Bacteriophages are abundantly distributed viruses , which are able to infect bacteria .Bacteriophages are becoming a focus of attention for microbiologists , as they can cause pollution to the fermentation industry and might serve as alternative therapies for antibiotic-resistant pathogenic bacteria .Effective bacteriophage infection normally involves adsorp-tion, injection, replication, assembly and release , against which bacteria have developed various resistance strategies .The research progress in the bacteriophage resistance mechanisms is briefly reviewed in this paper .

Objective To investigate the self-efficacy levels and its influencing factors of community-based patients with chronic obstructive pulmonary diseases (COPD).Methods From October 2008 to March 2009,320 community COPD patients were recruited from a Shanghai community.They undertook questionnaires,scale survey and pulmonary function testing so as to investigate the influencing factors of self-efficacy.Results The total scale of self-efficacy was 74.24 ± 9.50 and the level of selfefficacy in 286 cases( 89.4％ )was intermediate.The knowledge of COPD,social supports,forced expiratory volume at 1 second (FEV1)/forced vital capacity (FVC) and self-management level were entered into regression equation and could explain 57.1％ of the total variance of independent variables.Conclusions The knowledge of COPD,social supports,FEV1/FVC and self-management level are the major influencing factors of self-efficacy in the COPD patients.We should improve the knowledge of disease and strengthen the psychological care and social supports so as to improve their quality of life.

Objective To investigate the type of plasmid map of Y. pestis in the R. opimas natural plague loci in Junggar Basin. Methods A total of 39 plasmid DNA of Y. pestis which were isolated from the natural plague loci of Junggar Basin, Tianshan Mountain, Kunlun Mountain, Qinghai-Tibet Plateau and In-ner Mongolia were extracted by the methods of Kado and Liu. The plasmid map was analyzed by the methods of agarose gel eleetrophoretogram. Results Two types of plasmid map were found in 26 Y. pestis which were isolated from Junggar Basin. Of them 23 were 6 × 106, 45 × 106 and 65 × 106 type of plasmid map, and 3 were 6 × 106, 45 × 106 and 72 × 106 type. Conclusion There are two types of plasmid map in the R. opi-mus natural plague loci in Junggar Basin. One type, which is the dominant type in this area, is 6 × 106, 45 × 106 and 65 × 106 type. This type is also similar to the dominant plasmid map type of the nature plague loci of Tianshan Mountain, Kunlun Mountain, Qinghai-Tibet Plateau and Inner Mongolia. The other type is 6 × 106, 45 × 106 and 72 × 106 type, and this type is new plasmid map type of Y. pestis in our country.

Objective To explore the relationship between self-efficacy and self-management behaviors of patients with chronic obstructive pulmonary disease (COPD).Methods A total of 350 COPD patients form 5 residents' committees in shanghai were recruited by using a convenient sampling method and were scored using Chinese Self-efficacy Scale (CSES)and the self-management behaviors scale.Spearman's correlation analysis was performed to detect the relation of self-efficacy with self-management behaviors.Results Three hundred and twenty adults were included in this investigation,and their average FEV1/FVC was (57.86 ± 7.06)％,average score of self-efficacy was 74.2 ± 9.5.In self-management behaviors,time spent on physical exercise was (16.2 ± 33.9) minutes per week,and endurance exercises accounted for (109.0±49.0) minutes per week.The score of cognitive symptom management practice was 0.9 ± 1.0 and communication with physicians was 0.7 ± 0.8.Total score of self-efficacy was positively correlated with self-management behavior in each dimension (r values were 0.522,0.407,0.330 and 0.044,respectively ; all P ＜ 0.01).Conclusions Self-efficacy and self-management behaviors of COPD patients need to be improved,and self-efficacy may be related to self-management behaviors.

Objective To explore the primary teeth caries status of preschoolers in Pudong community and its relevant factors of parental knowledge-belief-practice (KBP).Methods Using stratified random cluster sampling,a total of 1 179 children from 9 kindergartens in Hudong community in Pudong new area were examined.Oral cavity check-ups and parental questionnaire survey were conduced to understand the primary teeth caries rate of preschoolers and its related influencing factors.Results The prevalence rate of primary teeth caries was 53.2％ and DMFT 2.79.The prevalence rate of primary teeth caries had statistical significance in different age groups (P ＜ 0.05).Multi-factor analysis showed that the influencing factors of primary teeth caries were age (P ＜ 0.05),parental education level (P ＜ 0.05),parental assistance of teeth brushing (P ＜ 0.05),children eating sweets before bedtime (P ＜ 0.05) and parental awareness for treating primary teeth (P ＜ 0.05).Conclusions The prevalence rate of primary teeth caries is high among the preschoolers of Pudong.And age,parental education level,parental preventive knowledge of teeth caries and poor eating habits are significant factors correlated with the incidence of dental caries in children.

Objective By the method of multiple polymerase chain reaction (PCR),we intend to amplify different regions (DFR) of Yersinia pestis DNA,and to establish a multiple DFR genotyping technique for detection of Yersinia pestis.Methods According to the product size of 23 DFRs and pMT plasmid,24 primers were optimized and combined,then multiple primers in one PCR reaction system were added,and positive template DNA was amplified.Meanwhile,200 wild strain DNAs were amplified by multiple PCR and normal PCR,to verify the coincidence rate of the two methods.Results Totally 24 target segments were amplified through the positive DNA template.Through different permutation and combination,24 primers were optimized and combined into 9 groups.Totally 200 wild strain DNAs were used for verification,the coincidence rate of multiple PCR and normal PCR was 100％.Conclusions Multiple PCR is applicable and feasible for DFR genotyping of Yersinia pestis.It is an efficient,economic and high accuracy experimental method for large quantities of Yersinia pestis DFR genotyping.

