转Cry1Ab基因水稻分子特征及其特异性PCR检测方法

转Cry1Ab基因水稻Bt01为一种新型的转基因水稻,文章首先利用Southern blotting验证了外源基因Cry1Ab转入了Bt01中,且为单拷贝,再利用TAIL-PCR方法获得了其插入位点信息,根据获得的Bt01的5′端插入位点序列,设计了相应的定性与定量PCR检测体系的引物及探针,实验结果显示,定性PCR检测体系的最低检测极限(LOD)为10个拷贝,定量PCR检测体系的LOD为5拷贝,最低定量极限(LOQ)为10拷贝。同时为了验证建立的定量PCR体系的准确性,利用该体系检测已知转基因水稻Bt01含量分别为3%和0.5%的样品,定量结果分别为2.7%和0.47%。研究结果表明,该转化体特异性定性与定量检测方法具有高度的特异性和良好的灵敏性,为转基因水稻Bt01的身份识别和检测提供了有效的方法。     

转Cry1Ab基因水稻分子特征及其特异性PCR检测方法

转Cry1Ab基因水稻Bt01为一种新型的转基因水稻, 文章首先利用Southern blotting验证了外源基因Cry1Ab转入了Bt01中, 且为单拷贝, 再利用TAIL-PCR方法获得了其插入位点信息, 根据获得的Bt01的5′端插入位点序列, 设计了相应的定性与定量PCR检测体系的引物及探针, 实验结果显示, 定性PCR检测体系的最低检测极限(LOD)为10个拷贝, 定量PCR检测体系的LOD为5拷贝, 最低定量极限(LOQ)为10拷贝。同时为了验证建立的定量PCR体系的准确性, 利用该体系检测已知转基因水稻Bt01含量分别为3%和0.5%的样品, 定量结果分别为2.7%和0.47%。研究结果表明, 该转化体特异性定性与定量检测方法具有高度的特异性和良好的灵敏性, 为转基因水稻Bt01的身份识别和检测提供了有效的方法。     

Cry1Ah蛋白标准物质候选物的制备与纯化

随着转基因技术的迅猛发展,转基因产品的安全性受到了广泛关注。转基因检测用有证标准物质在确保转基因产品定性、定量检测结果的可比性和可追溯性方面发挥着重要作用。但转基因蛋白质标准物质的开发相对缓慢,其中一个难点是制备高纯度的转基因蛋白质候选物。苏云金芽胞杆菌Bacillus thuringiensis cry1Ah1基因因其对亚洲玉米螟等鳞翅目害虫有很好的杀虫活性,已用于转基因抗虫作物的研制,并获得具有较好抗虫性状的转基因株系。为了研发Cry1Ah蛋白有证标准物质,亟需建立其制备及纯化体系。文中优化了利用Bt表达系统制备Cry1Ah蛋白的体系,利用离子交换色谱法和排阻色谱法逐级纯化的方法,获得了高纯度的Cry1Ah蛋白 (排阻色谱纯度：99.6%)。生物活性测定结果表明,纯化的Cry1Ah蛋白与原毒素对小菜蛾Plutella xylostella的杀虫活性没有显著差异。最后使用Edman降解法和质谱法确定了Cry1Ah蛋白活化后的氨基酸序列。综上所述,获得的Cry1Ah纯蛋白可用于蛋白质标准物质的研制。     

Cry1Ah蛋白标准物质候选物的制备与纯化（英文）

随着转基因技术的迅猛发展,转基因产品的安全性受到了广泛关注。转基因检测用有证标准物质在确保转基因产品定性、定量检测结果的可比性和可追溯性方面发挥着重要作用。但转基因蛋白质标准物质的开发相对缓慢,其中一个难点是制备高纯度的转基因蛋白质候选物。苏云金芽胞杆菌Bacillus thuringiensis cry1Ah1基因因其对亚洲玉米螟等鳞翅目害虫有很好的杀虫活性,已用于转基因抗虫作物的研制,并获得具有较好抗虫性状的转基因株系。为了研发Cry1Ah蛋白有证标准物质,亟需建立其制备及纯化体系。文中优化了利用Bt表达系统制备Cry1Ah蛋白的体系,利用离子交换色谱法和排阻色谱法逐级纯化的方法,获得了高纯度的Cry1Ah蛋白(排阻色谱纯度:99.6%)。生物活性测定结果表明,纯化的Cry1Ah蛋白与原毒素对小菜蛾Plutella xylostella的杀虫活性没有显著差异。最后使用Edman降解法和质谱法确定了Cry1Ah蛋白活化后的氨基酸序列。综上所述,获得的Cry1Ah纯蛋白可用于蛋白质标准物质的研制。     

