Aflatoxins

Identification of fungi-contaminated peanuts using hyperspectral imaging technology and joint sparse representation model

Peanuts with fungal contamination may contain aflatoxin, a highly carcinogenic substance. We propose the use of hyperspectral imaging to quickly and noninvasively identify fungi-contaminated peanuts. The spectral data and spatial information of hyperspectral images were exploited to improve identification accuracy. In addition, successive projection was adopted to select the bands sensitive to fungal contamination. Furthermore, the joint sparse representation based classification (JSRC), which considers neighboring pixels as belonging to the same class, was adopted, and the support vector machine (SVM) classifier was used for comparison. Experimental results show that JSRC outperforms SVM regarding robustness against random noise and considering pixels at the edge of the peanut kernel. The classification accuracy of JSRC reached 99.2% and 98.8% at pixel scale, at least 98.4% and 96.8% at kernel scale for two peanut varieties, retrieving more accurate and consistent results than SVM. Moreover, fungi-contaminated peanuts were correctly marked in both learning and test images.

Effect of probiotic supplement on aflatoxicosis and gene expression in the liver of broiler chicken

The present study aimed to investigate the toxic effect of aflatoxin B1 (AFB1) and the effectiveness of a biological mycotoxin binder (Nutritox^®) in detoxifying aflatoxicosis. Ninety one-day-old chicks were chosen and divided into 3 groups. The first group received standard basal diet only, the second group received a basal diet with AFB1 (0.25 mg/kg diet), and the third group received a basal diet with AFB1 (0.25 mg/kg diet) and Nutritox^® (1 kg/ton diet). AFB1 feed contamination significantly reduced growth performance and deteriorated FCR. Moreover, it significantly increased serum AST, ALT, and malondialdehyde and significantly decreased serum total protein, albumin, globulin, SOD, CAT activities and glutathione peroxidase gene expression as well. Aflatoxin residues were detected in the liver tissues. Furthermore, the liver and kidney of AFB1 treated group showed pathological changes. The supplementation of Nutritox^® significantly reduced aflatoxin levels in the liver and counteracted the negative effects of AFB1.

Review on biological degradation of mycotoxins

The worldwide contamination of feeds and foods with mycotoxins is a significant problem. Mycotoxins pose huge health threat to animals and humans. As well, mycotoxins bring enormous economic losses in food industry and animal husbandry annually. Thus, strategies to eliminate or inactivate mycotoxins in food and feed are urgently needed. Traditional physical and chemical methods have some limitations such as limited efficacy, safety issues, losses in the nutritional value and the palatability of feeds, as well as the expensive equipment required to implement these techniques. Biological degradation of mycotoxins has shown promise because it works under mild, environmentally friendly conditions. Aflatoxin (AF), zearalenone (ZEA) and deoxynivalenol (DON) are considered the most economically important mycotoxins in terms of their high prevalence and significant negative effects on animal performance. Therefore, this review will comprehensively describe the biological degradation of AF, ZEA and DON by microorganisms (including fungi and bacteria) and specific enzymes isolated from microbial systems that can convert mycotoxins with varied efficiency to non- or less toxic products. Finally, some strategies and advices on existing difficulties of biodegradation research are also briefly proposed in this paper.

Protective Effects of Bacillus subtilis ANSB060 on Serum Biochemistry, Histopathological Changes and Antioxidant Enzyme Activities of Broilers Fed Moldy Peanut Meal Naturally Contaminated with Aflatoxins

