Objective To identify small non-coding RNAs encoded by plasmid pPCP1 and investigate their roles in biofilm formation, stress tolerance and/or virulence in Yersinia pestis.Methods Seven plasmid pPCP1-encoded sRNAs were identified by RNA-seq results in Y.pestis in our previous studies.Northern blot was used to validate the presence of the seven sRNAs.The sRNA-deletion mutants were constructed via λ-Red homologous recombination system.The biofilm formation, high salt tolerance and virulence of the phenotypes were compared between Y.pestis WT strain and sRNA mutants.Results and Conclusion The expression of seven pPCP1-encoded sRNAs was validated and the transcript length detected by Northern blotting corresponded to the length observed by RNA-seq.On this basis, five sRNA-deletion mutants were obtained.The capacity of biofilm formation was weakened upon deletion of sR3446.The tolerance of sR3446, sR3457, sR4338 and sR4340 mutants was found weakened in vitro compared to that of wild-type strain,but the tolerance of sR6143 was found increased.Slight virulence attenuation was found in two sRNA mutants ( sR4338 and sR4340 ) .The results suggest that pPCP1-deriving sRNA might be implicated in stress response, biofilm and virulence in Y.pestis.

Objective To develop an up-converting phosphor technology based lateral flow assay ( UPT-LF) to detect ricin toxin ( RT) quickly, accurately and quantitatively.Methods Ricin-monoclonal antibodies were prepared and their affinity was evaluated before four types of monoclonal antibodies with the highest titer were applied to couple with the up-converting phosphor nano-particles ( UCP-NPs) as the bio-conjugate and disperse on the analysis membrane as the test line, respectively.Following systematic optimization to establish the RT-UPT-LF strip, the sensitivity, precision, quantita-tive ability and specificity of RT-UPT-LF were evaluated.Results The detection could be accomplished within 15 min and the detection limit of the RT-UPT-LF assay could reach 0.5 ng/ml within the quantitative detection range of 0.5-1000 ng/ml.Other non-specific toxins at a concentration of 1000 ng/ml did not cause any non-specific reactions.Conclusion The developed RT-UPT-LF strip provides a new means for on-site quantitative detection of ricin toxin.

Objective To observe the damage degree and expression pattern of Caveolin-3 mRNA by ischemia-reperfusion injury in rabbits of skeletal muscle cell at different phases.Methods In this study,from April 2013 to December 2013,30 lower limbs of 15 Chinese White Rabbits were used and divided into two groups:all the left lower limbs were experimental group,which were made as an experimental model of ischemia-reperfusion injury by occluding left common iliac artery using noninvasive vascular.All the right lower limbs without surgical treatment were the control group.Gastrocnemius samples were obtained at 4h and 8h after reperfusion and handled by HE staining and observed by optical microscopy.By Real-time PCR,Caveolin-3/GAPDH mRNA were detected.Results HE stain showed:in control group,there was no edema,degeneration and inflammatory cell infiltration; in experi-meatal group,muscle cell degeneration had occured at ischemic 5 h.The edema was aggravated,a large number vacuole were formed and inflammatory cell were infiltrated at 4 h reperfusion.Reperfusion injury at 8h significantly reduced compared to 4 h.The Caveolin-3/GAPDH mRNA expression levels by SPSS 19.0 showed:Control group:1.026 ± 0.065,1.004 ±0.037,1.022 ±0.051,experimental group:1.159 ±0.073,1.445 ±0.053,1.208 ±0.058 at ischemic 5 h,4 h and 8 h reperfusion,respectively.On-line analysis of variance cases of ischemic 5 h and 4 h reperfusion and 8 h reperfusion,the experimental group than the control group were increased,with statistical significance (P ＜ 0.05).The experimental group of ischemic 5 h and 8 h reperfusion was no significant difference (P ＞ 0.05).It showed Caveolin-3 mRNA expression levels in ischemia-reperfusion 8 h group returned to normal.There was significant statistical difference between the ischemic 5 h and 4 h reperfusion (P ＜ 0.05).There was significant statistical difference between the 4 h reperfusion and 8 h reperfusion (P ＜ 0.05).Conclusion The expression of Caveolin-3 in experimental group showed a trend of first increased and then decreased.The expression levels of Caveolin-3 mRNA in skeletal muscle cells after ischemia-reperfusion injury is consistent with the development and progression of muscle cell damage.The results indicate that Caveolin-3 may play a control role in the injury and recovery of skeletal muscle cell.