转基因抗虫作物鉴定质粒标准分子的构建与应用

苏云金芽胞杆菌基因是转基因抗虫作物中通用的外源功能基因,在绝大多数抗虫转基因作物中均有存在,然而Bt基因检测标准样品的缺乏却限制了我国转Bt基因抗虫作物检测工作的发展。为了弥补传统基体标准样品的缺失,首先将Cry1Ab、Cry1Ac、Cry3A 3种常用Bt外源基因克隆到pUC57质粒上,通过测序、酶切和qPCR等技术对质粒的序列和扩增功能进行了验证,然后对扩增效率和实际应用情况加以测试,评价其转基因检测的适用性,构建了质粒标准分子。结果显示,制备的质粒标准分子测序结果与靶标序列完全符合,酶切结果、qPCR扩增结果和扩增效率等均符合预期,在Cry1Ab、Cry1Ac、Cry3A基因特异性检测中的应用符合阳性对照要求,表明制备的阳性质粒标准分子能够作为转Cry1Ab、Cry1Ac、Cry3A基因qPCR基因特异性检测的阳性标准样品。     

PCR对转基因玉米CBH351品系的鉴定检测

成功建立了转基因玉米CBH351（Starlink^TM)的筛选和品系鉴定检测的PCR方法,该方法根据玉米自身IVR基因作为内源特异参照基因来检查模板DNA提取的质量,避免了假阴性结果,设计检测CaMV35S启动子的引物扩增195bp,来对转基因玉米进行筛选检测;并进一步设计转基因玉米CBH351（StarlinkTM)品系转化质粒图谱中CaMV35S启动子和Cry9C边界位置基因特异性引物扩增170bp,以及目标基因Cry9C的右端与CaMV35S终止子的左端边界位置基因特异性引物扩增171bp,以此来鉴定检测CBH351（StarlinkTM)的品系。     

LAMP实时浊度法检测转基因植物NPTⅡ基因

根据转基因植物常用的选择标记基因NPTⅡ(HE582394.1)的序列,设计6条特异性LAMP引物,利用实时浊度仪对反应体系中扩增产物的实时监控筛选出最佳引物,最终建立转基因植物NPTⅡ基因的LAMP检测方法,并对该方法的特异性、灵敏度、稳定性进行了评价。结果表明,该方法能够特异性检出含有NPTⅡ基因的植物及其加工产品,特异性高,灵敏度达0.5%。对转基因玉米MON863(含NPTⅡ基因)含量为10%、1%、0.5%、0%(W/W)的样品DNA分别进行扩增,其稳定性好,无假阳性和假阴性。所建立的LAMP方法适用于特异性筛选检测含NPTⅡ基因的植物及其加工样品。     

