摘要:

To study the aflatoxin‐adsorbent capacity of two Mexican aluminosilicates (ALS) identified as Atapulgita (AT) and Füller earth (FE), these ALS were compared with a commercial aluminosilicate, Novasil (NV), at two concentrations (005 and 1.0%) added to chick diets with 55% of experimentally contaminated corn (200μg/kg). Eight treatments were studied with two replicates for treatment and four chicks per cage. Results (weight gain, feed efficiency, gross and microscopic pathology) at 3 weeks showed that both Mexican ALS were as efficient as the commercial material in protecting chicks against the aflatoxin toxicity.

ISSN:0265-203X    

DOI:10.1080/02652039509374326

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The phytotoxic effects of aflatoxin B1(AFB1) onin vitrocultures of differentiating calli and regenerating plantlets ofNicotiana tabacumwere assessed. Callus appeared more sensitive to the effects of AFB1, with fresh mass accumulation and callus chlorophyll levels affected at low (approximately 0.5μg/ml) aflatoxin concentrations. Transmission electron microscopy revealed early deteriorative alterations in chloroplast morphology. Inhibitory effects of the toxin (up to and including 10 μg/ml) on callus fresh mass accumulation were reversed following a 3 week toxin‐free recovery period. In tobacco plantlets, root and leaf development, and root and leaf mass were significantly inhibited in a dose‐dependent fashion with increasing AFB1concentration above 0.5μg/ml. Inhibitory effects on plantlet root development were more pronounced that on leaf development.

ISSN:0265-203X    

DOI:10.1080/02652039509374327

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The addition of compounds able to peroxidize cell lipids (carbon tetrachloride (CCl4). cumene hydroperoxide (CUH), or linoleic acid hydroperoxide (LAH)) to 5‐day‐old Czapek‐Dox Medium cultures ofAspergillus parasiticusinduces a significant reduction of the tri‐unsaturated ergosterol (ERG) levels in fungal microsomes and mitochondria, whereas the concentrations of the di‐unsaturated linoleic acid (LA; C18:2 n‐6) are unaffected. Aflatoxin (AFT) output follows ERG reduction and is associated with both a renewal of fungal growth and a slow increase of ERG concentration in subcellular membranes. We suggest that, by analogy with the regulatory role played on cell proliferation and metabolism by polyunsaturated fatty acid by‐products (eicosanoids) in mammalian membranes, by‐products of ERG oxidation may be considered triggers sufficient to induce both further fungal growth and AFT biosynthesis.

ISSN:0265-203X    

DOI:10.1080/02652039509374328

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The influence of aflatoxins B1, B2, G1, and G2was studied on the electron transport chain (from water to methyl viologen) of freshly lysed chloroplasts from maize(Zea maysL.) and peas(Pisum sativumL.). A partially purified extract containing all four toxins was added to a chloroplast suspension. Basal, phosphorylating, and uncoupled electron transport were assessed immediately after its addition and 4 min later. In maize chloroplasts, all three types of electron transport were inhibited by the mixture. The inhibition did not increase with time. The basal electron transport of pea chloroplasts was inhibited very slightly (20%) by the aflatoxin mixture. Commercially purified aflatoxins B1, B2, G1, and G2were tested individually. Only aflatoxins B1and B2showed effects on the chloroplasts of both species. With 16 μ?/ml of aflatoxin B2in the assay medium, the three kinds of electron transport were drastically inhibited both in maize (75%) and pea (60%) chloroplasts. Aflatoxin B1showed no effect on maize chloroplasts; however, a slight increase (31 %) was observed on the electron transport rate of pea chloroplasts. Differential response between electron transport rate in maize and pea could be related to the toxin's chemical structure, with a slight difference between molecules resulting in enormous differences in activity.

ISSN:0265-203X    

DOI:10.1080/02652039509374329

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Over 30 strains of variousPenicilliumsp. isolated from food have been screened for the ability to synthesize mycotoxins of an alkaloid nature. The most productive wereP. expansum, P. raciborskii, P. puberulum, P. commune, P. viridicatum, P. chrysogenum, P. palitans, P. purpurescensandP. cyclopium.The separate components of the alkaloid mixtures have been isolated and identified. The range of metabolites synthesized by different strains of the same species was considerably expanded. New producers of aurantioclavine, meleagrin, roquefortine, rugulovasine, clavine alkaloids and some other compounds have been found. It was shown that the alkaloid composition and content were dependent on the medium, culture age and method of cultivation.

