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1.
Artigo em Inglês | MEDLINE | ID: mdl-34719233

RESUMO

A new deposition mechanism is presented in this study to achieve highly reversible plating and stripping of magnesium (Mg) anodes for Mg-ion batteries. It is known that the reduction of electrolyte anions such as bis(trifluoromethanesulfonyl)imide (TFSI-) causes Mg surface passivation, resulting in poor electrochemical performance for Mg-ion batteries. We reveal that the addition of sodium cations (Na+) in Mg-ion electrolytes can fundamentally alter the interfacial chemistry and structure at the Mg anode surface. The molecular dynamics simulation suggests that Na+ cations contribute to a significant population in the interfacial double layer so that TFSI- anions are excluded from the immediate interface adjacent to the Mg anode. As a result, the TFSI- decomposition is largely suppressed so does the formation of passivation layers at the Mg surface. This mechanism is supported by our electrochemical, microscopic, and spectroscopic analyses. The resultant Mg deposition demonstrates smooth surface morphology and lowered overpotential compared to the pure Mg(TFSI)2 electrolyte.

2.
J Immunol Res ; 2021: 4084566, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34734090

RESUMO

Nonalcoholic fatty liver disease (NAFLD) is closely related to glycolipid metabolism and liver inflammation. And there is no effective drug approved for its clinical therapy. In this study, we focused on mangiferin (Man) and explored its effects and mechanisms on NAFLD treatment based on the regulation of glycolipid metabolism and anti-inflammatory in vivo and in vitro. The results exhibited that Man can significantly attenuate liver injury, insulin resistance, and glucose tolerance in high-fat diet- (HFD-) induced NAFLD mice and significantly reduce fat accumulation and inflammation in hepatic tissue of NAFLD mice. The transcriptome level RNA-seq analysis showed that the significantly different expression genes between the Man treatment group and the HFD-induced NAFLD model group were mainly related to regulation of energy, metabolism, and inflammation in liver tissue. Furthermore, western blots, real-time PCR, and immunohistochemistry experiments confirmed that Man significantly activated the AMPK signal pathway and inhibited NLRP3 inflammasome activation and pyroptosis in NAFLD mice. In in vitro cell experiments, we further confirmed that Man can promote glucose consumption and reduce intracellular triglyceride (TG) accumulation induced by free fatty acids in HepG2 cells and further that it can be blocked by AMPK-specific inhibitors. Western blot results showed that Man upregulated p-AMPKα levels and exhibited a significant AMPK activation effect, which was blocked by compound C. At the same time, Man downregulated the expression of NLRP3 inflammasome-related proteins and inhibited the activation of NLRP3 inflammasome, alleviating cell pyroptosis and inflammation effects. These results indicate that Man anti-NAFLD activity is mediated through its regulation of glucolipid metabolism by AMPK activation and its anti-inflammatory effects by NLRP3 inflammasome inhibition. Our study indicates that Man is a promising prodrug for the therapy of NAFLD patients.

3.
Front Psychol ; 12: 770457, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34744947

RESUMO

Under the background of globalization and the popularity of distance learning ande-learning channels provided on the Internet, teaching methods that encourage the self-directed learning of students are becoming popular. There is an increasing number of domestic teachers joining in the practice for change. The various teaching methods that make the students acquire critical thinking skills can be summarized as learning by doing, critical thinking learning, multiple assessments, team discussion teaching, and cooperative learning. With the teachers of the universities in Shanghai as the questionnaire analysis objects, a total of 360 copies of questionnaires were distributed, and 256 valid copies were retrieved, with the retrieval rate of 71%. The research results are summarized as follows. (1) The "mental adaptation and engagement of students" is the most emphasized dimension, followed by the "professional development of teachers," "administration and parent support," and "material and teaching strategy." (2) The top five emphasized indicators, among 14, are the ordered cultivation of self-study and thinking habits, the development of the professional community for the collaborative lesson study of teachers, the support and cooperation of the president and the administration, adoption of heterogeneous grouping, and co-learning, discussion and cooperative learning. According to the results, it is expected to propose more definite practice directions for teachers intending to attempt such a teaching method, as well as provide some specific suggestions for the first movers of Sharestart.

