转基因作物的安全性争论及其对策

本文介绍了最近国际上对转基因植物安全性的争论情况,争论的本质并不纯粹是科学问题,而是政治和贸易问题,作者认为中国作为发展中国家应有自己的观点,并提出了相应的对策建议。     

转基因作物的食用与环境安全性问题及其对策

自转基因技术研发和商业化生产以来,针对转基因作物的食用安全性和环境安全性问题一直是公众争论的焦点。面对全球粮食安全形势的严峻压力,如何使公众对转基因技术及其产品的客观性保持一种科学性的认识,是摆在各国(特别是发展中国家)政府和科学家面前不可忽视的课题。本文从食品和环境两个方面简要介绍了转基因作物的安全性问题,旨在还原转基因技术的科学真实性,并简要提出转基因作物的安全性对策。     

转基因植物中外源基因及其表达产物转移的途径

随着转基因植物商品化应用的增多,全面了解转基因植物潜在的生态风险性尤为重要。国内外对“转基因植物中外源基因向野生亲缘物种漂移的可能性”、“昆虫对抗虫转基因植物的耐受性”以及“转基因植物对生物多样性的潜在影响”等问题已进行了广泛研究。对转基因植物中外源基因及其表达产物的几种可能转移途径作了概述。着重介绍了“经花粉散布或与野生亲缘物种杂交等途径引起的外源基因转移”以及“转基因植物对土壤生态系统的影响”等方面的研究情况。此外,还对“鉴定外源基因及其表达产物存在的方法”进行了简要探讨。     

Effects of successive seasons of genetically modified herbicide-tolerant maize cropping on weeds and invertebrates

The use of genetically modified herbicide‐tolerant (GMHT) crops influences the abundance of weeds and some invertebrate groups because the associated herbicide regime contrasts with that of conventional systems. However, it is not clear to what extent these effects might be cumulative; should GMHT crops be grown continuously. In northern Europe, in the near future, this situation is most likely to apply to maize crops. Here, we consider the effects of continuous GMHT maize cropping on plant and invertebrate taxa using a split‐field experiment. Half of each field was managed using GMHT and the other half with a conventional variety, with the treatments retained for two seasons. The treatment effects were broadly consistent with those found in the larger sample of non‐continuous maize sites within the Farm Scale Evaluations. There was little evidence of effects being significantly more pronounced in the second year; any cumulative differences in above‐ground biodiversity between GMHT and conventional cropping were too variable to be readily detected.     

转基因作物与非转基因作物的共存立法动态研究——以美、日、欧应对基因污染事件为视角

随着基因工程技术的运用与发展,越来越多的转基因作物基因污染事件的发生也引起了世界各国对转基因作物与非转基因作物之间的和谐发展问题的高度重视。以美、日、欧为代表,世界各国对转基因作物与非转基因作物的共存问题都进行了积极地探索。借鉴美、日、欧转基因与非转基因作物共存法律制度,以期为我国转基因与非转基因作物共存法律制度的构建提供参考。     

转基因抗虫作物对捕食性瓢虫的安全性研究进展

转基因抗虫作物的商业化种植带来了显著的经济、生态和社会效益,对转基因抗虫作物的安全性评价也一直是国内外学者研究的热点。对生物非靶标效应的研究是转基因抗虫作物安全性评价的重要组成部分,农田天敌类生物是其中的重点内容之一。瓢虫是农田生态系统重要的捕食性天敌,评价其在转基因抗虫作物田间是否能通过捕食猎物或取食花粉而接触到杀虫蛋白并富集于体内,进而对自身产生一定的非靶标效应,这对捕食性瓢虫的安全性研究具有重要的意义。本文从捕食性天敌瓢虫的生命表参数、行为功能参数、田间群落参数及体内微环境指标等方面综述了转基因抗虫作物对瓢虫的安全性研究进展,并对后期转基因抗虫作物对田间捕食性天敌的研究方向提出了建议,以期为转基因抗虫作物的环境安全性研究提供理论指导和为进一步完善转基因抗虫作物对瓢虫安全性评价的技术体系提供系统的数据资料。     

