ABSTRACT
RhlR plays a key role in the quorum sensing of Pseudomonas aeruginosa. The current structure-activity relationship (SAR) studies of RhlR inhibitors mainly focus on elucidating the functional groups. Based on a systematic review of previous research on RhlR inhibitors, this study aims to establish a systematic, hierarchical screening model for RhlR inhibitors. We initially established a database and utilized principal component analysis (PCA) to categorize the inhibitors into two classes. Based on the training set, pharmacophore models were established to elucidate the structural characteristics of ligands. Subsequently, molecular docking, molecular dynamics simulations, and the calculation of binding free energy and strain energy were performed to validate the crucial interactions between ligands and receptors. Then, the screening criteria for RhlR inhibitors were established hierarchically based on ligand structure characteristics, ligand-receptor interaction, and receptor affinity. Test sets were finally employed to validate the hierarchical virtual screening model by comparing it with the current SAR studies of RhlR inhibitors. The hierarchical screening model was confirmed to possess higher accuracy and a true positive rate, which holds promise for subsequent screening and the discovery of active RhlR inhibitors.
Subject(s)
Molecular Docking Simulation , Molecular Dynamics Simulation , Principal Component Analysis , Pseudomonas aeruginosa , Pseudomonas aeruginosa/drug effects , Ligands , Structure-Activity Relationship , Bacterial Proteins/antagonists & inhibitors , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Protein Binding , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Quorum Sensing/drug effects , Drug Evaluation, Preclinical/methods , PharmacophoreABSTRACT
Insomnia is a typical type of sleep disorder. Huanglian Wendan Decoction (HWD) is a traditional Chinese medicine (TCM) with the effects of regulating Qi, drying dampness and resolving phlegm, calming the mind, and relieving irritation. This study aims to investigate the effect of HWD on insomnia in rats and its mechanism. Para-chlorophenylalanine (PCPA)-induced insomnia in rats was used for in vivo experiments and then treated with HWD. Behavioral tests, Western blot, real-time PCR, immunofluorescent staining, 16S rRNA sequencing were conducted. The content of SCFAs was determined by GC-MS. Acetic acid-pretreated rat hippocampal nerve cells were used for in vitro experiments. The results showed that HWD significantly improved the learning memory ability, decreased sleep latency, and prolonged sleep duration in insomniac rats. HWD reduced TNF-α and IL-6 levels and increased IL-10 and Foxp3 levels. HWD also promoted the polarization of macrophages from M1 pro-inflammatory phenotype to M2 anti-inflammatory phenotype. In addition, HWD increased the expression levels of BDNF and TrkB in the hippocampus. Administration of the TrkB receptor agonist 7,8-dihydroxyflavone (7,8-DHF) confirmed the mechanism by which HWD activates BDNF/TrkB signaling to ameliorate insomnia. Furthermore, HWD restored gut microbiota richness and diversity and promoted short-chain fatty acid (SCFA) production in insomniac rats. In vitro experiments confirmed that the acetic acid-treated SCFA group could activate the BDNF/TrkB signaling pathway in neuronal cells, further promoting neuronal cell growth. In conclusion, HWD alleviated insomnia by maintaining gut microbiota homeostasis, promoting SCFA production, reducing neuroinflammatory response and microglia activation, and activating BDNF/TrkB signaling pathway.
ABSTRACT
Esophageal cancer (EC) has a high mortality rate and poor prognosis. Most patients are diagnosed at an advanced stage or with distant metastasis, making surgery impossible. Traditional curative radiotherapy and chemotherapy have limited efficacy. In recent years, with the development of clinical trials, immune checkpoint inhibitors (ICIs) have shown promising results in treating advanced and metastatic esophageal squamous cell carcinoma (ESCC) patients. ICIs have gradually become a primary therapeutic approach for EC. This review summarizes and provides an overview of the current research status and progress of ICIs in the treatment of advanced ESCC patients.