4.
Int J Biol Macromol ; 193(Pt A): 933-940, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34728307

RESUMO

The heat shock protein 70 family (HSP70) is among the most varied HSP family with respect to structure and function. The phloem-feeding insect Bemisia tabaci (Gennadius) is an important pest of cotton, vegetables and ornamentals that transmits several plant viruses and causes enormous agricultural losses. In this study, two new HSP70 genes (Bthsp70-2 and Bthsp70-3) were isolated from the MED cryptic species B. tabaci, an important phloem-feeding pest of vegetables and ornamentals. Bthsp70-2 and Bthsp70-3 encoded proteins comprised of 652 and 676 amino acids, and the deduced proteins were closely related to other HSP70s in Hemiptera. Expression analyses using real-time quantitative PCR indicated that Bthsp70-2 and Bthsp70-3 were induced in B. tabaci pupae and adults during high and low thermal stress. Bthsp70-2 and Bthsp70-3 exhibited similar, but not identical, expression patterns when exposed to different durations of high temperature stress. Oral ingestion of dsBthsp70 reduced the expression level of Bthsp70-2 and Bthsp70-3 in B. tabaci and increased the mortality of B. tabaci during heat shock. In conclusion, Bthsp70-2 and Bthsp70-3 exhibit different expression patterns during thermal stress, thus expanding the roles of HSPs in B. tabaci.

5.
Insects ; 12(11)2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34821841

RESUMO

Rapid cold hardening (RCH) is a rapid and critical adaption of insects to sudden temperature changes but is often overlooked or underestimated as a component of survival. Thus, interspecific comparisons of RCH are needed to predict how phenotypes will adapt to temperature variability. RCH not only enhances cold survival but also protects against non-lethal cold injury by preserving essential functions such as locomotion, reproduction, and energy balance. This study investigated the difference in basal cold tolerance and RCH capacity of L. trifolii and L. sativae. In both species, the cold tolerance of pupae was significantly enhanced after short-term exposure to moderately cold temperatures. The effect of RCH last for 4 h in L. sativae but only 2 h in L. trifolii. Interestingly, L. trifolii adults had a RCH response but L. sativae adults failed to acclimate. Short-term acclimation also lowered the supercooling point significantly in the pupae of both species. Based on these results, we propose a hypothesis that these differences will eventually affect their competition in the context of climate change. This study also provides the basis for future metabolomic and transcriptomic studies that may ultimately uncover the underlying mechanisms of RCH and interspecific competition between L. trifolii and L. sativae.

6.
Zootaxa ; 4996(2): 343-352, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34810526

RESUMO

A new genus of family Perlodidae, Tibetisoperla Huo Du, gen. nov. is described with one new species from Tibet, China. Male of the new genus is characterized by the divided tergum 10 with several large apical erect setae, highly reduced vesicle on sternum 8, and the sclerotized paraprocts with separate apical sclerite.


Assuntos
Insetos , Neópteros , Distribuição Animal , Animais , China , Masculino , Tibet
7.
Zootaxa ; 5071(1): 143-150, 2021 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-34810676

RESUMO

Two new species of Leuctridae (Plecoptera) from Wuyi Mountains, Fujian Province of southeastern China, Rhopalopsole wuyishanensis sp. nov. and Rhopalopsole trichotoma sp. nov. are described and illustrated. The new species are compared to the closely related species of the R. dentata group and the R. shaanxiensis group in this genus, respectively.


Assuntos
Insetos , Neópteros , Distribuição Animal , Animais , China
8.
Zootaxa ; 5068(1): 115-124, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34810719

RESUMO

Two new species of Nemouridae stoneflies, Amphinemura oblonga Rehman, Du Zhao sp. nov. and Mesonemoura diqinga Rehman, Du Zhao sp. nov., are described from China (Yunnan Province, Diqing Tibetan Autonomous Prefecture, Shangri-la city, Gezan township, Langdu Village). Diagnosis, description of terminalia, illustration of terminalia appendages and terminalia similarities with closely related species are provided and discussed.


