RESUMO
Engineering microorganisms for production of fuels and chemicals often requires major re-programming of metabolism to ensure high flux toward the product of interest. This is challenging, as millions of years of evolution have resulted in establishment of tight regulation of metabolism for optimal growth in the organism's natural habitat. Here, we show through metabolic engineering that it is possible to alter the metabolism of Saccharomyces cerevisiae from traditional ethanol fermentation to a pure lipogenesis metabolism, resulting in high-level production of free fatty acids. Through metabolic engineering and process design, we altered subcellular metabolic trafficking, fine-tuned NADPH and ATP supply, and decreased carbon flux to biomass, enabling production of 33.4 g/L extracellular free fatty acids. We further demonstrate that lipogenesis metabolism can replace ethanol fermentation by deletion of pyruvate decarboxylase enzymes followed by adaptive laboratory evolution. Genome sequencing of evolved strains showed that pyruvate kinase mutations were essential for this phenotype.
Assuntos
Ácidos Graxos não Esterificados/biossíntese , Engenharia Metabólica , Saccharomyces cerevisiae/metabolismo , Acetilcoenzima A/metabolismo , Glucose/metabolismo , Glicólise , Isocitrato Desidrogenase/genética , Isocitrato Desidrogenase/metabolismo , Lipogênese , NADP/metabolismo , Via de Pentose Fosfato/genética , Piruvato Quinase/genética , Piruvato Quinase/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
Genetic elements are foundational in synthetic biology serving as vital building blocks. They enable programming host cells for efficient production of valuable chemicals and recombinant proteins. The unfolded protein response (UPR) is a stress pathway in which the transcription factor Hac1 interacts with the upstream unfolded protein response element (UPRE) of the promoter to restore endoplasmic reticulum (ER) homeostasis. Here, we created a UPRE2 mutant (UPRE2m) library. Several rounds of screening identified many elements with enhanced responsiveness and a wider dynamic range. The most active element m84 displayed a response activity 3.72 times higher than the native UPRE2. These potent elements are versatile and compatible with various promoters. Overexpression of HAC1 enhanced stress signal transduction, expanding the signal output range of UPRE2m. Through molecular modeling and site-directed mutagenesis, we pinpointed the DNA-binding residue Lys60 in Hac1(Hac1-K60). We also confirmed that UPRE2m exhibited a higher binding affinity to Hac1. This shed light on the mechanism underlying the Hac1-UPRE2m interaction. Importantly, applying UPRE2m for target gene regulation effectively increased both recombinant protein production and natural product synthesis. These genetic elements provide valuable tools for dynamically regulating gene expression in yeast cell factories.
Assuntos
Fatores de Transcrição de Zíper de Leucina Básica , Regulação Fúngica da Expressão Gênica , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Resposta a Proteínas não Dobradas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Resposta a Proteínas não Dobradas/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Regiões Promotoras Genéticas , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Retículo Endoplasmático/metabolismo , Transdução de Sinais/genéticaRESUMO
BACKGROUND: Sequencing the mitochondrial genome has been increasingly important for the investigation of primary mitochondrial diseases (PMD) and mitochondrial genetics. To overcome the limitations originating from PCR-based mtDNA enrichment, we set out to develop and evaluate a PCR-independent approach in this study, named Pime-Seq (PCR-independent mtDNA enrichment and next generation Sequencing). RESULTS: By using the optimized mtDNA enrichment procedure, the mtDNA reads ratio reached 88.0 ± 7.9% in the sequencing library when applied on human PBMC samples. We found the variants called by Pime-Seq were highly consistent among technical repeats. To evaluate the accuracy and reliability of this method, we compared Pime-Seq with lrPCR based NGS by performing both methods simultaneously on 45 samples, yielding 1677 concordant variants, as well as 146 discordant variants with low-level heteroplasmic fraction, in which Pime-Seq showed higher reliability. Furthermore, we applied Pime-Seq on 4 samples of PMD patients retrospectively, and successfully detected all the pathogenic mtDNA variants. In addition, we performed a prospective study on 192 apparently healthy pregnant women during prenatal screening, in which Pime-Seq identified pathogenic mtDNA variants in 4 samples, providing extra information for better health monitoring in these cases. CONCLUSIONS: Pime-Seq can obtain highly enriched mtDNA in a PCR-independent manner for high quality and reliable mtDNA deep-sequencing, which provides us an effective and promising tool for detecting mtDNA variants for both clinical and research purposes.
