin B₁ (AFB₁)-lysine was determined in order to evaluate the in vivo efficacy of a hydrated sodium calcium aluminosilicate (HSCAS) in pigs fed AFB₁. Twenty-four 49-day-old crossbred barrows were maintained in individual cages and allowed ad libitum access to feed and water. A completely randomized design was used with six animals assigned to each of four dietary treatments for 21 days as follows: (A) basal diet (BD), (B) BD supplemented with 0.5 % HSCAS, (C) BD supplemented with 1.1 mg/kg AFB₁, and (D) BD supplemented with 0.5 % HSCAS and 1.1 mg/kg AFB₁. HSCAS was able to alleviate the toxic effects of AFB₁ on pigs and reduce (P < 0.05) the levels of serum AFB₁-lysine. Cumulative reductions of adduct yield values, calculated through the equation [(pg AFB₁-lysine/mg albumin) / (μg AFB₁/kg body weight)], were 53.0, 62.8, and 72.1 after 7, 14, and 21 days of oral exposure, respectively. AFB₁-lysine has potential as an AFB₁-specific biomarker for diagnostic purposes and for evaluating the efficacy of chemoprotective interventions in pigs.     

A novel strain of Cellulosimicrobium funkei can biologically detoxify aflatoxin B1 in ducklings

Two experiments were conducted to screen microorganisms with aflatoxin B₁ (AFB₁) removal potential from soils and to evaluate their ability in reducing the toxic effects of AFB₁ in ducklings. In experiment 1, we screened 11 isolates that showed the AFB₁ biodegradation ability, and the one exhibited the highest AFB₁ removal ability (97%) was characterized and identified as Cellulosimicrobium funkei (C. funkei). In experiment 2, 80 day‐old Cherry Valley ducklings were divided into four groups with four replicates of five birds each and were used in a 2 by 2 factorial trial design, in which the main factors included administration of AFB₁ versus solvent and C. funkei versus solvent for 2 weeks. The AFB₁ treatment significantly decreased the body weight gain, feed intake and impaired feed conversion ratio. AFB₁ also decreased serum albumin and total protein concentration, while it increased activities of alanine aminotransferase and aspartate aminotransferase and liver damage in the ducklings. Supplementation of C. funkei alleviated the adverse effects of AFB₁ on growth performance, and provided protective effects on the serum biochemical indicators, and decreased hepatic injury in the ducklings. Conclusively, our results suggest that the novel isolated C. funkei strain could be used to mitigate the negative effects of aflatoxicosis in ducklings.     

Production of aflatoxin byAspergillus parasiticus and its control

The aim of the present work was to investigate the production of aflatoxin byAspergillus parasiticus and to find out the possible ways to control it. Of 40 food samples collected from Abha region, Saudi Arabia, only 25% were contaminated with aflatoxins. Oil-rich commodities had the highly contaminated commodities by fungi and aflatoxins while spices were free from aflatoxins.Bacillus megatertum andB cereus were suitable for microbiological assay of aflatoxins. Czapek’s-Dox medium was found a suitable medium for isolation of fungi from food samples. The optimal pH for the growth ofA. parasiticus and its productivity of aflatoxin B₁ was found at 6.0, while the best incubation conditions were found at 30°C for 10 days. D-glucose was the best carbon source for fungal growth, as well as aflatoxin production. Corn steep liquor, yeast extract and peptone were the best nitrogen sources for both fungal growth and toxin production (NH₄)₂HPO₄ (1.55 gL^-1) and NaNO₂ (1.6 gL^-1) reduced fungal growth and toxin production with 37.7% and 85%, respectively. Of ten amino acids tested, asparagine was the best for aflatoxin B₁ production. Zn²⁺ and Co²⁺ supported significantly both fungal growth, as well as, aflatoxin B₁ production at the different tested concentrations. Zn²⁺ was effective when added toA. parasiticus growth medium at the first two days of the culture age. The other tested metal ions expressed variable effects depending on the type of ion and its concentration. Water activity (a_w) was an important factor controlling the growth ofA. parasiticus and toxin production. The minimum a_w for the fungal growth was 0.8 on both coffee beans and rice grains, while a_w of 0.70 caused complete inhibition for the growth and aflatoxin B₁ production. H₂O₂ is a potent inhibitor for growth ofA. parasiticus and its productivity of toxins. NaHCO₃ and C₆H₅COONa converted aflatoxin B₁ to water-soluble form which returned to aflatoxin B₁ by acidity. Black pepper, ciliated heath, cuminum and curcuma were the most inhibitory spices on toxin production. Glutathione, quinine, EDTA, sodium azide, indole acetic acid, 2,4-dichlorophenoxy acetic acid, phenol and catechol were inhibitory for both growth, as well as, aflatoxin B₁ production. Stearic acid supported the fungal growth and decreased the productivity of AFB₁ gradually. Lauric acid is the most suppressive fatty acid for both fungal growth and aflatoxin production, but oleic acid was the most potent supporter. Vitamin A supported the growth but inhibited aflatoxin B₁ production. Vitamins C and D₂ were also repressive particularly for aflatoxin production The present study included studying the activities of some enzymes in relation to aflatoxin production during 20-days ofA. parasiticus age in 2-days intervals. Glycolytic enzymes and pyruvate-generating enzymes seems to be linked with aflatoxin B₁ production. Also, pentose-phosphate pathway enzymes may provide NADPH for aflatoxin B₁ synthesis. The decreased activities of TCA cycle enzymes particularly from 4th day of growth up to 10th day were associated with the increase of aflatoxin B₁ production. All the tested enzymes as well as aflatoxin B₁ production were inhibited by either catechol or phenol.     

