Zhao Zhuoya, Li Yunhe, Xiao Yutao, Ali Abid, Dhiloo Khalid Hussain, Chen Wenbo, Wu Kongming
The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China.
Department of Entomology, University of Agriculture, Faisalabad 38000, Pakistan.
Toxins (Basel). 2016 Jul 7;8(7):212. doi: 10.3390/toxins8070212.
Crystal (Cry) proteins derived from Bacillus thuringiensis (Bt) have been widely used in transgenic crops due to their toxicity against insect pests. However, the distribution and metabolism of these toxins in insect tissues and organs have remained obscure because the target insects do not ingest much toxin. In this study, several Cry1Ac-resistant strains of Helicoverpa armigera, fed artificial diets containing high doses of Cry1Ac toxin, were used to investigate the distribution and metabolism of Cry1Ac in their bodies. Cry1Ac was only detected in larvae, not in pupae or adults. Also, Cry1Ac passed through the midgut into other tissues, such as the hemolymph and fat body, but did not reach the larval integument. Metabolic tests revealed that Cry1Ac degraded most rapidly in the fat body, followed by the hemolymph, peritrophic membrane and its contents. The toxin was metabolized slowly in the midgut, but was degraded in all locations within 48 h. These findings will improve understanding of the functional mechanism of Bt toxins in target insects and the biotransfer and the bioaccumulation of Bt toxins in arthropod food webs in the Bt crop ecosystem.
源自苏云金芽孢杆菌（Bt）的晶体（Cry）蛋白因其对害虫的毒性而被广泛应用于转基因作物中。然而，由于目标昆虫摄入的毒素不多，这些毒素在昆虫组织和器官中的分布及代谢情况仍不清楚。在本研究中，使用了几种对Cry1Ac具有抗性的棉铃虫品系，给它们喂食含有高剂量Cry1Ac毒素的人工饲料，以研究Cry1Ac在其体内的分布和代谢情况。仅在幼虫中检测到Cry1Ac，在蛹或成虫中未检测到。此外，Cry1Ac从中肠进入其他组织，如血淋巴和脂肪体，但未到达幼虫体表。代谢测试表明，Cry1Ac在脂肪体中降解最快，其次是血淋巴、围食膜及其内容物。该毒素在中肠中代谢缓慢，但在48小时内会在所有部位降解。这些发现将增进对Bt毒素在目标昆虫中的功能机制以及Bt毒素在Bt作物生态系统节肢动物食物网中的生物转移和生物积累的理解。