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DNA Mitocondrial , Sequenciamento de Nucleotídeos em Larga Escala , Doenças Mitocondriais , Reação em Cadeia da Polimerase , Humanos , DNA Mitocondrial/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Feminino , Reação em Cadeia da Polimerase/métodos , Doenças Mitocondriais/genética , Doenças Mitocondriais/diagnóstico , Gravidez , Reprodutibilidade dos Testes , Masculino , AdultoRESUMO
BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD) is a high-prevalence autosomal dominant neuromuscular disease characterized by significant clinical and genetic heterogeneity. Genetic diagnosis of FSHD remains a challenge because it cannot be detected by standard sequencing methods and requires a complex diagnosis workflow. METHODS: We developed a comprehensive genetic FSHD detection method based on Oxford Nanopore Technologies (ONT) whole-genome sequencing. Using a case-control design, we applied this procedure to 29 samples and compared the results with those from optical genome mapping (OGM), bisulfite sequencing (BSS), and whole-exome sequencing (WES). RESULTS: Using our ONT-based method, we identified 59 haplotypes (35 4qA and 24 4qB) among the 29 samples (including a mosaic sample), as well as the number of D4Z4 repeat units (RUs). The pathogenetic D4Z4 RU contraction identified by our ONT-based method showed 100% concordance with OGM results. The methylation levels of the most distal D4Z4 RU and the double homeobox 4 gene (DUX4) detected by ONT sequencing are highly consistent with the BSS results and showed excellent diagnostic efficiency. Additionally, our ONT-based method provided an independent methylation profile analysis of two permissive 4qA alleles, reflecting a more accurate scenario than traditional BSS. The ONT-based method detected 17 variations in three FSHD2-related genes from nine samples, showing 100% concordance with WES. CONCLUSIONS: Our ONT-based FSHD detection method is a comprehensive method for identifying pathogenetic D4Z4 RU contractions, methylation level alterations, allele-specific methylation of two 4qA haplotypes, and variations in FSHD2-related genes, which will all greatly improve genetic testing for FSHD.
Assuntos
Metilação de DNA , Distrofia Muscular Facioescapuloumeral , Sequenciamento Completo do Genoma , Distrofia Muscular Facioescapuloumeral/genética , Distrofia Muscular Facioescapuloumeral/diagnóstico , Humanos , Metilação de DNA/genética , Haplótipos/genética , Masculino , Estudos de Casos e Controles , Proteínas de Homeodomínio/genética , Feminino , Sequenciamento por Nanoporos/métodos , AdultoRESUMO
Myclobutanil (MYC) is a common triazole fungicide widely applied in agriculture. MYC extensively exists in the natural environment and can be detected in organisms. However, little is known about MYC-induced embryonic developmental damage. This study aimed to unravel the cardiotoxicity of MYC and the underlying mechanisms, as well as the cardioprotective effect of curcumin (CUR, an antioxidant polyphenol) using the zebrafish model. Here, zebrafish embryos were exposed to MYC at concentrations of 0, 0.5, 1 and 2â¯mg/L from 4 to 96â¯h post fertilization (hpf) and cardiac development was assessed. As results, MYC reduced the survival and hatching rate, body length and heart rate, but increased the malformation rate and spontaneous movement. MYC caused abnormal cardiac morphology and function in myl7:egfp transgenic zebrafish, and downregulated cardiac developmental genes. MYC promoted oxidative stress through excessive reactive oxygen species (ROS) accumulation and suppressed the activities of antioxidant enzymes, triggering cardiomyocytic apoptosis via upregulated expression of apoptosis-related genes. These adverse toxicities could be significantly ameliorated by the antioxidant properties of CUR, indicating that CUR rescued MYC-induced cardiotoxicity by inhibiting oxidative stress and apoptosis. Overall, our study revealed the potential mechanisms of oxidative stress and apoptosis in MYC-induced cardiotoxicity in zebrafish and identified the cardioprotection of CUR in this pathological process.
