ABSTRACT
Biofilms are complex three-dimensional bacterial assemblages that attach to biotic or abiotic solid surfaces, and frequently embed within a self-produced matrix of extracellular polymeric substances. Biofilm formation is a microbial defense response to biotic and abiotic stresses, and a key factor for survival in adverse environments. A wide variety of microorganisms can colonize distant tissues of higher plants, such as leaves, vascular network and roots, and adhere to the surface of the tissues to form biofilms. The dynamic processes in forming biofilms in response to plant internal environment are key steps required for full virulence of phytopathogenic bacteria. Exploring the mechanisms involved in regulation of bacterial biofilms is important for understanding the plant-pathogens interactions. In this review, we summarized the research progresses related to the biofilms of bacterial phytopathogens, including biofilm characteristics, essential regulatory mechanisms and key signals affecting the transition between a planktonic lifestyle and multicellular behavior.
ABSTRACT
Objective To observe blood glucose values and serum insulin levels at different times after acupoint injection of insulin with PVP as a sustained release agent and analyze the correlation between them in SD Rats.Methods One hundred and forty-four male SD rats were randomized into groups A (acupoint injection of insulin alone), B (acupoint injection of sustained-release insulin) and C (control). At one hour after every group received an oral gavage of 40% glucose solution (2.2 g/kg), groups A and B were given point Zusanli injection and group C was not treated. In the three groups of rats, blood glucose values and serum insulin levels were measured at six time points: 0.5, 3, 6, 8, 10 and 24 hours after acupoint injection (in group C at the corresponding time points). In every group, the reaction of Point Zusanli region to the stimulation was observed by optical microscopy in at three time points: 3, 10 and 24 hours after acupoint injection.Results The glucose-lowering rate reached its peak at 3 hours after acupoint injection and then declined in groups A and B. The hypoglycemic effect tended to be stable at 6 hours after acupoint injection in group A and at 10 hours after acupoint injection in group B. The hypoglycemic effect was better in group B than in group A at 6 and 8 hours after acupoint injection (P<0.01). In group A, serum insulin reached its peak at 3 hours and tended to be stable at 6 hours after acupoint injection (P<0.05). Serum insulin levels were significantly lower in group B than in group A at four time pints: 0.5, 3, 6 and 8 hours after acupoint injection (P<0.05). An analysis of the correlation between rat serum insulin levels and the glucose-lowering rate showed a significant positive correlation in group A (P<0.01) and a low positive correlation in group B (P<0.05). In groups A and B of rats, clear stripes and complete structure of muscle fibers were seen with no obvious degeneration, necrosis and inflammatory reaction around point Zusanli at three time points: 3, 8 and 24 hours after acupoint injection; there were no obvious pathological changes compared with group C.Conclusions PVP as a sustained release agent can slow down the absorption rate of insulin in rat point Zusanli region. Meanwhile, it prolongs the continuous time of the hypoglycemic effect of insulin. There is a low correlation between serum insulin levels and the hypoglycemic effect, suggesting that acupoint injection with a sustained release agent can prolong the effect of acupoint injection of medicine.
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Compared with the transgenic approach, transient assays provide a convenient alternative to analyze gene expression. To analyze the relationship between miRNAs and their target genes, a rice protoplast system to detect target gene activity was established. The MIRNA and GFP-fused target sequence (or GFP-fused mutated sequence as a non-target control) were constructed into the same plasmid, and then delivered into rice protoplasts. The GFP expression level decreased significantly when the protoplasts were transfected with the plasmid containing GFP-fused target compared to that of the plasmid with non-target sequence either by fluorescence microscopy or qRT-PCR method. Two microRNA genes, osaMIR156 and osaMIR397, and their target sequences were used to prove the feasibility of the rice protoplast transient assay system. This method will facilitate large-scale screening of rice miRNA target in vivo, and may be suitable for functional analysis of miRNAs of other monocot plants that might share the evolutionarily conserved small RNA processing system with rice.
Subject(s)
Gene Targeting , Green Fluorescent Proteins , Genetics , MicroRNAs , Genetics , Oryza , Genetics , Plasmids , Protoplasts , Metabolism , RNA, Plant , Genetics , TransfectionABSTRACT
To gain insights into the function of potential post-translational modifications on the activity of the Cucumber mosaic virus (CMV)-encoded silencing suppressor protein 2b, one predicted phosphorylation site (S40) and two predicted ubiquitination/sumoylation sites (K22 and K39) in CMV-Q2b protein were individually or simultaneously mutated by site-directed mutagenesis methods. These Q2b mutants were inserted into plant expression vectors, expressed in plant leaves, and then analyzed for their silencing suppressor activities. The results showed that S40A mutation greatly impaired both the local and systemic silencing suppressor activity, and the K22R mutation has no significant effect on the suppressor activity, while the K22R/K39R double mutation reduced the systemic silencing suppressor activity. To test if the decrease of suppressor activity were due to protein accumulation changes, western blot were performed to monitor the protein level of Q2b mutants. The results indicated that mutations of both K22 and K39 to R or S40 to A all significantly reduced the accumulation of the Q2b protein in plants, while the single mutation of K22 to R did not alter the accumulation of Q2b protein, suggesting that two potential post-translational modification sites, K39 and S40, contribute to the suppressor activity and stability of 2b protein in plant cells.