转基因玉米的七重PCR鉴定方法

以玉米内源基因IVR、外源抗除草剂基因(BAR、PAT)、抗虫基因Cry1Ab、筛选基因NPTII、CaMV35S启动子和NOS终止子为检测的目的片段,分别设计了7对引物,通过研究较佳引物终浓度配比和退火温度,建立了玉米转基因成分七重PCR检测体系。结果表明,建立的七重PCR体系用于同时检测内源基因和转基因成分是可行的,检测方法效率高、稳定性好。     

棉籽壳培养基及栽培银耳中转基因成分的PCR分析

通过定性PCR技术,对棉籽壳培养基及栽培银耳中的转基因成分进行检测。以棉籽壳培养基及栽培银耳的DNA为模板,设置棉花内源基因Sad1内参对照、转基因棉籽壳阳性对照、非转基因棉籽壳阴性对照和无菌双蒸水空白对照,利用不同的引物分别对CaMV35S启动子、NOS终止子以及Cry1A抗虫基因的特异片段进行PCR扩增及电泳检测。在棉籽壳培养基中可检测出35S、NOS及Cry1A的特异片段,而在棉籽壳栽培的银耳中仅检测出35S和NOS的特异片段,未检出Cry1A的特异片段。研究结果表明,棉籽壳培养基中含有外源转基因成分,并向银耳发生水平转移,而其外源抗虫基因可能未转入银耳中。对棉籽壳栽培银耳中基因水平转移的影响因素和潜在生物安全性进行了讨论。     

重组酶聚合酶扩增技术检测转基因水稻中的Cry1Ab/c基因

重组酶聚合酶扩增技术(RPA)是利用重组酶和单链结合蛋白在常温下协同实现引物与模板的特异结合,以代替传统PCR热循环中的变性和复性过程的新型恒温体外核酸扩增技术。本研究基于RPA技术建立了转基因水稻Cry1Ab/c基因的检测方法,可在37℃恒温条件下快速检测到转基因水稻中的Cry1Ab/c基因,具有较好的特异性,其绝对及相对检测灵敏度分别达到100个拷贝和0.1%(质量分数),适用于基层实验室及现场快速检测转Cry1Ab/c基因水稻及其制品。     

一种5 重real-time PCR筛查转基因水稻方法的建立

以转基因水稻中最常用的CaMV35S启动子、NOS终止子、Cry1Ab/Ac基因、HPT基因及SPS水稻内标基因为研究对象，利用5 种不同的荧光信号（FAM、HEX、Taxas Red、Cy5、Cy5.5）进行多重实时聚合酶链式反应（real-time polymerase chain reaction，real-time PCR）检测方法的研究。通过引物组合筛选、反应体系优化、特异性测试、灵敏度测试、适用性测试等一系列实验，建立了5 重real-time PCR方法，灵敏度可达0.032%。此方法具有灵敏度高、结果准确、通量大等优点，可实现水稻中转基因成分的快速、高效检测。     

应用多重PCR技术筛选检测转Bt基因作物

Bt基因在抗虫转基因作物中广泛应用,是转基因食品筛选检测中最主要的目的基因。本研究依据核苷酸序列分析结果,将在转基因作物中常见的8种Bt基因(cry1Ab、cry1Ac、cry1Ab/Ac、cry1A.105、cry1Ac-M、cry2Ab、cry3A和cry3Bb)划分为cry1A、cry2A、cry3A三个组,并根据每个组的一致性序列设计了可分别检测各组Bt基因的特异性检测引物,其中cry1A组采用了简并引物,经过特异性、灵敏度等测试,建立了针对cry1A组、cry2A组和cry3A组的单一PCR检测方法。此外,通过将这三对检测引物放入同一PCR体系中,还建立了可特异检测上述3组Bt基因的三重PCR方法。结果表明,本研究建立的单一PCR和三重PCR方法均可从各类样品中准确检测出预期Bt基因成分,检测灵敏度达到0.1%。本方法特异性强、灵敏度高,在转基因成分的筛选检测中有很好的应用前景。     