Assuntos
Apoptose , Cardiotoxicidade , Curcumina , Fungicidas Industriais , Estresse Oxidativo , Triazóis , Peixe-Zebra , Animais , Estresse Oxidativo/efeitos dos fármacos , Curcumina/farmacologia , Apoptose/efeitos dos fármacos , Triazóis/toxicidade , Fungicidas Industriais/toxicidade , Larva/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Animais Geneticamente Modificados , Embrião não Mamífero/efeitos dos fármacos , Antioxidantes/farmacologia , Poluentes Químicos da Água/toxicidade , Coração/efeitos dos fármacos , NitrilasRESUMO
BACKGROUND: Chromosomal microarray analysis (CMA) has been widely applied to explore the genetic etiology in recurrent pregnancy loss (RPL). However, the reproductive prognosis in RPL couples with different types of chromosomally abnormal miscarriage remains unclear. OBJECTIVES: The main purpose of this study was to evaluate the reproductive prognosis among RPL couples after genetic testing in products of conception (POCs) by CMA. STUDY DESIGN: In this retrospective study, 1101 RPL couples referred for genetic testing in POCs by CMA. A total of 830 couples who met the inclusion criteria were followed up for at least 24 months after the index miscarriage. The rates of live birth and adverse pregnancy events in subsequent pregnancy and cumulative pregnancies were examined. RESULTS: For couples with three or more miscarriage, compared with those with chromosomally normal miscarriage, a significantly higher subsequent live birth rate was found in couples with chromosomally abnormal miscarriage (66.9% vs 71.6%, P = .040). However, differences in cumulative live birth rate among couples with chromosomally abnormal miscarriage and normal miscarriage were nonsignificant (82.7% vs 80.2%, P = .131). Women with advanced maternal age showed a significant decrease in the live birth rate (P < 0.01) and an increase in the miscarriage rate (P < 0.01) than those aged < 35 years old, regardless of whether the miscarriage was chromosomally normal or abnormal. RPL couples with chromosomally normal miscarriage showed a significant decrease in live birth rates in subsequent pregnancy and cumulative pregnancies, when they had experienced a large number of previous miscarriages; however, no significant difference was observed in those with chromosomally abnormal miscarriage. CONCLUSION: For women with three or more previous miscarriages, RPL couples with chromosomally normal miscarriage manifested a poorer reproductive prognosis than those with chromosomally abnormal miscarriage in subsequent pregnancy, while the cumulative live birth rate was similar. Advanced maternal age was a predictor of adverse pregnancy events, regardless of embryonic chromosomal results. Furthermore, among RPL women with large numbers of previous miscarriages, the supportive care and counselling regarding individual risk is necessary for those with chromosomally normal miscarriage.
Assuntos
Aborto Habitual , Gravidez , Humanos , Feminino , Adulto , Estudos Retrospectivos , Aborto Habitual/genética , Nascido Vivo/genética , Testes Genéticos , Análise em MicrossériesRESUMO
Proteases, enzymes that catalyze the hydrolysis of peptide bonds in proteins, are important in the food industry, biotechnology, and medical fields. With increasing demand for proteases, there is a growing emphasis on enhancing their expression and production through microbial systems. However, proteases' native hosts often fall short in high-level expression and compatibility with downstream applications. As a result, the recombinant production of proteases has become a significant focus, offering a solution to these challenges. This review presents an overview of the current state of protease production in prokaryotic and eukaryotic expression systems, highlighting key findings and trends. In prokaryotic systems, the Bacillus spp. is the predominant host for proteinase expression. Yeasts are commonly used in eukaryotic systems. Recent advancements in protease engineering over the past five years, including rational design and directed evolution, are also highlighted. By exploring the progress in both expression systems and engineering techniques, this review provides a detailed understanding of the current landscape of recombinant protease research and its prospects for future advancements.
