Fusobacterium nucleatum induces oxaliplatin resistance by inhibiting ferroptosis through E-cadherin/ß-catenin/GPX4 axis in colorectal cancer.

Fusobacterium (F.) nucleatum is a carcinogenesis microbiota in colorectal cancer (CRC). Growing evidence shows that F. nucleatum contributes to chemoresistance. Ferroptosis is reported to restore the susceptibility of resistant cells to chemotherapy. However, the role of gut microbiota affecting ferroptosis in chemoresistance remains unclear. Here, we examined the CRC tissues of patients using 16S rRNA sequencing to investigate the possible connection between gut microbiota dysbiosis and the relapse of CRC. We found that a high abundance of F. nucleatum in CRC tissue is associated with relapse. We further demonstrated that F. nucleatum induced oxaliplatin resistance in vitro and in vivo. The transcriptome of an F. nucleatum-infected cell revealed ferroptosis was associated with F. nucleatum infection. We perform malondialdehyde, ferrous iron, and glutathione assays to verify the effect of F. nucleatum on ferroptosis under oxaliplatin treatment in vivo and in vitro. Mechanistically, F. nucleatum promoted oxaliplatin resistance by overexpressing GPX4 and then inhibiting ferroptosis. E-cadherin/ß-catenin/TCF4 pathway conducted the GPX4 overexpression effect of F. nucleatum. The chromatin immuno-precipitation quantitative PCR (CHIP-qPCR) and dual-luciferase reporter assay showed that F. nucleatum promoted TCF4 binding with GPX4. We also determined the E-cadherin/ß-catenin/TCF4/GPX4 axis related to tumor tissue F. nucleatum status and CRC relapse clinically. Here, we revealed the contribution of F. nucleatum to oxaliplatin resistance by inhibiting ferroptosis in CRC. Targeting F. nucleatum and ferroptosis will provide valuable insight into chemoresistance management and may improve outcomes for patients with CRC.

Analysis of the evolving factors of social media users' emotions and behaviors: a longitudinal study from China's COVID-19 opening policy period.

The outbreak of the COVID-19 pandemic has triggered citizen panic and social crises worldwide. The Chinese government was the first to implement strict prevention and control policies. However, in December 2022, the Chinese government suddenly changed its prevention and control policies and completely opened up. This led to a large-scale infection of the epidemic in a short period of time, which will cause unknown social impacts. This study collected 500+ epidemic-related hotspots and 200,000+ data from November 1, 2022, to March 1, 2023. Using a sentiment classification method based on pre-trained neural network models, we conducted inductive analysis and a summary of high-frequency words of various emotions. This study focuses on the inflection point of the emotional evolution of social media users and the evolution of "hot topic searches" events and emotional behavioral factors after the sudden open policy. Our research results show that, first of all, the positive emotions of social media users are divided into 4 inflection points and 5 time periods, and the negative emotions are divided into 3 inflection points and 4 time periods. Behavioral factors are different at each stage of each emotion. And the evolution patterns of positive emotions and negative emotions are also different. Secondly, the evolution of behavioral elements deserves more attention. Continue to pay attention: The treatment of diseases, the recovery of personal health, the promotion of festive atmosphere, and the reduction of publicity on the harm of "new crown sequelae and second infections" are the behavioral concerns that affect users' emotional changes. Finally, it is necessary to change the "hot topic searches" event by guiding the user's behavioral focus to control the inflection point of the user's emotion. This study helps governments and institutions understand the dynamic impact of epidemic policy changes on social media users, thereby promoting policy formulation and better coping with social crises.

Aerial images object detection method based on cross-scale multi-feature fusion.