ABSTRACT
This study aimed to characterize the risk factors, etiology, clinical manifestations, anatomical characteristics, stroke mechanisms, imaging features, and prognosis of bilateral medial medullary infarction (BMMI). A retrospective analysis was conducted on 11 patients with BMMI who met the inclusion criteria at the Affiliated Hospital of Xuzhou Medical University from January 2013 to January 2023. The patients' imaging and clinical features were analyzed and summarized. Eleven patients (7 male, 4 female), aged 46 to 62 years, met the inclusion criteria. Common clinical presentations included dysarthria (90.9%), dysphagia (90.9%), quadriplegia (81.8%), and so on. Within 72 hours of onset, 8 cases presented with quadriplegia, 2 cases with hemiplegia, and 1 case without limb paralysis. The main risk factor for BMMI was hypertension, followed by diabetes. "Heart appearance" infarcts occurred in 4 cases (36.4%), while "Y appearance" infarcts occurred in 7 cases (63.6%). Among the patients, 3 had unilateral vertebral artery stenosis or occlusion, 5 had bilateral vertebral artery stenosis or occlusion, 2 had normal vertebral basilar artery, and 1 did not undergo cerebrovascular examination. All patients received standardized treatment for cerebral infarction. The prognosis was poor, with 81.8% of patients having an unfavorable outcome, including 1 death, 9 cases of disability, and only 1 patient achieving self-care ability after recovery. BMMI is more prevalent in males aged 45 to 60 years. The main risk factors are hypertension and diabetes. Atherosclerosis is the primary etiological subtype. The main clinical manifestations are dyskinesia, dizziness, quadriplegia, and dysarthria. The prognosis of BMMI is poor. The specific imaging features of "heart appearance" or "Y appearance" infarcts aid in the diagnosis of BMMI.
Subject(s)
Brain Stem Infarctions , Medulla Oblongata , Humans , Male , Female , Middle Aged , Retrospective Studies , Medulla Oblongata/blood supply , Medulla Oblongata/pathology , Medulla Oblongata/diagnostic imaging , Brain Stem Infarctions/diagnostic imaging , Risk Factors , Prognosis , Quadriplegia/etiology , Hypertension/complications , Hypertension/epidemiologyABSTRACT
BACKGROUND: Several studies have suggested that transcutaneous vagus nerve stimulation (tVNS) may be effective for the treatment of epilepsy. However, auricular acupoint therapy (including auricular acupuncture and auricular point-sticking therapy), a method of stimulating the vagus nerve, has been poorly reviewed. This systematic review is the first to categorize auricular acupoint therapy as transcutaneous auricular vagus nerve stimulation (taVNS), aiming to assess the efficacy of taVNS in patients with epilepsy (PWE), and to analyse the results of animal experiments on the antiepileptic effects of taVNS. METHODS: We searched MEDLINE, EMBASE, Web of Science, Scopus, and various Chinese databases from their inception to June 10, 2023 and found nine clinical studies (including a total of 788 PWE) and eight preclinical studies. We performed a meta-analysis and systematic review of these articles to assess the efficacy of taVNS in PWE and the association between taVNS and electroencephalogram (EEG) changes. We also analysed the effects on epileptic behaviour, latency of the first seizure, and seizure frequency in epileptic animals. The PRISMA 2020 checklist provided by the EQUATOR Network was used in this study. RESULTS: taVNS had a higher response rate in PWE than the control treatment (OR = 2.94, 95 % CI = 1.94 - 4.46, P < 0.05). The analysis showed that the taVNS group showed wider EEG changes than the control group (OR = 2.17, 95 % CI 1.03 to 4.58, P < 0.05). The preclinical studies analysis revealed significant differences in epileptic behaviour (SMD = -4.78, 95 % CI -5.86 to -3.71, P < 0.05) and seizure frequency (SMD = -5.06, 95 % CI -5.96 to -4.15, P < 0.05) between the taVNS and control groups. No statistical difference was found in the latency of the first seizure between the two groups (SMD =13.54; 95 % CI 7.76 to 19.33, P < 0.05). CONCLUSION: Based on the available data, PWE may benefit from the use of taVNS. taVNS is an effective procedure for improving epileptic behaviour in animal models.
