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为了明确Cry2Ab杀虫蛋白的作用机制,利用透射电镜观察了棉铃虫Helicoverpa armigera(Hübner)3龄末幼虫取食含Cry2Ab蛋白(8μg/g)饲料后中肠的组织病理变化,并与分别取食含Cry1Ac蛋白(0.97μg/g)饲料和正常饲料的棉铃虫进行了比较。结果表明:棉铃虫取食Cry2Ab蛋白后中肠细胞及其细胞器均发生了明显的病变,主要表现为:中肠杯状细胞的杯腔肿胀或拉长,部分柱状细胞被杯状细胞挤压出来,微绒毛脱落,细胞核皱缩,质膜和核膜不清晰,染色质凝聚,线粒体拉伸变形,内质网肿胀断裂;并且随着取食时间的延长病变越来越明显。与取食Cry1Ac蛋白的棉铃虫相比,Cry2Ab引起棉铃虫中肠组织发生病变的速度较慢。本研究可为Cry2Ab作为转基因棉花的重要杀虫蛋白在将来更好地发挥作用提供理论依据。
In order to clarify the mechanism of action of Cry2Ab insecticidal protein, the histopathological changes of midgut of 3rd instar larvae of Helicoverpa armigera (Hübner) fed with Cry2Ab protein (8μg / g) were observed by transmission electron microscopy. Cotton bollworms containing Cry1Ac protein (0.97 μg / g) and normal diet were compared. The results showed that there were obvious lesions of midgut cells and organelles after Cry2Ab protein in the cotton bollworm. The main manifestations were as follows: the cup cavity of goblet cells swollen or elongated, some of the columnar cells were extruded by goblet cells , Microvilli shedding, nuclear shrinkage, unclear plasma membrane and nuclear membrane, chromatin condensation, mitochondrial tensile deformation, endoplasmic reticulum swelling and rupture; and with the extension of feeding time lesions become more apparent. Compared with the H. armigera which ingested Cry1Ac protein, Cry2Ab caused lesser lesions in the midgut tissues of H. armigera. This study may provide a theoretical basis for Cry2Ab as an important insecticidal protein in transgenic cotton to play a better role in the future.