北疆部分地区食源性大肠杆菌血清型、毒力基因及耐药基因的研究

目的研究北疆部分地区食源性大肠杆菌的优势血清型、毒力基因和耐药基因的相关性。方法采用玻片凝集法测定了大肠杆菌血清型分布,PCR方法调查11种耐药基因和9种毒力基因。结果血清试验,定型菌株26株,分别属于17种血清型,其中O1、O115为优势血清型;PCR结果表明,不含有所检测耐药基因的分离株占12.50%,至少含有2种以及以上的分离株占50.00%,分离株对blaOXA基因携带率高达57.14%;检出率较高的毒力基因为fimC(64.29%)和fimA(25.00%)。结论 O1、O115为主要的血清型,2种血清型菌株拥有的耐药基因谱和毒力基因谱不相同。     

单核细胞增生李斯特菌菌株分型与其致病潜力基因相关性研究进展

单核细胞增生李斯特菌是一种常见的食源性致病菌,该菌分型繁多。不同分型的单核细胞增生李斯特菌致病潜力不同,这与菌株所携带的抗性基因和毒力基因不同有关。本文综述了不同分型单核细胞增生李斯特菌与抗性基因和毒力基因的关系,结果发现与该菌抗性相关的基因,如热抗性、耐冷性、酸抗性、耐高渗、耐干燥、耐金属和杀菌剂及参与应激蛋白表达调控的基因较多,它们与分型之间的关系暂无明确相关性结论,但也发现应激生存岛（stress survival island,SSI）-1仅存在于谱系I和谱系II部分菌株中,SSI-2目前仅被发现在ST121菌株中携带。从功能毒力基因和李斯特菌毒力基因岛（Listeria pathogenicity islands,LIPI）两方面分述了毒力基因,LIPI-3和LIPI-4主要存在于谱系I菌株中。此外,ST5、ST8、ST9和ST121菌株的inlA基因中出现提前终止密码子,使得菌株的毒力降低。研究不同分型单核细胞增生李斯特菌致病潜力基因的差异有助于单核细胞增生李斯特菌的预警预测、防控,并为不同分型菌株致病机制的深入研究提供参考。     

婴幼儿食品中金黄色葡萄球菌污染情况及其耐药基因和新型肠毒素基因的检测

本文调查了婴幼儿奶粉和米粉中金黄色葡萄球菌的污染状况,并且检测其耐药基因和新型肠毒素基因。采集陕西省2010年和2012年间不同品牌的婴幼儿奶粉和米粉692份,进行金黄色葡萄球菌污染检验,采用PCR对分离菌株进行31种耐药基因和9种新型肠毒素基因的检测。692份样品中金黄色葡萄球菌的检出率为7.80%,其中2010年所采样品的检出率为8.17%,2012年所采样品的检出率为7.38%。分离的75株菌最终检测出12种耐药基因和2种新型肠毒素基因,检出率最高的耐药基因是tet K(72.00%),其次是bla Z(36.00%),erm C(29.33%),tet(K)F(21.33%),lin A/lin A’(12.00%),dfr G(8.00%),tet L(6.67%)和acc(6')(5.33%),最少的为erm B,msr A、msr B和drf K(均为1.33%)。新型肠毒素基因仅检测出sen(44.00%)和ser(4.00%)。不同采样年份、生产季节和货架期的样品中金黄色葡萄球菌的污染率不存在显著差异。并且这些菌株主要携带四环素、青霉素和大环内酯类抗生素的耐药基因,以及新型毒素基因sen。     

苏州市食品中单增李斯特菌污染状况及分子特征分析

目的 研究2016-2020年苏州市各类食品中单增李斯特菌的污染状况及分子特征.方法 将采样食品按WS/T 464-2015《食物成分数据表达规范》进行分类,计算各类食品污染率,通过聚合酶链式反应(polymerase chain reaction,PCR)和凝胶电泳对毒力基因(inlA、inlB)和耐药相关基因(vi...     

