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The copy number of genes in chromosomes can be modified by chromosomal integration to construct efficient microbial cell factories but the resulting genetic systems are prone to failure or instability from triggering homologous recombination in repetitive DNA sequences. Finding the optimal copy number of each gene in a pathway is also time and labor intensive. To overcome these challenges, we applied a multiple nonrepetitive coding sequence calculator that generates sets of coding DNA sequence (CDS) variants. A machine learning method was developed to calculate the optimal copy number combination of genes in a pathway. We obtained an engineered Yarrowia lipolytica strain for eicosapentaenoic acid biosynthesis in 6 months, producing the highest titer of 27.5 g l-1 in a 50-liter bioreactor. Moreover, the lycopene production in Escherichia coli was also greatly improved. Importantly, all engineered strains of Y. lipolytica, E. coli and Saccharomyces cerevisiae constructed with nonrepetitive CDSs maintained genetic stability.
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BACKGROUND: Schizophrenia is a complex neuropsychiatric disorder characterized by positive symptoms, negative symptoms, cognitive deficits, and co-occurring mood symptoms. Network analysis offers a novel approach to investigate the intricate relationships between these symptom dimensions, potentially informing personalized treatment strategies. METHODS: A cross-sectional study was conducted from November 2019 to October 2021, involving 1285 inpatients with schizophrenia in Liaoning Province, China. Symptom severity was assessed using the Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Rating Scale (HAMA-14), and Montreal Cognitive Assessment (MoCA). Network analysis was conducted to investigate the network structure, central symptoms, and bridge symptoms. RESULTS: The network analysis uncovered profound interconnectivity between core symptoms and the anxiety-depression community. Central symptoms, such as psychic anxiety, poor rapport, delusions, and attention, were identified as potential therapeutic targets. Bridge symptoms, including insomnia, depressed mood, anxiety-somatic, conceptual disorganization, and stereotyped thinking, emerged as key nodes facilitating interactions between symptom communities. The stability and reliability of the networks were confirmed through bootstrapping procedures. DISCUSSION: The findings highlight the complex interplay between schizophrenia symptoms, emphasizing the importance of targeting affective symptoms and cognitive impairment in treatment. The identification of central and bridge symptoms suggests potential pathways for personalized interventions aimed at disrupting self-reinforcing symptom cycles. The study underscores the need for a transdiagnostic, personalized approach to schizophrenia treatment.
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Esquizofrenia , Humanos , Esquizofrenia/fisiopatología , Adulto , Masculino , Femenino , Estudios Transversales , Persona de Mediana Edad , Disfunción Cognitiva/etiología , Disfunción Cognitiva/fisiopatología , China , Depresión/fisiopatología , Ansiedad/fisiopatología , Síntomas Afectivos/fisiopatología , Síntomas Afectivos/etiología , Adulto JovenRESUMEN
Thraustochytrids are marine microorganisms known for their fast growth and ability to store lipids, making them useful for producing polyunsaturated fatty acids (PUFAs), biodiesel, squalene, and carotenoids. However, the high cost of production, mainly due to expensive fermentation components, limits their wider use. A significant challenge in this context is the need to balance production costs with the value of the end products. This review focuses on integrating the efficient utilization of waste with Thraustochytrids fermentation, including the economic substitution of carbon sources, nitrogen sources, and fermentation water. This approach aligns with the 3Rs principles (reduction, recycling, and reuse). Furthermore, it emphasizes the role of Thraustochytrids in converting waste into lipid chemicals and promoting sustainable circular production models. The aim of this review is to emphasize the value of Thraustochytrids in converting waste into treasure, providing precise cost reduction strategies for future commercial production.