Aerial image target detection technology has essential application value in navigation security, traffic control and environmental monitoring. Compared with natural scene images, the background of aerial images is more complex, and there are more small targets, which puts higher requirements on the detection accuracy and real-time performance of the algorithm. To further improve the detection accuracy of lightweight networks for small targets in aerial images, we propose a cross-scale multi-feature fusion target detection method (CMF-YOLOv5s) for aerial images. Based on the original YOLOv5s, a bidirectional cross-scale feature fusion sub-network (BsNet) is constructed, using a newly designed multi-scale fusion module (MFF) and cross-scale feature fusion strategy to enhance the algorithm's ability, that fuses multi-scale feature information and reduces the loss of small target feature information. To improve the problem of the high leakage detection rate of small targets in aerial images, we constructed a multi-scale detection head containing four outputs to improve the network's ability to perceive small targets. To enhance the network's recognition rate of small target samples, we improve the K-means algorithm by introducing a genetic algorithm to optimize the prediction frame size to generate anchor boxes more suitable for aerial images. The experimental results show that on the aerial image small target dataset VisDrone-2019, the proposed method can detect more small targets in aerial images with complex backgrounds. With a detection speed of 116 FPS, compared with the original algorithm, the detection accuracy metrics mAP0.5 and mAP0.5:0.95 for small targets are improved by 5.5% and 3.6%, respectively. Meanwhile, compared with eight advanced lightweight networks such as YOLOv7-Tiny and PP-PicoDet-s, mAP0.5 improves by more than 3.3%, and mAP0.5:0.95 improves by more than 1.9%.

Clinicopathologic and mutational profiles of primary breast diffuse large B cell lymphoma in a male patient: case report and literature review.

INTRODUCTION: Primary breast lymphoma (PBL) is rare, and most cases occur in female patients, with few reported cases in male patients. The clinical presentation is similar to that of breast cancer, but the condition needs to be well understood, as treatment options and clinical course vary. Hence, we provide a relatively rare case of primary breast diffuse large B cell lymphoma (PB-DLBCL) in a male, including its complete clinicopathological features, radiological findings, genomic mutational profiles, and clinical course. CASE PRESENTATION: A 45-year-old male presented with a lump in his right breast for 1 week and was pathologically diagnosed with breast malignancy after a breast puncture biopsy at the local hospital. He came to our hospital for further treatment and underwent breast ultrasound and systemic positron emission tomography/computed tomography (PET/CT) imaging, followed by right mastectomy and sentinel lymph node biopsy. Histomorphology showed diffuse hyperplasia of tumor cells with clear boundaries and surrounding normal breast ducts. The adhesion of tumor cells was poor with obvious atypia. Immunohistochemical results showed that the tumor cells were positive for CD20, Bcl6, and MUM-1 but negative for CK (AE1/AE3), ER, PR, CD3, and CD10. Forty percent of the tumor cells were positive for c-Myc, and 80% of tumor cells were positive for Bcl2. The Ki-67 proliferation index was up to 80%. The tumor cells were negative for MYC and BCL2 rearrangements but positive for BCL6 rearrangement by fluorescent in situ hybridization. No abnormality was found in the pathological examination of bone marrow aspiration. Therefore, the male was diagnosed with PB-DLBCL, nongerminal center (non-GCB) phenotype, dual-expression type. The sample were sequenced by a target panel of 121 genes related to lymphoma. Next-generation sequencing revealed six tumor-specific mutated genes (IGH/BCL6, TNFAIP3, PRDM1, CREBBP, DTX1, and FOXO1). The patient was given six cycles of orelabrutinib plus R-CHOP chemotherapy and two cycles of intrathecal injection of cytarabine. The last follow-up was on April 13, 2023 (17 months). No recurrence or metastasis was found in laboratory and imaging examinations. CONCLUSION: We reported a relatively rare PB-DLBCL in a male, non-GBC phenotype, dual-expression type. It is worth mentioning that this case had IgH/BCL6 fusion, nonsense mutations in TNFAIP3, frameshift mutations in PRDM1, and missense mutations in CREBBP, DTX1, and FOXO1. To the best of our knowledge, this case is the first report of genomic mutational profiles of PB-DLBCL in males.

A study on the emotional and attitudinal behaviors of social media users under the sudden reopening policy of the Chinese government.

