ABSTRACT
BACKGROUND: The supplementation of betaine, an osmoprotective compatible solute, in the cultivation media has been widely used to protect bacterial cells. To explore the effects of betaine addition on industrial fermentation, Escherichia coli THRD, an L-threonine producer, was used to examine the production of L-threonine with betaine supplementation and the underlying mechanism through which betaine functions was investigated. RESULTS: Betaine supplementation in the medium of E. coli THRD significantly improved L-threonine fermentation parameters. The transcription of zwf and corresponding enzyme activity of glucose-6-phosphate dehydrogenase were significantly promoted by betaine addition, which contributed to an enhanced expression of zwf that provided more nicotinamide adenine dinucleotide phosphate (NADPH) for L-threonine synthesis. In addition, as a result of the betaine addition, the betaine-stimulated expression of enhanced green fluorescent protein (eGFP) under the zwf promoter within a plasmid-based cassette proved to be a transcription-level response of zwf. Finally, the promoter of the phosphoenolpyruvate carboxylase gene ppc in THRD was replaced with that of zwf, while L-threonine fermentation of the new strain was promoted by betaine addition. Conclusions: We reveal a novel mode of betaine that facilitates the microbial production of useful compounds. Betaine supplementation upregulates the expression of zwf and increases the NADPH synthesis, which may be beneficial for the cell growth and thereby promote the production of L-threonine. This finding might be useful for the production of NADPH-dependent amino acids and derivatives in E. coli THRD or other E. coli strains.
Subject(s)
Threonine/metabolism , Betaine/metabolism , Escherichia coli/metabolism , Osmosis , Pentose Phosphate Pathway , Reverse Transcriptase Polymerase Chain Reaction , Escherichia coli/enzymology , Fermentation , Glucosephosphate Dehydrogenase/metabolism , NADPABSTRACT
Cesarean section, as a stressor, inevitably produces negative emotions such as anxiety and may cause intraoperative discomfort and postoperative pain. Butorphanol is a commonly used analgesic in cesarean section. Butorphanols postoperative analgesia can reduce the incidence of postoperative respiratory depression and play a good sedative effect. In this study, we observed the effect of the combination of naloxone and butorphanol on postoperatively
analgesia. The result proved that the effect of naloxone and butorphanol on postoperative intravenous analgesia was significant, and the adverse effects of narcolepsy, dizziness, nausea and vomiting after operation were less. Medium
concentration of naloxone and high concentration of naloxone had better effect on labor pain, but the adverse reaction rate of high concentration naloxone was higher. Therefore, we suggest that the concentration of naloxone should be
0.200.30 Mug.kg[-1].h[-1]. At the same time, research shows that good psychological nursing can obviously relieve patients' anxiety, and also has a certain effect on reducing pain during and after operation
ABSTRACT
In order to investigate the effect ofArg-Gly-Asp (RGD) peptide-modified silk biomaterial on the adhesion and proliferation of bone marrow-derived mesenchymal stem cells (MSCs),MSCs of third generation were seeded onto the surface of RGD-decorated silk (silk-RGD group),silk alone (silk group) or tissue culture plate (TCP group).After incubation for 4 or 12 h,MSCs were examined quantitatively by using precipitation method for cell attachment.The cell proliferation,which was de-fined as cell density,was compared among the three groups after culture for 1,2,3,and 4 days.Cell skeleton,which was labeled fluorescently,was observed under laser confocal microscope after 24 h of culture.The results showed that cell adhesion rate in silk-RGD group was higher than in silk group (P<0.05),but similar to that in TCP group after incubation for 4 or 12 h (P>0.05).There were no sig-nificant differences in the cell proliferation among the three groups at different time points (P>0.05 for all).Laser confocal microscopy revealed that in silk-RGD group,MSCs,strongly fluorescently stained,spread fully,with stress fibers clearly seen,while in silk group,actin filaments were sparsely aligned and less stress fibers were found.It was concluded that RGD peptide could improve the ad-hesion of MSCs to the silk scaffold,but had no impact on the proliferation of the cells.