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Conservación de los Recursos Naturales , Fermentación , Estramenopilos , Residuos , Biocombustibles , Biotecnología/economía , Biotecnología/métodos , Carbono/metabolismo , Ácidos Grasos Insaturados/metabolismo , Lípidos/biosíntesis , Lípidos/química , Estramenopilos/metabolismoRESUMEN
Objective: In this study, we investigated the effect of various oxygen therapy regimens on oxygenation in patients with acute type A aortic dissection (AAD). Methods: A quasi-randomized controlled trial was conducted, in which patients with AAD hospitalized for surgery from June to September 2021 were assigned to the control group (patients received conventional oxygen therapy after postoperative mechanical ventilation, weaning, and extubation) and those who were admitted from October to December 2021 were assigned to the observation group [patients underwent optimally adjusted therapy based on the treatment of the control group, which mainly included prioritized elevation of positive end-expiratory pressure (PEEP) and restricted use of the fraction of inspired oxygen (FiO2)].The postoperative oxygenation index, blood gas analysis, and duration of mechanical ventilation were compared between the two groups. Results: There were significant differences in oxygenation observed at 2 h postoperatively between the groups. 12, 24, and 72 h postoperatively, the oxygenation index varied significantly between the two groups. There were statistically significant differences in the time effects of the oxygenation index and PaO2 between the two groups, as well as significant differences in the length of stay in the intensive care unit. Conclusion: For the postoperative care of patients with AAD, it is suggested that the minimum FiO2 required for oxygenation of patients be maintained. In addition, it is possible to enhance PEEP as a priority when PaO2 is low.
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Despite their excellent environmental stability, low defect density, and high carrier mobility, large-n quasi-two-dimensional halide perovskites (quasi-2DHPs) feature a limited application scope because of the formation of self-assembled multiple quantum wells (QWs) due to the similar thermal stabilities of large-n phases. However, large-n quasi-phase-pure 2DHPs (quasi-PP-2DHPs) can solve this problem perfectly. This review discusses the structures, formation mechanisms, and photoelectronic and physical properties of quasi-PP-2DHPs, summarises the corresponding single crystals, thin films, and heterojunction preparation methods, and presents the related advances. Moreover, we focus on applications of large-n quasi-PP-2DHPs in solar cells, photodetectors, lasers, light-emitting diodes, and field-effect transistors, discuss the challenges and prospects of these emerging photoelectronic materials, and review the potential technological developments in this area.
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Large-scale network recording technology is critical in linking neural activity to behavior. Stable, long-term recordings collected from behaving animals are the foundation for understanding neural dynamics and the plasticity of neural circuits. Penetrating microelectrode arrays (MEAs) can obtain high-resolution neural activity from different brain regions. However, ensuring the longevity of implantable devices and the consistency of neural signals over time remains one big challenge. A potential solution is to use flexible, polymer-based MEAs to minimize the foreign body response and prolong the lifetime of neural interfacing devices. Rodents and nonhuman primates (NHP) are commonly used animal models in neuroscience and neuroengineering studies. Specially designed MEAs that capture morphological features of different animal brains and various brain structures are powerful tools to simultaneously obtain neural activities from multiple brain regions. In this work, we develop a set of prototype designs of polymer MEAs that cover cortical, sub-cortical, and multiple brain regions of rodents and NHP.
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Neurociencias , Polímeros , Animales , Microelectrodos , Polímeros/química , Electrodos Implantados , Encéfalo/fisiologíaRESUMEN
Histone deacetylases (HDACs) catalyze the hydrolysis of acetyl-l-lysine side chains in histones and non-histones, which are key to epigenetic regulation in humans. Targeting HDACs has emerged as a promising strategy for treating various types of cancer, including myeloma and hematologic malignancies. At present, numerous small molecule inhibitors targeting HDACs are actively being investigated in clinical trials. Despite their potential efficacy in cancer treatment, HDAC inhibitors suffer from multi-directional selectivity and preclinical resistance issues. Hence, developing novel inhibitors based on cutting-edge medicinal chemistry techniques is essential to overcome these limitations and improve clinical outcomes. This manuscript presents an extensive overview of the properties and biological functions of HDACs in cancer, provides an overview of the current state of development and limitations of clinical HDAC inhibitors, and analyzes a range of innovative medicinal chemistry techniques that are applied. These techniques include selective inhibitors, dual-target inhibitors, proteolysis targeting chimeras, and protein-protein interaction inhibitors.