Assuntos
Insetos , Neópteros , Distribuição Animal , Animais , China
9.
Zootaxa ; 5040(4): 528-538, 2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34811026

RESUMO

We recently examined specimens of the Rhopalopsole from Hubei, Ningxia and Shaanxi, China and three new synonyms of Rhopalopsole sinensis Yang Yang, 1993 are established: Rhopalopsole furcata Yang Yang, 1994, Rhopalopsole hongpingana Sivec Harper, 2008 and Rhopalopsole ningxiana Li Yang, 2010 are synonymized with Rhopalopsole sinensis Yang Yang, 1993. We also place Rhopalopsole furcospina (Wu, 1973) as a nomen dubium. Long hairs on the antennae of R. sinensis thought to be diagnostic also occur on Rhopalopsole ampulla Du Qian, 2011, Rhopalopsole exiguspina Du Qian, 2011, and Rhopalopsole memorabilis Qian Du, 2014. We provide new images of several species to facilitate identification.


Assuntos
Insetos , Neópteros , Animais
10.
Zootaxa ; 5032(4): 563-576, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34811109

RESUMO

Hemacroneuria violacea Enderlein, 1909 is discovered and re-described from four provinces of southern China. A similar new species of Hemacroneuria from the Nanling Mountains is proposed. Meanwhile, Brahmana flavomarginata Wu, 1962 is transferred into Hemacroneuria, and the status of Kiotina spatulata Wu, 1948 is discussed in this paper.


Assuntos
Insetos , Neópteros , Distribuição Animal , Animais , China
11.
Front Psychol ; 12: 752188, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34616348

RESUMO

The emergence of e-books with the characteristics of easy access and reading any time anywhere is a subject of debate in academia. Topics include the use of e-books in libraries, their use in support teaching, new possibilities for reading activities, potential uses for library archives, and the motivation and intention of e-book users. Students at Guilin University of Technology participated in a survey. Of the 300 copies of the questionnaire distributed, 263 valid copies were returned, a retrieval rate of 88%. The research results show that (1) Usability and reading need are the key factors in e-book usage. Usability refers to convenient keyword searches, portability, and any time reading. E-books are considered to make searching and reading large amounts of data easier. (2) E-books are not restricted to time and space so that the overall reading quantity is increasing. Readers become accustomed to reading e-books, and the quality of their digital reading is gradually enhanced. (3) Students should complete e-book use courses offered by libraries to enhance their familiarity with e-books and their use of e-book software, thereby enhancing postgraduate student readers' e-book information literacy. The results of the research prompt suggestions to enhance the promotion of reading and e-book information to encourage student readers' e-book reading intention.

12.
Chemosphere ; : 132705, 2021 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-34710448

RESUMO

Atmospheric reaction mechanism and dynamics of phenol with nitrogen dioxide dimer were explored by the density functional theory and high-level quantum chemistry combined with statistical kinetic calculations within 220-800 K. The nitric acid and phenyl nitrite, the typical aerosol precursors, are the preponderant products because of the low formation free energy barrier (∼8.7 kcal/mol) and fast rate constants (∼10-15 cm3 molecule-1 s-1 at 298 K). Phenyl nitrate is the minor product and it would be also formed from the transformation of phenyl nitrite in NO2-rich environment. More importantly, kinetic effects and catalytic mechanism of a series of metal-free catalysts (H2O, NH3, CH3NH2, CH3NHCH3, HCOOH, and CH3COOH) on the title reaction were investigated at the same level. The results indicate that CH3NH2 and CH3NHCH3 can not only catalyze the title reaction by lowering the free energy barrier (about 1.4-6.5 kcal/mol) but also facilitate the production of organic ammonium nitrate via acting as a donor-acceptor of hydrogen. Conversely, the other species are non-catalytic upon the title reaction. The stabilization energies and donor-acceptor interactions in alkali-catalyzed product complexes were explored, which can provide new insights to the properties of aerosol precursors. Moreover, the lifetime of phenol determined by nitrogen dioxide dimer in the presence of dimethylamine may compete with that of determined by OH radicals, indicating that nitrogen dioxide dimer is responsible for the elimination of phenol in the polluted atmosphere. This work could help us thoroughly understand the removal of nitrogen oxides and phenol as well as new aerosol precursor aggregation in vehicle exhaust.

