Modulation of the antioxidant/pro-oxidant balance,cytotoxicity and antiviral actions of grape seed extracts

Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H₂O₂ insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.     

Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese

Ricotta Salata is a traditional ripened and salted whey cheese made in Sardinia (Italy) from sheep's milk. This product is catalogued as ready‐to‐eat food (RTE) since it is not submitted to any further treatment before consumption. Thus, foodborne pathogens, such as Listeria monocytogenes, can represent a health risk for consumers. In September 2012, the FDA ordered the recall of several batches of Ricotta Salata imported from Italy linked to 22 cases of Listeriosis in the United States. This study was aimed at evaluating the presence and virulence properties of L. monocytogenes in 87 samples of Ricotta Salata produced in Sardinia. The ability of this product to support its growth under foreseen packing and storing conditions was also evaluated in 252 samples. Of the 87 samples 17.2% were positive for the presence of L. monocytogenes with an average concentration of 2.2 log₁₀ cfu/g. All virulence‐associated genes (prfA, rrn, hlyA, actA, inlA, inlB, iap, plcA, and plcB) were detected in only one isolated strain. The Ricotta Salata samples were artificially inoculated and growth potential (δ) was assessed over a period of 3 mo. The value of the growth potential was always >0.5 log₁₀ cfu/g under foreseen packing and storing conditions. This study indicates that Ricotta Salata supports the L. monocytogenes growth to levels that may present a serious risk to public health, even while stored at refrigeration temperatures.     

Parameters affecting the frequencies of transformation and co-transformation with synthetic oligonucleotides in yeast.

Factors influencing the direct transformation of the yeast Saccharomyces cerevisiae with synthetic oligonucleotides were investigated by selecting for cyc1 transformants that contained at least partially functional iso-1-cytochrome c. Approximately 3 x 10(4) transformants, constituting 0.1% of the cells, were obtained by using 1 mg of oligonucleotide in the reaction mixture. Carrier, such as heterogeneous oligonucleotides, enhanced transformation frequencies. Transformation frequencies were dramatically reduced if the oligonucleotides had a large number of mismatches or had terminally located mismatches. Transformation with oligonucleotides, but not with linearized double-strand plasmid, was efficient in a rad52- strain, suggesting that the pathway for transformation with oligonucleotides is different from that with linearized double-strand plasmid. We describe a procedure of co-transformation with two oligonucleotides, one correcting the cyc1 defect of the target allele in the host strain, and the other producing a desired amino acid alteration elsewhere in the iso-1-cytochrome c molecule; approximately 20% of the transformants obtained by co-transformation contained these desired second alterations.     

发酵肉制品中细菌群落结构及其表皮葡萄球菌生物胺相关基因分析

该研究首先利用高通量测序技术对发酵肉制品中细菌群落结构进行分析;然后利用传统培养分离法及双层显色培养基对产生物胺的细菌进行分离筛选,并基于16S rRNA基因序列进行鉴定;最后利用聚合酶链式反应（PCR）对产生物胺细菌的赖氨酸脱羧酶、组氨酸脱羧酶和酪氨酸脱羧酶编码基因ldc、hdc、tdc进行扩增。结果表明,发酵肉制品中细菌主要为厚壁菌门（Firmicutes）的葡萄球菌属（Staphylococcus）。从发酵肉制品中共分离得到52株细菌,其中43株具有产生物胺能力,主要为表皮葡萄球菌（Staphylococcus epidermidis）;产生物胺能力较强的7株表皮葡萄球菌中均含有ldc和hdc基因,部分菌株检测到tdc基因,为评估发酵食品生物胺的潜在危害和快速检测奠定基础。     

High prevalence of antimicrobial‐resistant Escherichia coli from animals at slaughter: a food safety risk

BACKGROUND: There has been concern about the increase of antimicrobial resistant bacteria and protection of animal and public health, along with food safety. In the present study, we evaluate the incidence of antimicrobial resistance among 192 strains of Escherichia coli isolated from faecal samples of healthy food‐producing animals at slaughter in Portugal. RESULTS: Ninety‐seven % of the pig isolates, 74% from sheep and 55% from cattle were resistant to one or more antimicrobial agents, with the resistances to ampicillin, streptomycin, tetracycline and trimethoprim–sulfamethoxazole the most common phenotype detected. Genes encoding resistance to antimicrobial agents were detected in most of the resistant isolates. Ninety‐three % of the resistant isolates were included in the A or B1 phylogenetic groups, and the virulence gene fimA (alone or in association with papC or aer genes) was detected in 137 of the resistant isolates. Five isolates from pigs belonging to phylogroup B2 and D were resistant to five different antimicrobial agents. CONCLUSION: Our data shows a high percentage of antibiotic resistance in E. coli isolates from food animals, and raises important questions in the potential impact of antibiotic use in animals and the possible transmission of resistant bacteria to humans through the food chain. © 2012 Society of Chemical Industry     

食源性沙门氏菌分离株致病性研究和毒力相关基因检测

为研究零售鲜肉源沙门氏菌（Salmonella）优势血清型分离株的致病性及相关毒力基因的相关性,本研 究分别取4 种优势血清型S. derby、S. agona、S. enteritidis、S. typhimurium沙门氏菌分离株对SPF级昆明小鼠进行致 病性实验,采用改良寇氏法计算半数致死量,判断4 种血清型沙门氏菌的毒力,并通过聚合酶链式反应检测实验 菌株中9 种毒力相关基因的分布情况并分析其相关性。结果表明,4 种不同血清型的沙门氏菌分离株对小鼠均有 40%～70%的致死率,S. enteritidis、S. agona、S. derby对昆明小鼠的致病力相似,S. typhimurium较弱,且发现致病 力的强弱与毒力岛SPI-2中的sseL基因密切相关。     