Assuntos
Bacillus , Peptídeo Hidrolases , Peptídeo Hidrolases/metabolismo , Biotecnologia/métodos , Endopeptidases , Bacillus/metabolismo , Leveduras/metabolismo , Proteínas Recombinantes/metabolismoRESUMO
BACKGROUND: The urgency of ensuring adequate moral courage in clinical nursing practice is evident. However, currently, there are few formal intervention plans targeted at enhancing the moral courage of nurses. AIM: To develop a training program for improving the moral courage of nurses using the modified Delphi method. RESEARCH DESIGN: A modified Delphi study. PARTICIPANTS AND RESEARCH CONTEXT: From November to December 2022, a literature review and expert group discussion were conducted to develop a preliminary training plan framework. From January to March 2023, a two-round Delphi survey was performed, and a consensus was reached regarding the plan through online questionnaires. Descriptive statistics were used to analyze the data. ETHICAL CONSIDERATIONS: This study was approved by the institutional ethics committee (No. 138, 30 August 2021). All participants provided written informed consent. RESULTS: Consensus was reached on eight themes and 33 items to strengthen the moral courage training program for nurses. CONCLUSIONS: Guided by a unified goal of moral education, a multi-level and acceptable intervention plan was designed to enhance the moral courage of nurses.
RESUMO
The yeast Saccharomyces cerevisiae is a widely used cell factory for protein production. Increasing the protein production capacity of a yeast strain may be beneficial for obtaining recombinant proteins as a product or exerting its competence in consolidated bioprocessing. However, heterologous protein expression usually imposes stress on cells. Improving the cell's ability to cope with stress enhances protein yield. HAC1 is a key transcription factor in the unfolded protein response (UPR). In this study, several genes related to the UPR signal pathway, including unfolded protein sensing, HAC1 mRNA splicing, mRNA ligation, mRNA decay, translation, and Hac1p degradation, were selected as targets to engineer yeast strains. The final engineered strain produced α-amylase 3.3-fold, and human serum albumin 15.3-fold, greater than that of the control strain. Key regulation and metabolic network changes in the engineered strains were identified by transcriptome analysis and physiological characterizations. This study demonstrated that cell engineering with genes relevant to the key node HAC1 in UPR increased protein secretion substantially. The verified genetic modifications of this study provide useful targets in the construction of yeast cell factories for efficient protein production.
Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Humanos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Engenharia Celular , Resposta a Proteínas não Dobradas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
BACKGROUND: Emerging studies suggest that whole genome sequencing provides additional diagnostic yield of genomic variants when compared with chromosomal microarray analysis in the etiologic diagnosis of infants and children with suspected genetic diseases. However, the application and evaluation of whole genome sequencing in prenatal diagnosis remain limited. OBJECTIVE: This study aimed to evaluate the accuracy, efficacy, and incremental yield of whole genome sequencing in comparison with chromosomal microarray analysis for routine prenatal diagnosis. STUDY DESIGN: In this prospective study, a total of 185 unselected singleton fetuses with ultrasound-detected structural anomalies were enrolled. In parallel, each sample was subjected to whole genome sequencing and chromosomal microarray analysis. Aneuploidies and copy number variations were detected and analyzed in a blinded fashion. Single nucleotide variations and insertions and deletions were confirmed by Sanger sequencing, and trinucleotide repeats expansion variants were verified using polymerase chain reaction plus fragment-length analysis. RESULTS: Overall, genetic diagnoses using whole genome sequencing were obtained for 28 (15.1%) cases. Whole genome sequencing not only detected all these aneuploidies and copy number variations in the 20 (10.8%) diagnosed cases identified by chromosomal microarray analysis, but also detected 1 case with an exonic deletion of COL4A2 and 7 (3.8%) cases with single nucleotide variations or insertions and deletions. In addition, 3 incidental findings were detected including an expansion of the trinucleotide repeat in ATXN3, a splice-sites variant in ATRX, and an ANXA11 missense mutation in a case of trisomy 21. CONCLUSION: Compared with chromosomal microarray analysis, whole genome sequencing increased the additional detection rate by 5.9% (11/185). Using whole genome sequencing, we detected not only aneuploidies and copy number variations, but also single nucleotide variations and insertions and deletions, trinucleotide repeat expansions, and exonic copy number variations with high accuracy in an acceptable turnaround time (3-4 weeks). Our results suggest that whole genome sequencing has the potential to be a new promising prenatal diagnostic test for fetal structural anomalies.
