[EMA-pCR detection of enterohemorrhagic Eschrichia coli O157:H7].

OBJECTIVE: A rapid and effective method with ethidium monoazide bromide (EMA) in combination with PCR (EMA-PCR) was established to detect live Enterohemorrhagic Eschrichia Coli O157:H7. METHODS: The rfbE gene was used as the target gene for PCR detection of Eschrichia Coli O157:H7 by utilizing its pure isolates after the treatment of EMA as the template. The EMA concentration and reaction time was optimized. RESULTS: The use of 10 microg/mL or less EMA did not inhibit the PCR amplification of DNA derived from viable bacteria. The PCR amplification of DNA derived from 2 x 10(7) CFU/mL dead cells can be inhibited by 0.5 microg/mL EMA. The sensitivity of the method was 2 x 10(4) CFU/mL. The results demonstrated that it could detect 1% live bacteria from a mixed bacterial population. CONCLUSION: EMA-PCR can effectively detect live bacteria of O157:H7, it could be a potential rapid detection method applied in public health emergent events.

Comparison of two suspension arrays for simultaneous detection of five biothreat bacterial in powder samples.

We have developed novel Bio-Plex assays for simultaneous detection of Bacillus anthracis, Yersinia pestis, Brucella spp., Francisella tularensis, and Burkholderia pseudomallei. Universal primers were used to amplify highly conserved region located within the 16S rRNA amplicon, followed by hybridized to pathogen-specific probes for identification of these five organisms. The other assay is based on multiplex PCR to simultaneously amplify five species-specific pathogen identification-targeted regions unique to individual pathogen. Both of the two arrays are validated to be flexible and sensitive for simultaneous detection of bioterrorism bacteria. However, universal primer PCR-based array could not identify Bacillus anthracis, Yersinia pestis, and Brucella spp. at the species level because of the high conservation of 16S rDNA of the same genus. The two suspension arrays can be utilized to detect Bacillus anthracis sterne spore and Yersinia pestis EV76 from mimic "write powder" samples, they also proved that the suspension array system will be valuable tools for diagnosis of bacterial biothreat agents in environmental samples.

Analysis of ß-galactosidase production and their genes of two strains of Lactobacillus bulgaricus.

A bacterial ß-galactosidase delivery system is a potential therapy for lactose intolerance. Currently, two Lactobacillus bulgaricus strains with different biological characteristics are under consideration as potential sources. However, differences in these ß-galactosidase genes and their resulting production levels are poorly characterized. The ß-galactosidase ORF of L. bulgaricus yogurt isolate had high variability and was terminated at site 1924 due to a stop codon. However, the full 114 kDa ß-galactosidase band was still resolved by SDS-PAGE, which may indicate that the interrupted ORF was translated into more than one peptide, and they together were folded into the complete enzyme protein that showed much higher ß-galactosidase activity (6.2 U/mg protein) than the enzyme generated from L. bulgaricus reference strain (2.5 U/mg protein).

[Investigate the effects of compound radix notoginseng on renal interstitial fibrosis and kidney-targeting treatment].

OBJECTIVE: Investigate the effects of compound Radix Notoginseng on renal interstitial fibrosis and kidney-targeting treatment. METHODS: 100 healthy Sprague-Dawley rats were randomly divided into 5 groups: Unilateral ureteral obstruction (UUO) group, sham-operation (SOR) group, Radix Notoginseng (RN) group, compound Radix Notoginseng (CRN) group and Losartan (ARB) group. After operation, RN, CRN and ARB groups were intragastric administrated with RN (3 mL/d), CRN (3 mL/d) and ARB [20 mg/(kg x d)] respectively. Each group randomly included 18 rats for statistical analysis. The histological changes of renal interstitial tissues were observed by HE, Masson and PAS staining. Total kidney collagen content was determined by measuring the amount of hydroxyproline. The mRNA of alpha-SMA, collagen I and fibronectin were reverse transcribed and quantified by real-time PCR. The expression of alpha-SMA protein was assessed by immunohistochemistry and Western blot analysis. RESULTS: In UUO model, the obstructed kidney showed typical features of renal tubulointerstitial fibrosis, such as severe tubular loss, dilation, atrophy, infiltration of inflammatory cells, interstitial matrix deposition (P < 0.05). Partial correlation assay showed that the expression of alpha-SMA was related to the renal tubular injury (r = 0.55; P < 0.05). Administration of RN, CRN and ARB improved tubulointerstitial damage and collagen matrix accumulation induced by UUO in different degree. The expression of the alpha-SMA at mRNA and protein levels were significantly increased in the UUO group (P < 0.05), which was also suppressed by treatment with RN, CRN and ARB in different degree. Moreover, more effective role in preventing fibrosis was observed in CRN group than when compared with that of RN group. CONCLUSION: RN and CRN can inhibit UUO-induced renal interstitial fibrosis in rats, and CRN treatment is more effective than RN in reducing interstitial fibrosis.