Effects of Sodium Selenite on Aflatoxin B1-Induced Decrease of Ileac T cell and the mRNA Contents of IL-2, IL-6, and TNF-α in Broilers

The aim of this work was to assess the protective effect of sodium selenite on the ileum mucosal immunologic toxicity induced by aflatoxin B₁ (AFB₁). One hundred and eighty one-day-old healthy male avian broilers were divided into four groups of three replicates and 15 birds per replicate and fed with basal diet (control group), 0.3 mg/kg AFB₁ (AFB₁ group), 0.4 mg/kg Se (+Se group), and 0.3 mg/kg AFB₁?+?0.4 mg/kg Se (AFB₁+Se group), respectively. The ileac T-cell subsets were determined by the methods of flow cytometry (FCM), and the mRNA contents of interleukin-2 (IL-2), interleukin-6(IL-6), and tumor necrosis factor-alpha (TNF-α) by quantitative real-time PCR. Compared with those in control group, the percentages of CD₃ ⁺, CD₃ ⁺CD₄ ⁺, CD₃ ⁺CD₈ ⁺ intraepithelial lymphocytes (IELs) and LPLs, the CD4⁺/CD8⁺ ratio of IELs, and the mRNA contents of IL-2, IL-6, and TNF-α were decreased in AFB₁ group. However, compared with those in AFB₁ group, these parameters of AFB₁+Se group were increased to be close to those in control group. It was concluded that 0.3 mg/kg AFB₁ could reduce the cellular immune function of the ileum mucosa, but 0.4 mg/kg supplemented dietary selenium showed protective effects on AFB₁-induced immunologic injury.     

Natural occurrence of aflatoxins and ochratoxin a in corn and barley from mazandaran and golestan in north provinces of I. R. Iran

Fourteen barley and nine corn samples, destined for animal feed, collected from Golestan and Mazandaran provinces in the north of Islamic Republic of Iran (I. R. Iran) were analysed for aflatoxins (AF) and ochratoxin A (OA) by high performance liquid chromatography. In corn samples, aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) were detected in 8 (88.8%) and 6 (66.6%) samples at a mean level of 15.83 and 2.99 ppb (median 1.72 and 1 ppb), respectively. None of the corn samples contained detectable amounts of aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂). Only one of the AF-contaminated samples was co-contaminated with OA at a concentration of 0.35 ppb. This is the first report concerning natural occurrence of OA and co-occurrence with AF in corn samples of north of I. R. Iran.     

Effects of limited feeding of aflatoxin B1 contaminated feed on the performance of broilers

The forty-two days long experiment was conducted on a total of 1000 Arbor Acres broilers, divided into two groups. Both groups of broilers were fed with a commercial feed mixture which consisted of standard feedstuffs and contained enough nutrients regarding the requirements. During the first three weeks of the trial, corn naturally contaminated with AFB₁ 0.0445 ppm per kg dry matter was used in the amount of 20% in the experimental group, while AFB₁ free corn was given to birds in the control group. After the period of toxin administration until the end of the trial, broilers from both groups were normally fed another 5 weeks with uncontaminated feed. In the first phase of the trial, broilers in the control groups had an average daily gain (ADG) of 31 g, average daily feed intake (ADFI) of 45 g and a feed: gain ratio (FCR) of 1.42. In the same time, experimental broilers achieved an ADG of 25 g, ADFI of 35 g and a FCR of 1.39. During the whole period of the trial, control and experimental broilers achieved 49.12 g, 95.24 g and 1.94 and 39.71 g, 86.90 g and 2.19, respectively.     