Introduction: Since the outbreak of the COVID-19 pandemic, the Chinese government has implemented a series of strict prevention and control policies to prevent the spread of the virus. Recently, the Chinese government suddenly changed its approach and lifted all prevention and control measures. This sudden change in policy is expected to lead to a widespread outbreak of COVID-19 in China, and the public and local governments are not adequately prepared for the unknown impact on society. The change in the "emergency" prevention and control policy provides a unique research perspective for this study. Methods: The purpose of this study is to analyze the public's attitudes and emotional responses to COVID-19 under the sudden opening policy, identify the key factors that contribute to these attitudes and emotions, and propose solutions. In response to this sudden situation, we conducted data mining on topics and discussions related to the opening of the epidemic on Sina Weibo, collecting 125,686 interactive comments. We used artificial intelligence technology to analyze the attitudes and emotions reflected in each data point, identify the key factors that contribute to these attitudes and emotions, explore the underlying reasons, and find corresponding solutions. Results: The results of the study show that in the face of the sudden release of the epidemic, the public mostly exhibited negative emotions and behaviors, with many people experiencing anxiety and panic. However, the gradual resumption of daily life and work has also led some people to exhibit positive attitudes. Conclusion: The significance of this study is to help the government and institutions understand the impact of policy implementation on users, and to enable them to adjust policies in a timely manner to respond to potential social risks. The government, emergency departments, and the public can all prepare for similar situations based on the conclusions of this study.

A Model for Urban Environment Instance Segmentation with Data Fusion.

Fine-grained urban environment instance segmentation is a fundamental and important task in the field of environment perception for autonomous vehicles. To address this goal, a model was designed with LiDAR pointcloud data and camera image data as the subject of study, and the reliability of the model was enhanced using dual fusion at the data level and feature level. By introducing the Markov Random Field algorithm, the Support Vector Machine classification results were optimized according to the spatial contextual linkage while providing the model with the prerequisite of the differentiation of similar but foreign objects, and the object classification and instance segmentation of 3D urban environments were completed by combining the Mean Shift. The dual fusion approach in this paper is a method for the deeper fusion of data from different sources, and the model, designed more accurately, describes the categories of items in the environment with a classification accuracy of 99.3%, and segments the different individuals into groups of the same kind of objects without instance labels. Moreover, our model does not have high computational resource and time cost requirements, and is a lightweight, efficient, and accurate instance segmentation model.

Exploring the Catalytic Flexibility and Reversibility of Plant Glycosyltransferase HtUGT72AS1 for Glycodiversification of Phenolic Compounds.

Plant bioactive metabolites such as flavonoids are usually present in glycosylated forms by the attachment of various sugar groups. In this study, a catalytically flexible and reversible glycosyltransferase (HtUGT72AS1) was cloned and characterized from Helleborus thibetanus. HtUGT72AS1 could directly accept six sugar donors (UDP-glucose/-arabinose/-galactose/-xylose/-N-acetylglucosamine/-rhamnose) to catalyze the 3-OH glycosylation of flavonols. It also catalyzed the 4' and 7-OH glycosylation of other types of flavonoids, which lacked the 3-OH group. Additionally, the HtUGT72AS1-catalyzed reaction was highly reversible when using 2-chloro-4-nitrophenyl glycosides as substrates, which could be used for one-pot or coupled production of bioactive glycosides. It is the first reported UGT for the synthesis of arabinosides and galactosides using a transglycosylation platform. Based on structural modeling and mutagenetic analysis, the mutation of Tyr377 to Ara enhanced the catalytic efficiency of HtUGT72AS1 toward UDP-N-acetylglucosamine, and the V146S mutant gained an improvement in the regioselectivity toward 7-OH of flavonoids.

Structure-function crosstalk in liver cancer research: Protein structuromics.

Liver cancer can be primary (starting in the liver) or secondary (cancer that has spread from elsewhere to the liver, known as liver metastasis). Liver metastasis is more common than primary liver cancer. Despite great advances in molecular biology methods and treatments, liver cancer is still associated with a poor survival rate and a high death rate, and there is no cure. Many questions remain regarding the mechanisms of liver cancer occurrence and development as well as tumor reoccurrence after treatment. In this study, we assessed the protein structural features of 20 oncogenes and 20 anti-oncogenes via protein structure and dynamic analysis methods and 3D structural and systematic analyses of the structure-function relationships of proteins. Our aim was to provide new insights that may inform research on the development and treatment of liver cancer.

Exploration of seasonal fermentation differences and the possibility of flavor substances as regulatory factors in Daqu.

