This study was aimed to explore the features of clustered regularly interspaced short palindromic repeats (CRISPR) structures in Shigella by using bioinformatics. We used bioinformatics methods, including BLAST, alignment and RNA structure prediction, to analyze the CRISPR structures of Shigella genomes. The results showed that the CRISPRs existed in the four groups of Shigella, and the flanking sequences of upstream CRISPRs could be classified into the same group with those of the downstream. We also found some relatively conserved palindromic motifs in the leader sequences. Repeat sequences had the same group with corresponding flanking sequences, and could be classified into two different types by their RNA secondary structures, which contain "stem" and "ring". Some spacers were found to homologize with part sequences of plasmids or phages. The study indicated that there were correlations between repeat sequences and flanking sequences, and the repeats might act as a kind of recognition mechanism to mediate the interaction between foreign genetic elements and Cas proteins.
Base Sequence ; Clustered Regularly Interspaced Short Palindromic Repeats ; Computational Biology ; Genome, Bacterial ; Plasmids ; Shigella ; genetics

Objective To explore the influence of elevating the oxygen pressure on articular chondrocytes in vitro.Method A hydrogen peroxide induced human articular chondrocyte damage model was established.Then the articular chondrocyte viability was detected using the CCK-8 kit.Collagen Ⅱ(COL Ⅱ),The expression levels of aggrecan (ACAN),matrix metalloproteinase 13 (MMP13) and adisintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) were detected using the realtime PCR and Western blotting.Result The viability of articular chondrocytes improved at 12 h but decreased at 24 h after the stimulation of hydrogen peroxide.Twenty-four hours later,the average expression level of COL Ⅱ and ACAN decreased(P＜0.05),while that of MMP13 and ADAMTS5 elevated(P＞0.05).Conclusion Hydrogen peroxide induced elevation of the extracellular oxygen pressure can influence the synthesis and degradation of the articular chondrocyte extracellular matrix.

Objective To detect the distribution of clustered regularly interspaced short palindromic repeat(CRISPR)associated protein genes cas1 and cas2 in Shigella and to understand the characteristics of CRISPR with relationship between CRISPR and related characteristics on drug resistance. Methods CRISPR associated protein genes cas1 and cas2 in Shigella were detected by PCR,with its products sequenced and compared.Results The CRISPR-associated protein genes cas1 and cas2 were found in all the 196 Shigella isolates which were isolated at different times and locations in China. Consistencies showed through related sequencing appepared as follows:cas2,cas1 (a) and cas1(b)were 96.44%,97.61%and 96.97%,respectively. There were two mutations including 3177129 site(C→G)and 3177126 site(G→C)of cas1(b)gene in 2003135 strain which were not found in the corresponding sites of Z23 and 2008113. Results showed that in terms of both susceptibility and antibiotic-resistance,strain 2003135 was stronger than Z23 and 2008113. Conclusion CRISPR system widely existed in Shigella,with the level of drug resistance in cas1(b) gene mutant strains higher than in wild strains. Cas1(b)gene mutation might be one of the reasons causing the different levels of resistance.

There are several kinds of PICC tip positioning method in clinic at present,including body surface measurement, X-ray tip location, ultrasound guided assisted positioning and venous ECG. The limitations of former three methods were that the physical structure of the individual differences may affect the results of surface measurement accuracy; the differences of visual and subjective judgment may exist between different observers and the patient may easy to be affected by X-ray radiation; B ultrasound guidance assisted positioning can not show the whole process, and some of the central vein in the discount or too deep in the catheter tip can not be judged. The localization of the P wave in the center of the tube was observed by the technique of the intra cavity ECG localization to judge the position of the catheter tip, which can be positioned in a timely manner in order to reduce the risks caused by incorrect position of the catheter tip, avoid postoperative X-ray radiation and readjust the tube, reduce the cost of inspection. This study summarizes the PICC tip localization method, the principle, advantage, stability, influence factor and the method of improving the stability of the electrocardiogram.

Objective To investigate the association between phage-mediated shiga toxin and molecular distribution of CRISPR in Escherichia (E.) coli O26:H11 or NM.Methods A total of 135 E.coli O26:H11 or NM strains were collected from NCBI database.Software CRT and CRISPR Finder were used to extract CRISPR and Excel was used to assign the spacer of unique number and type CRISPR.And the relationship between CRISPR and stx phage was analyzed.Results All the 135 E.coli O26:H11 or NM strains had the CRISPR.For CRISPRI,CRISPR2.1,CRISPR2.2 and CRISPR3-4,19,22,1 and 1 subtypes were found,respectively.According to the four CRISPR sites,the strains could be divided into 40 subtypes.Stx-phage was only observed in the group C of CRISPR.Compared with E.coli of stx-phage negative,E.coli with stx-phage harbored more spacers.Conclusions CRISPR loci was extensively existed in E.coli O26:H11 or NM,and many subtypes were found in these strains.The presence of stx-phage was related to the molecular distribution of CRISPR in E.coli O26:H11 or NM.CRISPR might be a valuable biomarker to identify strains with high virulent potential.

OBJECTIVETo detect the distribution of clustered regularly interspaced short palindromic repeat (CRISPR) associated protein genes cas1 and cas2 in Shigella and to understand the characteristics of CRISPR with relationship between CRISPR and related characteristics on drug resistance.

METHODSCRISPR associated protein genes cas1 and cas2 in Shigella were detected by PCR, with its products sequenced and compared.

RESULTSThe CRISPR-associated protein genes cas1 and cas2 were found in all the 196 Shigella isolates which were isolated at different times and locations in China. Consistencies showed through related sequencing appeared as follows: cas2, cas1 (a) and cas1 (b) were 96.44%, 97.61% and 96.97%, respectively. There were two mutations including 3177129 site(C→G)and 3177126 site (G→C) of cas1 (b) gene in 2003135 strain which were not found in the corresponding sites of Z23 and 2008113.

RESULTSshowed that in terms of both susceptibility and antibiotic-resistance, strain 2003135 was stronger than Z23 and 2008113.

CONCLUSIONCRISPR system widely existed in Shigella, with the level of drug resistance in cas1 (b) gene mutant strains higher than in wild strains. Cas1 (b) gene mutation might be one of the reasons causing the different levels of resistance.

Bacterial Proteins ; genetics ; CRISPR-Associated Proteins ; genetics ; Clustered Regularly Interspaced Short Palindromic Repeats ; Drug Resistance, Bacterial ; genetics ; Mutation ; Shigella ; genetics