Objective:To express and purify hemoglobin receptor(HgbA) and its partial fragment(HgbAF) from Haemophilus ducreyi and to develop a sandwich ELISA for the detection of H.ducreyi infection.Methods:The HgbA,a hemoglobin-binding outer membrane protein of H.ducreyi and its partial fragment(HgbAF) were expressed by cloning the genes of hgbA and its 705bp fragment into pET30a and pET28a respectively,and the expressing products were purified from E.coli BL21 with Ni-NTA-His affinity chromatography.The polyclonal antibodies were developed by immunizing rabbits with the rHgbA and rHgbAF.The anti-rHgbA IgG and anti-rHgbAF IgG were purified respectively by saturated amine sulphate precipitation,and their immunoactivity with rHgbA and rHgbAF was tested by Westen blot and ELISA analysis.A Sandwich ELISA was developed for the detection of chinical infection of H.ducreyi using the specific polyclonal antibodies.Results:The HgbA and its partial fragment,HgbAF of H.ducreyi,were expressed and purified successfully by cloning their genes respectively.The results obtained by Western blot analysis showed that each of the antibodies could react with both antigens,rHgbA and rHgbAF.The results of the ELISA analysis showed that H.ducreyi strain was strongly positive,and all other bacteria,including H.influenzae and the bacteria known to relate to genital ulcers were negative.The results of the ELISA analysis showed that the minimum amount of rHgbA detected was 1.56 ng/ml and the minimum number of CFU of H.ducreyi detected was 2?105 cfu/ml in buffer and 1?106 cfu/ml in pus.Conclusion:HgbA and its partial fragment,HgbAF of H.ducreyi are expressed and purified successfully.The polyclonal antibodies developed by immunizing rabbits using rHgbA and rHgbAF could react not only with rHgbA and rHgbAF,but also with H.ducreyi specifically.They do not react with other bacteria,including H.influenzae and the bacteria known to relate to genital ulcers.So the ELISA based on the polyclonal antibodies was specific for the detection of H.ducreyi.Although the level of sensitivity of the ELISA may not be sufficient to detect H.ducreyi in all clinical specimens,further work to increase the sensitivity could potentially make this assay a valuable tool in areas where chancroid is endemic.

Objective To develop an up-converting phosphor technology-based lateral-flow ( UPT-LF) assay for rapid detection of Listeria monocytogenes, named LM -UPT-LF.Methods Monoclonal antibodies against p 60, which was the specific virulence factor of L.monocytogenes,were prepared and covalently conjugated with up-converting phosphor nanopar-ticles (UCP-NPs) as bio-label.Then, LM-UPT-LF was established with double-antibody sandwich mode-based LF assay. Detection performance , including sensitivity and specificity , was evaluated .Results The samples with absolute contamina-ted amount of L.monocytogenes cells <10, 10-99, and 100-1000 cfu could be significantly detected as positive after in-cubation at 20 h, 18 h, and 16 h, respectively.Other 13 kinds of food-borne pathogens with concentration of 109 cfu/ml did not caused any non-specific reaction .Conclusion The established LM-UPT-LF assay could detect L.monocytogenes with high sensitivity , specificity and simplicity and provides an alternative method for food safety control .

Objective To prepare recombinant plasminogen activator(Pla) protein in E.coli BL21 cells that can be used in studying interactions between Yersinia pestis proteins and immunologic diagnosis of plague.Methods The pla gene was amplified by PCR and cloned into the pET28a expression vector.E.coli BL21 competent cells were transformed with the recombinant vectors, and isopropyl-β-D-thiogalactopyranoside ( IPTG) was added to induce expression of Pla protein. The expressed protein was detected by SDS-PAGE electrophoresis.The inclusion bodies of Pla protein were denatured in 8 mol/L urea, and then refolded using gradient urea solutions.The purified protein was identified by SDS-PAGE electrophoresis and Western blot.Results and Conclusion The constructed expression vector was demonstrated to be correct through agarose gel electrophoresis and sequencing.The recombinant Pla protein was accumulated as an inclusion body in E.coli, and the overexpression product was mainly a target protein, the yield of which was very high.SDS-PAGE purity of the bioactive Pla protein was obtained by denaturing and refolding the inclusion bodies.This study provides a simple and quick method for highly efficient preparation of biologically active Pla protein.

