Development and Application of a GeXP-multiplex PCR Assay for Detection of Seven Foodborne Pathogenic Bacterias

This experiment was developed to simultaneously detect the seven common foodborne pathogenic bacterias include E. coli O157:H7, Salmonella, V. cholera, L. monocytogenes, C. jejuni, V. Parahemolyticus and S. aureus. Seven pairs of specific primers were designed according to the conserved sequences of the genes from each pathogen available in the GenBank database. Single and mixed pathogen DNA templates were used to evaluate the specificity of the GeXP-multiplex assay. Control group was set up, recombinant plasmids were constructed, and samples of different DNA concentrations were randomly combined to verify the sensitivity, specificity, accuracy and anti-interference of the established GeXP method. To certify the accuracy and reliability of the GeXP assay, it was evaluated using 120 clinical specimens that were compared with the single PCR. The obtained results showed that the corresponding specific fragments of genes were amplified by the single and the multiplex GeXP PCR assay. The detection limit of GeXP was 10³ copies·μL^-1 when all of seven bacterial pathogens were detected. The results of the interference assay showed the presence of specific amplification peaks when different templates. The detection rate of the GeXP multiplex PCR method was 2.50% (3/120)-15.83% (19/120) while the conventional PCR was 2.50% (3/120)-15.00% (18/120), and GeXP multiple PCR detected 8 more positive cases, which means that, the GeXP was more sensitive and accurate in the detection of the clinical samples. In conclusion, this GeXP-based multiplex PCR is a high-throughput, specific and sensitive test to detect seven common foodborne pathogenic bacterias. This assay provides a method in rapid molecular diagnosis for mix clinical seven common foodborne pathogenic bacterias.     

气候变化下的塔里木盆地西南部内陆河流域径流组分特征分析

气候变化对中亚高山区水循环影响显著,加剧了区域水资源供需矛盾.认识区域内陆河径流组分特征对于水资源管理具有重要意义.基于塔里木盆地西南部提孜那甫河流域过去60a(1957-2016年)的气象、径流数据,分析了区域气候变化特征及径流组分的响应.结果 表明:(1)过去60 a来,流域气温及山区降水呈现出明显的上升趋势,自2...     

烤烟种烤分离生产模式对其经济效益和产质量的影响

为了推动现代烤烟的专业化生产,以烤烟种烤分离生产模式和常规生产模式进行比较,研究了其对烤烟经济效益和产质量的影响。结果表明:采用种烤分离生产模式能获得成熟度较好的烟叶,且烘烤成本降低141.74元/hm2,烟叶产值和烟农收益分别增加2 064.29元/hm2和2 031.03元/hm2,此模式在保障烟农收入的同时还能将烟农的劳动力从烟叶烘烤中解放出来;同时烘烤更专业,烤后烟叶质量有保障,初烤烟叶的外观质量和内在化学成分均优于常规生产模式,是现代烤烟生产发展的一种有效模式。     

麦秆超临界醇解液化产物的萃取分离及分析

[目的]探寻生物油中高附加值化合物,提高生物油的利用价值和综合竞争力。[方法]将麦秆在超临界甲醇中醇解液化所得生物油通过减压蒸馏得到轻质组分和重质组分,重质组分(重油)用不同极性及溶解性的溶剂萃取分离。[结果]生物油重质组分(重油)5个馏分中,正己烷馏分(Fz)主要含酚类化合物;苯馏分(FB)主要含酚和环戊烯醇酮;乙醚馏分(FYM)主要含吡喃糖苷和呋喃糖苷;而乙酸乙酯馏分(FY)和丙酮馏分(FBT)经GC/MS检测不到物质。[结论]麦秆超临界醇解液化得到的生物质重质油,含有大量的高附加值化合物。     

不同枫树叶片中酚酸类物质高效毛细管电泳检测方法的研究

采用正交试验的方法,研究了缓冲液pH、分离电压、运行温度等电泳参数对枫树叶片中酚酸类物质提取检测的影响,建立了4种槭树科枫叶中绿原酸、原儿茶酸、没食子酸和咖啡酸4种酚酸类化合物检测分离的高效毛细管电泳(HPCE)方法。得出了最佳分离条件为:紫外检测波长214 nm,缓冲液为20 mmol·L-1的磷酸-硼砂,pH 8.0,电压为22 kV,温度25℃。在此条件下,4种酚酸类化合物在9 min内完全分离,且各组分浓度与峰面积呈良好的线性关系,r2为0.974 8～0.996 5。迁移时间的RSD≤0.84%,峰面积的RSD≤5.29%,加标回收率为80.38%～96.88%。4种枫树叶片中均含有绿原酸,其中蚜虫宿主三角枫中绿原酸含量最低。     