转Cry1Ac+Cry2Ab基因棉花主要生化物质含量变化及其对棉田昆虫的影响

【目的】新型转基因棉花在进入大规模商业化应用前,需对其生态环境安全性进行评价;同时,经基因改造的新型转基因抗虫棉花可能影响抗虫棉的次生代谢,进而导致一些综合的生态学效应,致使棉花生理上发生改变,这也是转基因植物安全性评价研究的重要内容。【方法】比较了不同关键时期新型转Cry1Ac+Cry2Ab基因棉花与转Cry1Ac基因棉花和非转基因棉花叶片的鲜重、干重和干鲜比、主要酶[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)]活性、营养物质(蛋白质、氨态氮、脯氨酸和可溶性糖)和次生代谢产物(棉酚和单宁)含量的差异及其对棉田不同昆虫营养层昆虫个体总数和物种数的影响。【结果】棉花生长的蕾期、花期和花铃期,转Cry1Ac+Cry2Ab基因棉花、转Cry1Ac基因棉花和非转基因棉花叶片的鲜重、干重和干鲜比呈先升高后降低的趋势;SOD和POD活性在花铃期明显升高,CAT、APX和GR活性无显著变化;蛋白质、氨态氮含量无明显变化,脯氨酸和可溶性糖含量均表现为先升高后下降的趋势;棉酚含量在3个时期无显著变化,而单宁含量呈逐渐升高的趋势。3种棉花叶片中干物质积累、主要酶活性、营养物质和次生代谢产物含量均无显著差异;单株大铃数表现为转Cry1Ac+Cry2Ab基因棉花转Cry1Ac基因棉花非转基因棉花,小铃数则表现为转Cry1Ac基因棉花Cry1Ac+Cry2Ab基因棉花非转基因棉花;昆虫群落和害虫亚群落的昆虫个体总数均表现为转Cry1Ac+Cry2Ab基因棉田转Cry1Ac基因棉田非转基因棉田,天敌亚群落昆虫个体总数无显著变化;3种棉田中昆虫群落、害虫亚群落和天敌亚群落的物种数均未发生显著变化。【结论】转Cry1Ac+Cry2Ab基因棉花叶片干物质积累、产量性状、生化物质含量、酶活性在不同生长期表现不同,但上述参数在3种棉花之间无显著差异;且转Cry1Ac+Cry2Ab基因棉花具有较好的抗虫性,能有效降低棉田害虫数量。     

5种转基因油菜转化体特异性多重PCR检测方法

【目的】全球转基因植物及其产品的数量和种类越来越多,迫切需要可同时精准高效检测多个转化载体的检测方法。【方法】针对RF1、MS8、Topas19/2、Oxy235和RF3等5个转基因油菜品系的侧翼序列及油菜内源基因cruciferin A(Cru A)序列设计多重聚合酶链式反应特异性引物,通过对转基因油菜、转基因大豆、转基因玉米、转基因水稻、转基因棉花等不同作物进行PCR扩增来测试所选择的引物特异性,优化多重PCR反应引物的浓度,用所建立的检测体系对不同混合比例的转基因油菜进行多重PCR扩增来测试所建立的检测方法的灵敏度。【结果】通过测试,仅在含有目标样品中检测出阳性结果,灵敏度达0.05%,表明所建立的6重PCR检测方法可同时精准检测RF1、MS8、Topas19/2、Oxy235和RF3等5种转基因油菜转化载体。【结论】所建立的6重转基因油菜转化体特异性PCR检测方法通量高、特异性好、灵敏度高,符合有关转基因产品检测的要求,可作为转基因油菜检测的有效方法。     

核酸层析法转基因快速检测体系的建立及应用

随着我国转基因研究及产业化进程提速,转基因检测的重要性日益凸显,因而快速、高效的分子检测新方法的研发具有重要的生产实践及科研意义。在转基因检测中,常规PCR技术具有检测范围广的特点,但较为费时费力,且对实验条件要求较高;而胶体金蛋白试纸法检测方便、快捷,但可检范围窄。基于此,建立了一套基于核酸层析法快速转基因检测的方法体系。将经液氨研磨后的样品通过一管法提取DNA后直接进行PCR扩增,再将PCR扩增产物滴加到胶体金检测卡上,通过直接观察胶体金卡条显色状况进行结果判别。此方法最终检验出玉米内参基因ZSSⅡB及Zein、大豆内参基因SPS、水稻内参基因Lectin,转基因元件启动子CaMV35S及终止子NOS,以及抗虫基因Cry1Ab/1Ac、抗除草剂基因Bar、Pat、CP4-EPSPS及选择标记基因NPTⅡ、Pmi等外源基因;并成功检出特异性转基因事件Mir604及Bt11。研究获得的核酸层析检测方法具有灵敏度高、省时省力且对检测条件要求低等优点,集PCR法与蛋白试纸检测法二者优势于一身,可广泛应用于转基因产品的精确快速检测,为我国转基因生物安全监管提供了良好的技术支撑。     