The aim of this study was to investigate the toxic effects of aflatoxins and evaluate the effectiveness of Bacillus subtilis ANSB060 in detoxifying aflatoxicosis in broilers. A total of 360 one-week-old male broilers (Ross 308) were assigned to six dietary treatments for five weeks. The treatment diets were: C0 (basal diet); C1.0 (C0 + 1.0 g B. subtilis ANSB060/kg diet); M0 (basal diet formulated with moldy peanut meal); M0.5, M1.0 and M2.0 (M0 + 0.5, 1.0 and 2.0 g B. subtilis ANSB060/kg diet, respectively). The contents of aflatoxin B1, B2, G1 and G2 in the diets formulated with moldy peanut meal were 70.7 ± 1.3, 11.0 ± 1.5, 6.5 ± 0.8 and 2.0 ± 0.3 µg/kg, respectively. The results showed that aflatoxins increased (p < 0.05) serum aspartate transaminase activity, decreased (p < 0.05) serum glutathione peroxidase activity, and enhanced (p < 0.05) malondialdehyde contents in both the serum and liver. Aflatoxins also caused gross and histological changes in liver tissues, such as bile duct epithelium hyperplasia, vacuolar degeneration and lymphocyte infiltration. The supplementation of ANSB060 reduced aflatoxin levels in the duodenum and counteracted the negative effects of aflatoxins, leading to the conclusion that ANSB060 has a protective effect against aflatoxicosis and this protection is dose-related.

Toxic synergism between aflatoxin and T-2 toxin in broiler chickens

The individual and combined effects of aflatoxin and T-2 toxin were studied in male broiler chicks (Hubbard X Hubbard). The experimental design was a 2 X 2 factorial design with dietary treatments of 0 and 2.5 micrograms/g aflatoxin and 0 and 4.0 micrograms/g T-2 toxin. The broilers were obtained at 1 day of age and housed in electrically heated batteries with feed and water available ad libitum until they reached 3 wk of age. Aflatoxicosis in this study was characterized by a significant (P less than .05) reduction in body weight, changes in red blood cell counts and serum levels of protein, albumin, glucose, cholesterol, and calcium, and magnesium, activity of the serum enzymes lactic dehydrogenase and alkaline phosphatase, and a significant (P less than .05) increase in relative weights of the liver, kidney, spleen, pancreas, proventriculus, and heart. Dietary T-2 toxin alone caused oral lesions, a significant (P less than .05) decrease in serum protein, albumin, potassium, and magnesium levels, and a significant (P less than .05) decrease in the activity of the serum enzymes lactic dehydrogenase and alkaline phosphatase. In the combination treatment of aflatoxin and T-2 toxin, significant (P less than .05) interactive effects were seen through a decrease in body weights, increase in the relative weights of the kidney, gizzard, and heart, and decrease in mean corpuscular volume and serum levels of potassium. These data indicate that aflatoxin and T-2 toxin can interact to produce synergistic toxicity. This synergism is a threat to poultry production due to the prevalence of these mycotoxins and severity of the interactive toxicity of these mycotoxins.

Progression of aflatoxicosis in broiler chickens

The progression of aflatoxicosis was evaluated in young broiler chickens (Hubbard X Hubbard). The experimental design consisted of four dietary treatments of aflatoxin (0, 1.25, 2.5, and 5.0 micrograms of aflatoxin/g of feed, ppm) and 11 replicates of 10 broilers/replicate. The broilers were maintained in electrically heated batteries with feed and water available ad libitum from hatching to 3 weeks of age. The broilers were weighed, bled, killed by cervical dislocation, and necropzied at 3, 6, 9, 12, 15, 17, and 21 days of age. Body weights were significantly decreased by 5.0 ppm aflatoxin at 6 days of age and by 2.5 ppm at 17 days of age. Aflatoxin induced a significant increase in the relative weight of the proventriculus, gizzard, spleen, and kidney. Liver atrophy was indicated in the early stages of aflatoxicosis by a decrease in the relative weight of this organ. As aflatoxicosis progressed, hepatomegaly became apparent due to lipid accumulation in the liver. Packed-cell volume and hemoglobin levels were significantly decreased by 5.0 ppm aflatoxin at 12 days and by 2.5 ppm aflatoxin at 21 days of age. Serum levels of albumin and total protein were significantly reduced at 5.0 and 2.5 ppm aflatoxin by 3 and 6 days of age, respectively. Serum levels of uric acid, triglycerides, and cholesterol were significantly decreased from control values from 12 through 21 days of age by 5.0 ppm aflatoxin and, to a lesser extent, by 2.5 ppm aflatoxin. The activity of serum lactic dehydrogenase was significantly decreased at all aflatoxin treatment levels from 12 through 21 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of immunity of young broiler chickens during simultaneous aflatoxicosis and ochratoxicosis