Construction and expression of food-grade ß-galactosidase gene in Lactococcus Lactis.

Recombinant Lactococcus lactis MG1363/pMG36e-lacZ exhibiting high ß-galactosidase activities were constructed by us in the previous study. However, erythromycin resistance present in these recombinants restricted their practical application in food preparation. This study was conducted to delete the gene coding for erythromycin resistance present in recombinant L. lactis, as a result of which these bacteria express food-grade ß-galactosidase. In this study, the recombinant plasmid pMG36e-lacZ was digested with restriction enzymes BclI and HpaI and the food-grade plasmid FGZW was rebuilt. FGZW was transformed into Escherichia coli JM109 and L. lactis MG1363. Erythromycin resistance, enzyme activity determination, gene sequencing and SDS-PAGE analysis indicated that these new recombinant bacteria lost erythromycin resistance and its relevant gene but still expressed ß-galactosidase activities, although a decrease in the expression of ß-galactosidase of these new strains was observed. The ß-galactosidase food-grade expression system was successfully constructed and it could provide a new solution for the management of lactose intolerance. These results might promote the usage of gene-modified microorganisms and related technology in the food sector, which has the highest priority for food safety.

[Hemagglutinin gene of influenza A (H3N2) virus from human samples in the 2009 influenza epidemic in Chengdu].

OBJECTIVE: To study the antigenic and genetic characteristics of influenza A (H3N2) virus in the 2009 influenza epidemics in Chengdu. METHODS: The influenza virus strains were isolated with MDCK cells from 4869 samples taken from the sentinel surveillance in 2009 in Chengdu. Hemagglutination inhibition (HI) and RT-PCR reaction tests were performed to guide the extraction of viral RNA from the culture fluid of the influenza A (H3N2) virus. The hemagglutinin gene was obtained by RT-PCR and sequenced. RESULTS: The separation rates of swine influenza H1N1, H3N2, H1N1, and B were 25.2%, 7.2%, 4.5%, and 1.5% respectively. The epidemic peaked in summer and autumn. Four amino acids changed in A, B, and D antigenic and receptor binding sites: site160N>K, site174K>R/N, site189K>Q, site277R>Q. Glycosylation sites were inserted to sitel60 or absent at site181 in some isolated strains. CONCLUSION: Swine influenza H1N1 viruses dominated the 2009 Chengdu epidemic, with H3N2, H1N1, and B strains coexisting. The influenza A(H3N2) viruses had gene variations due to antigenic drift.

Ginsenoside Rg1 modulation on thrombospondin-1 and vascular endothelial growth factor expression in early renal fibrogenesis in unilateral obstruction.

Renal interstitial fibrosis is the major histopathological change seen in a variety of renal disorders and is closely related to renal dysfunction. Progressive interstitial fibrosis accompanied by the loss of renal tubules and interstitial capillaries typifies all progressive renal disease. Thrombospondin-1 (TSP-1) is a major angiogenic inhibitor. It is demonstrated that TSP-1 levels were correlated with the loss of glomerular and peritubular capillaries and TSP-1 could promote renal scarring by effects on the endothelium. It has been reported that ginsenoside Rg1 inhibited renal interstitial fibrosis in rats via suppressing the expression of TSP-1. The present study was designed to examine whether ginsenoside Rg1 could modulate the integrity of the microvasculature and hence affect the progression of renal fibrosis in a rat unilateral ureteral obstruction (UUO) model. In UUO control kidneys, associated with interstitial fibrosis, lower peritubular capillary densities were prominent. These changes were all improved by ginsenoside Rg1 treatment. Interestingly, ginsenoside Rg1 decreased the expression of TSP-1 and enhanced vascular endothelial growth factor (VEGF) expression. The results show for the first time that ginsenoside Rg1 can evidently inhibit renal interstitial fibrosis in rats with UUO. The mechanism might be related to suppression of the expression of TSP-1 and to repair of the peritubular capillary.