转抗菌肽基因辣椒食用安全性和营养质量评价

依据中华人民共和国卫生部《转基因食品卫生管理办法》的有关规定，对转抗菌肽基因辣椒食用安全性和营养质量进行评价，探讨建立相关的模式和方法，为我国转基因食的卫生管理提供可资借鉴的模型和方法，以转抗菌肽基因辣椒及其对应的受体辣椒为材料，通过对其外源基因及其表达产物，主要营养成分的检测，鉴定转基因食品的特性，基因重组体的遗传稳定性，外源基因的表达忠实性，与受体辣椒的实质等同性，分析和评价其食用安全性和营养质量，抗菌肽基因辣椒其受体，外源基因供体均为传统食品，其基因重组体的主要特性的遗传是稳定的，其外源目的基因的表达是忠实的，其食安全性和营养质量不低于对应的原有食品。     

The telomere-associated MAL3 locus of Saccharomyces is a tandem array of repeated genes.

Saccharomyces strains capable of fermenting maltose contain any one of five telomere-associated MAL loci. Each MAL locus is a complex of three genes encoding the three functions required to ferment maltose: maltose permease (GENE 1), maltase (GENE 2) and the MAL trans-activator (GENE 3). All five loci have been cloned and all are highly sequence homologous over at least a 9.0 kbp region containing these GENEs (Charron et al., Genetics 122, 307-331, 1989). Our initial studies of strains carrying the MAL3 locus indicated the presence of linked, repeated MAL-homologous sequences (Michels and Needleman, Mol. Gen. Genet. 191, 225-230, 1983). Here we report our analysis of the centromere-proximal MAL3-linked sequences and show that the complete MAL3 locus spans approximately 40 kbp and consists of tandemly arrayed, partial repeats of the three GENE sequences described above. In addition, the structure of the MAL3 locus is compared to that of three partially functional alleles of MAL3. These alleles were shown to contain only MAL31 and MAL32 and their structure suggests that they resulted from MAL3 deletions removing the sequences centromere-proximal to MAL31. The amplification and rearrangement of the telomere-linked MAL3 sequences are discussed in the context of studies on other telemere-associated sequences from yeast and other species.     

广州市售鱼、虾、蛤蚌中四环素耐药菌及四环素耐药基因的研究

本文以广州市大型超市的鱼、虾、蛤蚌为研究对象,研究其四环素耐药菌的分布及四环素耐药基因的携带情况。采用平板涂布法分离四环素耐药菌并统计菌落数,计数结果在102~106 CFU/g之间,其中鱼肠中四环素耐药菌的数量达106 CFU/g。通过PCR对样本总DNA中四环素耐药基因的携带情况进行检测,发现每个样本均携带多个(3~7个)四环素耐药基因。9种四环素耐药基因中,tet(E)的检出率最高6.3%,其次分别为tet(S)(5.1%),tet(M)(3.1%),tet(C)(1.7%)和tet(G)(0.9%)。Southern杂交试验表明四环素抗性菌株Aeromonas spp.和Escherichia coli携带的耐药基因tet(E)存在于质粒上;在无四环素选择压力下对上述两种菌株进行连续传代,其耐药质粒仍稳定存在于菌株中。本研究表明广州市售鱼、虾、蛤蚌中分离得到的细菌对四环素耐药情况较为严重,应得到相关监管部门以及消费者的足够重视。     

Physical map locations of the phospholipid biosynthetic structural and regulatory genes of Saccharomyces cerevisiae

Here we report the physical map locations of five genes required for phospholipid biosynthesis in Saccharomyces cerevisiae. These include four structural genes (INO1, CHO2, OP13 and PIS1) and one global negative regulatory gene (UME6). Collectively, this information completes the mapping of all phospholipid biosynthetic structural and regulatory genes identified to date.     