A 2 X 2 factorial experimental design consisting of the treatments 0 and 2.5 micrograms/g aflatoxin and 0 and 2.0 micrograms/g ochratoxin A with 12 replicates of 10 birds per treatment level was used to evaluate the effects of these mycotoxins on various aspects of immunity. Male chicks (Hubbard X Hubbard) were maintained on these treatments from one day of age to 3 weeks of age at which time six replicate pens per treatment were sacrificed and various parameters measured. The additional six replicate pens per treatment were maintained on toxin feed beyond 3 weeks of age, and at 4 weeks of age, three replicate pens were immunized with sheep red blood cells (SRBC) and Brucella abortus. Antibody titers were measured up to 10 days postimmunization. Aflatoxin and ochratoxin A, individually, significantly (P less than .05) decreased body weight, and a synergistic toxicity was evident by a significant (P less than .05) decrease in body weight. Antibody titers and phagocytic activity of heterophils were not significantly (P less than .05) altered by any treatments. The relative weight of the bursa of Fabricius and the number of follicles for a given area of the folds of the bursa of Fabricius were significantly (P less than .05) decreased only by the interaction treatment. Complement activity was significantly (P less than .05) decreased by aflatoxin and the combination of aflatoxin and ochratoxin A and depressed, although not significantly (P less than .05), by ochratoxin A.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of dietary fibre sources on aflatoxicosis in the weanling male rat

1. Two experiments with male weanling rats were conducted in which they received individually and restrictedly either a basal semi-purified diet containing starch as the principal carbohydrate or the same diet to which mixed aflatoxins were added in quantities providing from 0.13 to 0.4 mg aflatoxin B1/kg diet. Various natural ingredients, or semi-purified sources of dietary fibre were substituted for a portion of the starch in the basal diet containing aflatoxin. The diets were fed for 13-14 weeks after which the rats were given ad lib. a commercial rodent diet until they were killed at 109 weeks of age. 2. Two further experiments were conducted in which twenty-four rats in each experiment received the basal diet plus aflatoxin, or diets in which a portion of the starch was replaced by gum arabic or by wheat offal. After 13 or more weeks the absorption, retention and excretion of 14C-labelled aflatoxin B1 was measured in each rat. 3. The addition of gum arabic or wheat bran to the diet decreased the effects of the toxin in the first two experiments, but as measured by several characteristics, only wheat bran provided an effect which persisted during the period when neither it nor the toxin was given. The effects included an apparent reduction in tumour incidence. The change in the content of starch in the basal diet, occurring as a consequence of adding the test ingredients is also considered to be an associated cause of the effects observed. 4. In comparison to starch, wheat offal increased the total 14C in the faeces and the proportion of the total found during the first 48 h after dosing. Rats receiving starch excreted more 14C in their urine and retained more 14C in their livers. The differences between gum arabic and starch were not significant as measured by 14C excretion and retention. Liver size as a proportion of carcass weight was less in rats receiving wheat offal or gum arabic, and rats receiving wheat offal had a lower incidence of fat-loaded hepatocytes. 5. The interaction of dietary toxins, or drugs, with the ingredient composition of diet may affect animal response even when the diets are adequate and similar in nutrient composition. This may be of significance both in drug-safety studies and in animal production.

Aflatoxin B1, a selective inhibitor of DNA synthesis in mammalian cells

Aflatoxin B1 in concentrations between 0.01 and 0.1 microgram/ml inhibits DNA synthesis in African green monkey cells in culture, but has little effect on RNA synthesis and no effect on protein synthesis. The drug even at concentrations up to 1.0 microgram/ml does not interfere with DNA repair promoted by ultraviolet irradiation nor does it induce DNA repair. The inhibition of DNA synthesis attains maximum values 3 h after addition of aflatoxin B1 and is irreversible upon removal of the drug. Profiles of pulselabeled DNA sedimented in alkaline sucrose gradients indicate that aflatoxin B1 blocks initiation of replication rather than elongation.