13.
Front Genet ; 12: 757350, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34659370

RESUMO

Background: Mechanical stretch is utilized to promote skin regeneration during tissue expansion for reconstructive surgery. Although mechanical stretch induces characteristic morphological changes in the skin, the biological processes and molecular mechanisms involved in mechanically induced skin regeneration are not well elucidated. Methods: A male rat scalp expansion model was established and the important biological processes related to mechanical stretch-induced skin regeneration were identified using Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and gene set enrichment analysis (GSEA). Analysis was also conducted by constructing a protein-protein interaction (PPI) network, identifying key modules and hub genes, determining transcription factor (TF)-mRNA regulatory relationships, and confirming the expression pattern of the TFs and hub genes. Results: We identified nine robust hub genes (CXCL1, NEB, ACTN3, MYOZ1, ACTA1, TNNT3, PYGM, AMPD1, and CKM) that may serve as key molecules in skin growth. These genes were determined to be involved in several important biological processes, including keratinocyte differentiation, cytoskeleton reorganization, chemokine signaling pathway, glycogen metabolism, and voltage-gated ion channel activity. The potentially significant pathways, including the glucagon signaling pathway, the Wnt signaling pathway, and cytokine-cytokine receptor interaction, were distinguished. In addition, we identified six TFs (LEF1, TCF7, HMGA1, TFAP2C, FOSL1, and ELF5) and constructed regulatory TF-mRNA interaction networks. Conclusion: This study generated a comprehensive overview of the gene networks underlying mechanically induced skin regeneration. The functions of these key genes and the pathways in which they participate may reveal new aspects of skin regeneration under mechanical strain. Furthermore, the identified TF regulators can be used as potential candidates for clinical therapeutics for skin pretreatment before reconstructive surgery.

14.
Bioengineered ; 12(1): 8885-8897, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34699328

RESUMO

In preeclampsia (PE), preexistent maternal endothelial dysfunction leads to impaired placentation and vascular maladaptation. Long noncoding RNAs (lncRNAs) have been shown to participate in the placentation process. LncRNA fms-related tyrosine kinase 1 pseudogene 1 (FLT1P1) was previously reported to be upregulated in PE. In this study, we verified the effect of FLT1P1 and its cognate gene FLT1 on trophoblast cell proliferation and angiogenesis by using Cell Counting Kit-8 (CCK-8) assay, tube formation assay, and western blot analysis. Their binding to RNA binding protein dyskeratosis congenita 1 (DKC1) was validated by conducting RNA immunoprecipitation (RIP) and RNA pulldown assays. In this study, knockdown of FLT1P1 or FLT1 was found to promote cell proliferation and angiogenesis in trophoblasts. In addition, FLT1P1 recruited DKC1 to stabilize FLT1. Importantly, silencing FLT1P1 or DKC1 decreased the stability of FLT1. Rescue assays revealed that FLT1 overexpression reversed the effect of silenced FLT1P1. Overall, FLT1P1 cooperates with DKC1 to restrain trophoblast cell proliferation and angiogenesis by targeting FLT1.

15.
Medicine (Baltimore) ; 100(40): e27407, 2021 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-34622846

RESUMO

BACKGROUND: The incidence of angina pectoris (AP) of coronary heart disease (CHD) is increasing in the world, which seriously affects people's lives and brings a huge economic burden. The clinical research on Xinkeshu (XKS) in the treatment of AP of CHD has been increasing. However, there is no systematic review and meta-analysis. This study intends to provide a basis for systematically evaluating the efficacy and safety of XKS combined with conventional western medicine in the treatment of AP of CHD. METHODS: CNKI, Wanfang, VIP, Web of Science, PubMed, Cochrane Library, and EMbase databases were searched for the period from the establishment of the database to August 31, 2021. The clinical randomized controlled trials of XKS in the treatment of AP of CHD were collected. Two systematic reviewers independently selected the literature, extracted the data, and evaluated the quality according to the inclusion and exclusion criteria. The methodological quality of the literature was evaluated using Cochrane Handbook 5.3.0 bias risk assessment tool, RevMan 5.3.0 software was used for meta-analysis and GRADE3.6 evidence quality grading system was used to evaluate the quality. RESULTS: This study intended to evaluate the efficacy and safety of XKS in the treatment of AP of CHD from many aspects, including the frequency of AP, the duration of AP, the dosage of nitroglycerin, and the efficacy of ECG (total effective rate = markedly effective + effective). The secondary indicators included the efficacy of AP (total effective rate = significant + effective), blood lipids (triglyceride, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol), hemorheology (whole blood viscosity, plasma viscosity, and fibrinogen), serum factors (C-reactive protein, endothelin-1, homocysteine, and nitric oxide), and adverse drug reactions. CONCLUSION: The conclusion of the systematic review intended to provide clear evidence of clinical application of XKS combined with conventional western medicine in the treatment of AP of CHD, which can be widely used in the clinic.


