Effect of Cholesterol Supplementation on Lipids: Role of Carboxylesterase in Philosamia ricini during 5th Instar Larval Development

Abstract

Effect of cholesterol on lipid content of Eri silkworm Philosamia ricini was investigated by spray supplementing cholesterol at 1mg/ml in their diet. The biochemical changes in the hemolymph and fat body of Eri silkworm Philosamia ricini larvae, as a result of cholesterol
supplementation showed initially sudden 10-fold increase in hemolymph lipid and decrease in fat body lipid in 5th instar first day larvae. Lipid content in fat body found to be increased 2-3 times in 5th instar third and fifth day larvae. A significant change was also observed in neutral, polar and non-polar lipids. Cholesterol is accumulated in fat body as a neutral lipid due to dietary cholesterol. Results done on TLC of neutral lipid component showed that cholesterol was present in low level on the 3rd and 5th day of larval hemolymph as compared to fat body cholesterol. Carboxylesterase activity decreased gradually in early 5th instar to late 5th instar larvae due to cholesterol supplementation. The enzyme activity appears to be associated with reducing juvenile hormone titer during metamorphosis and mobilization and energetic catabolism of fat substance.