Objective:To purify a kind of deoxyribonuclease from earthworm Eisenia foetida (named earthworm DNase, EDNase) and study its characteristics. Methods: Acetone precipitation, ion-exchange chromatography, high performance liquid chromatography, SDS-PAGE, CapiUary electrophoresis isoelectric focusing and MALDI-TOP MS were used for the study. Results: This purified protocol improved 137-fold purification and 45.6 % recovery of enzyme activity. The molecular mass of EDNase was estimated to be 63 000. Mg2+ , Mn2+ and Ca2+ were strong inhibitors of EDNase, while Na+ slightly increasd the enzyme activity. The enzyme was completely stable in the pH range from 4. 4 to 5.2 and had a pH optimum of 4.8. The optimum temperature was 37℃ and the enzyme was stable up to 40 ℃. The pI of the enzyme was 6. 20. Km and Vmax for the enzyme were 1.52 g/L and 4. 89 mg/(mL ·min), respectively, with calf thymus DNA as substrate. The enzyme was able to degrade chromosemal DNA, linear λbacteriophage DNA as well as supereoiled plasmid DNA, but didn' t display any RNase activity. Conclusion: This kind of deoxyribonuclease possesses unique characteristics, which is different from the deoxyribonucleases which we have known before.

Objective To construct a technical platform for scarless gene modification of Yersinia pestis and to study the functions of its specific genes.Methods The resistance fragment, including upstream and downstream homologous arms of targeted regions, was reamplified by asymmetric PCR.The amplicons were introduced into Y.pestis harboring plasmid pKD46.With the induction of L-arabinose,the recombinant related enzymes: Exo, Beta and Gam, were expressed to guide the homologous recombination.A donor plasmid, pKSI-1, which carried the desired modification fragment flanking by I-SceⅠ recognition sites, was introduced into Y.pestis as the second step of λ-Red recombination with the help of pREDTKI.Results and Conclusion Two mutant strains:△waaA and waaA(△9nt), were successfully constructed for Y.pestis strain 201.Scarless modification introduces no extra modification to the genome, and it is ideal for comprehensive functional genomic studies.

Abstract: Objective To observe the phenotypic characteristics of 3 wild-type plague phages under different experimental environments, providing scientific evidence for the identification of phage biological characteristics and the study of their interaction with host bacteria in the future. Methods The sensitivity of 3 wild-type plague phages were detected by using liquid culture method, emisolid medium method and micro-liquid culture method based on OmniLog TM microbial identification system. Results The growth result based on LB liquid medium showed that the growth of plague phage 476 for 20-24 hours at both 28 ℃ and 37 ℃was better than that of plague phages 087 and 072204 at 37 ℃, and the growth of plague phages 087 was better than that of plague phages 072204 at 37 ℃. With the attenuated plague bacterium EV76 as the host bacterium, phage 476 was able to form visible plaque on double-layer agar medium for 20-20 hours at both 28 ℃ and 37 ℃, phages 087 and 072204 were only able to form opaque plaque on double-layer agar medium for 20-24 hours at 37 ℃. The growth results based on OmniLogTM system showed that when plague phage was lysed in EV76 strain at 33 ℃, the first row appeared as a straight line with a peak of no more than 100 in the 96-well microplate curve chart. As the phage quantity decreased, the dilution plate appeared with growth curve similar to EV76 strain in turn, and the color of tetrazolium dyes in the experimental wells gradually deepened as the phage number decreased and the host bacteria number increased. Therefore, it indicates that phage 476 was sensitively at both 28 ℃ and 37 ℃, while phage 087 and 072204 were temperature-dependent only at 37 ℃ to attenuated plague bacterium EV76. Conclusions The lysing ability of 3 wild-type plague phages are temperature-dependent, and the growth results are consistent under the three experimental conditions.

Objective To purify native F1 antigen from E pestis EV76 strain and determine its ef-ficacy against Y. pestis. Methods A new purification method was developed by the substitution of physical disruption ( glass beads) for organic solvent ( acetone and toluene) one, followed by a combination of ammo-nium sulfate fractionation and SephacrylS-200HR column filtration chromatography. Groups of mice were im-munized with F1 antigen adsorbed to 25% aluminum hydroxide in PBS by intramuscular route. The immu-nized animals were challenged subeutaneously(s, c. ) with 104 CFU of Y. pestis strain 141 at 18 weeks after the primary immunization. Results There was no IgG titre difference between two groups of mice with one-dose immunization, whereas in the two-dose immunization groups, the group F1-40 μg induced a statistically higher antibody titre than the group F1-20 μg. Complete protection was observed for animals immunized with purified F1 antigen by s.c. route. In contrast, the control mice immunized with aluminum hydroxide suc-cumbed to a same dose of Y. pestis 141 challenge. Conclusion This purification strategy is a simple and ef-fective, and can be operated in a large scale. Native F1 antigen extracted from Y. pestis EV76 is highly im-munagenic, and can be used as a key antigen component to develop sub-unit vaccine of plague.