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1 December 1999 Comparative Studies of Ecdysteroid Metabolism between Diapause Eggs and Non-diapause Eggs of the Silkworm, Bombyx mori
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Abstract

2, 22, 25-Trideoxyecdysone (5β-ketodiol) has been shown to be derived from cholesterol in eggs of the silkworm, Bombyx mori. In order to investigate the difference in ecdysteroid metabolism between diapause eggs and non-diapause eggs of the silkworm, 3H-5β-ketodiol was microinjected into eggs at several stages of early embryogenesis, and the metabolites were characterized using high-performance liquid chromatography. The injected 3H-5β-ketodiol was metabolized not only to free ecdysteroids, but also to conjugates (phosphoric esters of ecdysteroids), in both diapause eggs and non-diapause eggs. Among these metabolites, 20-hydroxyecdysone, which is considered as the active hormone in silkworm eggs, was detected in non-diapause eggs. However, in diapause eggs, various radioactive putative precursors of 20-hydroxyecdysone, such as 2, 22-dideoxyecdysone, 2-deoxyecdysone and ecdysone, were detectable, but 3H-20-hydroxyecdysone was not found. These results suggest that the 20-hydroxylation of ecdysone, which is catalyzed by ecdysone 20-monooxygenase, may be a rate-limiting step in the formation of 20-hydroxyecdysone from ketodiol in the silkworm eggs.

Haruyuki Sonobe, Hideki Tokushige, Toshihiro Makka, Hibiki Tsutsumi, Noriyuki Hara, and Yoshinori Fujimoto "Comparative Studies of Ecdysteroid Metabolism between Diapause Eggs and Non-diapause Eggs of the Silkworm, Bombyx mori," Zoological Science 16(6), (1 December 1999). https://doi.org/10.2108/zsj.16.935
Received: 14 April 1999; Accepted: 1 June 1999; Published: 1 December 1999
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