Subject(s)
Epilepsy , Transcutaneous Electric Nerve Stimulation , Vagus Nerve Stimulation , Humans , Vagus Nerve Stimulation/methods , Epilepsy/therapy , Epilepsy/physiopathology , Transcutaneous Electric Nerve Stimulation/methods , AnimalsABSTRACT
Objective: Long-term alcohol consumption can cause organic damage to the brain, resulting in mental and nervous system abnormalities and intellectual impairment. Huanglian Jiedu decoction (HLJDD) is the classic representative of clearing heat and detoxifying. This study aimed to explore the effects and possible mechanisms of HLJDD on brain injury in chronic alcohol-exposed mice. Methods: The alcohol-exposed mice were treated with different doses of HLJDD to observe behavioral changes, hippocampal Aß1-42 deposition, number and ultrastructural changes of neurons in the hippocampus and prefrontal cortex, and expressions of synaptic proteins. On this basis, transcriptome sequencing was used to analyze the differentially expressed genes in different treatment groups, and functional enrichment analysis was performed. Then, WB and RT-PCR were used to verify the expression of the pathway. Results: Chronic alcohol exposure reduced body weight in mice, led to motor cognitive impairment, increased Aß1-42 in the hippocampus, decreased the number of neurons in the hippocampus and prefrontal cortex, and the expression of PSD95 and SYN in the hippocampus. HLJDD significantly improved the cognitive dysfunction of mice and alleviated the damage of the hippocampus and prefrontal cortex. Transcriptome sequencing results showed that the regulatory effects of HLJDD on chronic alcohol-exposed mice may be related to the RAS pathway. Further experiments confirmed that chronic alcohol exposure caused a significant increase in protein and gene expressions of the RAS-RAF-MEK-ERK pathway in mouse, and this activation was reversed by HLJDD. Conclusion: HLJDD may ameliorate brain damage caused by chronic alcohol exposure by regulating the RAS-RAF-MEK-ERK pathway.
ABSTRACT
Cas-assisted lambda Red recombineering techniques have rapidly become a mainstay of bacterial genome editing. Such techniques have been used to construct both individual mutants and massive libraries to assess the effects of genomic changes. We have found that a commonly used Cas9-assisted editing method results in unintended mutations elsewhere in the genome in 26% of edited clones. The unintended mutations are frequently found over 200 kb from the intended edit site and even over 10 kb from potential off-target sites. We attribute the high frequency of unintended mutations to error-prone polymerases expressed in response to dsDNA breaks introduced at the edit site. Most unintended mutations occur in regulatory or coding regions and thus may have phenotypic effects. Our findings highlight the risks associated with genome editing techniques involving dsDNA breaks in E. coli and likely other bacteria and emphasize the importance of sequencing the genomes of edited cells to ensure the absence of unintended mutations.
ABSTRACT
CONTEXT: Sepsis-induced acute lung injury (ALI) is associated with high morbidity and mortality. Rhodiola rosea L. (Crassulaceae) (RR) and its extracts have shown anti-inflammatory, antioxidant, immunomodulatory, and lung-protective effects. OBJECTIVE: This study elucidates the molecular mechanisms of RR against sepsis-induced ALI. MATERIALS AND METHODS: The pivotal targets of RR against sepsis-induced ALI and underlying mechanisms were revealed by network pharmacology and molecular docking. Human umbilical vein endothelial cells (HUVECs) were stimulated by 1 µg/mL lipopolysaccharide for 0.5 h and treated with 6.3, 12.5, 25, 50, 100, and 200 µg/mL RR for 24 h. Then, the lipopolysaccharide-stimulated HUVECs were subjected to cell counting kit-8 (CCK-8), enzyme-linked immunosorbent, apoptosis, and Western blot analyses. C57BL/6 mice were divided into sham, model, low-dose (40 mg/kg), mid-dose (80 mg/kg), and high-dose (160 mg/kg) RR groups. The mouse model was constructed through caecal ligation and puncture, and histological, apoptosis, and Western blot analyses were performed for further validation. RESULTS: We identified six hub targets (MPO, HRAS, PPARG, FGF2, JUN, and IL6), and the PI3K-AKT pathway was the core pathway. CCK-8 assays showed that RR promoted the viability of the lipopolysaccharide-stimulated HUVECs [median effective dose (ED50) = 18.98 µg/mL]. Furthermore, RR inhibited inflammation, oxidative stress, cell apoptosis, and PI3K-AKT activation in lipopolysaccharide-stimulated HUVECs and ALI mice, which was consistent with the network pharmacology results. DISCUSSION AND CONCLUSION: This study provides foundational knowledge of the effective components, potential targets, and molecular mechanisms of RR against ALI, which could be critical for developing targeted therapeutic strategies for sepsis-induced ALI.
