The effect of calorie restriction on growth and development in silkworm, Bombyx mori.

Caloric restriction (CR) is known to extend the life span in different species from yeast to mammals. In this report, a simple organism silkworm (Bombyx mori) was used to study the effect of moderate CR on the growth and development processes of insects. Here we show that an extension of life span upon moderate CR was observed in the silkworm. The total protein level in the 5th instar larvae hemolymph appeared to decline significantly under CR. SDS-PAGE analysis showed that the influence of CR was sex-dependent. The CR effects on female animals were much more significant than on the males. The MALDI-TOF MS study identified 16 proteins that expressed differentially among six groups of the male or female larvae fed at different time frequencies. Four of them, storage protein 1 (SP1), arylphorin (SP2), imaginal disk growth factor (IDGF), and 30-kDa lipoprotein, showed significant differences. It was demonstrated that these four proteins were up-regulated when the larvae were over-fed and down-regulated when the larvae were less-fed.