Assuntos
Angina Pectoris/tratamento farmacológico , Medicamentos de Ervas Chinesas/uso terapêutico , Humanos , Metanálise como Assunto , Revisões Sistemáticas como Assunto
16.
BMC Mol Cell Biol ; 22(1): 53, 2021 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-34663225

RESUMO

BACKGROUND: Organic anion transporter 1 (OAT1) is a drug transporter expressed on the basolateral membrane of the proximal tubule cells in kidneys. It plays an essential role in the disposition of numerous clinical therapeutics, impacting their pharmacological and toxicological properties. The activation of protein kinase C (PKC) is shown to facilitate OAT1 internalization from cell surface to intracellular compartments and thereby reducing cell surface expression and transport activity of the transporter. The PKC-regulated OAT1 internalization occurs through ubiquitination, a process catalyzed by a E3 ubiquitin ligase, neural precursor cell expressed developmentally down-regulated 4-2 (Nedd4-2). Nedd4-2 directly interacts with OAT1 and affects ubiquitination, expression and stability of the transporter. However, whether Nedd4-2 is a direct substrate for PKC-induced phosphorylation is unknown. RESULTS: In this study, we investigated the role of Nedd4-2 phosphorylation in the PKC regulation of OAT1. The results showed that PKC activation enhanced the phosphorylation of Nedd4-2 and increased the OAT1 ubiquitination, which was accompanied by a decreased OAT1 cell surface expression and transport function. And the effects of PKC could be reversed by PKC-specific inhibitor staurosporine. We further discovered that the quadruple mutant (T197A/S221A/S354A/S420A) of Nedd4-2 partially blocked the effects of PKC on Nedd4-2 phosphorylation and on OAT1 transport activity. CONCLUSIONS: Our investigation demonstrates that PKC regulates OAT1 likely through direct phosphorylation of Nedd4-2. And four phosphorylation sites (T197, S221, S354, and S420) of Nedd4-2 in combination play an important role in this regulatory process.

17.
J Chromatogr A ; 1655: 462496, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34492577

RESUMO

Carbohydrates in foods and other matrices plays vital roles in their diverse biological functions. Carbohydrates serve not only as functional substances but also as structural materials, such as components of membranes, and participate in cellular recognition. The fact that carbohydrates are indispensable has contributed to the need for pretreatment and analytical methods to be developed for their characterization. The aim of this review is to provide a comprehensive overview of carbohydrate pretreatment and determination methods in various matrices. The pretreatment methods include simple and more developed approaches (e.g., solid phase extraction, supercritical fluid extraction, and different microextraction methods, among others). The analytical methods include those by liquid chromatography (including high-performance anion-exchange chromatography), capillary electrophoresis, gas chromatography and supercritical fluid chromatography, and others. Different pretreatment methods and determination approaches are updated, compared, and discussed. Moreover, we discuss and compare the strengths and weaknesses of different methods and suggest their future prospects.


Assuntos
Alimentos , Extração em Fase Sólida , Carboidratos , Cromatografia Gasosa , Cromatografia Líquida , Análise de Alimentos
18.
Preprint em Inglês | bioRxiv | ID: ppbiorxiv-458951

RESUMO

Recently, patients co-infected by two SARS-CoV-2 lineages have been sporadically reported. Concerns are raised because previous studies have demonstrated co-infection may contribute to the recombination of RNA viruses and cause severe clinic symptoms. In this study, we have estimated the compositional lineage(s), tendentiousness, and frequency of co-infection events in population from a large-scale genomic analysis for SARS-CoV-2 patients. SARS-CoV-2 lineage(s) infected in each sample have been recognized from the assignment of within-host site variations into lineage-defined feature variations by introducing a hypergeometric distribution method. Of all the 29,993 samples, 53 (~0.18%) co-infection events have been identified. Apart from 52 co-infections with two SARS-CoV-2 lineages, one sample with co-infections of three SARS-CoV-2 lineages was firstly identified. As expected, the co-infection events mainly happened in the regions where have co-existed more than two dominant SARS-CoV-2 lineages. However, co-infection of two sub-lineages in Delta lineage were detected as well. Our results provide a useful reference framework for the high throughput detecting of SARS-CoV-2 co-infection events in the Next Generation Sequencing (NGS) data. Although low in average rate, the co-infection events showed an increasing tendency with the increased diversity of SARS-CoV-2. And considering the large base of SARS-CoV-2 infections globally, co-infected patients would be a nonnegligible population. Thus, more clinical research is urgently needed on these patients.