Subject(s)
Acute Lung Injury , Rhodiola , Sepsis , Humans , Animals , Mice , Mice, Inbred C57BL , Phosphatidylinositol 3-Kinases , Proto-Oncogene Proteins c-akt , Lipopolysaccharides/toxicity , Molecular Docking Simulation , Network Pharmacology , Oxidative Stress , Sepsis/complications , Sepsis/drug therapy , Acute Lung Injury/drug therapy , Acute Lung Injury/etiology , Human Umbilical Vein Endothelial CellsABSTRACT
Studies have shown that saikosaponin D (SSD) has favorable neurotherapeutic effects. Therefore, the objective of this study was to explore the efficacy and possible molecular mechanisms of SSD on pilocarpine (PP)-induced astrocyte injury. Primary astrocytes were isolated from juvenile rats and identified using immunofluorescence. The cells were treated with PP and/or SSD for 6 h and 12 h, respectively, followed by measurement of their viability through 3-(4,5-dimethylthiazol)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Next, quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression levels of Glial fibrillary acidic protein (GFAP), C3, S100 calcium binding protein A10 (S100a10), pentraxin 3 (Ptx3), toll-like receptor 4 (TLR4), and RAG in astrocytes after different treatments. Enzyme-linked immunosorbent assay and biochemical tests were utilized to evaluate the level of inflammatory factors [interleukin (IL)-1ß, IL-6, and tumor necrosis factor alpha (TNF-α)] secreted by cells and the content of oxidative stress-related factors (malondialdehyde [MDA] and glutathione [GSH]) or enzyme activity (catalase [CAT] and glutathione peroxidase [GPX]) in cells. The JC-1 mitochondrial membrane potential (MMP) fluorescence probe was used to measure the MMP in astrocytes. Additionally, western blot was applied to test the expression of proteins related to the nod-like receptor protein 3 (NLRP3)/caspase-1 signaling pathway. PP treatment (1 mM) induced cell injury by significantly reducing the viability of astrocytes and expression of cellular markers. SSD treatment (4 µM) had no toxicity to astrocytes. Besides, SSD (4 µM) treatment could significantly up-regulate the cell viability and marker expression of PP-induced astrocytes. Furthermore, SSD could be employed to inhibit inflammation (reduce IL-1ß, IL-6, and TNF-α levels) and oxidative stress (decrease MDA level, elevate GSH level, the activity of CAT and GPX), and ameliorate mitochondrial dysfunction (upregulate JC-1 ratio) in PP-induced astrocytes. Moreover, further mechanism exploration revealed that SSD treatment significantly reduced the activity of the NLRP3/caspase-1 signaling pathway activated by PP induction. SSD increased cell viability, inhibited inflammation and oxidative stress response, and ameliorated mitochondrial dysfunction in PP-induced astrocyte injury model, thus playing a neuroprotective role. The mechanism of SSD may be related to the inhibition of the NLRP3/caspase-1 inflammasome.
Subject(s)
Benzimidazoles , Carbocyanines , Mitochondrial Diseases , NLR Family, Pyrin Domain-Containing 3 Protein , Oleanolic Acid/analogs & derivatives , Saponins , Rats , Animals , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Astrocytes/metabolism , Astrocytes/pathology , Pilocarpine/toxicity , Tumor Necrosis Factor-alpha/genetics , Caspases/metabolism , Interleukin-6 , Signal Transduction , Inflammation/metabolismABSTRACT
Background: During the coronavirus disease-2019 (COVID-19) pandemic, there have been many studies on knowledge, attitudes, and practices (KAP) toward prevention of COVID-19 infection in China. Except for symptomatic treatment and vaccination, KAP toward COVID-19 plays an important role in the prevention of COVID-19. There is no systematic evaluation and meta-analysis of KAP toward COVID-19 in China. This study is the earliest meta-analysis of KAP toward COVID-19 in China's general population. Hence, this systematic review aimed to summarize the knowledge, attitudes, and practices (KAP) of Chinese residents toward COVID-19 during the pandemic. Methodology: Following the PRISMA guidelines, articles relevant to COVID-19 KAP that were conducted among the Chinese population were found in databases such as Scopus, ProQuest, PubMed, EMbase, Web of Science, Cochrane Library, China Biology Medicine, China National Knowledge Infrastructure, CQVIP, Wanfang and Google Scholar. A random-effect meta-analysis is used to summarize studies on knowledge, attitudes, and practice levels toward COVID-19 infection in China's general population. Results: Fifty-seven articles published between August 2020 and November 2022 were included in this review. Overall, 75% (95% CI: 72-79%) of Chinese