The Use of Tadpoles of Bufo melanostictus (Schneider) Rhacophorus leucomystax maculatus (Gray) and Uperodon sp. in the Bioassay of Aflatoxins

摘要

Aflatoxins have been found to be lethal to tadpoles of Bufo melanostictus (Schneider), Rhacophorus leucomystax maculatus (Gray) and Uperodon sp. Pathological changes consisting of cytoplasmic vacuolation, enlargement and increased vesicularity of nucleii, and foci of necrosis are produced in the liver and kidney of aflatoxin treated larvae. A method is described for the quantitation of aflatoxin based on the lethal response of the tadpoles. The method is cheap, easily handled and provides reproducible and accurate results; the duration of the test is 4 days. The mean LD50 of aflatoxin B1 on 15 mm. Bufo larvae, 20 mm. Rhacophorus and 15 mm. Uperodon larvae were approximately 2·8, 1·6 and 0·5 μg./ml. respectively while the LD50 of aflatoxin G1 on 15 mm. Bufo and 20 mm. Rhacophorus larvae were approximately 12·2 and 9·3 μg./ml. respectively. The sensitivity to aflatoxin decreased with increase of size of the larvae. Retardation of growth and delay in metamorphosis have been observed in aflatoxin treated larvae.The applicability of this method to the assay of aflatoxins in crude extracts of foodstuffs is being investigated.