High expression of citron kinase predicts poor prognosis of prostate cancer.

Citron kinase (CIT) is a Rho-effector protein kinase that is associated with several types of cancer. However, the role of CIT in prostate cancer (PCa) is unclear. The current study utilized microarray data obtained from The Cancer Genome Atlas, which was analyzed via Biometric Research Program array tools. Additionally, reverse transcription-quantitative (RT-q)PCR was performed to compare the mRNA expression of CIT in PCa tissue and in benign prostatic hyperplasia. The protein expression of CIT was detected in a consecutive cohort via immunochemistry and CIT was screened as a potential oncogene in PCa. The results of RT-qPCR demonstrated that the mRNA expression of CIT was increased in PCa tissues. Furthermore, immunochemistry revealed that CIT protein expression was positively associated with age at diagnosis, Gleason grade, serum PSA, clinical T stage, risk group, lymph node invasion and metastasis. When compared with the low expression group, patients with a high CIT expression exhibited shorter survival rates, cancer specific mortalities (CSM) and biochemical recurrence (BCR). In addition, multivariate analysis revealed that CIT was a potential predictor of CSM and BCR. The results revealed that CIT is overexpressed during the malignant progression of PCa and may be a predictor of a poor patient prognosis.

Association between TCF7L2 gene polymorphisms and susceptibility to type 2 diabetes mellitus: a large Human Genome Epidemiology (HuGE) review and meta-analysis.

BACKGROUND: Transcription factor 7-like 2 (TCF7L2) has been shown to be associated with type 2 diabetes mellitus (T2MD) in multiple ethnic groups in the past two years, but, contradictory results were reported for Chinese and Pima Indian populations. The authors then performed a large meta-analysis of 36 studies examining the association of type 2 diabetes mellitus (T2DM) with polymorphisms in the TCF7L2 gene in various ethnicities, containing rs7903146 C-to-T (IVS3C>T), rs7901695 T-to-C (IVS3T>C), a rs12255372 G-to-T (IVS4G>T), and rs11196205 G-to-C (IVS4G>C) polymorphisms and to evaluate the size of gene effect and the possible genetic mode of action. METHODS: Literature-based searching was conducted to collect data and three methods, that is, fixed-effects, random-effects and Bayesian multivariate mete-analysis, were performed to pool the odds ratio (OR). Publication bias and study-between heterogeneity were also examined. RESULTS: The studies included 35,843 cases of T2DM and 39,123 controls, using mainly primary data. For T2DM and IVS3C>T polymorphism, the Bayesian OR for TT homozygotes and TC heterozygotes versus CC homozygote was 1.968 (95% credible interval (CrI): 1.790, 2.157), 1.406 (95% CrI: 1.341, 1.476), respectively, and the population attributable risk (PAR) for the TT/TC genotypes of this variant is 16.9% for overall. For T2DM and IVS4G>T polymorphism, TT homozygotes and TG heterozygotes versus GG homozygote was 1.885 (95%CrI: 1.698, 2.088), 1.360 (95% CrI: 1.291, 1.433), respectively. Four ORs among these two polymorphisms all yielded significant between-study heterogeneity (P < 0.05) and the main source of heterogeneity was ethnic differences. Data also showed significant associations between T2DM and the other two polymorphisms, but with low heterogeneity (P > 0.10). Pooled ORs fit a codominant, multiplicative genetic model for all the four polymorphisms of TCF7L2 gene, and this model was also confirmed in different ethnic populations when stratification of IVS3C>T and IVS4G>T polymorphisms except for Africans, where a dominant, additive genetic mode is suggested for IVS3C>T polymorphism. CONCLUSION: This meta-analysis demonstrates that four variants of TCF7L2 gene are all associated with T2DM, and indicates a multiplicative genetic model for all the four polymorphisms, as well as suggests the TCF7L2 gene involved in near 1/5 of all T2MD. Potential gene-gene and gene-environmental interactions by which common variants in the TCF7L2 gene influence the risk of T2MD need further exploration.