Effects of aflatoxin B1 on in vitro cultures ofNicotiana tabacum var. Samsun

Calli ofNicotiana tabacum (tobacco) were treated with two dose ranges of aflatoxin B₁ (0.1–2.0 µg ml^–1 - low does; 5–25 µg ml^–1 aflatoxin B₁). The ability of calli to recover following 3 weeks of toxin exposure was also investigated. The I₅₀ (50% inhibition) value for fresh mass accumulation was approximately 2 µg ml^–1 AFB₁. Fresh mass accumulation was significantly lower than the control value from 0.5 µg ml^–1 AFB₁. Following 3 weeks growth without a toxin source, the growth of calli up to and including 10 µg ml^–1 AFB₁, was significantly greater than control calli, indicating reversibility of the toxic effects. With increasing toxin concentration, chlorophyll content of callus was inhibited from 0.5 µg ml^–1. Transfer to a toxin-free medium resulted in a degree of recovery (up to 0.5 µg ml^–1). In the dose range 5–25 µg ml^–1, the levels of chlorophyll were drastically reduced, with no recovery following AFB₁ removal. Electron microscopy revealed a disruption of chloroplast structure as an early deteriorative event in AFB₁ exposure of callus cells. Protein levels were less sensitive, with inhibition manifested only in the high dose range. Shoot development occurred at all concentrations, but was significantly inhibited from 5 µg ml^–1 AFB₁. Recovery following toxin removal was minimal at these higher AFB₁ concentrations. The number of necrotic calli increased progressively from 5 µg ml^–1 as toxin levels increased.     

Altered bacterial culture density following exposure to aflatoxins

Summary Eight species of bacteria were incubated in culture media containing 10 g/ml aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), or aflatoxin G₂ (AFG₂). Their culture density at 20°C was determined at four and eight days (d) after inoculation. In all species of bacteria studied (Bacillus cereus, Proteus mirabilis, Erysipylothrix rusiopathie (insidiosa), Streptococcus fecalis, Staphylococcus epidermis, Klebsiella pneumoniae, Micrococcus spp., andEscherichia coli), AFB₁, AFB₂ and AFG₂ substantially decreased culture sizes at 4 d, but not at 8 d. InB. cereus andP. mirabilis, culture sizes were increased by AFB₁, AFB₂, and AFG₂ at 8 d post inoculation. These results indicate that AFB₁, AFB₂, and AFG₂ suppressed initial growth of these species in vitro, while later growth in some species was either unaltered or enhanced.     

Aflatoxin B1-induced ultrastructural alterations in matureZea mays embryos

Mature maize (Zea mays L.) embryos were exposed to aflatoxin B₁ (AFB₁) concentrations ranging from 0.1 to 25 µg/ml for 9 days. With increasing toxin concentration above 2 µg/ml, primary root elongation of germinated embryos was progressively inhibited, to reach a maximum value of 81% at 25 µ/ml toxin. An ultrastructural investigation of the subcellular alterations induced following toxin exposure provided evidence of deteriorative changes in several compartments of the plant cell. Alteration in membrane integrity (e.g., the tonoplast, plasmalemma and inner mitochondrial membrane) was a frequent feature of many cells. Apparent fusion of vacuoles, incorporation of cytoplasmic components into vacuoles and intravacuolar membrane whorls might be interpreted as deteriorative alterations. The results are discussed in the light of ultrastructural findings for other plant systems exposed to similar AFB₁ concentrations, as well as findings for animal systems.     

A novel glass fiber disc culture system for testing of small amounts of compounds on growth and aflatoxin production byAspergillus flavus

A new method for growingAspergllius flavus for experimental studies is presented. The system consists of a humidified vial with a thick septum pierced by a pin on which a glass fiber disc is affixed. The disc contains the test solution and inoculum plus medium. The method has been used to assess the effect of variations in culture conditions on production of aflatoxin B₁ (AFB₁). The AFB₁ level was affected by the amount of medium placed on the disc and type of disc material. The results for different types of glass fiber and quartz discs were compared with AFB₁ produced by fungus grown in liquid medium or on paper discs. When compared to a liquid medium culture there was a 15 to 20-fold increase in AFB₁ for one type of disc. Incubations with less than 14 µl of medium gave satisfactory results. A crude phosphatidylcholine preparation at a concentration of 0.7% of the medium resulted in a 4-fold increase in AFB₁.Abbreviations AFB₁ aflatoxin B₁ - CV coefficient of variation - PC phosphatidylcholine - SD suspended disc     

Vaccination of Heifers with Anaflatoxin Improves the Reduction of Aflatoxin B1 Carry Over in Milk of Lactating Dairy Cows