Comparison of rpoA and pheS Gene Sequencing to 16S rRNA Gene Sequencing in Identification and Phylogenetic Analysis of LAB from Probiotic Food Products and Supplements

An investigation of the relevance of sequenced protein-coding genes in comparison with 16S rRNA gene sequences to correctly delineate and discriminate between closely related Lactobacillus isolates is presented. These reportedly probiotic Lactobacillus strains were obtained from probiotic supplements and food products. Probiotic Lactobacillus species have been found to have several potential health benefits and technological properties which may be strain-dependent. It was deemed necessary to investigate molecular techniques for the identification and discrimination between closely related isolates. The 16S rRNA, pheS, and rpoA genes were amplified in a polymerase chain reaction using the oligonucleotide pairs 27F/1492R, pheS-21-F/pheS-23-R, and rpoA-21-F/rpoA-23-R. The PCR amplicons were separated using gel agarose electrophoresis and observed by the Bio-Rad Gel Doc^TM XR+ Imaging system transilluminator. Sequencing of the PCR amplicons was done in an ABI PRISM^TM 3100 genetic analyzer. MEGA 5.05 software was employed in doing the phylogenetic analysis. Identification by 16S rRNA gene sequencing was confirmed by pheS and rpoA gene sequencing. Subsequent phylogenetic analysis and concatenation showed that interspecies and intraspecies degrees of diversity and similarity were better enabled by pheS and rpoA primers. Overall, findings revealed cases of inaccurate identification of Lactobacillus strains in probiotic supplements on the market, highlighting the relevance of the multigenic approach in more accurately identifying Lactobacillus strains. Supplemental materials are available for this article; see the publisher's online edition of Food Biotechnology to view the supplemental file.     

基于单拷贝核基因的数字PCR定量检测肉制品中羊源性成分

GeneBank搜索牛、绵羊、山羊、猪、马、驴、鸡、鸭、鹅、火鸡、狗、猫、鼠、兔、貂等15种动物的单拷贝核基因组序列信息,应用生物信息学分析筛选15种动物共有的种间保守区域,设计一对可同时扩增15种动物源性DNA的内参基因引物和探针;同时分析筛选绵羊和山羊共有且和其余动物种内特异性区域,设计一对只能扩增羊源性DNA的特异性基因引物和探针。基于微滴数字PCR技术,引入内参基因校正羊种属特异性基因测定方法,建立科学准确的肉制品中羊源性成分量化判定方法。结果表明,所建立方法具有良好的特异性和通用性,内参基因和羊种属特异性基因的最低检出限分别为32和26 copies/μL,模拟添加样品的正确度偏差均值为8.66%,符合数字PCR方法制定指南要求不得大于25%,说明量化判定方法结果具有较高的准确性。     

Contemporary approaches into obesity: drugs and genes

Obesity is a global epidemic effecting the health and life style of millions of people in both developed and developing countries. In this article, current medical treatments, recent scientific progresses toward understanding obesity, and future potentials in biotechnology applications in pharmaceutical research are reviewed in detail.     

1株耐热蜡样芽孢杆菌的鉴定及其缓解炎症性肠病的功效评价

目的：使用多种鉴定方法联合鉴定1株实验室未知菌株，并利用葡聚糖硫酸钠诱导的实验性小鼠结肠炎模型，评价其缓解炎症性肠病的功效。方法：利用16S rRNA和保守蛋白编码基因gyrA及gyrB进行初步鉴定，通过毒力基因nheA、nheB、nheC、hblA、hblC、hblD、becT、cytK、entFM及其生化反应特性确定种属，并测定分离菌在不同温度、pH值以及人工胃肠液的耐受特性。进一步建立实验性结肠炎小鼠模型，探究其缓解炎症性肠病的潜在功效。结果：分子及生理生化鉴定结果显示分离菌为蜡样芽孢杆菌（Bacillus cereus），并命名为HMPM18123。生长特性测定结果还显示，该菌株具有良好的耐高温和胃液肠液耐受特性。此外，该菌株具有改善实验性小鼠结肠炎的功效，具体表现为缓解小鼠结肠炎导致的体质量减低、结肠缩短、疾病活动指数评分升高、组织病变和炎症因子的表达水平上调。     

Detection and characterization of virulence genes and integrons in Aeromonas veronii isolated from catfish

