巴西学者科学实发现：转基因Bt对老鼠血液有毒性

Abstract: Formulated and sporulated cultures of Bacillus thuringiensis (Bt) have been widely used against insect pests, but after the advent of genetically modified plants expressing δ-endotoxins, the bioavailability of Cry proteins has been increased. For biosafety reasons their adverse effects should be studied, mainly for non-target organisms. Thus, we evaluated, in Swiss albino mice, the hematotoxicity and genotoxicity of four Bt spore-crystals genetically modified to express individually Cry1Aa, Cry1Ab, Cry1Ac, or Cry2A, administered alone by gavage with a single dose of 27 mg/ Kg, 136 mg/Kg or 270 mg/Kg, 24 h, 72 h or 7 days before euthanasia. Binary combinations of these four spore-crystal proteins were also assayed at 270 mg/Kg with a single administration 24 h before euthanasia. Control mice received filtered water or cyclophosphamide at 27 mg/kg. For hematotoxicity evaluations, blood samples were drawn by cardiac puncture and processed in a multiple automated hematology analyzer; for genotoxicity analyses, micronucleus test was carried out in mice bone marrow cells. Spore-crystal administrations provoked selective hematotoxicity for the 3 exposure times, particularly for erythroid lineage. A significant reduction in bone marrow cell proliferation demonstrated cytotoxic but not genotoxic effects. These effects persisted for all exposure times, becoming more evident at 7 days. Similar results were observed for binary combinations at 24 h, suggesting that further studies are required to clarify the mechanism involved in the hematotoxicity found in mice, and to establish the toxicological risks to non-target organisms, especially mammals, before concluding that these microbiological control agents are safe for mammals.

摘要：苏云金杆菌（Bt）的配方的与孢子培养液一直广泛用于治理害虫，但是，表达Bt毒素的转基因作物出现以后，Cry蛋白的生物可获得性增加了。为生物安全理由，应当对它们的负面影响，特别对于非靶生物，进行研究。为此，我们在瑞士albino小鼠中，单剂各自表达的四种Cry1Aa、Cry1Ab、Cry1Ac或者Cry2A的转基因Bt孢子晶体的血液毒性与基因毒性进行了评价。服用方式：安乐死前24小时、72小时、7天强饲单剂，比较实验用浓度为27 mg/ Kg、136 mg/Kg或者270 mg/Kg。对这四种孢子晶体的双体也进行了实验，服用方式：安乐死前24小时单剂。对照小鼠喂养过滤水或者环磷酰胺，27 mg/ Kg。为血液毒性评价，用心脏穿刺取血样，在多单元自动血液分析仪中处理；为基因毒性分析，对小鼠骨髓细胞进行了微核试验。服用孢子晶体对三次接触时间激发了有选择性血液毒性，特别对红血球。骨髓细胞增殖显著下降演示了细胞毒素而不是基因毒性影响。这些影响在所有接触时间都出现，七天内最为明显。双体试验在24小时观察到类似的结果，提议，在做出这些微生物学控制剂对哺乳动物是安全的结论前，有必要进行进一步的研究以便搞清小鼠中发现的血液毒性的机制，并且确立对哺乳动物等非靶生物的毒理学风险。

论文全文pdf文件： 

http://esciencecentral.org/journals/JHTD/JHTD-1-104.pdf