[VcDsbA enhances bioflim formation by stimulating MSHA expression in Vibrio cholera].

Objective: Biofilm plays an important role during the infection cycle of Vibrio cholerae. In this study, we try to demonstrate the role of VcDsbA in the biofilm formation of V. cholerae. Methods: By making the VcDsbA inframe knock-out construct, the vcdsbA null mutant (ΔdsbA) strain was obtained. And the complemented strain (CΔdsbA) was constructed by transferring a plasmid-coded VcDsbA expressed under the control of arabinose to ΔdsbA strain. Crystal violet staining assay was used to analyze the biofilm formation in the wild-type (WT), ΔdsbA and CΔdsbA strains. V. cholerae strains containing msh promoter luxCDABE transcriptional fusion were used to analyze the transcriptional level. Results: The ΔdsbA and CΔdsbA strains were constructed successfully. Biofilm formation analysis shows that the ability of biofilm formation of ΔdsbA was significantly reduced compared with WT, whereas CΔdsbA could form even stronger biofilm than WT does. Luminescence expression by Pmsh shows that VcDsbA enhanced msh expression. VcDsbA enhances the biofilm formation of V. cholerae by involving in the regulation of msh expression level. VcDsbA up-regulates msh expression probably through helping the folding of a msh expression activator. Conclusion: VcDsbA plays an important role in the biofilm formation of V. chlerae, which makes the bacteria better survive in their living niche.

Molecular cloning and expression of glutathione S-transferases involved in propargite resistance of the carmine spider mite, Tetranychus cinnabarinus (Boisduval).

The carmine spider mite (CSM) Tetranychus cinnabarinus has become a serious pest in China and has developed resistance to acaricide propargite as it is used to control mites worldwide including T. cinnabarinus. In this study, a resistant colony of T. cinnabarinus, PRR34 (37.78-fold resistant ratio), was established after 34 generations of propargite selection, and cross-resistance patterns of 7 other acaricides were determined in comparison with a susceptible strain (SS). The contribution of detoxification enzymes to propargite tolerance were investigated using biological, biochemical and molecular approaches. Enzyme inhibitor synergist tests suggested glutathione S-transferases (GST) involvement in propargite-resistance of PRR34, and GST activity against 1-chloro-2,4-dinitrobenzene (CDNB) was correlated with the development of resistance. Eight novel GST genes (TcGSTd1, TcGSTd2, TcGSTm1, TcGSTm2, TcGSTm3, TcGSTm4 and TcGSTm5) were cloned, and phylogenetic analysis showed that the eight GST genes were most closely related to GST family delta and mu from Tetranychusurticae. Quantitative RT-PCR revealed that the expression level of GSTs in PPR34 strain increased in larvae, nymphs and adults, while decreased in eggs compared with that of SS. Collectively, these results support a role of GSTs in mediating resistance to propargite in the PRR34 strain. TcGSTd1,TcGSTd2 and TcGSTm2 genes might play significant roles in propargite resistance of CSM, especially at adult stage. This is the first attempt to define specific genes involved in GST mediated propargite resistance of T. cinnabarinus at the transcriptional level.