Assuntos
Variações do Número de Cópias de DNA , Ultrassonografia Pré-Natal , Gravidez , Feminino , Lactente , Criança , Humanos , Estudos Prospectivos , Primeiro Trimestre da Gravidez , Diagnóstico Pré-Natal/métodos , Aneuploidia , Sequenciamento Completo do Genoma , Análise em Microsséries , Aberrações CromossômicasRESUMO
INTRODUCTION: Chromosomal aberrations are the most important etiological factors for birth defects. Optical genome mapping is a novel cytogenetic tool for detecting a broad range of chromosomal aberrations in a single assay, but relevant clinical feasibility studies of optical genome mapping in prenatal diagnosis are limited. MATERIAL AND METHODS: We retrospectively performed optical genome mapping analysis of amniotic fluid samples from 34 fetuses with various clinical indications and chromosomal aberrations detected through standard-of-care technologies, including karyotyping, fluorescence in situ hybridization, and/or chromosomal microarray analysis. RESULTS: In total, we analyzed 46 chromosomal aberrations from 34 amniotic fluid samples, including 5 aneuploidies, 10 large copy number variations, 27 microdeletions/microduplications, 2 translocations, 1 isochromosome, and 1 region of homozygosity. Overall, 45 chromosomal aberrations could be confirmed by our customized analysis strategy. Optical genome mapping reached 97.8% concordant clinical diagnosis with standard-of-care methods for all chromosomal aberrations in a blinded fashion. Compared with the widely used chromosomal microarray analysis, optical genome mapping additionally determined the relative orientation and position of repetitive segments for seven cases with duplications or triplications. The additional information provided by optical genome mapping will be conducive to characterizing complex chromosomal rearrangements and allowing us to propose mechanisms to explain rearrangements and predict the genetic recurrence risk. CONCLUSIONS: Our study highlights that optical genome mapping can provide comprehensive and accurate information on chromosomal aberrations in a single test, suggesting that optical genome mapping has the potential to become a promising cytogenetic tool for prenatal diagnosis.
Assuntos
Transtornos Cromossômicos , Gravidez , Feminino , Humanos , Transtornos Cromossômicos/diagnóstico , Transtornos Cromossômicos/genética , Hibridização in Situ Fluorescente , Variações do Número de Cópias de DNA , Estudos Retrospectivos , Aberrações Cromossômicas , Diagnóstico Pré-Natal/métodos , Mapeamento CromossômicoRESUMO
Spinal muscular atrophy (SMA) is an autosomal recessive and often fatal neurological disease. However, very little is known about the attitudes toward SMA carrier screening among Chinese pregnant people. In this study, pregnant women in Eastern China who were undergoing routine chromosomal screening programs were invited to view an educational video about SMA and complete a 26-item survey regarding their attitudes toward SMA screening by scanning a specific quick response code. A total of 1673 questionnaires were collected, and 81.1% of respondents were willing to undergo self-funded screening. If the screening program were included in the medical insurance, 97.8% of respondents were willing to accept screening. The important reasons for supporting SMA screening were a belief that it could help them make better reproductive decisions and avoid having a child with SMA. The key reason for declining SMA screening was not having a family history of genetic diseases. A higher score for SMA genetics knowledge was associated with a greater willingness to undergo SMA screening. We concluded that pregnant women in Eastern China had positive attitudes toward SMA carrier screening. Improving genetic knowledge and including the screening program in medical insurance would support the widespread implementation of SMA carrier screening. Steps should be taken to offer SMA carrier screening along with pre- and posttest education and genetic counseling to raise awareness and reduce misconceptions regarding SMA.
