Sensitivity of transketolase to the thiamin status of juvenile marine shrimp ( Penaeus monodon)

Abstract

Muscle, hemolymph and hepatopancreas transketolase activities and their thiamin pyrophosphate (TPP) effects were assessed for their potential to determine the thiamin status of juvenile Penaeus monodon after a 9-week feeding trial. Transketolase activity increased in response to increasing thiamin supplementation, while TPP effects decreased with increasing dietary thiamin levels. The TPP effect showed a significant increment when the dietary thiamin was reduced from 20 mg/kg diet to no supplement. Thiamin requirement assessed by TPP effect as the criterion was lower than that by transketolase activity; the thiamin requirement estimated by the TPP effect of the muscle (13.3 mg/kg) and hemolymph (18.3 mg/kg) was similar to that of the growth results (12.9 mg/km). These data suggest that, like vertebrates, measurement of the TPP effect in the tissues of the marine crustacean is a more sensitive indicator of thiamin status than measurement of transketolase activity. Among all criteria examined, the hemolymph TPP effect was the most sensitive and specific indicator of thiamin status.