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Inhibidores de Histona Desacetilasas , Mieloma Múltiple , Humanos , Inhibidores de Histona Desacetilasas/química , Histona Desacetilasas/metabolismo , Epigénesis Genética , Mieloma Múltiple/tratamiento farmacológico , Descubrimiento de DrogasRESUMEN
Introduction: Cognitive decline in the elderly population is a growing concern, and vascular factors, such as hypertension, diabetes, cerebrovascular disease, and coronary heart disease, have been associated with cognitive impairments. This study aims to provide deeper insights into the structure of cognitive function networks under these different vascular factors and explore their potential associations with specific cognitive domains. Methods: Cognitive function was assessed using a modified Chinese version of the mini-mental state examination (MMSE) scale, and intensity centrality and side weights were estimated by network modeling. The network structure of cognitive function was compared across subgroups by including vascular factors as subgroup variables while controlling for comorbidities and confounders. Results: The results revealed that cerebrovascular disease and coronary heart disease had a more significant impact on cognitive function. Cerebrovascular disease was associated with weaker centrality in memory and spatial orientation, and a sparser cognitive network structure. Coronary heart disease was associated with weaker centrality in memory, repetition, executive function, recall, attention, and calculation, as well as a sparser cognitive network structure. The NCT analyses further highlighted significant differences between the cerebrovascular disease and coronary heart disease groups compared to controls in terms of overall network structure and connection strength. Conclusion: Our findings suggest that specific cognitive domains may be more vulnerable to impairments in patients with cerebrovascular disease and coronary heart disease. These insights could be used to improve the accuracy and sensitivity of cognitive screening in these patient populations, inform personalized cognitive intervention strategies, and provide a better understanding of the potential mechanisms underlying cognitive decline in patients with vascular diseases.
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Single-atom copper (Cu) embedded within carbon catalysts have demonstrated significant potential in the electrochemical reduction of carbon dioxide (CO2) into valuable chemicals and fuels. Herein, we develop a straightforward and template-free strategy for synthesizing atomically dispersed CuNC catalysts (CuG) by annealing the self-assembled guanosine. The CuG catalysts display two-dimensional morphology, tunable pore size and large surface areas that can be adjusted by changing carbonization temperature. Spherical aberration-corrected transmission electron microscopy reveals that single-atom Cu are homogeneously dispersed on the surface of carbon nanosheets. The optimum CuG-1000 catalysts achieve a high CO Faradaic efficiency (FEco) up to 99% and a high CO current density of 6.53 mA cm-2 (-0.65 V vs. RHE). Besides, the flow cell test of CuG-1000 shows a high current density up to 25.2 mA cm-2 and the FEco still exceeded 91% after more than 20 h of testing. Specifically, the existence of Cu-N3-C active sites was proved by extended X-ray absorption fine structure (EXAFS). Density functional theory evidences that tricoordinated copper with N can largely regulate the adsorption and desorption of key intermediates by transferring electrons to *COOH through Cu atoms, thereby improving selectivity toward CO. This work demonstrates the active origin of CuNC catalysts in CO2 electroreduction and offers a blueprint to construct atomically dispersed transition site catalysts by supramolecular self-assembly strategy.