大豆加工食品中转基因成分多重PCR检测体系的建立

以大豆内源基因 (Lectin)、筛选基因 3 5S启动子 (Cauliflowermosaicvirus 3 5S ,CaMV3 5S)、Nos终止子 (Nopalinesynthase,Nos)和外源基因 (5 enolpyruvylshikimate 3 phosphatesynthase ,Ep sps)为检测对象 ,通过对PCR扩增体系中各引物终浓度及PCR扩增过程中退火温度的探讨 ,研究了不同引物终浓度配比及退火温度对转基因大豆多重PCR检测的影响 ,建立了大豆加工食品中转基因成分多重PCR检测体系。结果表明 ,当各组引物的终浓度分别为 1 0、2 0、2 0、3 0 μmol/L即引物终浓度配比为 1∶2∶2∶3 ,退火温度为 5 5 4℃时 ,所建立的多重PCR检测方法能够有效地检测出大豆中的转基因成分 ,具有特异性好 ,简便 ,快速 ,准确等优点。     

四重PCR结合全自动电泳系统检测食品转基因成分

根据转基因食品中最常见的四种外源元件(CaMV35S启动子、NOS终止子、cry1Ab/cry1Ac基因、bar基因)的核苷酸序列,设计特异性检测引物,扩增产物大小分别为101、180、301、430bp,通过引物浓度、退火温度的优化,特异性、灵敏度测试,并结合微流体芯片全自动电泳技术,建立了同时检测这4个参数的四重PCR方法。结果表明,该方法可特异性地从复杂样品中检测出预期转基因成分,检测灵敏度达到0.1%。本方法特异性好,灵敏度高,适用于食品中转基因成分的快速筛查。     

转基因水稻定性PCR检测体系的建立

采用PCR技术检测CaMV35S启动子、NOS终止子、Bt基因,判断水稻样品中是否含转基因成分,建立了稳定快速的转基因水稻定性PCR检测体系.PCR检测的灵敏度达到0.1%,稳定性良好.结果表明:PCR技术检测外源基因是灵敏和准确的,可以广泛地应用到转基因作物及其加工产品的转基因成分检测中.此外,进一步讨论了转基因成分检测中存在的问题、转基因产品标识的必要性和目前转基因检测技术在检测中的问题.     

痕量及微量转基因大米成分半巢式PCR检测方法的建立

采用半巢式PCR技术建立了食品中痕量及微量转基因大米成分的检测方法。根据大米内源SPS基因以及转基因大米Bt63含有的外源Cry1A(b)/Cry1A(c)融合基因和Btc基因,分别设计了6对普通与半巢式PCR引物。扩增结果显示,针对理论DNA浓度的检测灵敏度,普通PCR扩增灵敏度为1ng/μl左右,半巢式PCR扩增灵敏度达到10-3～10-4ng/μl,半巢式PCR比普通PCR方法提高了103～104倍;在质量百分比的检测灵敏度方面,普通PCR方法扩增灵敏度在0.1%～1%之间,半巢式PCR方法的检测灵敏度能够达到0.001%～0.01%,半巢式PCR比普通PCR方法要提高10倍以上。在实际样品的检测中,速冻汤圆、婴儿米粉及芝士小圆饼等食品经普通PCR扩增,其内源SPS基因条带模糊或未扩增到,进一步采用半巢式PCR扩增后,能够得到清晰明亮的特异性条带。所有样品均未扩增到外源Cry1A(b)/Cry1A(c)和Btc基因。     

转基因水稻Bt63的外源基因相对含量分析

为分析转基因Bt63稻米外源基因含量,利用新型、灵敏和高通量的实时荧光定量PCR技术,以RBE-4作为转基因水稻的内源参照基因,通过梯度稀释法,分别获得了Bt 63和RBE-4基因的Ct值与起始模板相关性的标准曲线,相关系数分别为0.996 6和0.995 4。通过转基因水稻外源基因(Bt63)和内标基因(RBE-4)起始模板数的比较,测定了外源基因在转基因水稻中的相对含量,这项研究将为建立转基因水稻抗虫能力评价体系和转基因稻谷的流通和监管提供技术支撑。     

Expression,purification and refolding of recombinant Cry1Ab/Ac obtained in Escherichia coli as inclusion bodies

