Isolation and characterization of two novel plasmids from pathogenic Leptospira interrogans serogroup Canicola Serovar Canicola strain Gui44.

BACKGROUND: Previous genomic analysis of pathogenic Leptospira has identified two circular chromosomes but no plasmid. This study aims to investigate potential extrachromosomal elements of L.interrogans serovar Canicola strain Gui44. METHODOLOGY: Two novel plasmids, pGui1 and pGui2, were isolated from the pathogenic strain Gui44, using a modified alkaline lysis method. Southern blotting was performed to determine the presence and size of them. Then, 454 and Hiseq sequencing were applied to obtain and analyze the complete sequences of the two plasmids. Furthermore, real-time quantitative PCR and next-generation sequencing were used to compare relative copy numbers of the two plasmids with that of the chromosomes. Finally, after serial passages in vitro for more than 2 years, the strain Gui44 was subsequently re-sequenced to estimate stability of the two plasmids. PRINCIPAL FINDINGS: The larger plasmid, pGui1, 74,981 base pairs (bp) in length with GC content of 34.63%, possesses 62 open reading frames (ORFs). The smaller plasmid, pGui2, is 66,851 bp in length with GC content of 33.33%, and contains 63 ORFs. The replication initiation proteins encoded by pGui1 and pGui2 demonstrate significant sequence similarity with LA1839 (86% and 88%), a well-known replication protein in another pathogenic L.interrogans serovar Lai strain Lai, suggesting the ability for autonomous plasmid replication. Quantitative PCR and next-generation sequencing confirms a single copy of both plasmids and their stable presence in the strain Gui44 with in vitro serial passages after more than 2 years. Interestingly, the two plasmids both contain a significant number of novel genes (35 in pGui1 and 52 in pGui2). CONCLUSIONS: This report confirms the presence of two separate circular plasmids in serovar Canicola strain Gui44 and provides a new understanding of genomic organization, adaptation, evolution and pathogenesis of Leptospira, which will aid in the development of in vivo genetic manipulation systems in pathogenic Leptospira species.

[Preparation, in vitro and in vivo evaluation of cataplasm of white mustard seed varnish to prevent asthma].

The aim of the manuscript was to optimize formulations and preparation technologies of cataplasm of white mustard seed varnish, and to evaluate its anti-asthma effect on rats. The single factor experiments included spreading thickness, types of crosslinking agents, dihydroxyaluminum aminoacetate amount, sodium polyacrylate amount, types of adhesive agents with human sense as the evaluation index. Blank cataplasm matrix was optimized by the orthogonal experiment with the amount of glycerine, citric acid, and sodium carboxymethylcellulose as the major influential factors. Initial adhesive force, peeling strength and human sense were as the evaluation index. The optimized formulation of blank cataplasm were as followings: glycerine-water-ethanol-PEG400-dihydroxyaluminum aminoacetate-citric acid-sodium carboxymethylcellulose-sodium carboxymethylcellulose 2 : 8 : 0.8 : 0.4 : 0.07: 0.15 : 0.1 : 0.5. The active ingredients of white mustard seed, corydalis, and gansui root were extracted by alcohol extraction method. Asiasarum volatile oil was extracted by oil extractor. The optimized drug loading amount was 11% with initial adhesive force, peeling strength and human sense as the evaluation index. Asthma rats model were established by sensitized with ovalbumin and nose-scratching time as the evaluation index. High dose (17%) group of drug-loaded cataplasm had the obvious inhibition effect on nose-scratching time of rats (P = 0.037 < 0.05). In comparison, middle dose (11%), low dose (4%) and positive-control groups had no obvious inhibitive effect on rats. White mustard seed cataplasm supplied a novel choice for anti-asthma therapy. And the overall pharmacodynamics assessment will be carried out on molecular level in near future.

[Experimental study on rabbit periosteal osteoblasts and renal vascular endothelial cells indirect co-culture in vitro].

OBJECTIVE: To determine an optimal co-culture ratio of the rabbit periosteal osteoblasts (RPOB) and rabbit renal vascular endothelial cells(RRVEC) without direct contact for future study of bone tissue engineering. METHODS: RPOB and RRVEC in the ratios of 1:0(control group), 2:1(group 1), 1:1(group 2) and 1:2(group 3) were co-cultured by six well plates and cell inserts. Four days later, the proliferation of RPOB and RRVEC were examined through cell count. Differentiated cell function was assessed by alkaline phosphatase (ALP) activity assay and 3H proline incorporation assay. RESULTS: When RPOB and RRVEC were indirectly co-cultured, the proliferation of RPOB and 3H proline incorporation was higher in group 1 than in the other experimental groups and control group (P < 0.05). ALP activity of RPOB was higher in group 1 than in control group and group 3 (P < 0.05), but there was no significant difference between group 1 and group 2 (P > 0.05). CONCLUSION: These results suggest that RPOB and RRVEC co-cultured in a ratio of 2:1 is optimal for future study of bone tissue engineering.