19.
J Craniofac Surg ; 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34560753

RESUMO

ABSTRACT: The expanded pedicled deltopectoral flap (EPDF) has been widely used to repair large facial scars. Although doctors and patients are usually satisfied with the outcomes, the actual functional recovery and cosmetic effects of EPDF are still unknown. It is, therefore, necessary to objectively investigate the effect of transferred EPDF by using a variety of methods. From January 2008 to December 2018, 52 patients who underwent EPDF surgery at Xijing Hospital were enrolled. Sense of touch, static 2-point discrimination, elasticity, and color were measured. Thermesthesia and algesthesia were also tested. Postoperative scars were evaluated using the patient and observer scar assessment scale. Satisfaction of patients, doctors, and laypersons was investigated. The algaesthesis, thalposis, and rhigosis scores were 4.7 ±â€Š0.7, 3.7 ±â€Š0.9, and 4.5 ±â€Š0.8, respectively. The tactile score was 0.3 ±â€Š0.2 mN, and 2-point discrimination was 10.1 ±â€Š4.8 mm. L*, a*, hemoglobin, and melanin content of the flaps were significantly different when compared with normal skin (P < 0.05). The satisfaction of doctors, patients, and laypersons was 88.5%, 71.2%, and 67.3%, respectively. The higher satisfaction of patients was mainly associated with the smaller color difference between the flap and the surrounding skin, and lower patient and observer scar assessment scale score. These results confirm that excellent functional recovery and reliable cosmetic effects are observed when facial scars are repaired with EPDF. The methods used in this study can be applied to the evaluation of functional recovery and cosmetic outcomes of transferred flaps, which may provide a more comprehensive understanding of flap assessment.

20.
Microb Cell Fact ; 20(1): 189, 2021 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-34565359

RESUMO

Escherichia coli is the most widely used bacterium in prokaryotic expression system for the production of recombinant proteins. In BL21 (DE3), the gene encoding the T7 RNA polymerase (T7 RNAP) is under control of the strong lacUV5 promoter (PlacUV5), which is leakier and more active than wild-type lac promoter (PlacWT) under certain growth conditions. These characteristics are not advantageous for the production of those recombinant proteins with toxic or growth-burdened. On the one hand, leakage expression of T7 RNAP leads to rapid production of target proteins under non-inducing period, which sucks resources away from cellular growth. Moreover, in non-inducing or inducing period, high expression of T7 RNAP production leads to the high-production of hard-to-express proteins, which may all lead to loss of the expression plasmid or the occurrence of mutations in the expressed gene. Therefore, more BL21 (DE3)-derived variant strains with rigorous expression and different expression level of T7 RNAP should be developed. Hence, we replaced PlacUV5 with other inducible promoters respectively, including arabinose promoter (ParaBAD), rhamnose promoter (PrhaBAD), tetracycline promoter (Ptet), in order to optimize the production of recombinant protein by regulating the transcription level and the leakage level of T7 RNAP. Compared with BL21 (DE3), the constructed engineered strains had higher sensitivity to inducers, among which rhamnose and tetracycline promoters had the lowest leakage ability. In the production of glucose dehydrogenase (GDH), a protein that causes host autolysis, the engineered strain BL21 (DE3::ara) exhibited higher biomass, cell survival rate and foreign protein expression level than that of BL21 (DE3). In addition, these engineered strains had been successfully applied to improve the production of membrane proteins, including E. coli cytosine transporter protein (CodB), the E. coli membrane protein insertase/foldase (YidC), and the E. coli F-ATPase subunit b (Ecb). The engineered strains constructed in this paper provided more host choices for the production of recombinant proteins.

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