Objective:To obtain oligonucleotide aptamers which can specifically bind to Bacillus anthracis spores by in vitro selection protocol-SELEX (system evolution of ligands by exponential enrichment).Methods:An in vitro synthesized 78 mer random DNA library (≤1014-15types of different DNAs ) was subjected to 15 rounds of selection using SELEX method against spores of B.anthracis vaccine strain A.16R. Binding of the aptamers to spores was visualized by biotin-streptavidin-horseradish peroxidase system.Results:PCR amplification band pattern of the first round selection was different from that of the ninth round. The binding assay demonstrated that D absorbance at 450 nm of the fifteenth round pool increased 9 times as compared with that of the first round , and the D absorbance increased with the increment of aptamers′ quantity binding to spores. Conclusions: A set of aptamers with considerable binding affinity to B.anthracis spores were successfully selected from the initial random DNA pool.

Objective To identify critical genes in evolution of Staphylococcus aureus (S.aureus).Methods A total of 2457 genes from two whole genomes of S.aureus strains were amplified for fabricating whole genome microarray,which was employed for comparative genome hybridization (CGH) analysis of 23 strains of divergent MRSA clones,including ST239-spa t037 and ST239-spa t030.Representatives of differential genes were confirmed by PCR.Results Four gene clusters were identified to be associated with evolution of major epidemic MRSA clones.The four gene clusters were specific to ST239-spa t030,and belonged to three known genomic islands (vSa4,prophage ΦSa1 and ΦSa3).Eight genes were variable expressed in ST239-spa t030 MRSA from different coutries.Conclusion The acquisition of genomic islands vSa4,prophage ΦSa1 and ΦSa3 enhanced the virulence and resistance of ST239-spa t030 MRSA,and contributed to its rapid replacement of ST239-spa t037 MRSA in China.

Objective To develop and evaluate an up-converting phosphor technology-based lateral flow assay ( UPT-LF) for detection of aflatoxin M1(AFM1) in milk powder and milk.Methods AFM1-UPT-LF was established with up-converting phosphor ( UCP) nano-particles as the bio-label of competitive mode based LF assay .Sensitivity, quantitative ability and precision were evaluated using simulated AFM 1-postive samples with serial standard concentrations .The qualita-tive and quantitative detection performance of AFM 1-UPT-LF was evaluated with reference to liquid chromatography-mass spectrography ( LC-MS) to detect samples of milk powder and milk simultaneously .Results AFM1-UPT-LF could conduct qualitative and quantitative detection without sample pretreatment within 20 min.The detection limit of AFM1-UPT-LF reached 0.1 μg/kg in milk powder and 0.3 μg/L in milk.There was good linearity ranging from 0.1 to 0.7 μg/kg and 0.3 to 0.7 μg/L for milk powder and milk, respectively.The sensitivity, specificity and receiver operating characteristic ( ROC) area under the curve ( AUC) of AFM1-UPT-LF for qualitative result could meet the need of national standards for AFM1 limit in dairy products.After statistical analysis, there was no significant difference (milk powder: t=0.66, P>0.05;milk:t=1.01, P>0.05) between AFM1-UPT-LF and LC-MS for quantitative detection .Conclusion The good qualitative and quantitative detection performance of AFM 1-UPT-LF for milk powder and milk makes possible on-site rapid detection of AFM1 in dairy products quantitatively .

Objective To develop an up-converting phosphor technology based lateral flow (UPT-LF) assay for rapid detection of Salmonella paratyphi A, S.paratyphi B, Escherichia coli O157 ∶H7 and Vibrio parahaemolyticus. Methods With up-converting phosphor nano-particles ( UCP-NPs ) as the bio-marker, four double-antibody-sandwich mode based UPT-LF strips for detecting the above mentioned four pathogens were prepared respectively and their sensitivi-ty, accuracy, linearity and specificity were evaluated .Furthermore, the feasibility of detecting bacteria in food samples was evaluated by different food samples artificially contaminated with less than 10 CFU target pathogens .Results The sensitivi-ty of UPT-LF assays for four pathogens was 105 ~106 CFU/ml with excellent specificity .The four strips had a good linear response with the linear fitting coefficient of determination (r) for each target pathogen ranging from 0.985 to 0.996.The positive rate of detecting pathogens from samples was acceptable .Conclusion The four developed UPT-LF strips provide a new choice for rapid , specific and sensitive and quantitative detection of S.paratyphi A , S.paratyphi B, E.coli O157∶H7 and V.parahemolyticus.