residents had good knowledge about COVID-19, 80% (95% CI: 73-87%) of Chinese residents had a positive attitude toward COVID-19 pandemic control and prevention (they believe that Chinese people will win the battle against the epidemic), and the aggregated proportion of residents with a correct practice toward COVID-19 was 84% (95% CI: 82-87%, I2 = 99.7%).In the gender subgroup analysis, there is no significant difference between Chinese men and Chinese women in terms of their understanding of COVID-19. However, Chinese women tend to have slightly higher levels of knowledge and a more positive attitude toward the virus compared to Chinese men. When considering the urban and rural subgroup analysis, it was found that Chinese urban residents have a better understanding of COVID-19 compared to Chinese rural residents. Interestingly, the rural population displayed higher rates of correct behavior and positive attitudes toward COVID-19 compared to the urban population. Furthermore, in the subgroup analysis based on different regions in China, the eastern, central, and southwestern regions exhibited higher levels of knowledge awareness compared to other regions. It is worth noting that all regions in China demonstrated good rates of correct behavior and positive attitudes toward COVID-19. Conclusion: This study reviews the level of KAP toward COVID-19 during the pandemic period in China. The results show that the KAP toward COVID-19 in Chinese residents was above a favorable level, but the lack of translation of knowledge into practice should be further reflected on and improved. A subgroup analysis suggests that certain groups need more attention, such as males and people living in rural areas. Policy makers should pay attention to the results of this study and use them as a reference for the development of prevention and control strategies for major public health events that may occur in the future. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=348246, CRD42022348246.
Subject(s)
COVID-19 , East Asian People , Female , Humans , Male , China/epidemiology , COVID-19/epidemiology , Health Knowledge, Attitudes, Practice , Pandemics/prevention & control , Surveys and QuestionnairesABSTRACT
Currently, the L-malic acid titer achieved through Aspergillus niger fermentation reaches 201 g/L, meeting industrial demands satisfactorily. However, the co-presence of structurally similar fumaric acid and succinic acid in fermentation products suggests a theoretical potential for further improvement in L-malic acid production. In the tricarboxylic acid cycle, fumarate reductase mediates the conversion of succinic acid to fumaric acid. Subsequently, fumarase catalyzes the conversion of fumaric acid to L-malic acid. Notably, both enzymatic reactions are reversible. Our investigation revealed that A. niger contains only one mitochondria-located fumarase FumA. Employing CRISPR-Cas9 technology, we performed a replacement of the fumA promoter with a doxycycline-induced promoter Tet. Under non-inducing condition, the conditional strain exhibited increased levels of fumaric acid and succinic acid. It strongly suggests that FumA mainly promotes the flow of fumaric acid to L-malic acid. Furthermore, a promoter PmfsA that is exclusively activated in a fermentation medium by calcium carbonate was identified through RNA-sequencing screening. Utilizing PmfsA to regulate fumA expression led to a 9.0% increase in L-malic acid titer, an 8.75% increase in yield (glucose to L-malic acid), and an 8.86% enhancement in productivity. This research serves as a significant step toward expediting the industrialization of L-malic acid synthesis via biological fermentation. Additionally, it offers valuable insights for the biosynthesis of other organic acids.IMPORTANCEThis study focuses on enhancing L-malic acid synthesis by modifying the tricarboxylic acid cycle within the mitochondria of Aspergillus niger. We emphasize the significant role of fumarase in converting fumaric acid into L-malic acid, enhancing our understanding of metabolic pathways in A. niger. The precise regulation of fumA is highlighted as a key factor in enhancing L-malic acid production. Furthermore, this research introduces a stringent conditional promoter (PmfsA), exclusively activated by CaCO3. The utilization of PmfsA for fumA expression resulted in heightened L-malic acid titers. The progress in metabolic engineering and bioprocess optimization holds promise for expediting industrial L-malic acid synthesis via biological fermentation. Moreover, it carries implications for the biosynthesis of various other organic acids.