“Gene-fouled or gene-improved?” Media framing of GM crops and food in Hungary

This paper presents results from a research which analyzed the reporting on genetically modified crops and food in the Hungarian tabloids and political papers with the highest circulation from 1 May 2007 to 31 October 2009. Both quantitative and qualitative media analysis was conducted. It was found that in contrast to some Western countries the issue had low salience in the investigated period; it featured especially marginally in the tabloids. Two distinct valenced frames could be differentiated: a dominant ANTI-GM (Threat) frame – which was particularly frequent compared to what has been found for some other countries, and a minority PRO-GM (Advancement and Benefits) frame. Despite a range of similarities with what had been reported by previous research from some other countries, argumentation on the GMO topic in the Hungarian press had several distinct characteristics, one of which was the relative prominence of economic arguments against the technology.     

Field trials and tribulations--making sense of the regulations for experimental field trials of transgenic crops in Europe

Transgenic plants that are being developed for commercial cultivation must be tested under field conditions to monitor their effects on surrounding wildlife and conventional crops. Developers also use this opportunity to evaluate the performance of transgenic crops in a typical environment, although this is a matter of commercial necessity rather than regulatory compliance. Most countries have adapted existing regulations or developed new ones to deal specifically with transgenic crops and their commodities. The European Union (EU) is renowned, or perhaps notorious, for having the broadest and most stringent regulations governing such field trials in the world. This reflects its nominal adherence to the precautionary approach, which assumes all transgenic crops carry an inherent risk. Therefore, field trials in the EU need to demonstrate that the risk associated with deploying a transgenic crop has been reduced to the level where it is regarded as acceptable within the narrowly defined limits of the regulations developed and enforced (albeit inconsistently) by national and regional governments, that is, that there is no greater risk than growing an equivalent conventional crop. The involvement of national and regional competent authorities in the decision-making process can add multiple layers of bureaucracy to an already-intricate process. In this review, we use country-based case studies to show how the EU, national and regional regulations are implemented, and we propose strategies that could increase the efficiency of regulation without burdening developers with further unnecessary bureaucracy.     

Stable expression of Gal/GalNAc lectin of Entamoeba histolytica in transgenic chloroplasts and immunogenicity in mice towards vaccine development for amoebiasis

Chloroplast genetic engineering offers several advantages, including high levels of transgene expression, transgene containment via maternal inheritance and multigene engineering in a single transformation event. Entamoeba histolytica infects 50 million people, causing about 100 000 deaths annually, but there is no approved vaccine against this pathogen. LecA , a potential target for blocking amoebiasis, was expressed for the first time in transgenic plants. Stable transgene integration into chloroplast genomes and homoplasmy were confirmed by polymerase chain reaction and Southern blot analyses. LecA expression was evaluated by Western blots and quantified by enzyme-linked immunosorbent assay (up to 6.3% of total soluble protein or 2.3 mg LecA/g leaf tissue). Subcutaneous immunization of mice with crude extract of transgenic leaves resulted in higher immunoglobulin G titres (up to 1 : 10 000) than in previous reports. An average yield of 24 mg of LecA per plant should produce 29 million doses of vaccine antigen per acre of transgenic plants. Such high levels of expression and immunogenicity should facilitate the development of a less expensive amoebiasis vaccine.     

