Hsi-Tang Tung

Altered lipid transport during aflatoxicosis.

The effects of graded doses of dietary aflatoxin (0, 0.625, 1.25, 2.5, 5.0 and 10.0 μg/g) on serum triglyceride fatty acids, serum total phospholipids and serum free and esterified cholesterol were measured in chickens. These classes of lipid were decreased significantly (P < 0.05) by a dose of 0.625 μg/g, and a dose of 2.5 μg/g was required to decrease the growth rate and the ribonucleic acid content of liver. The deoxyribonucleic acid content of liver was unaffected even by 10 μg/g. These data suggest that lipid transport is a primary lesion during aflatoxicosis in the chicken and is not secondary to the general effects on nucleic acid metabolism.

Concentrations of serum proteins during aflatoxicosis

The concentrations of different classes of serum proteins of chickens to graded doses of dietary aflatoxin (0, 0.625, 1.25, 2.5, 5.0, and 10.0 μg/g of diet) were measured using disc gel electrophoresis. Total serum proteins were reduced significantly (p < 0.05) by a dose of 1.25 μg/g or greater. The α-globulins and β-globulins were reduced at levels of 2.5 and 1.25 μg/g, respectively. The IgG component was reduced at 2.5 μg/g while the IgM component was not affected significantly at any level. The prealbumin fraction was reduced at 5 μg/g. The most sensitive component was serum albumin that was decreased significantly at the smallest level and was decreased to the greatest extent at the highest level. Its response curve roughly paralleled that of total serum lipids. Serum lipoproteins were decreased at 1.25 and 2.5 μg/g but not at lower or higher levels. These data can be explained by a hypothesis that aflatoxin or an active metabolite binds randomly to template deoxyribonucleic acid and inhibits the larger transcribing units such as those for serum albumin and lipid before the smaller transcribing units are inhibited.

Depression of fatty acid synthesis in chick liver (Gallus domesticus) by aflatoxin

Abstract 1. 1. Dietary aflatoxin reduced the incorporation of acetate-14C into long-chain fatty acids of chick liver (Gallus domesticus) in a dose-related fashion. 2. 2. Feeding 10 μg of aflatoxin per g of diet for 3 weeks depressed the activities of the microsomal system of fatty acid elongation and fatty acid synthetase in liver. 3. 3. Crystalline aflatoxin did not inhibit fatty acid synthetase in vitro at levels up to 20 μg/ml of incubation medium. 4. 4. It is suggested that aflatoxin exerts its effects on lipogenesis by depressing the formation of the enzymes involved in fatty acid synthesis.