Metabolism of hydrogen peroxide in univoltine and polyvoltine strains of silkworm (Bombyx mori).

Recent work has demonstrated that hydrogen peroxide functions as a signaling molecule controlling different essential processes in plants and mammals, which can be produced by superoxide dismutase (SOD) and xanthine oxidase (XO) and decomposed by catalase (CAT), respectively. Progeny diapause of the silkworm, Bombyx mori, is induced by diapause hormone (DH) and the expression of DH gene in the maternal generation has been determined. In order to investigate the relationship between the metabolism of H(2)O(2) and the expression of DH gene, level of H(2)O(2) and activities of SOD, XO and CAT between univoltine and polyvoltine strains, which can produce diapause and non-diapause eggs, respectively, at embryonic and pupal stages were measured. Our results showed that there were significant differences in the metabolism of hydrogen peroxide between two strains and between embryonic and pupal stages. Compared to polyvoltine strain, level of hydrogen peroxide in univoltine strain was significantly higher from stage 19 to stage 21 but lower from stage 24 to stage 29 and the whole pupal stage (Fig. 1). Variations of hydrogen peroxide indicated that hydrogen peroxide may be involved in the active release of DH and the progeny diapause decision by DH rather than the expression of DH gene.