ABSTRACT
In order to construct an Escherichia coli strain with high sensitivity and specificity to detect arsenic ion using fluorescence as reporter, a sensitive strain to arsenic ion was obtained by knocking out the gene arsB that acts as an arsenic efflux pump. The pET28b vector containing arsenite detecting cassette Pars-arsR-egfp was constructed and then transformed into arsB deleted mutant. Measuring conditions of this constructed whole-cell biosensor were optimized and its linear concentration range, limit of detection and specificity were determined. This modified biosensor was much more sensitive than that using wild-type strain as host. The optimal detection range of As³⁺ concentration was 0.013 to 42.71 μmol/L, and the limit concentration of detection was as low as 5.13 nmol/L. Thus we successfully improved the sensitivity of arsenite detecting biosensor by modification of E. coli genome, which may provide useful strategies for development and optimization of microbial sensors to detect heavy metals.
Subject(s)
Arsenites , Biosensing Techniques , Escherichia coli , Genetics , Gene Knockout Techniques , Metals, Heavy , Microorganisms, Genetically-Modified , Water , ChemistryABSTRACT
Objective To investigate the protective role of senegenin(SEN)in the mouse ischemia-reperfusion injury and its mechanism.Methods Mice were divided at random into control group(the ligature was placed but not ligated for 225 min),is-chemia-reperfusion model group(the anterior descending coronary artery remained ligated for 45 min and then reperfused for 180 min)and SEN treatment group(30 mg/kg SEN was used 10 min before reperfusion).The myocardial infarct size was meas-ured by using Evans blue-TTC staining.Fluorescence assay was employed to detect the activity of Caspase-1 2 and Caspase-3 to assess the myocardial apoptosis.Western blot was used to detect the expression of two endoplasmic reticulum stress (ERS) markers,GRP78 and CHOP,in infarcted myocardia.Results Compared with the control group,the myocardial infarct size was significantly increased,the activities of Caspase-12 and Caspase-3 were increased by 4.71 fold and 3.37 fold,respectively,and the expression levels of ERS markers GRP78 and CHOP were conspicuously elevated in the ischemia-reperfusion model group.Pretreatment with SEN(30 mg/kg)could significantly reduce the myocardial infarct size,the activities of Caspase-12 and Caspase-3 and the expression levels of GRP78 and CHOP when compared with those in the ischemia-reperfusion model group and there was significant difference between the two groups(P<0.05 or P<0.01).Conclusion SEN can protect against the myocardial ischemia-reperfusion inj ury by ameliorating ERS-mediated myocardial apoptosis in mice.
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ObjectiveTo explore the relationship between the T3394C mutation of the mitoehondrial DNA ND1 gene and type 2 diabetes mellitus (T2DM) in the elderly. MethodsDirect sequencing of PCR product was applied to study the T3394C mutation of mitochondrial DNA in 340 unrelated individuals in T2DM patients (90 cases of elderly patients, 250 cases of non-elderly patients) and 265 normal controls (130 cases of elderly controls, 135 cases of non-elderly controls) from Zhejiang province. The mutation was analyzed by DNASTAR and Antheprot 5.0 softwares. ResultsThe T3394C mutation of mitochondrial DNA was found in 5 of 90 elderly T2DM patients (5.6%),1 of 130 elderly controls(0.8%), and 2 of 250 non-elderly T2DM patients (0.8%). The incidence of the mutation was significantly different between the elderly T2DM patients and elderly controls(P＜0.05), as well as between the elderly T2DM patients and non-elderly T2DM patients(P＜0.05). The T3394C mutation caused the change of the ND1 protein secondary structure. ConclusionsThe T3394C mutation of the mitochondrial DNA ND1 gene may contribute to the pathogenesis of T2DM in the elderly with other genetic and environment factors.
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AIM: To study the activation and the immune regulation of paecilomyces cicadidae total polysaccharides on macrophages in old rats. METHODS: The ability of devouring neutral red and stimulating index in the alveolar macrophages (AM) and peritoneal macrophages (PM) were observed. The activities of lactate dehydrogenase (LDH), acid phosphatase (ACP) and arginase (Arg) were detected by automatic biochemistry analyzer. The shape and structure of spleen macrophages were observed by electron microscope. RESULTS: Compared with control group, the activity of the LDH/ACP/Arg in the AM or PM and in the culture fluid of the AM or PM were significantly increased (P