Red-based recombineering has been widely used in Escherichia coli genome modification through electroporating PCR fragments into electrocompetent cells to replace target sequences. Some mutations in the PCR fragments may be brought into the homologous regions near the target. To solve this problem in markeless gene deletion we developed a novel method characterized with two-step recombination and a donor plasmid. First, generated by PCR a linear DNA cassette which comprises a I-Sec I site-containing marker gene and homologous arms was electroporated into cells for marker-substitution deletion of the target sequence. Second, after a donor plasmid carrying the I-Sec I site-containing fusion homologous arm was chemically transformed into the marker-containing cells, the fusion arms and the marker was simultaneously cleaved by I-Sec I endonuclease and the marker-free deletion was stimulated by double-strand break-mediated intermolecular recombination. Eleven nonessential regions in E. coli DH1 genome were sequentially deleted by our method, resulting in a 10.59% reduced genome size. These precise deletions were also verified by PCR sequencing and genome resequencing. Though no change in the growth rate on the minimal medium, we found the genome-reduced strains have some alteration in the acid resistance and for the synthesis of lycopene.
Chromosomes, Bacterial ; genetics ; DNA ; Endonucleases ; metabolism ; Escherichia coli ; genetics ; Genetic Engineering ; methods ; Recombination, Genetic ; Sequence Deletion

To explore and compare the response of the protease inhibitors or non-nucleoside reverse transcriptase inhibitors-based therapeutic impact on metabolic indices in hepatitis C virus (HCV)/human immunodeficiency virus(HIV) co-infected patients.A randomized,open,and control approach was performed to enroll 273 cases of HCV/HIV co-infected patients on their initial visits and to choose protease inhibitors(PIs group) or non-nucleoside reverse transcriptase inhibitors (NNRTIs group) based therapy treatments for one year.Laboratory results of metabolic indices before and after the treatment were collected.After treatment,the levels of triglyceride in NNRTIs and Pls groups were (1.93 ± 0.99) mmol/L and (1.62 ± 0.93) mmol/L respectively,high density lipoprotein-cholesterol were(1.28 ± 0.55) mmol/L and (1.08 ± 0.53) mmol/L,low density lipoprotein-cholesterol were (2.60 ± 1.44) mmol/L and (2.22 ± 1.16) mmol/L,fasting plasma glucose were (5.92 ± 1.21) mmol/L and (4.79 ± 0.47) mmol/L,serum creatinine were (70.5 ± 14.6) μmol/L and (56.6 ± 8.3) μmol/L,and serum amylase were(66.9 ± 27.5) U/L and(62.7 ± 33.8) U/L respectively.The difference between the two groups was statistically significant(all P＜0.01).There is a therapeutic impact on metabolic indices in patients wtih HCV / HIV co-infection after non-nucleoside reverse transcriptase inhibitors-based regimen.

OBJECTIVETo develop a bacteria expression system to produce the fusion protein of humanized anti-HBsAg scFV and interferon-alpha.

METHODSThe expression vector was constructed after cleaving the plasmids harboring the humanized anti-HBsAg scFv and interferon alpha respectively and ligating to linearized pET22b subsequence. The expression of fusion protein in E.coli was analyzed by SDS-PAGE. The binding activity and antiviral activity of the fusion protein was characterized by competing inhibition test and cytopathic effect reduction.

RESULTSThe plasmid harboring the in frame arranged fusion gene was constructed and identified. After induction for 12h, a new band close to 4.5 10(4) was observed using SDS-PAGE. Results of competing ELISA and cytopathic effect reduction showed the fusion protein retained its specific binding activity and antiviral activities.

CONCLUSIONSThe construction and expression of the fusion gene of humanized anti-HBsAg scFv and interferon in E.coli are successful.

Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; genetics ; Gene Expression ; Hepatitis B Antibodies ; biosynthesis ; genetics ; immunology ; Hepatitis B Surface Antigens ; immunology ; Hepatitis B virus ; drug effects ; Humans ; Immunoglobulin Fragments ; biosynthesis ; genetics ; immunology ; Interferon-alpha ; biosynthesis ; genetics ; pharmacology ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology

To demonstrate the fructose metabolism pathway in Bifidobacterium Longum NCC2705 and to construct its fermentation model, we explored the comparative proteome cultivating the strain on glucose or fructose, based on a proteomic reference map of B. longum NCC2705 constructed earlier. Then, we used matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry and electro-spray ionization tandem mass spectrometry (ESI-MS/MS) for differently expressed proteins identification. Furthermore, with semi-quantitative RT-PCR we determined the distinctively expressed proteins at the level of transcription. Proteomic comparison of glucose- and fructose-grown cells demonstrated much similarity. On the page of fructose there were all the enzymes and proteins that exist during the process of glucose degradation. We observed a greater variation of more than three-fold for the identified 9 spots representing 5 protein entries by MALDI-TOF MS. The sugar-binding protein specific to fructose (BL0033) and an ABC transporter ATP binding protein (BL0034) showed higher expression level from cells grown on fructose. It was also determined by semi-quantitative RT-PCR subsequently. BL0033 time course and concentration experiments showed that the induction time correlated to higher fructose concentration, and increased expression of BL0033. Fructose was catabolized via the same degradation pathway as glucose at the level of proteomics. BL0033 was induced by fructose. All results suggest that the uptake of fructose into the cell may be conducted by a specific ABC transport system, in which BL0033 and BL0034 as components might have played an important role.
Bifidobacterium ; chemistry ; genetics ; metabolism ; Culture Media ; Fermentation ; Fructose ; pharmacology ; Glucose ; pharmacology ; Proteome ; analysis ; genetics ; Proteomics ; methods

Artemisinin-based combination therapies (ACTs) are recommended to be the most effective therapies for the first-line treatment of uncomplicated falciparum malaria. However, artemisinin is often in short supply and unaffordable to most malaria patients, which limits the wide use of ACTs. Production of amorpha-4,11-diene, an artemisinin precursor, was investigated by engineering a heterologous isoprenoid biosynthetic pathway in Escherichia coli. The production of amorpha-4,11-diene was achieved by expression of a synthetic amorpha-4,11-diene synthase gene in Escherichia coli DHGT7 and further improved by about 13.3 fold through introducing the mevalonate pathway from Enterococcus faecalis. After eliminating three pathway bottlenecks including amorpha-4,11-diene synthase, HMG-CoA reducase and mevalonate kinase by optimizing the metabolic flux, the yield of amorpha-4,11-diene was increased by nearly 7.2 fold and reached at 235 mg/L in shaking flask culture. In conclusion, an engineered Escherichia coli was constructed for high-level production of amorpha-4,11-diene.
Alkyl and Aryl Transferases ; genetics ; Antimalarials ; metabolism ; Artemisinins ; metabolism ; Enterococcus faecalis ; genetics ; Escherichia coli ; genetics ; metabolism ; Metabolic Engineering ; methods ; Phosphotransferases (Alcohol Group Acceptor) ; metabolism ; Sesquiterpenes ; metabolism ; Transformation, Bacterial

Objective:To understand the degree of professional autonomy of nurses in Pediatric Nursing Alliance and the status of pediatric nursing practice environment, which providing guidance for the development of a series of specialized training in the alliance.Methods:Stratified random sampling method was used to conduct a questionnaire survey on nursing staff of different professional levels in Pediatric Nursing Alliance, which through the questionnaire star by using the questionnaire general information and training demand questionnaire, nurses practice professional autonomy scale, pediatric nursing staff structural empowerment questionnaire and nursing practice influencing factors questionnaire through the questionnaire star.Results:The total score for professional autonomy of nurses in the pediatric alliance was 192.66±18.63, the structural empowerment ( OR=1.137, 95% CI=1.084-1.194), lack of caring team ( OR=2.763, 95% CI=1.443-5.292) and performance evaluation ( OR=0.498, 95% CI= 0.274-0.908), specialized education and professional experience ( OR=0.548, 95% CI= 0.334-0.871) were affecting the clinical nursing practice. Conclusion:The degree of professional autonomy of nurses in the Pediatric Nursing Alliance is in the middle and high level. Key factors affecting nursing practice including insufficient structural empowerment, lack of opportunities to continue learning, lack of nursing teams, lack of effectiveness evaluation and the lack of specialized education and work experience, which guiding the pediatric nursing alliance to continuously deepen the connotation of pediatric nursing professional and innovative team collaboration new model, utilize the advantages of resources to actively cultivate specialized nursing research personnel, carry out multi-disciplinary and cross-disciplinary cooperation, improve the nursing quality evaluation index system, so as to enhance the professional nursing service capacity and value.