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BACKGROUND: Colorectal cancer (CRC) is a common malignancy, and radioresistance limits the effectiveness of radiotherapy for rectal cancer. This study is performed to investigate the role and regulatory mechanism of Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 4 (KCNE4) in the radioresistance of CRC cells. METHODS: Immunohistochemical staining results of KCNE4 in normal tissues and CRC tissues were obtained from the Human Protein Atlas (HPA) database. The UALCAN database was used for analyzing KCNE4 mRNA expression in normal tissue samples and CRC tissue samples and its relationship with tumor stage. The relationship of KCNE4 expression with prognosis was analyzed utilizing the data of GEPIA database. LinkedOmics database was searched to analyze the co-expressed gene sets of KCNE4 in CRC, and to analyze the signaling pathways related with KCNE4 in CRC. GO and KEGG enrichment analyses were carried out on the co-expressed genes of KCNE4 with DAVID database. Ionizing radiation (IR)-resistant cell lines (HCT116/IR and HT29/IR) were established; cell viability was assessed via cell counting kit-8 (CCK-8) and EdU assays, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay was performed for detecting cell apoptosis. Western blotting was carried out to detect the expressions of p-p85 and p-AKT. RESULTS: KCNE4 was highly expressed in CRC tissues and linked to advanced tumor stage, lymph node metastasis and poor prognosis of CRC patients. KCNE4 overexpression promoted HCT116/IR cell proliferation and inhibited the apoptosis, while KCNE4 knockdown suppressed HT29/IR cell proliferation and facilitated the apoptosis. Furthermore, high KCNE4 expression was associated with the activation of the PI3K/AKT signal pathway. CONCLUSION: KCNE4 is associated with the clinicopathological characteristics of CRC patients, and its high expression level contributes to the radioresistance of cancer cells via activating the PI3K/AKT signal pathway.
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Neoplasias Colorrectales , Canales de Potasio con Entrada de Voltaje , Humanos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Transducción de Señal , Células HCT116 , Proliferación Celular/genética , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/radioterapia , Neoplasias Colorrectales/metabolismo , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Canales de Potasio con Entrada de Voltaje/genética , Canales de Potasio con Entrada de Voltaje/metabolismoRESUMEN
OBJECTIVES: We conducted a comprehensive meta-analysis of all available trials to evaluate the efficacy and safety of estrogen and selective estrogen receptor modulators as adjunctive treatment for women with schizophrenia. METHODS: Multiple databases were searched from the inception until March 2022. Only randomized, double-blind, placebo-controlled studies (randomized controlled trials) were included. Mean differences (MDs) and their 95% confidence intervals (CIs) were calculated using random effects models. RESULTS: The meta-analysis included six estradiol versus placebo studies (n = 724) and seven raloxifene versus placebo studies (n = 419), covering a total of 1143 patients. Adjunctive estradiol outperformed the placebo in terms of the Positive and Negative Syndrome Scale (PANSS) total score (MD = -7.29; 95% CI = -10.67 to -3.91; I2 = 59.1%; p < 0.001; k = 9; N = 858), positive symptom score (MD = -1.54; 95% CI = -3.04 to -0.72; I2 = 45.8%; p < 0.001; k = 7; N = 624), negative symptom score (MD = -1.9; 95% CI = -1.77 to -0.34; I2 = 37.6%; p < 0.05; k = 14; N = 1042), and general psychopathology score (MD = -4.27; 95% CI = -7.14 to -1.41; I2 = 76.3%; p < 0.005; k = 7; N = 624). Adjunctive raloxifene outperformed the placebo in terms of the PANSS total score (MD = -6.83; 95% CI = -11.69 to -1.97; I2 = 67.8%; p = 0.006; k = 8; N = 432) and general psychopathology score (MD = -3.82; 95% CI = -6.36 to -1.28; I2 = 65.3%; p < 0.005; k = 8; N = 432). CONCLUSIONS: Our meta-analysis showed that estradiol and raloxifene are effective and safe adjunctive treatments that improve schizophrenia symptoms in women. Moreover, the effects of estradiol and raloxifene differed in terms of timing and dosage. Both are promising adjunctive treatments that merit further study.