BACKGROUND: The Cry toxins are already a useful alternative or supplement to synthetic chemical pesticide application in commercial agriculture and forest management. RESULTS: The Cry1ab/ac gene from Bacillus thuringiensis was cloned from the genome of genetically modified rice by polymerase chain reaction (PCR). Owing to the large number of Escherichia coli low‐usage codons in the Cry1ab/ac gene, the first 20 codons were optimised by PCR to improve the expression of the Cry1ab/ac gene in E. coli. The Cry1Ab/Ac protein was highly expressed in E. coli as inclusion bodies that could be dissolved in 8 mol L^?1 urea and purified on a His Trap^? FF crude column under denaturing conditions. The purified Cry1Ab/Ac protein was dialysed in refolding buffers to obtain a soluble and biologically active protein. To achieve better biological activity, the His‐tag was digested from the Cry1Ab/Ac protein with enterokinase, and the Cry1Ab/Ac protein was further purified by gel filtration on a fast performance liquid chromatography Superdex 75 HR 10/30 column using an AKTA purifier. The identity of the purified Cry1Ab/Ac protein sequence was confirmed by western blot and matrix‐assisted laser desorption ionisation time‐of‐flight mass spectrometry. The final purified Cry1Ab/Ac protein was 99.2% pure and retained its biological activity, as determined in a growth inhibition assay of Chilo suppressalis. CONCLUSION: The purified Cry1Ab/Ac protein could be used to evaluate the food safety of transgenic plants containing the Cry1ab/ac gene and to produce antibodies for immune‐based methods employed in the detection of genetically modified organisms containing the Cry1ab or Cry1ac gene. It might also serve as a new biological insecticide to reduce the use of broad‐spectrum insecticides. Copyright © 2009 Society of Chemical Industry     

Adsorption of transgenic insecticidal Cry1Ab protein to silica particles. Effects on transport and bioactivity

Bt crops are genetically modified to be resistant against insect pests by expressing insecticidal Cry proteins. The processes governing the fate and bioavailability of the expressed transgenic Cry proteins in soils are poorly understood. We studied adsorption of Cry1Ab to negatively charged silica (SiO(2)) particles, a major soil constituent and a model for negatively charged mineral surfaces, at pH 5 to 10 and ionic strengths I = 10 mM to 250 mM, both in solution depletion and saturated column transport experiments. Cry1Ab-SiO(2) interactions were dominated by patch-controlled electrostatic attraction (PCEA), as evident from increasing Cry1Ab attraction to SiO(2) with decreasing I at pH at which both Cry1Ab and SiO(2) were net negatively charged. Experimental and modeling evidence is provided that the surface heterogeneity of SiO(2) particles modulated PCEA, leading to a fraction of adsorption sites with slow Cry1Ab desorption kinetics. Desorption rates from these sites increased upon increasing the solution pH. In toxicity bioassays, we demonstrated that Cry1Ab retained insecticidal activity when adsorbed to SiO(2), suggesting high protein conformational stability during adsorption-desorption cycles. Models predicting Cry1A protein adsorption in soils therefore need to account for combined effects of the nonuniform protein surface charge distribution and of sorbent surface heterogeneity.     

Loop-mediated isothermal amplification (LAMP) method for rapid detection of cry1Ab gene in transgenic rice (Oryza sativa L.)

The cry1Ab gene is a foreign gene which encodes Bt insecticidal Cry1Ab protein and was transferred into genomic DNA of plants to acquire insect resistance. Here a loop-mediated isothermal amplification (LAMP) assay with high specificity and rapidity under isothermal conditions was developed for detecting cry1Ab gene in transgenic rice. Partial sequence of cry1Ab gene was used as the target template to design LAMP primers. The reaction conditions were optimized as follows: 60 min of reaction time, 1:3 of outer primer and inner primer concentration ratio, 25 μL of reaction volume and 0.6 μM of betaine. The results of detection could be evaluated by the white precipitate or the fluorescence intensity under ultraviolet irradiation, both visible to naked eyes. The sensitivity and specificity of the LAMP assay were further analyzed in comparison with that of regular PCR and real-time PCR. The results showed that the LAMP assay exhibited high specificity and the sensitivity of 3 × 10² copies number of the positive control plasmid, and of 0.5 % genetically modified (GM) contents. In comparison with real-time PCR method, LAMP showed the same results with simple instruments. The amplified reaction could be accomplished in about 1 h, with the results visible to naked eyes. Hence, the LAMP assay developed by this study can provide a rapid and simple approach for detecting cry1Ab gene from transgenic rice plants and rice ingredients in processed foods aimed at screening the growing transgenic crops in the fields and detecting genetically modified (GM) ingredients in imported and domestic foods.     

