a The Bioscience Resource Project , Ithaca , NY , USA.
b Independent Scholar , Victoria , Australia.
Biotechnol Genet Eng Rev. 2017 Apr;33(1):62-96. doi: 10.1080/02648725.2017.1357295. Epub 2017 Sep 13.
The Cry toxins are a family of crystal-forming proteins produced by the bacterium Bacillus thuringiensis. Their mode of action is thought to be to create pores that disrupt the gut epithelial membranes of juvenile insects. These pores allow pathogen entry into the hemocoel, thereby killing the insect. Genes encoding a spectrum of Cry toxins, including Cry mutants, Cry chimaeras and other Cry derivatives, are used commercially to enhance insect resistance in genetically modified (GM) crops. In most countries of the world, such GM crops are regulated and must be assessed for human and environmental safety. However, such risk assessments often do not test the GM crop or its tissues directly. Instead, assessments rely primarily on historical information from naturally occurring Cry proteins and on data collected on Cry proteins (called 'surrogates') purified from laboratory strains of bacteria engineered to express Cry protein. However, neither surrogates nor naturally occurring Cry proteins are identical to the proteins to which humans or other nontarget organisms are exposed by the production and consumption of GM plants. To-date there has been no systematic survey of these differences. This review fills this knowledge gap with respect to the most commonly grown GM Cry-containing crops approved for international use. Having described the specific differences between natural, surrogate and GM Cry proteins this review assesses these differences for their potential to undermine the reliability of risk assessments. Lastly, we make specific recommendations for improving risk assessments.
Cry 毒素是一种由苏云金芽孢杆菌产生的晶体形成蛋白家族。其作用模式被认为是形成孔，破坏幼年昆虫的肠道上皮膜。这些孔允许病原体进入血腔，从而杀死昆虫。编码一系列 Cry 毒素的基因，包括 Cry 突变体、Cry 嵌合体和其他 Cry 衍生物，被商业用于增强转基因（GM）作物的昆虫抗性。在世界上大多数国家，此类 GM 作物受到监管，必须对其人类和环境安全性进行评估。然而，此类风险评估通常不会直接测试 GM 作物或其组织。相反，评估主要依赖于天然 Cry 蛋白的历史信息和从工程化表达 Cry 蛋白的实验室菌株中纯化的 Cry 蛋白（称为“替代物”）收集的数据。然而，替代物和天然 Cry 蛋白都与人类或其他非目标生物体通过生产和消费 GM 植物所接触的蛋白质不同。迄今为止，尚未对这些差异进行系统调查。本综述填补了有关国际上批准使用的最常见 GM Cry 含作物的这一知识空白。在描述了天然、替代物和 GM Cry 蛋白之间的具体差异后，本综述评估了这些差异对降低风险评估可靠性的潜在影响。最后，我们提出了具体建议以改进风险评估。