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Antipsicóticos , Esquizofrenia , Humanos , Femenino , Clorhidrato de Raloxifeno/farmacología , Clorhidrato de Raloxifeno/uso terapéutico , Esquizofrenia/tratamiento farmacológico , Esquizofrenia/diagnóstico , Estradiol , Antipsicóticos/farmacología , Antipsicóticos/uso terapéutico , Quimioterapia Combinada , Posmenopausia , Método Doble Ciego , Ensayos Clínicos Controlados Aleatorios como AsuntoRESUMEN
We introduce the Study variety of conformal kinematics and investigate some of its properties. The Study variety is a projective variety of dimension ten and degree twelve in real projective space of dimension 15, and it generalizes the well-known Study quadric model of rigid body kinematics. Despite its high dimension, co-dimension, and degree it is amenable to concrete calculations via conformal geometric algebra (CGA) associated to three-dimensional Euclidean space. Calculations are facilitated by a four quaternion representation which extends the dual quaternion description of rigid body kinematics. In particular, we study straight lines on the Study variety. It turns out that they are related to a class of one-parametric conformal motions introduced by Dorst in (Math Comput Sci 10:97-113, 2016, 10.1007/s11786-016-0250-8). Similar to rigid body kinematics, straight lines (that is, Dorst's motions) are important for the decomposition of rational conformal motions into lower degree motions via the factorization of certain polynomials with coefficients in CGA.
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BACKGROUND: To compare the effects of two biologic disease-modifying antirheumatic drug (bDMARD) administration strategies on the maintenance effect and safety of patients with rheumatoid arthritis (RA) in remission, to analyze the effects of gradual drug reduction and dose maintenance treatment on clinical outcomes in patients who have achieved remission with different types of bDMARDs, to search and screen out people who may benefit from drug reduction strategies, and to provide references for drug reduction strategies and treatment options for patients with RA in remission, so as to help improve the safety of the treatment and reduce the economic burden. METHODS: The study will be a 24-month non-inferiority randomized, controlled, single-blind trial and is planned to be launched in our hospital from September 2021 to August 2023. Patients will be randomized in a ratio of 2:1 to two groups: maintenance or injection spacing by 50%/gradual reduction of dosage every 3 months up to complete stop. When the patient relapses, return to the last effective dose. If the remission can be maintained, the medication of bDMARDs can be stopped 9 months after enrollment. The primary outcome will be the persistent flare rate. DISCUSSION: Our study may provide a reference for the selection of drug reduction strategies and treatment options for patients with RA in remission, so as to help improve the safety of the treatment and reduce the economic burden. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100044751. Registered on 26 March 2021.
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Antirreumáticos , Artritis Reumatoide , Productos Biológicos , Antirreumáticos/efectos adversos , Artritis Reumatoide/diagnóstico , Artritis Reumatoide/tratamiento farmacológico , Productos Biológicos/uso terapéutico , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto , Inducción de Remisión , Método Simple Ciego , Resultado del TratamientoRESUMEN
Building on theoretical and empirical insights and applying the thriving theory as the conceptual framework, the authors developed two new teacher-specific scales, namely the Teacher Stress Scale (TSS) and the Teacher Thriving Scale (TTS). The goal of this investigation was to evaluate the psychometric properties of these two scales. Data were collected through an online questionnaire administered to a national sample of 122 participating early childhood teachers (ages 22-72 years, M = 41.01) teaching in preschool through third grade in 26 states of the United States during the 2020-2021 school year amidst COVID-19. This study revealed some important psychometric results. First, with respect to their internal structures, both the TSS and the TTS appeared to be best represented as bifactorial and trifactorial, respectively. Specifically, the TSS comprised two constructs: (1) Inadequate School-based Support, and (2) Teaching-related Demands; and the TTS encompassed three constructs: (1) Adaptability and Flexibility, (2) Personal Strengths and Professional Growth, and (3) Positive Mindset. Second, the negative correlation between the TSS and the TTS provided discriminant evidence for each other's construct validity, while the positive correlations between the TTS and six conceptually cognate constructs (Stress Resilience, Resilience Coping, Coping Efficacy, Teaching Satisfaction, Emotional Support, and Gratitude) demonstrated convergent evidence for construct validity for the TTS. Third, both the overall TSS and the overall TTS as well as their subscales exhibited good internal consistency reliability. Fourth, both the overall TSS and the overall TTS also demonstrated test-retest reliability.