Assuntos
Atrofia Muscular Espinal , Gestantes , Criança , Humanos , Feminino , Gravidez , Aconselhamento Genético , Atrofia Muscular Espinal/diagnóstico , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/psicologia , China , Conhecimentos, Atitudes e Prática em Saúde , Triagem de Portadores GenéticosRESUMO
Fenvalerate (FEN), a typical type II pyrethroid pesticide, is widely used in agriculture. FEN has been detected in the environment and human body. However, the neurotoxicity of FEN has not been well elucidated. This study aimed to explore the mechanisms underlying FEN-induced neurotoxicity using the zebrafish (Danio rerio) model. We also investigated whether curcumin (CUR), a polyphenol antioxidant that exhibits neuroprotective properties, can prevent FEN-induced neurotoxicity. Here, zebrafish embryos were exposed to 0, 3.5, 7 and 14 µg/L of FEN from 4 to 96 h post fertilization (hpf) and neurotoxicity was assessed. Our results showed that FEN decreased the survival rate, heart rate, body length and spontaneous movement, and increased malformation rate. FEN caused neurobehavioral alterations, including decreased swimming distance and velocity, movement time and clockwise rotation times. FEN also suppressed neurogenesis in transgenic HuC:egfp zebrafish, reduced cholinesterase activity and downregulated the expression of neurodevelopment related genes (elavl3, gfap, gap43 and mbp). In addition, FEN enhanced oxidative stress via excessive reactive oxygen species and antioxidant enzyme inhibition, then triggered apoptosis by upregulation of apoptotic genes (p53, bcl-2, bax and caspase 3). These adverse outcomes were alleviated by CUR, indicating that CUR mitigated FEN-induced neurotoxicity by inhibiting oxidative stress. Overall, this study revealed that CUR ameliorated FEN-induced neurotoxicity via its antioxidant, indicating a promising protection of CUR against environmental pollutant-induced developmental anomalies.
Assuntos
Curcumina , Piretrinas , Humanos , Animais , Peixe-Zebra , Curcumina/farmacologia , Antioxidantes , Larva , Estresse Oxidativo , Piretrinas/toxicidadeRESUMO
Recombinant proteins produced by cell factories are now widely used in various fields. Many efforts have been made to improve the secretion capacity of cell factories to meet the increasing demand for recombinant proteins. Recombinant protein production usually causes cell stress in the endoplasmic reticulum (ER). The overexpression of key genes possibly removes limitations in protein secretion. However, inappropriate gene expression may have negative effects. There is a need for dynamic control of genes adapted to cellular status. In this study, we constructed and characterized synthetic promoters that were inducible under ER stress conditions in Saccharomyces cerevisiae. The unfolded protein response element UPRE2, responding to stress with a wide dynamic range, was assembled with various promoter core regions, resulting in UPR-responsive promoters. Synthetic responsive promoters regulated gene expression by responding to stress level, which reflected the cellular status. The engineered strain using synthetic responsive promoters P4UPRE2 - TDH3 and P4UPRE2 - TEF1 for co-expression of ERO1 and SLY1 had 95% higher α-amylase production compared with the strain using the native promoters PTDH3 and PTEF1. This work showed that UPR-responsive promoters were useful in the metabolic engineering of yeast strains for tuning genes to support efficient protein production.
Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Engenharia Metabólica/métodosRESUMO
BACKGROUND: Moral courage is a recognized virtue. In the context of the COVID-19 pandemic, the master's students of nursing (MSNs) in China have shown tenacious moral courage. OBJECTIVE: This study elaborates on the moral courage of Chinese MSNs through their experiences of volunteering during the pandemic. RESEARCH DESIGN: Descriptive qualitative, interview-based. PARTICIPANTS AND RESEARCH CONTEXT: Participants were nursing postgraduate students who participated in the prevention and control of the COVID-19 pandemic selected by purposeful sampling. The sample size was determined by data saturation, which was reached with 10 participants. Data were analyzed using a deductive method of content analysis. Because of the isolation policy, telephone interviews were adopted. ETHICAL CONSIDERATIONS: After obtaining the approval of the ethical institution of the author's school (No. 138, 30 August 2021), verbal consent was obtained before the interview with the participants. All data were processed anonymously and confidentially. In addition, we recruited participants through MSNs' counselors, and obtained their phone numbers with their permission. RESULTS: Data analysis resulted in 15 subcategories that were subsequently grouped into 3 major categories including proceed without hesitation, the outcome of practicing moral courage, and develop and maintain moral courage. CONCLUSION: This qualitative study is based on the special background of the COVID-19 pandemic, and the MSNs in China have shown tenacious moral courage in the work of epidemic prevention and control. Five factors led them to take action without hesitation, and six possible outcomes followed. Lastly, this study provides some suggestions for nurses and nursing students to enhance their moral courage. To better develop and support moral courage in the future, it is necessary to use different methods and multidisciplinary approaches to study moral courage.