酸樱桃中原花青素的分离与纯化

以NKA树脂为吸附剂,对酸樱桃(Prunus cerasus)中原花青素的分离纯化进行了研究。通过单因素试验分析确定了原花青素分离纯化的最佳工艺条件为,上样浓度7 mg/L,上样流速1.0 mL/min,用体积分数为95%的乙醇溶液作为洗脱剂,以1.0 mL/min流速进行洗脱。经树脂纯化后的原花青素通过HPLC/ESI-MS分析确定其主要含两种组分,分别为原花青素-3-葡萄糖苷和(-)-表儿茶素没食子酸酯。     

酪蛋白糖巨肽的生理功能特性及其应用

阐述了酪蛋白糖巨肽(CGMP)的化学结构、制备、分离纯化、检测方法和生物学性质,及研究现状与应用前景。     

Surveillance of verocytotoxigenic Escherichia coli in Irish bovine dairy herds

Verocytotoxigenic Escherichia coli (VTEC) are highly significant zoonotic threats to public health, and have been the causative agent implicated in numerous high-profile outbreaks affecting large numbers of people. Serovar O157 is most frequently linked with human illness; however, other serovars, such as O26, O103, O111 and O145, have also been implicated. This study aimed to characterize the prevalence and virulence determinants of these five serovars in Irish dairy farm herds, and their milk. Using real-time PCR (RTi-PCR), bovine rectal faecal swabs and raw milk samples, along with milk filters, were screened for the presence of vt genes. Positive samples were then screened for the five serovars using sero-specific PCR. Serovar-positive samples were subjected to immunomagnetic separation, to isolate viable VTEC strains. These isolates were subsequently screened for four virulence factors: vt1, vt2, eaeA and hlyA. Three hundred and eighty six of the 600 rectal faecal swabs, 85 of the 117 milk-filters and 43 of the 120 bulk-tank milk samples, were positive for vt genes. From these 514 total vt-positive samples, 58 O26, 162 O103, 1 O111, 324 O145 and 26 O157 positives were detected by sero-specific RTi-PCR. Immunomagnetic separation yielded 12 O26, 26 O103, 0 O111, 19 O145 and 10 O157 isolates. Ten of these isolates contained at least one of the four virulence determinants screened for (i.e. vt1, vt2, eaeA and hlyA). Of these 10 isolates, pulsed-field gel electrophoresis showed that two of the O26 isolates from different farms were indistinguishable. Two O157 isolates were also indistinguishable. This study found serovars O103 and O145 to be the most prevalent in samples tested. Apart from the occurrence of VTEC in dairy herds, this study shows a high occurrence of vt genes in the environment, creating the possibility of horizontal gene transfer and emergence of new VTEC strains.     

蚯蚓纤溶酶的分离纯化及临床作用研究进展

蚯蚓纤溶酶是从蚯蚓中分离的一种丝氨酸蛋白水解酶,有抗凝溶血栓、抗癌抗肿瘤、抗炎、神经修复等作用,在临床上是预防和治疗血栓疾病的有效药物。本文对蚯蚓纤溶酶的分离纯化与药理作用加以概述,为临床蚯蚓溶栓药物的研究提供依据。     

Preparation and Antioxidant Activity of Chitosan Dimers with Different Sequences

As a popular marine saccharide, chitooligosaccharides (COS) has been proven to have good antioxidant activity. Its antioxidant effect is closely related to its degree of polymerization, degree of acetylation and sequence. However, the specific structure–activity relationship remains unclear. In this study, three chitosan dimers with different sequences were obtained by the separation and enzymatic method, and the antioxidant activity of all four chitosan dimers were studied. The effect of COS sequence on its antioxidant activity was revealed for the first time. The amino group at the reducing end plays a vital role in scavenging superoxide radicals and in the reducing power of the chitosan dimer. At the same time, we found that the fully deacetylated chitosan dimer DD showed the strongest DPPH scavenging activity. When the amino groups of the chitosan dimer were acetylated, it showed better activity in scavenging hydroxyl radicals. Research on COS sequences opens up a new path for the study of COS, and is more conducive to the investigation of its mechanism.