Refuges in reverse: the spread of Bacillus thuringiensis resistance to unselected greenhouse populations of cabbage loopers Trichoplusia ni

1 The dispersal of susceptible insects between refuges and Bacillus thuringiensis (Bt) treated fields is the key to resistance management of Bt crops. Here we describe the opposite situation; the movement of Bt resistant Trichoplusia ni moths from over‐wintered, greenhouse populations in British Columbia (BC) exposed to high Bt use to neighbouring greenhouses where Bt sprays have not been used. 2 The spread of Bt resistance to non‐selected populations of T. ni, and the resulting increase in resistance, indicates a surprising level of dispersal of resistant moths among greenhouses even in the face of fitness costs. 3 Field populations of T. ni in BC are seasonal migrants from regions of California where Bt cotton is grown. In 2006, field populations surveyed along the migration path from California through Oregon were highly susceptible to Bt insecticides and, thus, showed no indication of selection for resistance among these source populations. 4 The arrival of the immigrant moths provides a potential source of susceptible individuals to dilute the levels of resistance in greenhouse populations in BC later in the summer, but this has not occurred. Thus, field populations in BC do not appear to serve as refuges to combat Bt resistance in greenhouse populations.     

Stable transformation of the cotton plastid genome and maternal inheritance of transgenes

Chloroplast genetic engineering overcomes concerns of gene containment, low levels of transgene expression, gene silencing, positional and pleiotropic effects or presence of vector sequences in transformed genomes. Several therapeutic proteins and agronomic traits have been highly expressed via the tobacco chloroplast genome but extending this concept to important crops has been a major challenge; lack of 100 homologous species-specific chloroplast transformation vectors containing suitable selectable markers, ability to regulate transgene expression in developing plastids and inadequate tissue culture systems via somatic embryogenesis are major challenges. We employed a Double Gene/Single Selection (DGSS) plastid transformation vector that harbors two selectable marker genes (aphA-6 and nptII) to detoxify the same antibiotic by two enzymes, irrespective of the type of tissues or plastids; by combining this with an efficient regeneration system via somatic embryogenesis, cotton plastid transformation was achieved for the first time. The DGSS transformation vector is at least 8-fold (1 event/2.4 bombarded plates) more efficient than Single Gene/Single Selection (SGSS) vector (aphA-6; 1 event per 20 bombarded plates). Chloroplast transgenic lines were fertile, flowered and set seeds similar to untransformed plants. Transgenes stably integrated into the cotton chloroplast genome were maternally inherited and were not transmitted via pollen when out-crossed with untransformed female plants. Cotton is one of the most important genetically modified crops ($ 120 billion US annual economy). Successful transformation of the chloroplast genome should address concerns about transgene escape, insects developing resistance, inadequate insect control and promote public acceptance of genetically modified cotton.     

The role of biotechnology for agricultural sustainability in Africa

Sub-Saharan Africa could have a shortfall of nearly 90Mt of cereals by the year 2025 if current agricultural practices are maintained. Biotechnology is one of the ways to improve agricultural production. Insect-resistant varieties of maize and cotton suitable for the subcontinent have been identified as already having a significant impact. Virus-resistant crops are under development. These include maize resistant to the African endemic maize streak virus and cassava resistant to African cassava mosaic virus. Parasitic weeds such as Striga attack the roots of crops such as maize, millet, sorghum and upland rice. Field trials in Kenya using a variety of maize resistant to a herbicide have proven very successful. Drought-tolerant crops are also under development as are improved varieties of local African crops such as bananas, cassava, sorghum and sweet potatoes.     