The presence of virulence genes and integrons was determined in 81 strains of Aeromonas veronii isolated from farm-raised catfish. Polymerase chain reaction (PCR) protocols were used to determine the presence of genes for cytotoxic enterotoxin (act), aerolysin (aerA), two cytotonic enterotoxins (ast, alt), lipase (lip), glycerophospholipid:cholesterol acyltransferase (gcaT), serine protease (ser), DNases (exu), elastase (ahyB) and the structural gene flagellin (fla) in the template DNA. Oligonucleotide primers amplified a 231-bp region of the act gene from the template DNA of 97.0% of the isolates. Primers specific for the amplification of the aerA gene amplified a 431-bp region of the aerA gene from the template DNA of 96.0% of the isolates. None of the isolates contained ast or alt genes. Oligonucleotide primers specific for the amplification of lip, gcaT, ser and fla genes, amplified their respective amplicons from 85.0, 78.0, 82.0 and 80.0% of the isolates. None of the isolates contained exu or the elastase genes. Several of the isolates (48.0%) contained class I integrons that confer resistance to multiple antibiotics; various sizes between 0.6 and 3.1 kb were found. None of the isolates contained Class II integrons. Our results indicate that farm-raised catfish may be a source of pathogenic A. veronii and that the potential health risks posed by virulent strains of A. veronii should not be underestimated.     

Genetic and molecular analysis of DNA43 and DNA52: two new cell-cycle genes in Saccharomyces cerevisiae.

Two Saccharomyces cerevisiae genes previously unknown to be required for DNA synthesis have been identified by screening a collection of temperature-sensitive mutants. The effects of mutations in DNA43 and DNA52 on the rate of S phase DNA synthesis were detected by monitoring DNA synthesis in synchronous populations that were obtained by isopycnic density centrifugation. dna43-1 and dna52-1 cells undergo cell-cycle arrest at the restrictive temperature (37 degrees C), exhibiting a large-budded terminal phenotype; the nuclei of arrested cells are located at the neck of the bud and have failed to undergo DNA replication. These phenotypes suggest that DNA43 and DNA52 are required for entry into or completion of S phase. DNA43 and DNA52 were cloned by their abilities to suppress the temperature-sensitive lethal phenotypes of dna43-1 and dna52-1 cells, respectively. DNA sequence analysis suggested that DNA43 and DNA52 encode proteins of 59.6 and 80.6 kDa, respectively. Both DNA43 and DNA52 are essential for viability and genetic mapping experiments indicate that they represent previously unidentified genes: DNA43 is located on chromosome IX, 32 cM distal from his5 and DNA52 is located on chromosome IV, 0.9 cM from cdc34.     

The housekeeping genes GAPDH and cyclophilin are regulated by metabolic state in the liver of dairy cows

Steady-state levels of mRNA are often used to infer treatment effects on the levels of the corresponding protein. In addition, an internal standard RNA is usually measured to document specificity of treatment and to correct for intersample variation. Our objective was to evaluate whether glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and cyclophilin could be used as internal standards when studying changes in hepatic gene expression in dairy cows. Hepatic expression of GAPDH and cyclophilin was measured in 6 cows in late pregnancy (28 d prepartum) and early lactation (10 d postpartum). Each gene displayed 2- to 3-fold higher expression in early lactation than in late pregnancy. Next, we determined whether negative energy balance alone or in combination with exogenous growth hormone could mimic the effects of early lactation. Late-lactating cows were fed 120% of predicted energy requirements or 33% of maintenance requirements. During each feeding period, cows were administered excipient or bovine somatotropin in a single-reversal design with 4-d periods separated by a 2-d interval. Underfeeding increased hepatic expression of GAPDH and cyclophilin by 1- to 2-fold, whereas bovine somatotropin had no effect. Finally, the effects of insulin were studied by performing hyperinsulinemic-euglycemic clamps in late pregnancy (28 d prepartum) and early lactation (28 d postpartum). Hyperinsulinemia reduced GAPDH expression in both states, and cyclophilin expression in early lactation. In conclusion, GAPDH and cyclophilin are regulated in the liver of dairy cows and should not be used to standardize hepatic gene expression in studies involving the transition period, undernutrition, and sustained changes in plasma insulin.