Sensitive and rapid detection of Flavobacterium columnare in channel catfish Ictalurus punctatus by a loop-mediated isothermal amplification method

AIMS: To evaluate the loop-mediated isothermal amplification method (LAMP) for rapid detection of Flavobacterium columnare and determine the suitability of LAMP for rapid diagnosis of columnaris infection in channel catfish, Ictalurus punctatus. METHODS AND RESULTS: A set of four primers, two outer and two inner, were designed specifically to recognize 16S ribosomal RNA gene of this pathogen. Bacterial genomic DNA templates were prepared by hot lysis in a lysis buffer. Amplification of the specific gene segments was carried out at 65 degrees C for 1 h. The amplified gene products were analysed by agarose gel electrophoresis and detected by staining gels with ethidium bromide. A PCR assay was also included in this study. Our results demonstrate that the ladder-like pattern of bands from 204 bp specific to the Fl. columnare 16S ribosomal RNA gene was amplified. The detection limit of the LAMP assay was comparable to that of PCR in prepared genomic DNA reactions. In addition, this optimized LAMP assay was able to detect the Fl. columnare 16S ribosomal RNA gene in experimentally infected channel catfish. CONCLUSIONS: The LAMP assay for Fl. columnare detection in channel catfish was established. SIGNIFICANCE AND IMPACT OF THE STUDY: Because LAMP assay is a rapid, sensitive, specific, simple and cost-effective assay for Fl. columnare detection in channel catfish, it is useful for rapid diagnosis of Fl. columnare in fish hatcheries and the field.     

Expression of a modified Cry1Ie gene in E. coli and in transgenic tobacco confers resistance to corn borer

The wild-type Crylle gene from Bacillus thuringiensis was modified for its efficient expression in transgenic plants. Modified Crylle gene (designated as Cryllem) was cloned into prokaryotic expressionvector pET28b and its expression in E.coli was confirmed by SDS-PAGE analysis. Bioassays using crude expression products in E.coli revealed that CrylIem protein had a similar toxicity to corn borer as wild-type CrylIe. CrylIem gene was then inserted downstream of the maize ubiquitin-1 promoter in plant expression vector p3301. Transgenic tobacco plants carrying Cryllem showed insecticidal activity against corn borer.     

Sensitive and Rapid Detection of Giardia lamblia Infection in Pet Dogs using Loop-Mediated Isothermal Amplification

Giardia lamblia is recognized as one of the most prevalent parasites in dogs. The present study aimed to establish a loop-mediated isothermal amplification (LAMP) assay for rapid and specific detection of G. lamblia from dogs. The fecal samples were collected and prepared for microscopic analysis, and then the genomic DNA was extracted directly from purified cysts. The concentration of DNA samples of G. lamblia were diluted by 10-fold serially ranging from 10^-1 to 10^-5 ng/µl for LAMP and PCR assays. The LAMP assay allows the amplification to be finished within 60 min under isothermal conditions of 63℃ by employing 6 oligonucleotide primers designed based on G. lamblia elongation factor 1 alpha (EF1α) gene sequence. Our tests showed that the specific amplification products were obtained only with G. lamblia, while no amplification products were detected with DNA of other related protozoans. Sensitivity evaluation indicated that the LAMP assay was sensitive 10 times more than PCR. It is concluded that LAMP is a rapid, highly sensitive and specific DNA amplification technique for detection of G. lamblia, which has implications for effective control and prevention of giardiasis.     