Assuntos
COVID-19 , Coragem , Ética em Enfermagem , Estudantes de Enfermagem , Humanos , Pandemias , Princípios MoraisRESUMO
4-Hydroxyphenylacetic acid (4HPAA) is an important building block for synthesizing drugs, agrochemicals, and biochemicals, and requires sustainable production to meet increasing demand. Here, we use a 4HPAA biosensor to overcome the difficulty of conventional library screening in identification of preferred mutants. Strains with higher 4HPAA production and tolerance are successfully obtained by atmospheric and room temperature plasma (ARTP) mutagenesis coupled with adaptive laboratory evolution using this biosensor. Genome shuffling integrates preferred properties in the strain GS-2-4, which produces 25.42 g/L 4HPAA. Chromosomal mutations of the strain GS-2-4 are identified by whole genome sequencing. Through comprehensive analysis and experimental validation, important genes, pathways and regulations are revealed. The best gene combination in inverse engineering, acrD-aroG, increases 4HPAA production of strain GS-2-4 by 37% further. These results emphasize precursor supply and stress resistance are keys to efficient 4HPAA biosynthesis. Our work shows the power of biosensor-assisted screening of mutants from libraries. The methods developed here can be easily adapted to construct cell factories for the production of other aromatic chemicals. Our work also provides many valuable target genes to build cell factories for efficient 4HPAA production in the future.
Assuntos
Técnicas Biossensoriais , Escherichia coli , Embaralhamento de DNA , Escherichia coli/genética , Escherichia coli/metabolismo , Engenharia Metabólica/métodos , FenilacetatosRESUMO
The cellular machinery that supports protein synthesis and secretion lies at the foundation of cell factory-centered protein production. Due to the complexity of such cellular machinery, the challenge in generating a superior cell factory is to fully exploit the production potential by finding beneficial targets for optimized strains, which ideally could be used for improved secretion of other proteins. We focused on an approach in the yeast Saccharomyces cerevisiae that allows for attenuation of gene expression, using RNAi combined with high-throughput microfluidic single-cell screening for cells with improved protein secretion. Using direct experimental validation or enrichment analysis-assisted characterization of systematically introduced RNAi perturbations, we could identify targets that improve protein secretion. We found that genes with functions in cellular metabolism (YDC1, AAD4, ADE8, and SDH1), protein modification and degradation (VPS73, KTR2, CNL1, and SSA1), and cell cycle (CDC39), can all impact recombinant protein production when expressed at differentially down-regulated levels. By establishing a workflow that incorporates Cas9-mediated recombineering, we demonstrated how we could tune the expression of the identified gene targets for further improved protein production for specific proteins. Our findings offer a high throughput and semirational platform design, which will improve not only the production of a desired protein but even more importantly, shed additional light on connections between protein production and other cellular processes.
Assuntos
Interferência de RNA , Proteínas Recombinantes/biossíntese , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Genoma Fúngico , Microfluídica , Proteínas Recombinantes/genética , Recombinação Genética , Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
Baker's yeast Saccharomyces cerevisiae is one of the most important and widely used cell factories for recombinant protein production. Many strategies have been applied to engineer this yeast for improving its protein production capacity, but productivity is still relatively low, and with increasing market demand, it is important to identify new gene targets, especially targets that have synergistic effects with previously identified targets. Despite improved protein production, previous studies rarely focused on processes associated with intracellular protein retention. Here we identified genetic modifications involved in the secretory and trafficking pathways, the histone deacetylase complex, and carbohydrate metabolic processes as targets for improving protein secretion in yeast. Especially modifications on the endosome-to-Golgi trafficking was found to effectively reduce protein retention besides increasing protein secretion. Through combinatorial genetic manipulations of several of the newly identified gene targets, we enhanced the protein production capacity of yeast by more than fivefold, and the best engineered strains could produce 2.5 g/L of a fungal α-amylase with less than 10% of the recombinant protein retained within the cells, using fed-batch cultivation.