Subject(s)
Aspergillus niger , Fumarate Hydratase , Fumarates , Aspergillus niger/genetics , Aspergillus niger/metabolism , Fumarate Hydratase/genetics , Fumarate Hydratase/metabolism , Malates/metabolism , Succinic AcidABSTRACT
Purpose: Previous studies have reported mixed results regarding the importance of cortical abnormalities in patients with migraines. However, cortical sulci, as a component of the cerebral cortex, have not been specifically investigated in migraine patients. Therefore, we aim to evaluate alterations in cortical sulcal morphology among patients with chronic migraine (CM), episodic migraine (EM), and healthy controls (HCs). Patients and Methods: In this cross-sectional study, structural magnetic resonance images were acquired from 35 patients with CM, 35 with EM, and 35 HCs. Cortical sulci were identified and reconstructed using the BrainVisa 5.0.4 software. We focused on regions involved in pain processing in which abnormal cortical structure were identified in previous neuroimaging studies. Morphometric analysis was performed to calculate sulcal parameters including mean depth, cortical thickness, and opening width. Partial correlation analyses of clinical characteristics and sulcal parameters were performed for CM, EM and the combined migraine (CM + EM) groups. Results: In comparison with HCs, both CM and EM groups showed increased opening width in bilateral insula. In comparison with HC and EM groups, CM patients showed increased cortical thickness in bilateral superior postcentral sulcus, bilateral median frontal sulcus and left superior parietal sulcus, as well as increased mean depth in the left anterior callosomarginal fissure and decreased mean depth in bilateral superior frontal sulcus and left median frontal sulcus. Migraine frequency and disease duration were both correlated with cortical thickness in bilateral superior postcentral sulcus. Conclusion: Abnormal sulcal morphometry primarily affected areas associated with pain processing in patients with migraine, with CM exhibiting more extensive abnormalities in areas related to sensory and affective processing. These changes may contribute to understanding the pathology of EM and CM.
ABSTRACT
Pseudomonas aeruginosa is a clinically challenging pathogen due to its high resistance to antibiotics. Quorum sensing inhibitors (QSIs) have been proposed as a promising strategy to overcome this resistance by interfering with the bacterial communication system. Among the potential targets of QSIs, PqsR is a key regulator of quorum sensing in Pseudomonas aeruginosa. However, the current research on PqsR inhibitors is limited by the lack of diversity in the chemical structures and the screening methods. Therefore, this study aims to develop a multidimensional screening model for PqsR inhibitors based on both ligand- and receptor-based approaches. First, a pharmacophore model was constructed from a training set of PqsR inhibitors to identify the essential features and spatial arrangement for the activity. Then, molecular docking and dynamics simulations were performed to explore the core interactions between PqsR inhibitors and their receptor. The results indicate that an effective PqsR inhibitor should possess two aromatic rings, one hydrogen bond acceptor, and two hydrophobic groups and should form strong interactions with the following four amino acid residues: TYR_258, ILE_236, LEU_208, and GLN_194. Moreover, the docking score and the binding free energy should be lower than -8 kcal/mol and -40 kcal/mol, respectively. Finally, the validity of the multidimensional screening model was confirmed by a test set of PqsR inhibitors, which showed a higher accuracy than the existing screening methods based on single characteristics. This multidimensional screening model would be a useful tool for the discovery and optimization of PqsR inhibitors in the future.
Subject(s)
Molecular Dynamics Simulation , Pharmacophore , Molecular Docking Simulation , Quorum Sensing , Anti-Bacterial Agents/chemistryABSTRACT
The efficient production of l-malic acid using Aspergillus niger requires overcoming challenges in synthesis efficiency and excessive byproduct buildup. This study addresses these hurdles, improving the activity of NADH-dependent malate dehydrogenase (Mdh) in the early stages of the fermentation process. By employing a constitutive promoter to express the Escherichia coli sthA responsible for the transfer of reducing equivalents between NAD(H) and NADP(H) in A. niger, the l-malic acid production was significantly elevated. However, this resulted in conidiation defects of A. niger, limiting industrial viability. To mitigate this, we discovered and utilized the PmfsA promoter, enabling the specific expression of sthA during the fermentation stage. This conditional expression strain showed similar phenotypes to its parent strain while exhibiting exceptional performance in a 5 L fermenter. Notably, it achieved a 65.5% increase in productivity, reduced fermentation cycle by 1.5 days, and lowered succinic acid by 76.2%. This work marks a promising advancement in industrial l-malic acid synthesis via biological fermentation, showcasing the potential of synthetic biology in A. niger for broader applications.