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In this paper, the research emphasis focuses on the tracking precision of position loading and torque loading systems with velocity-sensitive and adaptive robust control. Compared with conventional PID control, the improved PID control based on velocity-sensitive fully manifests its superiority to position loading. By contrast, we analyzed the possible influence for the control difference of conventional PID and velocity-sensitive with PID. Furthermore, for the purpose of accurate torque loading, a mathematical model was established through dynamics analysis and the adaptive robust controller, where the adaptive robust control algorithm is designed to generate the reference position trajectory for the servo system in the upper controller while closed-loop position tracking is performed in the underlying controller, was built based on a state space equation. In the end, an experimental platform was built to verify the feasibility and advantages of the position and torque loading system with the velocity-sensitive and adaptive robust control.
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Algoritmos , Modelos Teóricos , TorqueRESUMEN
Schizochytrium sp. has received increasing attention as promising commercial resource for the sustainable production of lipids, due to their fast growth rate and high lipid content. However, the price of glucose represents a significant proportion of the total substrate cost. Therefore, in this study, the lignocellulosic hydrolysate of corn stover hydrolysate (CSH) was used as low-cost culture medium to replace glucose in Schizochytrium sp. fermentation. When Schizochytrium sp. HX-308 was fermented with 20% glucose from CSH and 80% of glucose from pure glucose, the lipid production reached 21.2 g L-1 , which is lower than that of using 100% of pure glucose. However, the shifts of fatty acid composition indicated that CSH has great potential to enhance the percentage of polyunsaturated fatty acids (PUFAs) in total lipids. However, as the second largest carbon source in CSH, xylose was not utilized by the Schizochytrium sp. HX-308, and further analysis showed that probably because it does not possess a functional xylulose kinase. In addition, the degradation products in lignocellulosic hydrolysate have a strong inhibitory effect on cell growth, so it is necessary to investigate the tolerance of Schizochytrium sp. HX-308 to degradation products. Here, the effects of five typical degradation products on the growth and lipid synthesis were further investigated. Schizochytrium sp. HX-308 showed good tolerance to furan derivatives and organic acids, but low tolerance to phenolic compounds. Furthermore, in order to improve the lipid accumulation using CSH, the two-stage fermentation strategy was developed, resulting in a 54.8% increase compared to that of the one-stage strategy. In summary, this study provides a reference for further fermentation engineering with cheap lignocellulosic biomass as substrate.
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Estramenopilos , Zea mays , Ácidos Grasos Insaturados/metabolismo , Fermentación , Glucosa/metabolismo , Estramenopilos/metabolismo , Xilosa/metabolismoRESUMEN
Escherichia coli BL21 (DE3) is the most widely used host for recombinant protein expression. However, not every protein can be highly expressed in BL21 (DE3), so individual optimization strategies are often required for different proteins, which is time-consuming and difficult to apply rapidly for industrial production. Constructing more hosts is a good choice to enrich protein expression selection. The expression level of T7 RNAP is the core control node of the pET expression system, so regulating its expression level is an effective way of improving the production of difficult-to-express proteins. Various BL21 (DE3)-derived variant hosts with different translation levels of T7 RNAP could be obtained by changing the ribosomal binding site (RBS) sequences of T7 RNAP in a genome. Here, a BL21 (DE3)-derived variant strain library with different RBS sequences of T7 RNAP was constructed using a base editor and CRISPR-Cas9. Notably, the CRISPR-Cas9 system combined with degenerate primers enabled the construction of an RBS library with 87.5% of the theoretical coverage in single editing, which is more convenient and efficient than the use of a base editor. The expression level of a target gene in the variant strain library ranged from 28 to 220% of the parental strain. Furthermore, a high-throughput host-screening platform for recombinant protein production was constructed, which enabled us to obtain the best expression host for certain target proteins in only 3 days. As a proof of concept, the production of all eight difficult-to-express proteins was greatly improved, including autolytic protein, membrane proteins, antimicrobial peptides, and hardly soluble proteins. Among them, the expression of glucose dehydrogenase in the best host exhibited a 298-fold increase compared to the parental strain. This strategy is simple and effective, requires no advanced equipment, and can be carried out in any laboratory.