Assuntos
Engenharia Metabólica/métodos , Biossíntese de Proteínas/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/metabolismo , Via Secretória/fisiologia , alfa-Amilases/biossíntese , Endossomos/metabolismo , Complexo de Golgi/metabolismo , Histona Desacetilases/genética , Transporte Proteico/genética , Proteínas Recombinantes/genética , Saccharomyces cerevisiae/genética , Via Secretória/genéticaRESUMO
Genome-wide association studies (GWAS) have identified 45 susceptibility loci associated with lung cancer. Only less than SNPs, small insertions and deletions (INDELs) are the second most abundant genetic polymorphisms in the human genome. INDELs are highly associated with multiple human diseases, including lung cancer. However, limited studies with large-scale samples have been available to systematically evaluate the effects of INDELs on lung cancer risk. Here, we performed a large-scale meta-analysis to evaluate INDELs and their risk for lung cancer in 23,202 cases and 19,048 controls. Functional annotations were performed to further explore the potential function of lung cancer risk INDELs. Conditional analysis was used to clarify the relationship between INDELs and SNPs. Four new risk loci were identified in genome-wide INDEL analysis (1p13.2: rs5777156, Insertion, OR = 0.92, p = 9.10 × 10-8 ; 4q28.2: rs58404727, Deletion, OR = 1.19, p = 5.25 × 10-7 ; 12p13.31: rs71450133, Deletion, OR = 1.09, p = 8.83 × 10-7 ; and 14q22.3: rs34057993, Deletion, OR = 0.90, p = 7.64 × 10-8 ). The eQTL analysis and functional annotation suggested that INDELs might affect lung cancer susceptibility by regulating the expression of target genes. After conducting conditional analysis on potential causal SNPs, the INDELs in the new loci were still nominally significant. Our findings indicate that INDELs could be potentially functional genetic variants for lung cancer risk. Further functional experiments are needed to better understand INDEL mechanisms in carcinogenesis.
Assuntos
Predisposição Genética para Doença/genética , Mutação INDEL/genética , Neoplasias Pulmonares/genética , Estudo de Associação Genômica Ampla , HumanosRESUMO
BACKGROUND & AIMS: Esophageal adenocarcinoma (EAC) occurs most frequently in men. We performed a Mendelian randomization analysis to investigate whether genetic factors that regulate levels of sex hormones are associated with risk of EAC or Barrett's esophagus (BE). METHODS: We conducted a Mendelian randomization analysis using data from patients with EAC (n = 2488) or BE (n = 3247) and control participants (n = 2127), included in international consortia of genome-wide association studies in Australia, Europe, and North America. Genetic risk scores or single-nucleotide variants were used as instrumental variables for 9 specific sex hormones. Logistic regression provided odds ratios (ORs) with 95% CIs. RESULTS: Higher genetically predicted levels of follicle-stimulating hormones were associated with increased risks of EAC and/or BE in men (OR, 1.14 per allele increase; 95% CI, 1.01-1.27) and in women (OR, 1.28; 95% CI, 1.03-1.59). Higher predicted levels of luteinizing hormone were associated with a decreased risk of EAC in men (OR, 0.92 per SD increase; 95% CI, 0.87-0.99) and in women (OR, 0.93; 95% CI, 0.79-1.09), and decreased risks of BE (OR, 0.88; 95% CI, 0.77-0.99) and EAC and/or BE (OR, 0.89; 95% CI, 0.79-1.00) in women. We found no clear associations for other hormones studied, including sex hormone-binding globulin, dehydroepiandrosterone sulfate, testosterone, dihydrotestosterone, estradiol, progesterone, or free androgen index. CONCLUSIONS: In a Mendelian randomization analysis of data from patients with EAC or BE, we found an association between genetically predicted levels of follicle-stimulating and luteinizing hormones and risk of BE and EAC.