Effect of aflatoxin B1 on hepatic polyribosomes and protein synthesis in the rat

This study was concerned with the effect of aflatoxin B1 on protein synthesis in rat liver. Specifically, the effect of the administration of aflatoxin B1 (6.0 mg/kg body weight) on hepatic polyribosomes (free and membranebound), protein synthesis in vitro, and initiation factors activity of rats within 3-12 h was investigated. The results revealed that aflatoxin B1 rapidly led to disaggregation of free and membrane-bound polyribosomes, to inhibition of in vitro protein synthesis by both populations of polyribosomes, to little or no effect on the activities of initiation factors, and to defective ribosomes, particularly the 60S ribosomal subnits, of both types of polyribosomes. Comparative studies on the effects of aflatoxin B1 and actinomycin D revealed progressive disaggregation by both hepatic free and membrane-bound polyribosomes after aflatoxin B1 but not only of the free polyribosomes after actinomycin D.

The anemia caused by aflatoxin

The effects of graded doses of dietary aflatoxin (0, 0.625, 1.25, 2.5, 5.0, and 10.0 mug./g.) on hemoglobin, packed blood cell volume, erythrocyte count, leucocyte counts, bone marrow lipid, and bone marrow nucleic acids of chickens were measured. The hemoglobin, packed cell volume, and erythrocyte count were reduced significantly (P less than 0.05) to about the same extent by any given dose. Microscopic examination of stained smears of the bone marrow revealed a hyperplastic response including the granulocytic elements. Chemical analyses of the marrow revealed a decreased lipid content and an increased content of ribonucleic acid and deoxyribonucleic acid. Total leucocytes were increased about three fold by aflatoxin (10 mug./g). Differential leucocyte counts revealed that the heterophils were increased while the eosinophils were unaffected and the basophils, lymphocytes, and monocytes were decreased. The increase in nucleic acids of the marrow and in circulating leucocytes occurred with doses which inhibit growth rate. These data suggest that aflatoxin causes a hemolytic anemia in chickens, that aflatoxin, by itself, is not involved in the hemorrhagic anemia syndrome of chickens, and that aflatoxin does not cause in chickens a general inhibition of ribonucleic acid and protein synthesis as assumed from studies on rats.

Translational step inhibited in vivo by aflatoxin B1 in rat-liver polysomes

Aflatoxin B1 strongly inhibits protein synthesis in rat liver cells. We previously demonstrated that this inhibition could be divided into two steps: up to 5 h aflatoxin blocks protein synthesis directly and specifically at the polysome level; beyond 7 h protein synthesis inhibition appears chiefly as a consequence of transcription impairment due to drug action. This paper confirms the foregoing results and represents an attempt to localize the translational step inhibited in vivo by aflatoxin B1. We used the simulation study developed by Li, Kisilevsky, Wasan and Hammond, 1972 (Biochim. Biophys. Acta, 272, 451-462) to determine precisely the site inhibited in vivo after drug intoxication. This analysis is based on two parameters: the kinetics of polysome labeling to follow the nascent peptide synthesis, and the kinetics of supernatant labeling to follow the completed protein synthesis. Up to 5 h after dosing, aflatoxin specifically inhibits the elongation and/or termination steps during protein synthesis; after longer periods of time inhibition occurs essentially at the initiation step. When the intracellular concentration of aflatoxin is too high, particularly 2 h after dosing, each step of protein synthesis is blocked. Polypeptide synthesis by the postmitochondrial supernatants isolated from aflatoxin-treated animals is impaired in the same proportion as protein synthesis in vivo. The damage caused by aflatoxin is mostly observed on microsomes. However, purified polysomes isolated from aflatoxin-treated rats synthesize proteins in vitro to the same extent as those from controls. These results suggest that aflatoxin metabolite(s) are bound to polysomes with noncovalent bonds. These active metabolites are probably lost during polysome isolation procedures. Finally, relationships between protein metabolism and aflatoxin carcinogenesis are discussed.