Changes of triglyceride and glycogen content in the silkworm ( Bombyx mori) eggs during diapause and embryogenesis

Abstract

1. 1. In diapause eggs of the silkworm glycogen content decreased with the onset of diapause and reached a minimum level, and increased again when the diapause was terminated by prolonged chilling. 2. 2. The triglyceride (TG) content gradually decreased during the pre-diapause and diapause period, about 10% of the initial amount having been lost up to the termination. 3. 3. During embryogenesis the glycogen content gradually decreased for 5–6 days after oviposition, then there was a rapid decrease until the day of hatching. 4. 4. In natural, non-diapause eggs and post-diapause eggs which were activated by chilling TG content decreased from day 3 after oviposition to about 40% of the initial amount on the day of hatching. 5. 5. On the other hand, in artificial, non-diapause eggs (which were obtained by HCl treatment of diapause eggs) TG content decreased from day 5, only 20% of TG being depleted up to hatching. 6. 6. In all silkworm eggs, the respiratory quotient values were close to 1.0 during the early and middle stage of embryogenesis, after which they all decreased to about 0.8. 7. 7. These observations show early preferential utilization of carbohydrates and following concomitant consumption of TG in late stage.