The genus Rhodococcus is of considerable interest in recent years, stemming from their diverse applications in biodegradation, bioremediation, biotransformation and biosurfactant. Using Nocardia/Rhodococcus-Escherichia coli shuttle plasmid pNV18.1 as the backbone vector, we tested the driven efficiency of promoters Ptac and PlacZ of E. coli and Pami-1/Pami-2 of R. ruber in host R. rhodochrous ATCC 33278 by overexpression of nitrile hydratase. Results showed that the specific activity of nitrile hydratase per dry cell weight in engineered Rhodococcus strains driven by Ptac, Pami-1, Pami-2 and PlacZ was 7.5, 6.3, 5.3 and 1.8 times of that in the wild, respectively. It indicated that these promoters could be well recognized by RNA polymerase of Rhodococcus. We further expressed the beta-galactosidase reporter gene (lacZ) in R. ruber driven by promoter PlacZ. Results indicated that lacZ was an appropriate reporter gene for genetic or metabolic engineering research of Rhodococcus.
Escherichia coli ; genetics ; Gene Expression Regulation, Bacterial ; Genes, Reporter ; genetics ; Lac Operon ; genetics ; Promoter Regions, Genetic ; genetics ; Rhodococcus ; enzymology ; genetics ; beta-Galactosidase ; genetics

OBJECTIVE：To study the improvement effects of sinapic acid （SA）on PC 12 cell damage induced by Aβ1-42，and to investigate its effect on brain-derived neurotrophic factor （BDNF）/tyrosine kinase B （TrkB）/extracellular signal-regulated kinase （ERK）signaling pathway. METHODS ：PC12 cells were divided into blank group ，model group ，SA low-dose and high-dose groups（50，100 μmol/L）. Except for blank group ，cell damage was induced by Aβ1-42 in other groups ；24 h after modeling ， administration groups were added with the corresponding solution and cultured for 24 h. Morphological changes of cells in each group were observed. Cell survival rate ，mRNA expression and protein level of BDNF ，protein expression of TrkB ，ERK1/2 and phosphorylated ERK 1/2（p-ERK1/2）were detected. p-ERK/ERK ratio was calculated. RESULTS ：Compared with blank group ，the model group had shorter synapses ，looser intercellular junctions ，poor adhesion ，dim cytoplasm and more granules in cytoplasm. Cell survival rate and mRNA expression and protein level of BDNF ，the relative expression of TrkB and p-ERK 1/2 protein，p-ERK/ ERK ratio were significantly decreased （P＜0.05 or P＜0.01）. Compared with model group ，in SA high-dose group the pathological changes of the cells were significantly improved ，the survival rate of the cells ，the mRNA expression and protein level of BDNF，the relative expression of TrkB and p-ERK 1/2 protein， p-ERK/ERK ratio were significantly increased （P＜0.05 or P＜ 0.01）. CONCLUSIONS：SA can i mprove PC 12 cells damage induced by Aβ1-42，the mechanism of which may be associated with activating BDNF/TrkB/ERK signaling pathway. qq.com