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OBJECTIVE@#This study aimed to investigate whether the VCA0560 gene acts as an active diguanylate cyclase (DGC) in Vibrio cholerae and how its transcription is regulated by Fur and HapR.@*METHODS@#The roles of VCA0560 was investigated by utilizing various phenotypic assays, including colony morphological characterization, crystal violet staining, Cyclic di-GMP (c-di-GMP) quantification, and swimming motility assay. The regulation of the VCA0560 gene by Fur and HapR was analyzed by luminescence assay, electrophoretic mobility shift assay, and DNase I footprinting.@*RESULTS@#VCA0560 gene mutation did not affect biofilm formation, motility, and c-di-GMP synthesis in V. cholerae, and its overexpression remarkably enhanced biofilm formation and intracellular c-di-GMP level but reduced motility capacity. The transcription of the VCA0560 gene was directly repressed by Fur and the master quorum sensing regulator HapR.@*CONCLUSION@#Overexpressed VCA0560 functions as an active DGC in V. cholerae, and its transcription is repressed by Fur and HapR.
Assuntos
Vibrio cholerae/genética , Biofilmes , Percepção de Quorum , Mutação , Regulação Bacteriana da Expressão Gênica , Proteínas de Bactérias/genéticaRESUMO
Objective@#To study the effects of serum and its components on biofilm formation of Pseudomonas aeruginosa. @*Methods@#96 well microplates combined with crystal violet staining was used to detect the effects of serum, albumin and transferrin on biofilm formation of Pseudomonas aeruginosa. And confocal laser scanning microscope was used to observe the morphology of the biofilm. @*Results@#The biofilm of PAO1 was significantly enhanced from 2.26±0.42 to 3.42±0.08（t=4.71, p<0.01）with horse serum and but reduced to 0.807±0.10（t=4.71,p<0.01） by human serum; And the total biofilm biomass was significantly increased and clump-changed with horse serum, but decreased and scattered in distribution by human serum. Besides, horse serum could also enhance the biofilm formation of part of the clinical isolates of Pseudomonas aeruginosa, however, human serum could inhibit the biofilm formation of all of the clinical isolates. And 2.5g/L albumin could significantly enhance the biofilm of PAO1 from 1.96±0.22 to 2.54±0.18（t=3.55，p<0.05）, but 5 g/L could reduce the biofilm of PAO1 from 1.85±0.36 to 0.84±0.24（t=4.03，p<0.05）.@*Conclusion@#Horse serum and albumin could significantly promote the biofilm formation of Pseudomonas aeruginosa, but human serum and transferrin could decrease its biofilm formation.
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DNA marked-assisted selection of medicinal plants accelerated the breeding and promotion of new cultivars, and guaranteed the healthy development of Chinese medicinal materials industry. The first disease-resistant cultivar of notoginseng, namely "Miaoxiang Kangqi 1", served as the object of study. We evaluated the Kangqi's resistance of seeds, seedlings and root against the pathological bacteria (Fusarum oxysporum) of root rot. Compared to the traditional cultivars, the disease index of notoginseng seeds declined by 52.0% after inoculation for seven days; the death rate of seedlings and disease index of root respectively decreased by 72.1% and 62.4% after inoculation for 25 days. Additionally, the growth inhibition ratio of notoginseng seeds and seedlings declined after inoculation. The seeds, seedlings and roots of "Miaoxiang Kangqi 1" showed significantly resistant to root rot. The evaluation of disease-resistance of Kangqi provided the basis for the popularization of new cultivar and guaranteed the favoring conduct of notoginseng pollution-free cultivation.