四川泡菜发酵原料-灯笼辣椒附生乳酸菌的抗生素耐药性评估与耐药基因分析

以四川泡菜蔬菜原料——新鲜灯笼辣椒为对象,分析其表面附生乳酸菌Enterococcus mundtii（5 株）、Enterococcus faecalis（2 株）、Enterococcus hirae（5 株）、Lactococcus lactis（7 株）、Leuconostocmesenteroides（2 株）、Leuconostoc holzapfelii（3 株）和Weissella cibaria（79 株）对青霉素（penicillin,PEN）、红霉素（erythromycin,ERY）、四环素（tetracycline,TET）、链霉素（streptomycin,STR）和氯霉素（chloramphenicol,CHL）的抗生素耐药性和耐药基因分布,为制定合理的食品安全防控措施提供科学依据。研究表明：所有分离菌株均无PEN和ERY耐药性,其他种属部分菌株对TET、STR和CHL表现出单一、二重或三重耐药性。除E. hirae、E. faecalis和L. holzapfelii部分菌株对STR表现出单一耐药性外,所有L. mesenteroide菌株只表现出了STR单一耐药性;STR和TET、STR和CHL二重耐药菌株在E. faecalis、E. hirae、L. lactis和W. cibaria分离菌株中都有发现,但是STR、TET、CHL三重耐药菌株仅在W. cibaria中发现。聚合酶链式反应检测发现：除基因norA、sepA、tet(A)、tet(O)和aac(6’)-aph(2’)未被检出外,其他耐药菌株都有相应1 个或多个耐药基因被检出。多重耐药外排泵基因efrA、tolC、norC、sugE和mdfA较核糖体蛋白质保护和酶修饰基因检出率高,分别达到了49%、41%、48%、41%和47%。虽然辣椒表面附生乳酸菌的抗生素耐药基因在四川泡菜发酵过程中的扩散行为需要进一步研究,但根据食品加工过程安全规范标准,也应关注其表面附生的乳酸菌抗生素耐药性存在的潜在食品安全问题。     

Characterization of Antibiotic Resistance Genes from Lactobacillus Isolated from Traditional Dairy Products

Lactobacilli are widely used as starter cultures or probiotics in yoghurt, cheese, beer, wine, pickles, preserved food, and silage. They are generally recognized as safe (GRAS). However, recent studies have shown that some lactic acid bacteria (LAB) strains carry antibiotic resistance genes and are resistant to antibiotics. Some of them may even transfer their intrinsic antibiotic resistance genes to other LAB or pathogens via horizontal gene transfer, thus threatening human health. A total of 33 Lactobacillus strains was isolated from fermented milk collected from different areas of China. We analyzed (1) their levels of antibiotic resistance using a standardized dilution method, (2) their antibiotic resistance gene profiles by polymerase chain reaction (PCR) using gene‐specific primers, and (3) the transferability of some of the detected resistance markers by a filter mating assay. All Lactobacillus strains were found to be resistant to vancomycin, but susceptible to gentamicin, linezolid, neomycin, erythromycin, and clindamycin. Their susceptibilities to tetracycline, kanamycin, ciprofloxacin, streptomycin, quinupristin/dalfopristin, trimethoprim, ampicillin, rifampicin, and chloramphenicol was different. Results from our PCR analysis revealed 19 vancomycin, 10 ciprofloxacin, and 1 tetracycline‐resistant bacteria that carried the van(X), van(E), gyr(A), and tet(M) genes, respectively. Finally, no transferal of the monitored antibiotic resistance genes was observed in the filter mating assay. Taken together, our study generated the antibiotic resistance profiles of some milk‐originated lactobacilli isolates and preliminarily assessed their risk of transferring antibiotic gene to other bacteria. The study may provide important data concerning the safe use of LAB.     

橄榄苦苷改善db/db小鼠糖尿病的肝脏转录组学及生物信息学分析

通过转录组学及其生物信息学分析,研究了橄榄苦苷缓解db/db小鼠糖尿病的肝脏差异表达基因及相关信号通路。结果发现与db/db对照组相比,橄榄苦苷处理组的539个基因发生显著变化,其中450个基因显著上调,89个基因显著下调。将上调和下调的差异表达基因在基因本体论数据库中注释,这些差异表达基因主要在细胞过程、细胞部分和结合中分布。京都基因与基因组百科全书通路富集分析结果显示上调的差异表达基因主要富集在磷酸肌醇3-激酶-蛋白激酶B信号通路途径,该通路共涉及27个差异表达基因;下调的差异表达基因主要富集在花生四烯酸代谢和真核生物中核糖体的生物发生信号通路途径,分别涉及4个差异表达基因。本研究为进一步阐明橄榄苦苷缓解2型糖尿病的分子机制奠定了基础。     

大豆TPS基因家族全基因组鉴定、分类与表达分析

利用大豆基因组数据库,通过生物信息学分析,鉴定并获得大豆TPS家族基因所有成员的全序列、基因结构和定位信息。利用序列比对对大豆TPS家族基因进行进化和分类分析,同时通过soybase大豆发育表达芯片数据库相关信息,对该家族基因成员的组织表达谱进行了检测。研究结果表明,大豆基因组中含有20个TPS家族基因成员。系统发育分析将这些TPS基因分成了两个亚家族。基因定位分析表明,这些成员基因分别分布于大豆的14条染色体上。启动子分析表明,全部大豆TPS家族基因的启动子区都含有逆境反应顺式作用元件。转录水平芯片数据分析同时显示,大豆TPS家族基因大多在花、根、根瘤等组织中存在优势表达。该研究结果将促进大豆TPS家族基因的功能研究与利用。