SPHINGOLIPID LEVELS IN CATFISH CONSUMING FUSARIUM-MONILIFORME CORN CULTURE MATERIAL CONTAINING FUMONISINS

Fumonisin, a secondary metabolite of Fusarium moniliforme, is frequently found in foods and feeds of humans and animals. Fumonisins are specific inhibitors of sphinganine (sphingosine) N-acyltransferase, a key enzyme in the pathway for de novo sphingolipid biosynthesis and reacylation of sphingosine derived from dietary sources or complex sphingolipid turnover. The objective of this study was to evaluate the effect of F. moniliforme toxins on sphingolipids in year-2 channel catfish. In a 12-week feeding trial, four groups of catfish per treatment were fed pelleted balanced diets containing F. moniliforme cultured corn. The fumonisin B-1 (FB1) concentrations in diets were 0.3 (control), 2.5, 5, 10, 20, 40, 80 and 240 mg/kg. The free sphinganine to free sphingosine ratio was significantly (P < 0.05) elevated (with exception of brain) at 10, 20, 40 and 80 mg FB, per kg diet in kidney, serum, liver and muscle, respectively. The increase in free sphingolipid ratios observed were found to be due to increases in the levels of free sphinganine in tissues. These results demonstrate that a mode of action of F. moniliforme toxins in catfish is similar to other species (ponies, pigs, rats), and is suggestive of fumonisin toxicity. It also demonstrated the potential diagnostic value of ratios of free sphingolipids in catfish.