Aspergillus flavus is a very important toxigenic fungus that produces aflatoxins, a group of extremely toxic substances to man and animals. Toxigenic fungi can grow in feed crops, such as maize, peanuts, and soybeans, being thus of high concern for public health. There are toxigenic and non-toxigenic A. flavus variants, but the necessary conditions for expressing the toxigenic potential are not fully understood. Therefore, we have studied total-DNA polymorphism from toxigenic and non toxigenic A. flavus strains isolated from maize crops and soil at two geographic locations, 300 km apart, in the Southeast region of Brazil. Total DNA from each A. flavus isolate was extracted and subjected to polymerase chain reaction amplification with five randomic primers through the RAPD (random amplified polymorphic DNA) technique. Phenetic and cladistic analyses of the data, based on bootstrap analyses, led us to conclude that RAPD was not suitable to discriminate toxigenic from non toxigenic strains. But the present results support the use of RAPD for strain characterization, especially for preliminary evaluation over extensive collections.

O objetivo do presente trabalho foi estudar os efeitos da aflatoxina B1 (AFB1) sobre as vísceras (fígado, baço e moela) de codornas poedeiras japonesas, em condições de exposição a baixas doses, tendo em vista que são poucos os dados de toxicidade de longa duração nesta espécie. Assim, foram constituídos 4 grupos formados, cada um, por 6 codornas de linhagem comercial, as quais receberam rações contendo AFB1 nas concentrações de 0 (controle), 25, 50 e 100mg.kg-1, durante 168 dias. As aves do grupo 100mg kg_1 apresentaram fígados com peso relativo médio menor (p < 0,05) do que o controle. Alterações histológicas foram constatadas apenas no fígado, sendo que todas as amostras provenientes das codornas intoxicadas apresentaram degeneração vacuolar macrogoticular, sugestivas de metamorfose gordurosa moderada a severa, particularmente nos grupos que receberam ração com os maiores níveis de AFB1 (50 e 100mg.kg-1). A hiperplasia de ductos biliares foi observada somente no grupo alimentado com 100mg.kg-1. Os resultados indicaram que a AFB1, a partir de 50mg.kg-1, pode ocasionar lesões hepáticas significativas em codornas de postura, em condições de exposição prolongada.

The aim of the present record was to study the effects of aflatoxin B1 (AFB1) on selected viscera (liver, spleen and gizzard) of laying Japanese quail under conditions of low level exposure, in view of the little information regarding the long term toxicity on this specie. Thus, four experimental groups of six commercial quails were constituted and given rations containing either 0 (controls), 25, 50 or 100mg aflatoxin B1 (AFB1)/kg feed, during 168 days. When compared to controls, birds from group 100mg.kg-1 presented low relative liver weight (p < 0.05). Histological changes were observed only in the livers, and all samples from quail exposed to AFB1 revealed moderate to severe hepatic cell vacuolation with fatty change, particularly in birds from groups receiving highest levels of toxin (50 and 100mg.kg-1). Bile duct hyperplasia occurred only in the birds exposed to 100mg.kg-1 of AFB1. The results indicated that long term administration of AFB1 at levels above 50mg.kg-1 can cause significant hepatic lesions in Japanese quail.