COMPARATIVE STUDIES ON MAJOR NUTRITIONAL COMPONENTS AND PHYSICOCHEMICAL PROPERTIES OF THE TRANSGENIC RICE WITH A SYNTHETIC Cry1Ab GENE FROM BACILLUS THURINGIENSIS

Book reviewed in this article:
The major nutritional components and physicochemical properties in the transgenic rice containing a synthetic Cry 1 Ab gene from Bacillus thuringiensis were comparatively studied together with the wild type and the recurrent parent. There were almost no differences in major nutritional components, i.e. crude protein, crude lipid, free amino acids, total ash, and mineral elements, both between the primary transgenic rice 'KMD' and the wild type 'Xiushui 11', the recurrent parent 'Jiazao 935' and new transgenic line 'Huachi B6', which was bred using 'KMD' as the insect-resistant donor. No significant changes in apparent amylose content (AAC), alkali spreading value (ASV), and gel consistency (GC) were observed between the transgenic lines and the parents. The major parameters of starch viscosity profile in the transgenic rice, i.e. peak viscosity (PKV), hot paste viscosity (HPV), cool paste viscosity (CPV), breakdown viscosity (BDV), setback viscosity (SBV), and peak time (pTime), were the same as the parents, respectively. Cry1Ab protein was only detected in the transgenic rice, however, the amounts of Cry1Ab protein were undetectable in the cooked transgenic rice. The results above indicate that the transgenic rice is substantially equivalent to the conventional rice in terms of the major nutritional components and physicochemical properties.     

玉米及其制品中转基因成分的单一 PCR及多重PCR检测

采用CTAB法提取玉米及其制品的总DNA，用PCR方法检测其中的转基因成分如花椰菜花叶病毒（Cauliflower mosaic virus，CaMV）35S启动子、根癌农杆菌（Agrobacterium tumefaciens）胭脂碱合成酶甚因（nos）终止子、根癌农杆菌CP4菌株的EPSPS基因、吸水链霉菌（Treptomyces hygroscopicus）bar基因及苏云金芽孢杆菌库尔斯塔克亚种（Bacillus thuringiensis subsp．kurstaki）crylA（b）基因，筛选到阳性样品，并建立了几组玉米内源zein基因和转基因成分之间的多重PCR检测方法。结果表明，建立的多重PCR方法用于同时检测玉米内源基因和转基因成分是可行的，值得推广；虽然我国还未有己获准商品化生产的转基因玉米，但国外转基因玉米已流入福建省。     

High-throughput detection of genetically modified rice ingredients in foods using multiplex polymerase chain reaction coupled with high-performance liquid chromatography method

The aim of this study was to develop a method for simultaneous detection of a variety of genetically modified (GM) rice ingredients in foods using multiplex polymerase chain reaction (PCR) coupled with high-performance liquid chromatography (HPLC) assay. The following exogenous genes found in GM rice were selected as targets: CaMV35S, NOS, Cry1Ac, Bar, and Xa21. The endogenous gene PEPCex of rice was selected as an internal control. In brief, six pairs of primers for multiplex PCR were designed according to the specific region of CaMV35S, NOS, Cry1Ac, Bar, Xa21, and PEPCex, and following the optimization, a multiplex PCR assay was developed, and then the multiplex PCR products were subjected to HPLC analysis. The GM rice lines ShanYou 63, KeFeng 6, KangYou 97, and LLrice 62 were used as reference GM rice samples to evaluate the potential diagnostic capability of the method. Results demonstrated that the multiplex PCR-HPLC developed in this work was an efficient diagnostic method for simultaneous identification of the target genes with 0.15 ng/mL of high sensitivity, suggesting a better alternative for the rapid detection of many genetic modification events.     

多重实时荧光PCR快速检测转基因大豆及其加工产品

本研究运用多重实时荧光聚合酶链式反应技术(polymerase chain reaction,PCR)对转基因大豆及其深加工制品进行筛选检测。通过设计大豆内源基因植物凝集素(Lectin)和常用的外源基因花椰菜花叶病毒35S启动子(CaMV35S)、根癌农杆菌胭脂碱合成酶基因终止(nos)的特异性引物和探针,反应条件和反应体系的优化,特异性、重复性和灵敏性的实验比对分析等开发建立了多重荧光定量PCR检测技术。以10%Roundup Ready转基因大豆标准品为材料,建立并优化转基因大豆的定量检测体系,对大豆中的转基因成分进行定量分析。结果表明:该方法重复性好,检测特异性强,扩增效率在90%～110%,标准曲线相关系数R2≥0. 98,确定了最低检测限为每20μL反应2. 4个拷贝。结论:由于使用多重实时荧光PCR技术,可实现一管多检的实际需要,降低试剂成本,缩短检测时间,为大豆及其深加工产品转基因成分的快速检测提供了有效方法,为促进农产品和食品进出口提供技术保障。