Ginsenoside Rb1, a panoxadiol saponin against oxidative damage and renal interstitial fibrosis in rats with unilateral ureteral obstruction.

OBJECTIVE: To investigate the possible protective effect and mechanism of ginsenoside Rb1 against oxidative damage and renal interstitial fibrosis on rats with unilateral ureteral obstruction (UUO). METHODS: In total, 80 male rats were randomly divided into 4 groups, 20 in each group: the sham operated group (SOR), UUO group, UUO with ginsenoside Rb1 treatment group (treated with intraperitoneal injection of 50 mg/ kg daily) and UUO with Losartan treatment group (as the positive control, treated with 20 mg/kg by gastrogavage per day). The rats were randomly sacrificed on day 3, 7 and 14 after surgery, respectively. The histopathologic changes of renal interstitial tissues were observed with Masson staining. The mRNA of transforming growth factor beta 1 (TGF-beta 1), collagen I and fibronectin were reversed transcribed and quantified by Real-time PCR. Enzyme-linked immunosorbent assay was used to quantitatively detect TGF-beta 1 and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. P47phox protein expression was assessed by immunohistochemistry and Western blot analysis. RESULTS: In the UUO model, the obstructed kidney showed typical features of progressive renal tubulointerstitial fibrosis, and the levels of TGF-beta1, collagen I and fibronectin increased (P<0.05). As compared with the UUO group, ginsennoside Rb1 significantly inhibited the interstitial fibrosis including tubular injury and collagen deposition, and decreased the levels of TGF-beta1 (P<0.05). Ginsenoside Rb1 also inhibited the heme oxygenase (HO-1) and 8-OHdG, two markers of oxidative stress (P<0.05). Moreover, ginsenoside Rb1 suppressed the expression of p47phox, a subunit of nicotinamide adeninedinucleotide phosphate (NADPH) oxidase (P<0.05). CONCLUSION: Ginsenoside Rb1 can obviously inhibit renal interstitial fibrosis in rats with UUO, its mechanism possibly via against the oxidative damage and suppressing TGF-beta1 expression.

[Development of a universal primers PCR-coupled liquid bead array to detect biothreat bacteria].

OBJECTIVE: To develop a fast, high-throughput screening method with suspension array technique for simultaneous detection of biothreat bacteria. METHODS: 16 S rDNA universal primers for Bacillus anthracis, Francisella tularensis, Yersinia pestis, Brucella spp.and Burkholderia pseudomallei were selected to amplify corresponding regions and the genus-specific or species-specific probes were designed. After amplification of chromosomal DNA by 16 S rDNA primers 341A and 519B, the PCR products were detected by suspension array technique. The sensitivity, specificity, reproducibility and detection power were also analyzed. RESULTS: After PCR amplification by 16 S rDNA primers and specific probe hybridization, the target microorganisms could be identified at genus level, cross reaction was recognized in the same genus. The detection sensitivity of the assay was 1.5 pg/microl (Burkholderia pseudomallei), 20 pg/microl (Brucella spp.), 7 pg/microl (Bacillus anthracis), 0.1 pg/microl (Francisella tularensis), and 1.1 pg/microl (Yersinia pestis), respectively. The coefficient of variation for 15 test of different probes was ranged from 5.18% to 17.88%, it showed good reproducibility. The assay could correctly identify Bacillus anthracis and Yersinia pestis strains in simulated white powder samples. CONCLUSION: The suspension array technique could be served as an opening screening method for biothreat bacteria rapid detection.

[Optimization of the REP-PCR molecular classification method of Salmonella and its application in drug-resistant strains].