Bt水稻秸秆还田对赤子爱胜蚓生长发育和生殖的影响

Bt蛋白能通过转Bt基因作物的秸秆还田进入土壤,进而可能会对土壤动物如蚯蚓的生长发育和生殖造成影响.为评估Bt水稻对赤子爱胜蚓的影响,本文模拟秸秆还田,在土壤中添加2.5%、5%、7.5%和10% Bt水稻(b2B138)及其同源水稻(安丰A)秸秆,分别在饲养赤子爱胜蚓7、15、30、45、60、75和90 d后观测蚯蚓的存活率、相对生长率和生殖情况,以及秸秆土壤混合物和蚯蚓体内的Cry1Ab蛋白含量.结果表明:较高还田量(7.5%和10%)Bt水稻秸秆处理对赤子爱胜蚓存活率有抑制作用;Bt水稻秸秆还田对赤子爱胜蚓的相对生长率没有不利影响;还田量为5%、7.5%和10%时,Bt水稻秸秆还田能促进蚯蚓的生殖.酶联免疫吸附测定法(ELISA)结果表明: 在Bt水稻土壤混合物中,蚯蚓体内均能检测到Cry1Ab蛋白,且前者随着时间延长而显著减少.因此,还田量为2.5%和5%时,Bt水稻秸秆还田释放的Cry1Ab蛋白对赤子爱胜蚓的生长发育和生殖没有不利影响.     

组学技术评价转基因农作物的非预期效应

安全性评价是转基因农作物商品化应用的必要环节。组学技术能在转录物、蛋白质、代谢物水平上对转基因农作物进行无偏倚的安全性评价。文章综述了近10年来应用转录组学、蛋白质组学和代谢物组学技术评价转基因农作物非预期效应的研究进展, 结果表明在转基因农作物非预期变异中, 环境因素(种植地点和季节)和基因型差异比转基因本身的影响更大。     

阿根廷转基因作物安全管理制度概况及进展

阿根廷是最早采用转基因技术的国家之一,目前已成为全球第三大转基因作物种植国。阿根廷是全球尤其是拉美国家在生物技术产品监管和审批方面的先驱,其在转基因作物监管问题方面的丰富经验以及联合国粮食及农业组织的认可使阿根廷成为全球转基因作物监管的领导者之一。介绍了阿根廷转基因作物研发和应用、转基因作物监管体系、新型育种技术监管体系、转基因作物进出口情况以及追溯体系,讨论了转基因技术的引进对阿根廷的影响,旨在全面了解阿根廷转基因作物及新型育种技术的监管体系,为我国转基因作物安全管理提供参考。     

转Bt基因抗虫作物对鳞翅目非靶标昆虫生态影响的研究进展

任何转基因作物在进入商业化应用之前都必须经过严格的环境风险评价。评价转基因作物特别是抗虫作物对农田重要非靶标节肢动物的生态影响是其中一项重要内容。当前,全球种植的转基因抗虫作物大多表达对鳞翅目害虫具有活性的Cry1或Cry2类杀虫蛋白。由于非靶标鳞翅目昆虫如斑蝶、家蚕等与靶标害虫具有较近的亲缘关系,其幼虫可能同样对这类杀虫蛋白敏感。因此,这类转基因抗虫作物对非靶标鳞翅目害虫的潜在影响引起了研究者的广泛关注。在总结国内外相关研究数据的基础上,系统分析了转基因抗虫作物对非靶标蝶类和蚕类昆虫的潜在影响,获得以下结论：虽然蚕类和蝶类昆虫对Cry1或Cry2类杀虫蛋白敏感,但在自然条件下这类非靶标昆虫暴露于Cry杀虫蛋白的水平很低,抗鳞翅目害虫转基因作物的种植不可能显著影响田间蝶类昆虫的种群密度,也不会给我国的蚕丝产业带来负面影响。     

生物育种产业化面临的机遇与政策保障

随着中国转基因玉米和大豆产业化试点的推进，间接食用转基因农产品在中国大范围产业化种植到了关键时刻。为有序推进生物育种产业化进程，本文在回顾全球和中国转基因作物产业化历史的基础上，着重分析了中国生物育种产业化遇到的两大机遇: 一是中国转基因农产品的持续进口和间接食用在下游加工业和群众中积累了一定的消费基础；二是过去这些年中国转基因技术的研发和技术储备已为转基因作物产业化做出了良好准备。最后，本文从充分利用现有群众消费基础、进一步释放技术储备潜力、更加严格地做好全流程监管等方面，提出有序推进生物育种产业化的政策建议。