Medium-high temperature Daqu is a characteristic starter for Chinese strong-flavor Baijiu fermentation, and its final quality determines the character and type of Baijiu. Nonetheless, its formation is affected by the interaction of physical and chemical, environmental and microbial interaction, and the differences in seasonal fermentation performance emerge. Here, the differences in the two seasons' Daqu fermentation properties were revealed by the detection of the enzyme activity. The respective dominant enzyme in summer Daqu (SUD) was protease and amylase, while cellulase and glucoamylase in spring Daqu (SPD). The underlying causes of this phenomenon were then investigated through an evaluation of nonbiological variables and microbial community structure. A greater absolute number of microorganisms, particularly Thermoactinomyces, were created in the SPD as a result of the superior growth environment (higher water activity). Additionally, the correlation network and discriminant analysis hypothesized that the volatile organic compound (VOC) guaiacol, which had a different content between SUD and SPD, may be a contributing element to the microbial composition. In contrast to SUD, the enzyme system activity related to guaiacol production in SPD was significantly higher. To support this notion that the volatile flavor chemicals mediate microbial interactions in Daqu, the growth effect of guaiacol on several bacteria isolated from the Daqu was examined in both a contact and non-contact manner. This study emphasized that VOCs not only have the basic characteristics of flavor compounds but also have ecological significance. Because the strains' varied structures and enzyme activities affected how the microorganisms interacted, the VOCs produced in this way ultimately had a synergistic effect on the various effects of Daqu fermentation.

Independent and joint associations of general and abdominal obesity with the risk of conventional adenomas and serrated polyps: A large population-based study in East Asia.

Evidence regarding associations of general and abdominal obesity with the risk of conventional adenomas (ADs) and serrated polyps (SPs) from Asian population is scarce. Our study aimed to investigate the independent and joint associations of general obesity assessed by body mass index (BMI) and abdominal obesity assessed by waist circumference (WC) or waist-to-hip ratio (WHR) with the risk of ADs and SPs among 25 222 participants recruited by a population-based screening program. Compared to participants with normal BMI, those with a BMI ≥28 kg/m2 had increased risk of ADs (odds ratio [OR] 1.52, 95% confidence interval [CI]: 1.36-1.70) and SPs (OR 1.69, 95% CI: 1.38-2.07). For participants with a WC ≥102 cm (≥88 cm for females), the risk of ADs (OR 1.37, 95% CI: 1.25-1.51) and SPs (OR 1.81, 95% CI: 1.52-2.16) was higher than that of the reference group. For participants with a WHR ≥0.95 (≥0.90 for females), the risk of ADs (OR 1.26, 95% CI: 1.16-1.36) and SPs (OR 1.46, 95% CI: 1.26-1.69) was higher than that of the reference group. Moreover, participants with both BMI ≥28 kg/m2 and WC ≥102 cm (≥88 cm for females) had 61% and 119% higher risk of ADs (OR 1.61, 95% CI: 1.39-1.85) and SPs (OR 2.19, 95% CI: 1.70-2.82) compared to those with both normal BMI and WC. These findings indicate that both general and abdominal obesity are associated with SPs and ADs, presenting stronger association with SPs than ADs. Moreover, the association is more evident when both obesities exist.

Serum from acupuncture-treated asthmatic rats regulates p38-MAPK activation in airway smooth muscle cells.

OBJECTIVES: This study aimed to investigate the regulation function of acupuncture on airway smooth muscle cells (ASMCs) of asthmatic rats. METHODS: Male Sprague-Dawley rats were challenged using inhalational Ovalbumin (OVA) to establish an asthma model. The acupuncture points (GV14 for Dazhui, bilateral BL12 for Fengmen, and bilateral BL13 for Feishu) were stimulated for asthma relief. The ASMCs isolated from asthmatic rats were incubated in medium containing the serum obtained from asthmatic rats treated with acupuncture. The expression levels of p38 MAPK and p-p38 MAPK were determined by immunocytochemical and western blot. RESULTS: ASMCs were successfully isolated and cultured. The 20% acupuncture treatment of asthmatic rat serum had the least effect on the proliferation ability of asthmatic ASMCs. The serum from asthmatic rats treated with acupuncture could decrease the expression of p-p38 MAPK in asthmatic rat ASMCs. CONCLUSIONS: The serum from acupuncture-treated asthmatic rats has an effect on treating asthma in rats, and the mechanism of action may be by regulating the p38 pathway.