OBJECTIVE: To optimize the reaction conditions of REP-PCR molecular classification method of Salmonella; primarily apply it in drug-resistant strains, and supply data to a system of Salmonella homology tracing. METHODS: Genomic DNA of Salmonella enteritidis 510041 was used as the template for PCR. Target sequences in 510041 genomic DNA were amplified with the primers designed according to the references. To optimize template concentration, Mg2+ concentration, primers concentration of PCR, the factor to be optimized was designed in different concentration grads and other factors were fixed. The REP-PCR fingerprint maps of 24 strains of Salmonella epidemic drug-resistant isolates were analyzed with the optimum reaction conditions. The 24 strains of Salmonella epidemic drug-resistant isolates were classified according to their fingerprint maps, and the classification results were compared to classification results form drug-resistant spectrum. RESULTS: The fingerprint map bands were most clear when 25 microl of the reaction system contained 100 ng template, 2.0 mmol/L Mg2+ and 0.4 micromol/L each primer. The REP-PCR fingerprint maps of different serotypes and serum clusters of Salmonella were different. The amplification products contained 2 to 6 bands, whose length were between 0.5 kb to 2.5 kb. The 24 strains of Salmonella isolates were classified in 15 types according to fingerprint maps and 7 types according to drug-resistant spectrum. CONCLUSION: The optimum REP-PCR molecular classification method of Salmonella was established fingerprint maps classification method was more sensitive than drug-resistant spectrum classification method.

[Construction and property study of recombinant Lactococcus lactis with non-fusion expressing of beta-galactosidase].

OBJECTIVE: To construct recombinant Lactococcus lactis strains exhibiting high beta-galactosidase activity in non-fusion way, and study their enzyme activities and enzyme secretion rates. METHODS: The recombinant plasmids pMG36e-lacZ 1.1480 and pMG36e-lacZ wch9901 which could express beta-galactosidase from Lactobacillus delbrueckii subsp. bulgaricus in non-fusion way in Escherichia coli were obtained and transformed into Lactococcus lactis subsp. lactis MG1363. The beta-galactosidase activity of resulting recombinant L. lactis in different incubation periods and lactose concentrations, and their enzyme secretion rates in different culture conditions were examined. RESULTS: Recombinant L. lactis carrying pMG36e-lacZ wch9901 (MG1363/pMG36e-lacZ wch9901) exhibited the highest beta-galactosidase activity. Its enzyme activity was (16.95 +/- 0.09) U/mg pro, which was 2.75 folds of that of the native counterpart; recombinant L. lactis reached its enzyme producing peak after grown for 24 h; decreased enzyme activity of recombinant L. lactis were observed when incubated in medium containing lactose; the beta-galactosidase expressed by recombinant strains could be secreted into the culture medium, and the highest secretion rate (27.09 +/- 0.05)% was observed when the culture medium contained 20 g/L of lactose and without erythromycin. CONCLUSION: High level expression of non-fusion beta-galactosidase with secretion in recombinant L. lactis strains was obtained. This will be very helpful for the further developing of live delivery bacteria of beta-galactosidase.

[Effects of ginsenoside Rb1 on TGF-beta1 induced p47phox expression and extracellular matrix accumulation in rat renal tubular epethelial cells].

OBJECTIVE: To investigate the effects of Ginsenoside Rb1 (G-Rb1) on the oxidative damage and extracellular matrix accumulation in rat renal tubular epethelial cells induced by transforming growth factor-beta1 (TGF-beta1). METHODS: Cultured normal rat renal tubular epethelial cells (NRK-52E) were divided into control group, 10 ng/mL TGF-beta1-induced group, G-Rb1 treated groups in which rat renal tubular epethelial cells were treated with different concentration of G-Rb1 (10 ng/mL, 20 ng/mL, 40 ng/mL) after TGF-beta1 induction, G-Rb1 40 ng/mL group and 100 nmol/L DPI(diphenyleneiodonium, an inhibitor of NADPH oxidase) group. Intracellular reactive oxidative species (ROS) level was measured by flowcytometry. p47phox protein expression was assessed by immunohistochemistry and western blotting method. The expressions of collagen I (Col-I) and fibronectin(FN) gene were measured by real-time PCR analysis. The protein level of Col-I and FN were quantitatively detected by enzyme-linked immunosorbent assay. RESULTS: TGF-beta1 at 10 ng/mL significantly increased the intercellular ROS production and p47phox expression (P < 0.05). The levels of Col-I and FN were also significantly up-regulated with the stimulation of 10 ng/mL TGF-beta1 (P < 0.05). Compared to TGF-beta1-induced group, G-Rb1 and DPI depressed TGF-beta1-induced ROS production and p47phox overexpression. Meanhile, G-Rb1 and DPI decreased the levels of Col-I and FN. CONCLUSION: G-Rb1 could inhibit TGF-beta1 induced ROS production and decrease the levels of Col-I and FN in a dose-dependent manner. The mechanism might be partly related to the suppression of p47phox expression.

