Metabolism of hydrogen peroxide between diapause and non-diapause eggs of the silkworm, Bombyx mori during chilling at 5 degrees C.

When diapause and non-diapause eggs of the same bivoltine strain of Bombyx mori were chilled at 5 degrees C for more than 30 days, the hatchability of diapause eggs increased while that of non-diapause eggs decreased, respectively. To investigate the relationship between effects of chilling on the hatchability and the metabolism of hydrogen peroxide (H2O2), content of H2O2 and activities of superoxide dismutase (SOD), xanthine oxidase (XO), and catalase (CAT) between diapause and non-diapause eggs were determined during the chilling at 5 degrees C. The significant enhancement of H2O2 occurred prior to the quick increase of the hatchability in diapause eggs and coincided with the quick decline of the hatchability in non-diapause eggs, respectively. Diapause eggs contained significantly higher H2O2 and XO activity and lower CAT activity compared to non-diapause eggs. Our results showed that there were significant differences in the metabolism of H2O2 between diapause and non-diapause eggs during chilling and that significant enhancement of H2O2 may be involved in the diapause termination of diapause eggs and the cell damage of non-diapause eggs.