Design, synthesis and antibacterial evaluation of a novel class of tetrahydrobenzothiophene derivatives.

In this study, a new series of tetrahydrobenzothiophene derivatives have been designed. Newly designed molecules have been synthesized through a medicinal chemistry route, and their characterization was done by using NMR and HR-MS techniques. Biological evaluation of the synthesized compounds has been done on Gram-negative and Gram-positive bacteria. The marketed antibiotics such as ciprofloxacin and gentamicin were used as controls. The in vitro evaluation results have shown that most of the targeted compounds exhibit good potency in inhibiting the growth of bacteria, including E. coli (MIC: 0.64-19.92 µM), P. aeruginosa (MIC: 0.72-45.30 µM), Salmonella (MIC: 0.54-90.58 µM) and S. aureus (MIC: 1.11-99.92 µM). In particular, compound 3b showed excellent activity with an MIC value of 1.11 µM against E. coli, 1.00 µM against P. aeruginosa, 0.54 µM against Salmonella, and 1.11 µM against S. aureus. From the results, a promising lead compound was identified for future development.

circ-IARS depletion inhibits the progression of non-small-cell lung cancer by circ-IARS/miR-1252-5p/HDGF ceRNA pathway.

This study aims to explore the role and mechanism of circ-IARS in non-small-cell lung cancer (NSCLC) progression. Expression of circ-IARS, microRNA (miR)-1252-5p, and hepatoma-derived growth factor (HDGF) was measured by real-time quantitative PCR and western blotting. The interactions among circ-IARS, miR-1252-5p, and HDGF were determined by dual-luciferase reporter assay and RNA immunoprecipitation. Cell behaviors were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, scratch wound assay, and transwell assay, and validated in in vivo xenograft model. Exosomes were isolated using commercial kit, and the expression and functions of exosomal circ-IARS (exo-circ-IARS) were analyzed as described above. Results showed that the expression of circ-IARS was upregulated in NSCLC cells, NSCLC tissues, and serum exosomes from NSCLC patients. circ-IARS exhaustion antagonized cell proliferation, cell cycle progression, migration, and invasion and promoted apoptosis in NSCLC. Molecularly, circ-IARS could sponge miR-1252-5p to modulate the expression of the downstream gene HDGF. In addition, miR-1252-5p downregulation attenuated circ-IARS exhaustion-mediated effects in H1299 and A549 cells. MiR-1252-5p mimic-induced effects were relieved by increasing HDGF expression in H1299 and A549 cells. Exo-circ-IARS promoted H460 cell proliferation, migration, and invasion and inhibited cell apoptosis. Silencing circ-IARS retarded tumor growth of NSCLC cells in vivo. Thus, circ-IARS, secreted by exosomes, was a novel oncogene in NSCLC and regulated the malignant development of NSCLC cells via circ-IARS/miR-1252-5p/HDGF competing endogenous RNA regulatory axis.

Revealing novel synergistic defense and acid tolerant performance of Escherichia coli in response to organic acid stimulation.

Escherichia coli is an important producer of mono- and di-acids, such as D-lactic acid, itaconic acid, and succinic acid. However, E. coli has limited acid tolerance and requires neutralizers in large-scale fermentation, which leads to increased production costs. Mutagenesis breeding has been shown to be inefficient in improving the acid tolerance of strains. Therefore, it is crucial to analyze the acid resistance mechanism of E. coli. To this end, important regulatory genes and metabolic pathways in the highly evolved acid-resistant E. coli were identified based on transcriptome sequencing. By analyzing the overlap of the genes with significantly different expression levels in the four groups, a synergistic membrane-centric defense mechanism for E. coli against organic acid stress was identified. The mechanism includes four modules: signal perception, energy countermeasures, input conditioning, and envelope reinforcement. In addition, genes related to the ABC transporter pathway, polyketide metabolism, pyrimidine metabolism, and dual-arginine translocation system pathways were found for the first time to be potentially resistant to organic acid stress after overexpression. A new antacid ingredient, RffG, increases the survival rate of E. coli by 4509.6 times. This study provides new clues for improving the performance of acid-tolerant cells and reducing the production cost of industrial organic acid fermentation. KEY POINTS: • Systematic analysis of the mechanism of membrane protein partitioning in E. coli to resist organic acids • TAT system transports correctly folded hydrogenase accessory proteins to resist D-lactic acid stress • Enhanced PG synthesis and weakened hydrolysis to reduce acid penetration into cells • Overexpression of RffG in the polyketide synthesis pathway enhances acid tolerance.