[Development of a multiplex PCR-suspension array for simultaneous detection of five bioterrorism bacteria].

OBJECTIVE: To develop a rapid, high-throughput screening method of gene suspension array technique to simultaneously detect five bioterrorism bacteria: Bacillus anthracis, Francisella tularensis, Yersinia pestis, Brucella spp. and Burkholderia pseudomallei. METHODS: Highly validated specific primers were used to amplify diagnostic regions unique to each pathogen. Biotin labelled PCR products were hybridized to corresponding probes coupling on the unique sets of fluorescent beads. The hybridized beads were processed through the Bio-plex, which identified the presence of PCR products. RESULTS: Multiplex PCR-suspension array can detect five bioterrorism bacteria correctly with high specificity and high sensitivity, the results suggest the utility of suspension array system for high-throughput screening of bioterrorism samples. CONCLUSION: A multiplex PCR-suspension array for rapid detection of five bioterrorism bacteria was established.

[Carrying rate of Neissria meningitides in a healthy population in the Mianzhu post-earthquake residential area].

OBJECTIVE: To predict the possibility of epidemic outbreak of meningitis by testing Neissria Meningitides in a healthy population in the Mianzhu post-earthquake residential area. METHODS: A simple random sampling strategy was adopted to collect 887 throat swabs from a healthy population in the Mainzhu post-earthquake residential area. The TaqMan assay were performed to detect Neissria Meningitides. RESULTS: Three positive samples were identified. CONCLUSION: The carrying rate of Neissria Meningitides is not high enough to bring about an epidemic outbreak of Meningitis. However, efforts to maintain a hygienic environment in the post-earthquake residential area should be continued.

Non-fusion and fusion expression of beta-galactosidase from Lactobacillus bulgaricus in Lactococcus lactis.

OBJECTIVE: To construct four recombinant Lactococcus lactis strains exhibiting high beta-galactosidase activity in fusion or non-fusion ways, and to study the influence factors for their protein expression and secretion. METHODS: The gene fragments encoding beta-galactosidase from two strains of Lactobacillus bulgaricus, wch9901 isolated from yogurt and 1.1480 purchased from the Chinese Academy of Sciences, were amplified and inserted into lactococcal expression vector pMG36e. For fusion expression, the open reading frame of the beta-galactosidase gene was amplified, while for non-fusion expression, the open reading frame of the beta-galactosidase gene was amplified with its native Shine-Dalgarno sequence upstream. The start codon of the beta-galactosidase gene partially overlapped with the stop codon of vector origin open reading frame. Then, the recombinant plasmids were transformed into Escherichia coli DH5 alpha and Lactococcus lactis subsp. lactis MG1363 and confirmed by determining beta-galactosidase activities. RESULTS: The non-fusion expression plasmids showed a significantly higher beta-galactosidase activity in transformed strains than the fusion expression plasmids. The highest enzyme activity was observed in Lactococcus lactis transformed with the non-fusion expression plasmids which were inserted into the beta-galactosidase gene from Lactobacillus bulgaricus wch9901. The beta-galactosidase activity was 2.75 times as high as that of the native counterpart. In addition, beta-galactosidase expressed by recombinant plasmids in Lactococcus lactis could be secreted into the culture medium. The highest secretion rate (27.1%) was observed when the culture medium contained 20 g/L of lactose. CONCLUSION: Different properties of the native bacteria may have some effects on the protein expression of recombinant plasmids. Non-fusion expression shows a higher enzyme activity in host bacteria. There may be a host-related weak secretion signal peptide gene within the structure gene of Lb. bulgaricus beta-galactosidase, and its translation product may introduce the enzyme secretion out of cells in special hosts.

[Optimization and primary application of one molecular typing method of Salmonella, enterobacteia repetitive intergenic consensus sequences-based PCR in Salmonella].

