Raybould Alan, Burns Andrea, Hamer Mick
a Syngenta ; Jealott's Hill International Research Center ; Bracknell , Berkshire , UK.
GM Crops Food. 2014;5(4):296-301. doi: 10.4161/21645698.2014.950540.
Laboratory testing for possible adverse effects of insecticidal proteins on non-target organisms (NTOs) is an important part of many ecological risk assessments for regulatory decision-making about the cultivation of insect-resistant genetically modified (IRGM) crops. To increase confidence in the risk assessments, regulatory guidelines for effects testing specify that representative surrogate species for NTOs are exposed to concentrations of insecticidal proteins that are in excess of worst-case predicted exposures in the field. High concentrations in effects tests are achieved by using protein test substances produced in microbes, such as Escherichia coli. In a study that exposed Daphnia magna to a single high concentration of a microbial test substance containing Vip3Aa20, the insecticidal protein in MIR162 maize, small reductions in growth were observed. These effects were surprising as many other studies strongly suggest that the activity of Vip3Aa20 is limited to Lepidoptera. A plausible explanation for the effect on growth is that high concentrations of test substance have a non-toxic effect on Daphnia, perhaps by reducing its feeding rate. A follow-up study tested that hypothesis by exposing D. magna to several concentrations of Vip3Aa20, and a high concentration of a non-toxic protein, bovine serum albumin (BSA). Vip3Aa20 and BSA had sporadic effects on the reproduction and growth of D. magna. The pattern of the effects suggests that they result from non-toxic effects of high concentrations of protein, and not from toxicity. The implications of these results for regulatory NTO effects testing and ERA of IRGM crops are discussed.
检测杀虫蛋白对非靶标生物（NTOs）可能产生的不利影响，是许多生态风险评估的重要组成部分，这些评估用于就抗虫转基因（IRGM）作物种植进行监管决策。为了增强对风险评估的信心，效应测试的监管指南规定，将NTOs的代表性替代物种暴露于超过田间最坏情况预测暴露浓度的杀虫蛋白浓度下。效应测试中的高浓度是通过使用微生物（如大肠杆菌）产生的蛋白质测试物质来实现的。在一项将大型溞暴露于单一高浓度含MIR162玉米杀虫蛋白Vip3Aa20的微生物测试物质的研究中，观察到生长有小幅下降。这些效应令人惊讶，因为许多其他研究强烈表明Vip3Aa20的活性仅限于鳞翅目。对生长产生影响的一个合理的解释是，高浓度的测试物质对大型溞有非毒性作用，可能是通过降低其摄食率。一项后续研究通过将大型溞暴露于几种浓度的Vip3Aa20和高浓度的无毒蛋白牛血清白蛋白（BSA）来验证这一假设。Vip3Aa20和BSA对大型溞的繁殖和生长有零星的影响。这些效应模式表明，它们是由高浓度蛋白质的非毒性作用导致的，而非毒性作用。本文讨论了这些结果对IRGM作物监管NTO效应测试和环境风险评估的影响。