It was previously reported that injection of anaflatoxin B₁ (AnAFB₁) conjugated to keyhole limpet hemocyanin (KLH), together with Freund''s adjuvant, was effective in inducing in cows a long lasting titer of anti-aflatoxin B₁ (AFB₁) antibodies (Abs), cross-reacting with other aflatoxins, which were able to hinder, proportionally to their titer, the secretion of aflatoxin M₁ (AFM₁) into the milk of cows continuously fed with AFB₁. According to anti-AFB₁ Ab titer, 50% of the vaccinated cows were recognized as high responder animals. In an attempt to prepare a more effective formulation for vaccination of cows, it was compared the immunogenicity, in Holstein Friesian heifers, of AnAFB₁ covalently conjugated to KLH or to recombinant diphtheria toxin (CRM₁₉₇) molecules, and injected together with various adjuvants. This study demonstrated that injection of AnAFB₁ conjugated to KLH and mixed with complete (priming) and incomplete Freund''s adjuvant (boosters), as in the previous schedule of immunization, was the most effective regimen for inducing Ab responses against AFB₁, although pre-calving administration could increase the effectiveness of vaccination, resulting in 100% high responder animals. After one booster dose at the beginning of the milk production cycle, anti-AFB₁ Ab titers were comparable to those recorded at the end of the immunization schedule, and proved to be effective in reducing significantly AFB₁ carry over, as AFM₁, from feed to milk. Pre-calving vaccination of dairy heifers with conjugated AnAFB₁, adjuvated with complete and incomplete Freund''s adjuvant, may represent the most effective tool for preventing the public health hazard constituted by milk and cheese contaminated with aflatoxins.     

Effects of Aflatoxin B1 Exposure and Sodium Selenite Supplementation on the Histology,Cell Proliferation,and Cell Cycle of Jejunum in Broilers

The aim of this study was to investigate the effects of aflatoxin B₁ (AFB₁) exposure and sodium selenite supplementation on the histology, cell proliferation and cell cycle of jejunum in broilers. A total of 240 1-day-old male AA broilers were divided into four groups of 60 each, fed with basal diet (control group), 0.3 mg/kg AFB₁ (AFB₁ group), 0.4 mg/kg supplement Se (Se group), and 0.3 mg/kg AFB₁?+?0.4 mg/kg supplement Se (AFB₁ + Se group) for 21 days, respectively. Compared with the control group, decreased jejunal villus height, villus height/crypt ratio, and proliferation cell nuclear antigen (PCNA)-positive cells, and G₂/M phase arrest and shedded epithelial cells on the tip of jejunal villus were observed in AFB₁ groups at 7 and 14 days of age. However, the villus/crypt ratio, PCNA-positive cells and cell percentage of G₀/G₁, S, and G₂/M phases had no significant differences between AFB₁ group and control group at 21 days. Simultaneous supplementation with sodium selenite restored these parameters to be close to those in control group. In conclusion, 0.3 mg/kg AFB₁ in the diet inhibits the development of broiler’s jejunum by reducing cellular proliferation and inducing G₂/M arrest during only the first 2 weeks after hatching. Supplementation of dietary sodium selenite at the concentration of 0.4 mg/kg Se had protective action against these toxic effects of AFB₁.     

In vivo covalent binding of aflatoxin B1 and aflatoxin M1 to liver DNA of rat,mouse and pig

[¹⁴C]Aflatoxin B₁ (AFB₁) was isolated from cultures of Aspergillus parasiticus grown on [1-¹⁴C]sodium acetate. Covalent binding of AFB₁ to liver DNA of rat and mouse was determined 6–8 h after oral administration. The effectiveness of covalent binding, expressed as DNA binding per dose in the units of a ‘Covalent Binding Index’ (CBI), (μmol aflatoxin/mol DNA nucleotides)/(mmol aflatoxin/kg animal), was found to be 10 400 for rats and 240 for mice. These CBI partly explain the different susceptibility of the two species for the incidence of hepatic tumors.The corresponding values for pig liver DNA, 24 and 48 h after oral administration, were found to be as high as 19 100 and 13 300. DNA-binding has not so far been reported for this species although it could represent an appropriate animal model for studies where a human-like gastrointestinal tract physiology is desirable.Aflatoxin M₁ (AFM₁) is a metabolite found in the milk of cows that have been fed AFB₁-contaminated diet. [¹⁴C]AFM₁ was also found to be produced by cultures of A. parasiticus giving a yield of about 0.3% of the total aflatoxins. A test for covalent binding to rat liver DNA revealed a CBI of 2100 showing that AFM₁ must also be regarded as a strong hepatocarcinogen. It is concluded that AFB₁ contaminations should be avoided in dairy feed.