OBJECTIVE: To optimize the reaction conditions of enterobacteia repetitive intergenic consensus sequences-based PCR (ERIC-PCR), a molecular typing method of Salmonella, study the genomic DNA ERIC-PCR fingerprint maps of Salmonella standard strains and epidemic isolates, and supply data for a system of Salmonella epidemiology investigation and homology tracing. METHODS: Genomic DNA of S. typhimurium was abstracted and used as the template for PCR. Enterobacteia repetitive intergenic consensus sequences were used as primers to amplify the target sequences in S. typhimurium genomic DNA: Amplification products were separated by agarose gel electrophoresis, and electrophoresis maps were analyzed by gel image analysis system. To optimize template concentration, Mg2+ concentration, primers concentration and annealing temperature of PCR, the factor to be optimized was designed in different concentration grads and other factors were fixed. Analyzed 16 Salmonella strains and one E. coli strain by PCR conditions optimized. RESULTS: The electrophoresis bands of amplified products were entire and most clear when template concentration was 100 ng/25 microl, Mg2+ concentration was 2.0 mmol/L, primers concentrations were 0.4 micromol/L respectively in the total volume of 25 microl of the reaction system, and annealing temperature was 52 degrees C. The ERIC-PCR fingerprint maps of different Salmonella strains with different sources were different. From 250 to 5000 bp, there were 3 to 13 bands, and in those there was a specific 250 bp band. CONCLUSION: Important reaction conditions of ERIC-PCR had been optimized in this study. ERIC-PCR technique could discriminate Salmonella strains isolated from different regions. It could be used in Salmonella epidemiology investigation and homology tracing, so as to make up for the flaws of the traditional classification methods for salmonella.

[Beta-galactosidase gene from Lactobacillus delbrueckii subsp. bulgaricus gets non-fusion expression in Escherichia coli].

OBJECTIVE: To construct the food-grade recombinant probiotic strain with high activity beta-galactosidase, the beta-galactosidase gene (lacZ)from Lactobacillus delbrueckii subsp. bulgaricus was in non-fusion expressed in Escherichia coli. METHODS: From Lb. delbrueckii subsp. bulgaricus lacZ gene, the DNA sequence containing Shine-Dalgarno (SD) and ATGA sequences between upstream 18 bp and downstream 1 bp at start codon ATG was selected as upstream primer for PCR amplifying lacZ gene. Then lacZ cDNA was inserted into expression plasmid pMG36e to construct recombinant expression plasmid. Recombinant plasmids were introduced into E. coli, and positive clones were screened. To identify the gene recombination, the recombinant plasmid was cut by restriction enzyme and sequenced. To identify the protein expression, the beta-galactosidase activities of recombinant strains were determined. RESULTS: The restriction maps of recombinant plasmids were acceptable. The gene inserted into the recombinant plasmid had more than 99% homology with the lacZ gene of Lb. delbrueckii subsp. bulgaricus. The enzyme activity and enzyme activity ratio of E. coli DH5 alpha carrying pMG36e-lacZ 1.1480 were 3.074 U/mL and 6.939 U/mg pro respectively. The enzyme activity and enzyme activity ratio of E. coli DH5a carrying pMG36e-lacZ wch9901 were 4.755 U/mL and 8.537 U/mg pro respectively. CONCLUSION: lacZ from Lb. delbrueckii subsp. bulgaricus have gotten non-fusion expression in E. coli. The SD and ATGA sequences we selected can introduce lacZ non-fusion expression in E. coli.

[Development of a molecular beacon real-time PCR for the rapid detection of Mycobacterium tuberculosis].

OBJECTIVE: To develop a molecular beacon real-time PCR for rapid detection of Mycobacterium tuberculosis. METHOD: One set of primers was selected from the IS6110 gene in GenBank and the corresponding molecular beacon probe was designed. The specificity and sensitivity of the developed method were evaluated by tested with 10 different bacteria species. The developed assay were also applied to the diagnosis of tuberculosis. RESULTS: Only Mycobacterium tuberculosis strains possessing IS6110 gene generated fluorescent signals, and no cross reaction was observed with other 9 bacteria. The detection limit was 4 copies/PCR reaction. 100 Mycobacterium tuberculosis strains were positive tested by Real-time PCR. CONCLUSION: The established molecular beacon real-time PCR is a rapid, specific and sensitive method, and is a beneficial supplement of traditional methods for the tuberculosis diagnosis.