Hypermethylation of tumor suppressor lncRNA MEF2C-AS1 frequently happened in patients at all stages of colorectal carcinogenesis.

BACKGROUND: The novel long noncoding RNA MEF2C-AS1 has been identified to play suppressor roles during tumorigenesis. DNA methylation has a regulatory effect on gene expression in cancer initiation and progression. However, the methylation status of MEF2C-AS1 and its role in colorectal cancer (CRC) development remain unclear. METHODS: The expression and methylation levels of MEF2C-AS1 were systematically analyzed among 31 cancers with available qualified data in GEPIA and UCSC Xena databases. Then, the MEF2C-AS1 methylation status was firstly examined among 12 CRCs by Illumina Infinium MethylationEPIC BeadChip in in-house step 1 and further quantified among 48 CRCs by the MassARRAY method in in-house step 2. Subsequently, its methylation and expression levels were quantified among 81 non-advanced adenomas (NAAs), 81 advanced adenomas (AAs), and 286 CRCs using the MassARRAY method, and among 34 NAAs, 45 AAs, and 75 CRCs by qRT-PCR, in in-house step 3, respectively. The effect of MEF2C-AS1 methylation on CRC survival was analyzed by the Kaplan-Meier method. Additionally, in vitro cell proliferation, migration and invasion assays, and bioinformatics analysis were performed to explore the role of MEF2C-AS1 in colorectal carcinogenesis. RESULTS: Lower expression and higher methylation of MEF2C-AS1 were found in CRC by online databases. In the comparisons of lesion tissues with adjacent normal tissues, MEF2C-AS1 hypermethylation of each individual site and mean level was found among CRC patients in in-house step 1 and step 2, more meaningfully, among NAA patients, AA patients, and CRC patients at all stages during colorectal carcinogenesis in in-house step 3 (all p < 0.05). Further comparisons demonstrated significant differences between CRC and NAA (p = 0.025), AA and NAA (p = 0.020). Moreover, MEF2C-AS1 hypermethylation was associated with poorer disease-specific survival of CRC patients (p = 0.044). In addition, hypermethylation and lower expression of MEF2C-AS1 were verified in RKO cells, and the MEF2C-AS1 overexpression significantly suppressed RKO cell proliferation, migration, and invasion. CONCLUSIONS: The findings reveal that MEF2C-AS1 hypermethylation might be an early driven event during colorectal carcinogenesis. It might serve as a promising prognostic biomarker for CRC survival. Our study also indicates the potential tumor-suppressing role of MEF2C-AS1 in CRC.

Knockdown of sortilin improves the neurological injury and regional cerebral blood flow in rats after subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a severe subtype of stroke. Sortilin protein is elevated in cerebrospinal fluid (CSF) of SAH patients. This study explored the mechanism of sortilin in SAH. SAH model was established by occipital cisternal blood injection. Neurological evaluation was performed on SAH rats using the Gracia scoring system and beam-balance tests. Regional cerebral blood flow (rCBF) and intracranial pressure (ICP) changes were measured using a laser Doppler blood flow monitor and an intraparenchymal Camino ICP probe. The correlation between rCBF changes and neurological deficit was analyzed using the Spearman method. Sortilin protein level in rat cerebral cortex and CSF was detected by Western blot. The Garcia score and beam-balance score of rats at 1, 12, 24, 48, and 72 h after SAH were lowered. Blood clots were observed on the ventral surface of the brain in SAH rats, around Willis ring, and ventral surface of brain stem, but no blood clots were found in the control group. At 1, 12, 24, 48, and 72 h after SAH in rats, the severity of SAH was aggravated, rCBF was decreased, and ICP was increased. The changes of rCBF in rat cerebral cortex at 1 and 72 h after SAH were correlated with the Garcia score. Sortilin was highly expressed in the cerebral cortex and CSF of SAH rats. Knockdown of sortilin improved the neurological injury and rCBF in rats. Sortilin was highly expressed in the cerebral cortex and CSF of SAH rats. Sortilin silencing improved neurological injury and CBF in rats.