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Escherichia coli , Proteínas de la Membrana , Ingeniería de Proteínas , Sistemas CRISPR-Cas , Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de la Membrana/genética , Ingeniería de Proteínas/métodos , Proteínas Recombinantes/biosíntesisRESUMEN
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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Clonación Molecular/métodos , ARN Polimerasas Dirigidas por ADN/genética , Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , Proteínas Recombinantes/biosíntesis , Proteínas Virales/genética , Vectores Genéticos , Proteínas de Transporte de Membrana/genética , Transporte de Proteínas , Proteínas Recombinantes/genéticaRESUMEN
Terpenoids are an important class of secondary metabolites that play an important role in food, agriculture, and other fields. Microorganisms are rapidly emerging as a promising source for the production of terpenoids. As an oleaginous yeast, Yarrowia lipolytica contains a high lipid content which indicates that it must produce high amounts of acetyl-CoA, a necessary precursor for the biosynthesis of terpenoids. Y. lipolytica has a complete eukaryotic mevalonic acid (MVA) pathway but it has not yet seen commercial use due to its low productivity. Several metabolic engineering strategies have been developed to improve the terpenoids production of Y. lipolytica, including developing the orthogonal pathway for terpenoid synthesis, increasing the catalytic efficiency of terpenoids synthases, enhancing the supply of acetyl-CoA and NADPH, expressing rate-limiting genes, and modifying the branched pathway. Moreover, most of the acetyl-CoA is used to produce lipid, so it is an effective strategy to strike a balance of precursor distribution by rewiring the lipid biosynthesis pathway. Lastly, the latest developed non-homologous end-joining strategy for improving terpenoid production is introduced. This review summarizes the status and metabolic engineering strategies of terpenoids biosynthesis in Y. lipolytica and proposes new insights to move the field forward.
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Yarrowia , Acetilcoenzima A , Ingeniería Metabólica , Ácido Mevalónico , Terpenos , Yarrowia/genéticaRESUMEN
PURPOSE: The purpose of this study was to explore the factors influencing the occupational attitudes of nursing students in the probation period. METHODS: Nursing students in the probation period from five hospitals completed an anonymous survey. The instruments included the nursing occupational attitude scale, family adaptability, partnership, growth, affection, and resolve index, and perceived social support scale. The study examined the moderation model between family function, perceived social support, and occupational attitudes using PROCESS 3.2. RESULTS: For nursing students, when social support was low, family function had a significant positive impact on occupational attitudes and intentions, and the effect was much higher than that of perceived social support. CONCLUSION: Family function has a significant positive explanatory effect on attitude and intention (ß = .13, p < .001 and ß = .12, p < .001); the interaction term between family function and perceived social support are significant (ß = .01, p < .001 and ß = .01, p < .001). Perceived social support has a significant moderating effect on the relationship between family function and occupational attitudes of nursing students in the probation period. Family function has a significant difference in the occupational attitudes and intentions of nursing students with low perceived social support. Nursing students perceive social support in the probation period has a significant moderation effect in the relationship between their family function and occupational attitudes. Interns with low family function should be given more social support to improve their occupational attitudes.