Subject(s)
Aspergillus niger , Aspergillus , Malates , Aspergillus niger/genetics , Aspergillus niger/metabolism , Malates/metabolism , Fermentation , Escherichia coli/genetics , Escherichia coli/metabolism , NAD/metabolism , Gene ExpressionABSTRACT
CRISPR-Cas-based genome editing is widely used in bacteria at scales ranging from construction of individual mutants to massively parallel libraries. This procedure relies on guide RNA-directed cleavage of the genome followed by repair with a template that introduces a desired mutation along with synonymous "immunizing" mutations to prevent re-cleavage of the genome after editing. Because the immunizing mutations do not change the protein sequence, they are often assumed to be neutral. However, synonymous mutations can change mRNA structures in ways that alter levels of the encoded proteins. We have tested the assumption that immunizing mutations are neutral by constructing a library of over 50,000 edits that consist of only synonymous mutations in Escherichia coli. Thousands of edits had substantial effects on fitness during growth of E. coli on acetate, a poor carbon source that is toxic at high concentrations. The percentage of high-impact edits varied considerably between genes and at different positions within genes. We reconstructed clones with high-impact edits and found that 69% indeed had significant effects on growth in acetate. Interestingly, fewer edits affected fitness during growth in glucose, a preferred carbon source, suggesting that changes in protein expression caused by synonymous mutations may be most important when an organism encounters challenging conditions. Finally, we showed that synonymous edits can have widespread effects; a synonymous edit at the 5' end of ptsI altered expression of hundreds of genes. Our results suggest that the synonymous immunizing edits introduced during CRISPR-Cas-based genome editing should not be assumed to be innocuous.
Subject(s)
Escherichia coli , RNA, Guide, CRISPR-Cas Systems , Escherichia coli/genetics , Gene Library , Carbon , AcetatesABSTRACT
Bismuth(III)-based complexes have garnered increasing attention in fluorescence sensing due to their environmentally friendly and sustainable characteristics. A Bismuth(III) coordination polymer (CP),1-Cl based on a naphthalene diimides(NDI)-pyridinium is synthesized by an in situ reaction method. Notable for its sensitivity to visible light, 1-Cl shows excellent photochromic properties, and the integration of NDI and pyridinium in one ligand makes photogenerated radicals more stable. Structural analysis and theoretical calculations are employed to investigate the potential pathway of photoinduced electron transfer (ET) during the photochromic process. Notably, in aqueous solutions, 1-Cl displays an extraordinary fluorescence enhancement response to bromide ion (Br-), resulting in a distinct transition from yellow to orange in color. The potential mechanism of fluorescence sensing has been revealed through single-crystal X-ray diffraction analysis. This insight highlights a continuous substitution process where the Cl- ions are successively replaced by Br- ions. Consequently, a single-crystal-to-single-crystal transformation (SCSC) occurs, yielding the intermediate species, 1-Cl-Br, which ultimately transforms into the final product, 1-Br. Finally, the photochromic film is successfully prepared and applied to practical applications such as ink-free printing, information anti-counterfeiting, and the visual detection of Br- ions. This work combines photochromism with fluorescence sensing, broadening the research field and practical application of photochromic materials.
ABSTRACT
Carbon fiber composites have great application prospects as a potential electromagnetic (EM) wave-absorbing material, yet it remains extremely challenging to integrate multiple functions of EM wave absorption, mechanical strength, thermal insulation, and flame retardancy. Herein, a novel carbon fiber reinforced C/SiOC aerogel (CF/CS) composite is successfully prepared by sol-gel impregnation combined with an ambient drying process for the first time. The density of the obtained CF/CS composites can be controlled just by changing sol-gel impregnation cycles (original carbon fiber felt (S0), and samples with one (S1) and two (S2) impregnation cycles are 0.249, 0.324, and 0.402 g cm-3, respectively), allowing for efficient tuning of their properties. Remarkably, S2 displays excellent microwave absorption properties, with an optimal reflection loss of -65.45 dB, which is significantly improved than S0 (-10.90 dB). Simultaneously, compared with S0 (0.75 and 0.30 MPa in the x/y and z directions), the mechanical performance of S2 is dramatically improved with a maximum compressive strength of 10.37 and 4.93 MPa in the x/y and z directions, respectively. Moreover, CF/CS composites show superior thermal insulation capability than S0 and obtain good flame-retardant properties. This work provides valuable guidance and inspiration for the development of multifunctional EM wave absorbers.