Comparative transcriptome analysis reveals the contribution of membrane transporters to acid tolerance in Lactococcus lactis.

Acid stress caused by the accumulation of acidic metabolites severely affects the fermentation performance of lactic acid bacteria. In this study, to overcome the impact of acid stress during growth, nine membrane transporters were introduced in Lactococcus lactis NZ9000 to study their effects on acid tolerance. The engineered strains that overexpressed the metal ATP-binding cassette (ABC) transporters zitP (metal ABC transporter permease) and zitQ (metal ABC transporter ATP-binding protein) exhibited 14.5 and 9.5-fold higher survival rates, respectively, at pH 4.0 for 4 h than the control strain. During acid stress, the two recombinant strains maintained relatively higher ATP concentrations, i.e., 7.7- and 11.7-fold higher, respectively, than the control strain at pH 4.0 for 3 h. Subsequently, transcriptome analysis revealed that genes associated with ABC transporters, metal ion transport, transcriptional regulation, and stress response exhibited differentially expressed. The transcriptional level of ecfA2 gene (energy-coupling factor transporter ATPase) was substantially higher in L. lactis (ZitQ) during acid stress, and the ecfA2 gene was overexpressed in L. lactis. This recombinant strain L. lactis (EcfA2) exhibited a 598.7-fold higher survival rate than the control strain at pH 4.0 for 4 h. This study showed that the membrane transporters ZitP and ZitQ could increase acid tolerance and provided a strategy for constructing robust strains that can be used in food industry.

The Role of Intestinal Mucosal Barrier in Autoimmune Disease: A Potential Target.

Autoimmune diseases are a series of diseases involving multiple tissues and organs, characterized by the over production of abnormal multiple antibodies. Although most studies support that the impaired immune balance participates in the development of autoimmune diseases, the specific pathogenesis of it is not fully understood. Intestinal immunity, especially the intestinal mucosal barrier has become a research hotspot, which is considered to be an upstream mechanism leading to the impaired immune balance. As an important defense barrier, the intestinal mucosal barrier regulates and maintains the homeostasis of internal environment. Once the intestinal barrier function is impaired under the effect of multiple factors, it will destroy the immune homeostasis, trigger inflammatory response, and participate in the development of autoimmune diseases in the final. However, the mechanism of the intestinal mucosal barrier how to regulate the homeostasis and inflammation is not clear. Some studies suggest that it maintains the balance of immune homeostasis through the zonulin pathway, intestinal microbiome, and Toll-like receptor signaling pathway. Our review focused on the composition and the function of the intestinal mucosal barrier to describe the research progress of it in regulating the immune homeostasis and inflammation, and also pointed that the intestinal mucosal barrier was the potential targets in the treatment of autoimmune diseases.

Engineering Metabolic Pathways for Cofactor Self-Sufficiency and Serotonin Production in Escherichia coli.

Serotonin is a neurotransmitter that plays an essential regulatory role in numerous cognitive and behavioral functions. Recent advances in synthetic biology have enabled engineering of non-natural biosynthetic pathways for serotonin production in E. coli. Here, an optimized heterologous serotonin biosynthetic pathway was engineered in E. coli and coupled with the biosynthetic and regeneration modules of the endogenous vital cofactor tetrahydrobiopterin (BH4) for efficient serotonin production using whole-cell catalysis. Further metabolic engineering efforts were performed to ensure an adequate endogenous BH4 supply, including enhancements of GTP biosynthesis and intracellular reducing power availability. Using the optimized fed-batch fermentation, an overall maximum serotonin yield of 40.3% (mol/mol) and a peak titer of 1.68 g/L (production rate of 0.016 g/L/h) were achieved. The strategies employed in this study show the promise of using E. coli for pterin self-sufficiency and high-level serotonin production, and the engineered strains hold the potential for use in industrial applications.