Effects of the levels of fatty acids and carbohydrates in a diet on the biosynthesis of fatty acids in larvae of the silkworm, Bombyx mori

Abstract

The effects of varying levels of fatty acids and carbohydrates in the diet on fatty acid synthesis from glucose in the larvae of the silkworm, Bombyx mori, were investigated. Elevation of the level of dietary fatty acids resulted in the decrease of the rate of fatty acid synthesis in the larvae. The addition of palmitate, stearate, or oleate to a diet had an inhibitory effect on fatty acid synthesis. The prolonged feeding of larvae on a diet containing a high level of fatty acid intensified the depression of the synthesis. The inhibitory effect of dietary fatty acid was found in the presence of both high and low levels of dietary carbohydrates. On the other hand, the rate of fatty acid synthesis was greatly accelerated by increasing the level of sucrose in a diet but not by the addition of starch. Furthermore, the fatty acid composition of the larval tissue shows a marked difference between the two groups of larvae fed on a diet containing sucrose and on a diet containing potato starch. Palmitic and oleic acid contents of larval tissue were increased significantly on the sucrose diet. It is thus evident that the rate of fatty acid synthesis in the silkworm is regulated by the dietary levels of fatty acids and carbohydrates.