ABSTRACT
Alzheimer's disease (AD) is the prevailing type of dementia in the elderly, yet a comprehensive comprehension of its precise underlying mechanisms remains elusive. The investigation of the involvement of cerebral small veins in the advancement of AD has yet to be sufficiently explored in previous studies, primarily due to constraints associated with pathological staining techniques. However, recent research has provided valuable insights into multiple pathophysiological occurrences concerning cerebral small veins in AD, which may manifest sequentially, concurrently, or in a self-perpetuating manner. These events are presumed to be among the initial processes in the disease's progression. The impact of cerebral small vein loss on amyloid beta (Aß) clearance through the glial lymphatic system is noteworthy. There exists a potential interdependence between collagen deposition and Aß deposition in cerebral small veins. The compromised functionality of cerebral small veins can result in decreased cerebral perfusion pressure, potentially leading to cerebral tissue ischemia and edema. Additionally, the reduction of cerebral small veins may facilitate the infiltration of inflammatory factors into the brain parenchyma, thereby eliciting neuroinflammatory responses. Susceptibility-weighted imaging (SWI) is a valuable modality for the efficient assessment of cerebral small veins, precisely the deep medullary vein (DMV), and holds promise for the identification of precise and reliable imaging biomarkers for AD. This review presents a comprehensive overview of the current advancements and obstacles to the impairment of cerebral small veins in AD. Additionally, we emphasize future research avenues and the importance of conducting further investigations in this domain.
Subject(s)
Alzheimer Disease , Humans , Aged , Alzheimer Disease/complications , Alzheimer Disease/diagnostic imaging , Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Brain/metabolism , Neuroglia/pathologyABSTRACT
Ethylene plays an important role in plant development and stress resistance. The rate-limiting enzyme in ethylene biosynthesis is 1-aminocyclopropane-1-carboxylic acid synthase (ACS). C. quinoa (Chenopodium quinoa) is an important food crop known for its strong tolerance to abiotic stresses. However, knowledge regarding the ACS gene family in C. quinoa remains restricted. In this study, we successfully identified 12 ACS genes (CqACSs) from the C. quinoa genome. Through thorough analysis of their sequences and phylogenetic relationships, it was verified that 8 out of these 12 CqACS isozymes exhibited substantial resemblance to ACS isozymes possessing ACS activity. Furthermore, these eight isozymes could be categorized into three distinct groups. The four remaining CqACS genes grouped under category IV displayed notable similarities with AtACS10 and AtACS12, known as amido transferases lacking ACS activity. The CqACS proteins bore resemblance to the AtACS proteins and had the characteristic structural features typically observed in plant ACS enzymes. Twelve CqACS genes were distributed across 8 out of the 18 chromosomes of C. quinoa. The CqACS genes were expanded from segment duplication. Many cis-regulatory elements related with various abiotic stresses, phytohormones, and light were found. The expression patterns of ACS genes varied across different tissues of C. quinoa. Furthermore, the analysis of gene expression patterns under abiotic stress showed that CqACS genes can be responsive to various stresses, implying their potential functions in adapting to various abiotic stresses. The findings from this research serve as a foundation for delving deeper into the functional roles of CqACS genes.
ABSTRACT
Background: Neurosyphilis refers to an infection of the central nervous system by Treponema pallidum. The clinical manifestations of neurosyphilis are diverse, making it easy to miss or misdiagnose. Anti-myelin oligodendrocyte glycoprotein antibody-associated disease is a recently defined immune-mediated inflammatory demyelinating central nervous system disease. Few studies have reported the coexistence of the two diseases. Case presentation: This case report presents a 37 years-old male patient with neurosyphilis manifested as optic neuritis with a positive myelin oligodendrocyte glycoprotein (MOG) antibody. This patient received intravenous administration of 3.2 million units of procaine penicillin every 4 h for 2 weeks, followed by a two-week intramuscular injection of benzathine penicillin. Additionally, methylprednisolone sodium succinate was administered intravenously at 1,000 mg/day, gradually reduced to 500 mg/day and 240 mg/day every 3 days. Subsequently, prednisone tablets at a dosage of 60 mg/day were orally administered, with a gradual reduction of 5 mg/day every 3 days until reaching a dosage of 30 mg/day. The patient's visual acuity was improved after 26 days of hospitalization. However, the visual field and color vision did not. At 3 months of follow-up, the symptoms remained unchanged despite the patient continued taking oral prednisone tablets at a dosage of 30 mg/day. Conclusion: Neurosyphilis could be a potential triggering factor for MOGAD. In patients with neurosyphilis, it is strongly recommended to perform testing for MOG antibody along with other brain disease antibodies.