Expression of a Modified Cry1Ie Gene in E. coli and in Transgenic Tobacco Confers Resistance to Corn Borer

Gene transfer technology provides an alternativeapproach to breed insect-resistant crops. Insect-resistantgenes from plants or microbes could be introduced intoplants and the expressed insecticidal protein in plantcells could kill the target insects. Transgenic plantsexpressing a corresponding insecticidal crystal protein genefrom Bacillus thuringiensis (Bt) have been developed sincethe early 1980s [1,2]. Analysis of Bt gene sequencesrevealed that they contain numerous motifs seldom foundin p…     

Cry1A(b)16 toxin from Bacillus thuringiensis: Theoretical refinement of three‐dimensional structure and prediction of peptides as molecular markers for detection of genetically modified organisms

Transgenic maize produced by the insertion of the Cry transgene into its genome became the second most cultivated crop worldwide. Cry gene from Bacillus thuringiensis kurstaki expresses protein derivatives of crystalline endotoxins which confer insect resistance onto the maize crop. Mandatory labeling of processed food containing or made by genetically modified organisms is in force in many countries, so, it is very urgent to develop fast and practical methods for GMO identification, for example, biosensors. In the absence of an available empirical structure of Cry1A(b)16 protein, a theoretical model was effectively generated, in this work, by homology modeling and molecular dynamics simulations based on two available homologous protein structures. Molecular dynamics simulations were carried out to refine the selected model, and an analysis of its global structure was performed. The refined models of Cry1A(b)16 showed a standard fold and structural characteristics similar to those seen in Bacillus thuringiensis Cry1A(a) insecticidal toxin and Bacillus thuringiensis serovar kurstaki Cry1A(c) toxin. After in silico analysis of Cry1A(b)16, two immunoreactive candidate peptides were selected and specific polyclonal antibodies were produced resulting in antibody–peptide interaction. Biosensing devices are expected to be developed for detection of the Cry1A(b) protein as a marker of transgenic maize in food. Proteins 2017; 85:1248–1257. © 2017 Wiley Periodicals, Inc.     

Localisation of the Putative Magnetoreceptive Protein Cryptochrome 1b in the Retinae of Migratory Birds and Homing Pigeons

Cryptochromes are ubiquitously expressed in various animal tissues including the retina. Some cryptochromes are involved in regulating circadian activity. Cryptochrome proteins have also been suggested to mediate the primary mechanism in light-dependent magnetic compass orientation in birds. Cryptochrome 1b (Cry1b) exhibits a unique carboxy terminus exclusively found in birds so far, which might be indicative for a specialised function. Cryptochrome 1a (Cry1a) is so far the only cryptochrome protein that has been localised to specific cell types within the retina of migratory birds. Here we show that Cry1b, an alternative splice variant of Cry1a, is also expressed in the retina of migratory birds, but it is primarily located in other cell types than Cry1a. This could suggest different functions for the two splice products. Using diagnostic bird-specific antibodies (that allow for a precise discrimination between both proteins), we show that Cry1b protein is found in the retinae of migratory European robins (Erithacus rubecula), migratory Northern Wheatears (Oenanthe oenanthe) and pigeons (Columba livia). In all three species, retinal Cry1b is localised in cell types which have been discussed as potentially well suited locations for magnetoreception: Cry1b is observed in the cytosol of ganglion cells, displaced ganglion cells, and in photoreceptor inner segments. The cytosolic rather than nucleic location of Cry1b in the retina reported here speaks against a circadian clock regulatory function of Cry1b and it allows for the possible involvement of Cry1b in a radical-pair-based magnetoreception mechanism.     

Rapid and Sensitive Detection of Listeria ivanovii by Loop-Mediated Isothermal Amplification of the smcL Gene

A loop-mediated isothermal amplification (LAMP) assay for rapid and sensitive detection of the L. ivanovii strains had been developed and evaluated in this study. Oligonucleotide primers specific for L. ivanovii species were designed corresponding to smcL gene sequences. The primers set comprise six primers targeting eight regions on the species-specific gene smcL. The LAMP assay could be completed within 1 h at 64°C in a water bath. Amplification products were directly observed by the Loopamp Fluorescent Detection Reagent (FD) or detected by agarose gel electrophoresis. Moreover, the LAMP reactions were also detected by real-time measurement of turbidity. The exclusivity of 77 non-L. ivanovii and the inclusivity of 17 L. ivanovii were both 100% in the assay. Sensitivity of the LAMP assay was 250 fg DNA and 16 CFU per reaction for detection of L. ivanovii in pure cultures and simulated human stool. The LAMP assay was 10 and 100-fold more sensitive than quantitative PCR (qPCR) and conventional PCR assays,respectively. When applied to human stool samples spiked with low level (8 CFU/0.5 g) of L. ivanovii strains, the new LAMP assay described here achieved positive detection after 6 hours enrichment. In conclusion, the new LAMP assay in this study can be used as a valuable, rapid and sensitive detection tool for the detection of L. ivanovii in field, medical and veterinary laboratories.     

Rapid and simple detection of Clostridium botulinum types A and B by loop-mediated isothermal amplification

Aims:  To develop a convenient and rapid detection method for toxigenic Clostridium botulinum types A and B using a loop-mediated isothermal amplification (LAMP) method.
Methods and results:  The LAMP primer sets for the type A or B botulinum neurotoxin gene, BoNT / A or BoNT / B , were designed. To determine the specificity of the LAMP assay, a total of 14 C. botulinum strains and 17 other Clostridium strains were tested. The assays for the BoNT/A or BoNT/B gene detected only type A or B C. botulinum strains, respectively, but not other types of C. botulinum or strains of other Clostridium species. Using purified chromosomal DNA, the sensitivity of LAMP for the BoNT/A or BoNT/B gene was 1 pg or 10 pg of DNA per assay, respectively. The assay times needed to detect 1 ng of DNA were only 23 and 22 min for types A and B, respectively. In food samples, the detection limit per reaction was one cell for type A and 10 cells for type B.
Conclusions:  The LAMP is a sensitive, specific and rapid detection method for C. botulinum types A and B.
Significance and Impact of the Study:  The LAMP assay would be useful for detection of C. botulinum in environmental samples.     

Identification of cry1I-type genes from Bacillus thuringiensis strains and characterization of a novel cry1I-type gene

A PCR-restriction fragment length polymorphism method for identification of cry1I-type genes from Bacillus thuringiensis was established by designing a pair of universal primers based on the conserved regions of the genes to amplify 1,548-bp cry1I-type gene fragments. Amplification products were digested with the Bsp119I and BanI enzymes, and four kinds of known cry1I-type genes were successfully identified. The results showed that cry1I-type genes appeared in 95 of 115 B. thuringiensis isolates and 7 of 13 standard strains. A novel cry1I-type gene was found in one standard strain and six isolates. The novel cry1I gene was cloned from B. thuringiensis isolate Btc007 and subcloned into vector pET-21b. Then it was overexpressed in Escherichia coli BL21(DE3). The expressed product was shown to be toxic to the diamondback moth (Plutella xylostella), Asian corn borer (Ostrinia furnacalis), and soybean pod borer (Leguminivora glycinivorella). However, it was not toxic to the cotton bollworm (Helicoverpa armigera), beet armyworm (Spodoptera exigua), or elm leaf beetle (Pyrrhalta aenescens) in bioassays. Subsequently, the Cry protein encoded by this novel cry gene was designated Cry1Ie1 by the B. thuringiensis delta-endotoxin nomenclature committee.     

Principle of LAMP method--a simple and rapid gene amplification method

So far nucleic acid test (NAT) has been employed in various fields, including infectious disease diagnoses. However, due to its complicated procedures and relatively high cost, it has not been widely utilized in many actual diagnostic applications. We have therefore developed a simple and rapid gene amplification technology, Loop-mediated Isothermal Amplification (LAMP) method, which has shown prominent results of surpassing the performance of the conventional gene amplification methods. LAMP method acquires three main features: (1) all reaction can be carried out under isothermal conditions; (2) the amplification efficiency is extremely high and tremendous amount of amplification products can be obtained; and (3) the reaction is highly specific. Furthermore, developed from the standard LAMP method, a rapid LAMP method, by adding in the loop primers, can reduce the amplification time from the previous 1 hour to less than 30 minutes. Enormous amount of white precipitate of magnesium pyrophosphate is produced as a by-product of the amplification, therefore, direct visual detection is possible without using any reaction indicators and detection equipments. We believe LAMP technology, with the integration of these features, can rightly apply to clinical genetic testing, food and environmental analysis, as well as NAT in different fields.