关键词: 家蚕, 变态, 细胞凋亡, 程序性细胞死亡, 20-羟基蜕皮酮

Abstract:

The characteristics of degeneration and apoptosis of silk glands, during the larval-pupal metamorphosis in the silkworm, Bombyx mori were studied by the general morphological observation, the molecular methods, and in vitro cultivation with 20-hydroxyecdysone and cycloheximide. The microscopic observation showed that silk gland degeneration gradually occurred during the spinning period. Analysis using DNA ladder electrophoresis indicated that programmed cell death might be involved in gland degeneration. In vitro incubation of silk glands from larvae of  day 6 of the last instar  with 20-hydroxyecdysone showed an accelerated apoptosis as compared with those in controls, indicating that the pulses of 20-hydroxyecdysone before larval-pupal metamorphosis trigger genetic regulatory hierarchies that mediate apoptosis and hydrolysis.  From these results, it was concluded that molting hormone 20-hydroxyecdysone could turn on programmed cell death of the silk gland during larval-pupal metamorphosis.

Key words: Bombyx mori, metamorphosis, apoptosis, programmed cell death, 20_hydroxyecdysone