家蚕蛹变态期丝腺组织的退化与细胞凋亡特征

利用形态学观察方法、分子生物学检测方法以及20-羟基蜕皮酮(20-hydroxyecdysone)和放线菌酮(cycloheximide)体外培养方法, 研究了家蚕Bombyx mori 蛹变态期丝腺组织的退化与细胞凋亡特征。显微镜的观察显示家蚕丝腺的逐渐退化发生在吐丝期间。DNA梯度电泳的分析表明程序性细胞死亡(programmed cell death)可能伴随发生在丝腺的退化过程中。在离体培养条件下, 用20-羟基蜕皮酮处理5龄第6天幼虫的丝腺, 导致的细胞凋亡提前于对照, 提示在进入蛹变态期前, 20-羟基蜕皮酮提早激发了介导家蚕丝腺细胞凋亡与水解机制的遗传调控级联系统。上述结果表明, 20-羟基蜕皮酮能够诱导家蚕丝腺组织在蛹变态期发生程序性细胞死亡。

Characteristics of degeneration and apoptosis of silk gland during the larval-pupal metamorphosis in the silkworm, Bombyx mori

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.