不同家蚕品种与野桑蚕大龄期幼虫血淋巴和体壁中的多酚氧化酶活性检测分析

Analysis of Polyphenol Oxidase Activity in Hemolymph and Integument During Late Developmental Stage of Different Bombyx mori Varieties and Bombyx mandarina Larvae

多酚氧化酶(PPO)在昆虫的变态发育和免疫防御中有重要作用。选择菁松、黑缟和大造3个家蚕品种及来自桑园的野桑蚕作供试昆虫,以其担负免疫功能的血淋巴和作为免疫屏障的体壁组织为材料,测定与分析家蚕、野桑蚕幼虫大龄期及化蛹前血淋巴和体壁中的PPO活性变化。3个家蚕品种幼虫血淋巴中的PPO活性由高到低依次为菁松、黑缟、大造,体壁中的PPO活性由高到低依次为大造、黑缟、菁松。野桑蚕幼虫不论是血淋巴还是体壁,其PPO活性均低于家蚕,其中血淋巴的PPO活性显著低于家蚕。家蚕幼虫血淋巴的PPO活性在整个5龄期都较高,体壁的PPO活性则是在5龄中后期和上蔟期较高。野桑蚕幼虫血淋巴的PPO活性在5龄中期较高,体壁的PPO活性则是在5龄末期较高。另外发现2个供试家蚕品种幼虫血淋巴和体壁间的PPO活性变化呈完全相反的情况:菁松的幼虫是血淋巴中的PPO活性较高,体壁中的PPO活性较低;大造的幼虫是血淋巴中的PPO活性较低,而体壁中的PPO活性较高。上述结果提示:家蚕、野桑蚕幼虫的PPO活性变化具有明显的发育时期和组织特异性,且家蚕的PPO活性高于野桑蚕,家蚕品种间的PPO活性的组织差异性也不尽相同。这些结果为研究家蚕蜕皮变态过程中的体壁形成和先天免疫功能等提供了新的信息。

Polyphenol oxidase （PPQ） plays an important role in metamorphosis and immune defense of insects. Three domestic silkworm （ Bombyx mori） varieties named Jingsong, Heigao and Dazao and one wild silkworm （ Bombyx man- darina） collected from mulberry field were chosen as test insects for measuring and analyzing change of PPO activity in hemolymph （which bears immune function） and integument （which acts as immune barrier） at late developmental stageof larvae and transient stage of larva to pupa. The results showed that, among the three domestic silkworm varie- ties, PPO activity in hemolymph was the highest in Jing- song, the second in Heigao and the lowest in Dazao. PP~ activity in integument was the highest in Dazao, the second in Heigao and the lowest in Jingsong. PPO activity in both hemolymph and integument of the wild silkwormwas lower than that of the domestic silkworm, among which PPO activity in hemolymph of wild silkworm was significantly lower than that in domestic silkworm. PPO in hemolymph of domestic silkworm had higher activity during the whole 5th in- star, while PPO in integument had higher activity during the middle and late stages of the 5th instar and during the mounting stage. PPO in hemolymph of wild silkworm had a higher activity at the middle stage of the 5th instar, and PPO in integument had a higher activity at the end of the 5th instar. In addition, PPO activity in hemolymph and integument of two domestic silkworm varieties showed a reverse relationship. PPO activity was higher in hemolymph but lower in integu- ment of Jingsong larvae, whereas PPO activity was lower in hemolymph but higher in integument of Dazao larvae. The above results suggest that PPO activity in larvae of domestic silkworm and wild silkworm varies obviously with develop- mental period and tissue. Moreover, PPO activity of domestic silkworm is higher than that of wild silkworm, and PPO ac- tivity in different varieties of domestic silkworm also varies. These results provide new references for exploring mechanisms of integument formation and innate immune function during metamorphosis of silkworm.