Fumio Mukaiyama

Relationship between protein content of diets and xanthine oxidase activity in the silkworm, Bombyx mori L.

The interrelationship between the quantity of dietary protein and the xanthine oxidase activity of larval tissues of the silkworm, Bombyx mori L., was investigated. The enzyme activity of fat body, midgut, and Malpighian tubes increased with an increase in the level of dietary soybean meal. Furthermore, production (excretion) of uric acid by larvae increased on a high-protein diet.

Amylase of digestive juice and utilization of dextrin and starch in the silkworm, Bombyx mori L.

Abstract Larvae of the silkworm, Bombyx mori L., were examined for their ability to utilize dextrin and starch in relation to the presence or absence of the amylase of digestive juice, according to races. Normal larvae possessing high amylase activity showed a marked increase in total blood sugar, blood trehalose, and fat body glycogen after oral administration of either dextrin or starch, whereas no increase occurred in mutant races virtually free from amylase. However, when amylase-free larvae were fed mulberry leaves, blood sugars and fat body glycogen were synthesized. Oral administration of starch prolonged the survival period of normal larvae, whereas little or no effect was observed in amylase-free larvae. Utilization of polysaccharides in both normal and amylase-free larvae is discussed in relation to the nutritive values of carbohydrates.