ISSN:0265-203X    

DOI:10.1080/02652039509374330

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Liver and kidney tissues and urine from calves chronically or acutely intoxicated by aflatoxin were surveyed to detect the presence of aflatoxins B1, B1(AFB1, AFM1) and aflatoxicol (AFL). Aflatoxins B1, M1, and aflatoxicol were not found in the liver, kidney or urine from animals intoxicated by chronic forms. However in a calf that received a single dose of 0.8 mg of AFB1/kg of live weight and one submitted to a single dose of 1.8 mg of AFB1/kg of live weight detectable levels of aflatoxins occurred in tissues and urine.

ISSN:0265-203X    

DOI:10.1080/02652039509374331

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Fumonisins are a class of mycotoxins produced byFusarium moniliformeand otherFusariumspp. These compounds are widely distributed in corn. Equine leukoencephalomalacia, pulmonary oedema in swine, and nephrotoxicity, hepatotoxicity and liver cancer in male rats, all of which are caused by toxicF. moniliformehave been experimentally reproduced using fumisin B1(FB1) (ca90–94% purity). To investigate the effect of purified ( ≥ 99% purity) FB1, to compare the effects of FB1in males and females, and to obtain dose‐response information for FB1, three rats per sex were fed diets containing 0, 15, 50 or 150 FB1for 4 weeks. Serum chemical, organ weight and histopathological evidence showed that 150 mg/kg FB1was hepatotoxic in both sexes. Nephrosis was found in males fed ≥ 15 mg/kg and females fed ≥ 50 mg/kg FB1. Altered sphingolipid profiles, specifically increased free sphinganine concentrations and increased sphinganine: sphingosine ratios, were found in the liver, kidney, serum and urine of FB1‐fed rats. These findings support the hypothesis thatin vivotoxicity caused by fumonisins may result from altered sphingolipid metabolism.

ISSN:0265-203X    

DOI:10.1080/02652039509374332

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Chitosanase, a new class of enzymes with antifungal properties was induced by toxigenicAspergillus flavusin both germinating corn and peanut seeds. The enzyme was partially purified and fractioned by SDS‐Polyacrylamide Gel Electrophoresis activity and copolymerized with chitosan or glycolchitosan as substrate, then quantified by scanning densitometry and a 2‐dimensional analysis software program. Chitosanase enzyme was markedly induced by toxigenicA. flavusgrowing in germinating corn and peanut seeds, as compared to control (water) which showed the lowest activity (almost nil in corn). However, chitosanase induction was higher in seeds treated with chitosan from Crustacea. Overall, enzyme activity was higher in peanut than in corn seeds. However, electrophoresed gels from peanut treated withA. flavusor water showed more polypeptides (three and one, respectively) than gels from corn seeds, which only showed one polypeptide for bothA. flavusand water treatment. The enzyme molecular weight was estimated to be between 36000 and 45000.

ISSN:0265-203X    

DOI:10.1080/02652039509374333

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This research was carried out in order to show that certain substances of algal origin are toxic to animals, particularly to fish, and to determine if a relationship exists between toxicity and the latitude where the algae were collected. Twenty‐nine species of algae were collected in different localities off the Pacific coast of Mexico. The samples were frozen shortly after collection and kept frozen until used. Crude ethanolic extracts of the algae were prepared and tested for ichthyotoxicity. The extracts were classified as nontoxic (NT), weakly toxic (WT) and highly toxic (with lethal effects) (T). The reactions exhibited by the fish to the presence of the algal extracts in their environment ranged from initial adaptative behaviour to death. Only four species (14%) out of the 29 algal species tested were highly toxic, 13 (45%) weakly toxic and 12 (41%) non‐toxic. The high percentage of algal extracts that showed some degree of toxicity suggests that algae might have some kind of defence mechanism that could be noxious, thus being inedible by fish. The highest toxicity values were found among tropical algae. These results suggest that a relationship could exist between toxicity and the latitude of the collecting locality.

ISSN:0265-203X    

DOI:10.1080/02652039509374334

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The efficiency of selection for resistance to aflatoxin development caused byAspergillus flavusL. ex Fries, in maize(Zea maysL.) grain was studied in three CIMMYT lowland tropical maize populations. Seed samples of each population were inoculated with a spore suspension of cultures ofAspergillusspp. known to produce aflatoxins. Inoculated seeds were maintained at 85% RH in plastic boxes kept at room temperature. At 50% germination, seed samples were planted in the field. At flowering time, selected plants were bulk pollinated. After three cycles of selection, gains for tolerance to aflatoxin formation and improvement for agronomic characters were evaluated. The results indicate there are differences in aflatoxin accumulation between different genotypes and cycles of selection. Populations 22 (DMR) and 28 (DMR) were the most damaged and Population 31 DMR suffered the lowest infection. The study suggests that there are differences in aflatoxin production between the maize genotypes tested. However, our results failed to show that tolerance to aflatoxin development can be accumulated through a recurrent selection breeding scheme.

ISSN:0265-203X    

DOI:10.1080/02652039509374335

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor