黄曲霉毒素B1人工抗原的合成及鉴定

采用衍生化在黄曲霉毒素B1(aflatoxin B1,AFB1）上引入羧基合成AFB1羧甲基活化物,通过N-羟琥珀酰亚胺酯(N-hydroxy-succinimide NHS）法将AFB1O与牛血清白蛋白(BSA)偶联,制备黄曲霉毒素B1完全抗原AFB1-BSA。ECI-MS和紫外光谱法的鉴定结果表明目标半抗原合成成功。结合紫外分光光度法和回归方程,分别测得不同浓度的半抗原和蛋白质线性曲线为：Y=0.1440X+0.0103,R2=0.9986;Y=0.0059X+0.0808,R2=0.9889。偶联物中半抗原和蛋白质的浓度分别为186.32 μg/mL、6127.46 μg/mL,即求得抗原分子结合比为5.13:1,从而为制备抗AFB1抗体奠定基础。     

氯霉素人工抗原的合成

以重氮化法分别将氯霉素(chloramphenicol,CAP)与牛血清白蛋白(bovine serum albumin,BSA)及卵清白蛋白(ovaibumin,OVA)进行偶联,得到复合物CAP-BSA和CAP-OVA。对复合物紫外扫描显示其扫描谱图与BSA和氯霉素的图谱有明显的差异,BSA及OV与氯霉素偶联成功。分析CAP-BSA中CAP与BSA的摩尔比,偶联时,CAP与BSA的起始质量比为1∶1、1∶2、2∶1时,偶联物中CAP:BSA摩尔比分别为4.69∶1、8.90∶1、7.94∶1,说明反应起始时不同的CAP与蛋白质配比会对偶联效果有较大的影响。以摩尔比为8.90∶1的CAP-BSA免疫BALB/c小鼠65d后,间接ELISA检测测定效价达1∶20000。     

土霉素人工抗原的合成

以碳化二亚胺和戊二醛作为偶联剂，分别将土霉素(oxytetracycline，OTC)与牛血清白蛋白(bovine serum albumin，BSA)进行偶联，得到复合物OTC—BSA。对复合物紫外扫描显示其扫描谱图与BSA和上霉素的图谱有明显的差异，表明BSA与土霉素偶联。分析OTC—BSA中OTC与BSA的摩尔比，以碳化二亚胺为偶联剂时，OTC：BSA摩尔比为7．97：1，而以戊二醛作为偶联剂时仅为2．58：1，说明不同的偶联剂得到的的复合物之间存在较大的差异。以摩尔比为7．97：1的OTC—BSA免疫BALB／c小鼠65d后，间接ELISA检测测定效价达1：20000。     

黄曲霉毒素B1人工抗原及鼠源多克隆抗血清的制备

目的:研究合成并鉴定了黄曲霉毒素B1(aflatoxin B1,AFB1)人工抗原,通过动物免疫生产亲和力高、特异性好的鼠源AFB1多克隆抗血清。方法:采用N-羟琥珀酰亚胺酯(N-hydroxy-succinimide NHS)法将AFB1分别偶联于载体蛋白BSA和OVA上,分别合成免疫抗原AFB1-BSA和包被抗原AFB1-OVA,采用紫外分光光度法和SDS-PAGE进行鉴定,通过动物免疫实验获得鼠源多抗血清,并使用间接ELISA和阻断ELISA的方法对多抗血清进行了鉴定。结果:结果表明半抗原AFB1分别和载体蛋白BSA及OVA偶联成功;免疫的6只小鼠效价均达1×10-4以上,3号小鼠多抗血清敏感性最好,半数抑制浓度IC50(50% inhibitive concentration,IC50)为8.199ng/mL。结论:实验成功合成了AFB1人工抗原,并生产了高效价、高敏感性的鼠源多克隆抗体血清,为AFB1单克隆抗体制备及其快速检测试剂的研制奠定了坚实的基础。     

两种特异性氰戊菊酯人工抗原的合成与鉴定

选择化学结构具有典型研究意义的氰戊菊酯(fenvalerate,Fen)为研究对象,利用有机化学合成法在氰戊菊酯分子的一端分别引入两种不同连接长度的连接臂。通过核磁共振(1H-NMR)、液相色谱-质谱联用仪(LC-MS-MS)鉴定,成功合成两种半抗原Fen1和Fen2,并与牛血清蛋白(bovine serum albumin,BSA)偶联合成了两种氰戊菊酯免疫特异性人工抗原Fen1-BSA、Fen2-BSA,经紫外分光光度仪扫描,人工抗原的紫外图谱相对于半抗原和载体蛋白有明显差异,测得偶联比分别约为9:1和10:1,经SDS-PAGE电泳检测表明偶联成功。     

EDC法制备黄曲霉毒素B1人工抗原的研究

本研究采用EDC法制备了黄曲霉毒素B1人工抗原，通过TLC与ELISA对制备过程监控，确定了最佳的肟化反应时间与偶联反应时间。同时，就黄曲霉毒B1与牛血清白蛋白的起始摩尔比对偶联产物中这两物质摩尔比的影响进行了研究。结果显示，在25℃肟化反应24h、偶联反应24h，当黄曲霉毒素B1与牛血清白蛋白的起始摩尔比为30：1时，得到了黄曲霉毒素B1与牛血清白蛋白的摩尔比为5：1的黄曲霉毒素B1人工抗原。     

高特异性黄曲霉毒素B_1单克隆抗体的制备及特性研究

本研究将黄曲霉毒素B1转化为半缩醛B2a,在硼氢化钠（NaBH4）还原作用下与载体蛋白偶联制备完全抗原。将制备的完全抗原免疫Balb/c小鼠,经4次免疫后取其脾脏与小鼠骨髓瘤细胞Sp2/0细胞融合,采用半固体培养基筛选后鉴定,获得杂交瘤细胞株3A12,抗体的灵敏度可达6.1±0.025ng/mL,抗体与其它黄曲霉毒素B2、G1及G2的交叉反应率依次为7.8%、20.2%及0.6%,与黄曲霉毒素M1交叉反应率小于0.1%。本研究为研发花生等农产品黄曲霉毒素B1特异性免疫分析技术及产品奠定了重要基础。     

利用荧光免疫层析卡测定黄曲霉毒素M1的研究

将量子点与抗黄曲霉毒素M1(AFM1)的单克隆抗体偶联,以AFM1-BSA偶联物包被于NC膜作为检测线,山羊抗鼠二抗包被于NC膜上作为质控线,构建了直接竞争检测AFM1的荧光定量免疫层析检测卡体系,在0.156μg/L~1.25μg/L范围内能够准确定量黄曲霉毒素B1,灵敏度达到0.156μg/L。     

HPLC-MS/MS法测定曲霉菌代谢物中黄曲霉毒素及同系物

建立了同时检测曲霉菌代谢物中黄曲霉毒素和同系物的高效液相色谱-线性离子阱质谱测定方法。产黄曲霉毒素B1(AFB1)寄生曲霉(菌株3.124)经PDA固体培养基培养,提取净化后经线性离子阱(QTrap)质量分析器分析(正离子模式,多反应检测),以AFB1二级碎片(MS2)信息和其同系物分子式信息预测代谢物MRM方法,检出3.124代谢物中黄曲霉毒素B2(AFB2)、黄曲霉毒素G1(AFG1)、黄曲霉毒素G2(AFG2)、O-甲基杂色曲霉素(MST)、杂色曲霉素(ST)5种真菌毒素,并用标准品进行了确证。结果表明,AFB2和AFG2在0.5μg/L~40μg/L,其它4种代谢物在0.2μg/L~40μg/L范围内线型关系良好,相关系数均大于0.99。本方法 6种代谢物日内回收率81.3%~92.3%,相对标准偏差(RSD)为3.4%~6.2%;日间回收率82.1%~91.7%,RSD为3.8%~7.7%。该方法为快速检测霉菌代谢物中的同系物提供新的方法。     

黄曲霉毒素B1完全抗原构建中结合位点研究

通过衍生化反应,合成了AFB1羧甲基活化物,然后利用碳二亚胺法合成AFB1-O-BSA偶联物,构建AFB1完全抗原,并通过多种光谱和质谱对合成完全抗原过程中偶联比和结合位点进行研究。通过荧光光谱在分子水平上探讨AFB1与BSA载体蛋白的偶联机制及偶联反应对BSA的构象影响,推测黄曲霉毒素和牛血清白蛋白反应的结合部位,同时发生在BSA的酪氨酸残基和色氨酸残基上,使得BSA疏水性增加,肽链伸展程度降低。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status