Low concentrations of tetrabromobisphenol A promote the biofilm formation of methicillin-resistant Staphylococcus aureus.

The effect and underlying mechanism of tetrabromobisphenol A (TBBPA), a plastic additive, on biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA USA300) remain unknown. This study first investigated the impact of different concentrations of TBBPA on the growth and biofilm formation of USA300. The results indicated that a low concentration (0.5 mg/L) of TBBPA promoted the growth and biofilm formation of USA300, whereas high concentrations (5 mg/L and 10 mg/L) of TBBPA had inhibitory effects. Further exploration revealed that the low concentration of TBBPA enhance biofilm formation by promoting the synthesis of extracellular proteins, release of extracellular DNA (eDNA), and production of staphyloxanthin. RTqPCR analysis demonstrated that the low concentration of TBBPA upregulated genes associated with extracellular protein synthesis (sarA, fnbA, fnbB, aur) and eDNA formation (atlA) and increased the expression of genes involved in staphyloxanthin biosynthesis (crtM), suggesting a potential mechanism for enhanced resistance of USA300 to adverse conditions. These findings shed light on how low concentrations of TBBPA facilitate biofilm formation in USA300 and highlight the indirect impact of plastic additives on pathogenic bacteria in terms of human health. In the future, in-depth studies about effects of plastic additives on pathogenicity of pathogenic bacteria should be conducted. CAPSULE: The protein and eDNA contents in biofilms of methicillin-resistant Staphylococcus aureus are increased by low concentrations of TBBPA.

Endoscopic retrograde cholangiopancreatography using a pediatric colonoscope in patients with Roux­en­Y gastrectomy and an intact major duodenal papilla.

Endoscopic retrograde cholangiopancreatography (ERCP) in patients with Roux-en-Y gastrectomy and an intact major duodenal papilla is challenging and difficult, with unsatisfactory outcomes using various endoscopes. Limited data are available regarding the outcomes of ERCP using a pediatric colonoscope in such patients. To evaluate the efficacy of a pediatric colonoscope in patients with Roux-en-Y gastrectomy and an major duodenal intact papilla, 93 consecutive patients with Roux-en-Y gastrectomy and an intact major duodenal papilla who underwent ERCP using a pediatric colonoscope at the Medical Center for Digestive Diseases, The Second Affiliated Hospital of Nanjing Medical University, (Nanjing, China) between January 2018 and December 2022 were retrospectively reviewed. Following the failure of bile duct cannulation, a double-guidewire or precut technique was utilized for advanced cannulation. Interventions were performed using standard ERCP therapeutic accessories. The results indicated that distal gastrectomy with Roux-en-Y reconstruction was performed in 38 out of 93 patients, while 55 patients underwent total gastrectomy with Roux-en-Y reconstruction. The success rates associated with endoscope insertion, endoscopic cannulation and therapeutic ERCP were 88.17% (82/93), 85.37% (70/82) and 95.71% (67/70), respectively, while the clinical intervention success and complication rates were 72.04% (67/93) and 7.53% (7/93), respectively. The endoscope insertion time was 40.78±10.04 min, and the ERCP procedure time was 88.55±16.38 min. Student's t-test showed that the endoscope insertion time and the ERCP procedure time in patients undergoing distal gastrectomy were longer than those in patients undergoing total gastrectomy (P<0.05). Binary logistic regression analysis showed that age and number of previous abdominal surgeries were independent risk factors associated with endoscope insertion failure. In conclusion, the present study demonstrated that the use of a pediatric colonoscope is efficacious and safe for patients with Roux-en-Y gastrectomy and an intact major duodenal papilla undergoing ERCP.

Spontaneous water oozing of a soft drain bed via energy-free atmospheric water harvesting.

Atmospheric water harvesting has emerged as an efficient strategy for addressing the global challenge of freshwater scarcity. However, the in being energy-consuming water-collecting process has obstructed its practicality. In this work, a soft drain bed, which was composed of hydrophilic cloth and hygroscopic gel, has been demonstrated to capture atmospheric water effectively, followed by converting it into liquid water spontaneously and sustainably, under all-weather humidity conditions. Under the optimal working condition of 30°C with a relative humidity level of 75%, the bed can provide a spontaneous water oozing ability of 1.25 g (liquid water)/hour within the 8 h of working time. More importantly, after 5 working cycles, 80% of the oozing ability can be reserved, suggesting the high potential for practical freshwater supply application. The proposed design strategy is expected to provide new hints for the development of future energy-saving decentralized freshwater supply systems.

Linking performance to dynamic migration of biofilm ecosystem reveals the role of voltage in the start-up of hybrid microbial electrolysis cell-anaerobic digestion.

Applied voltage is a crucial parameter in hybrid microbial electrolysis cells-anaerobic digestion (MEC-AD) systems for enhancing methane production from waste activated sludge (WAS). This study explored the impact of applied voltage on the initial biofilm formation on electrodes during the MEC-AD startup using raw WAS (Rr) and heat-pretreated WAS (Rh). The findings indicated that the maximum methane productivity for Rr and Rh were 3.4 ± 0.5 and 3.4 ± 0.2 mL/gVSS/d, respectively, increasing 1.5 times and 2.6 times over the productivity at 0 V. The biomass on electrode biofilms for Rr and Rh at 0.8 V increased by 70 % and 100 % compared to 0 V. The core functional microorganisms in the cathode biofilm were Methanobacterium and Syntrophomonas, and Geobacter in the anode biofilm, enhancing methane production through syntrophism and direct interspecies electron transfer, respectively. These results offer academic insights into optimizing AD functional electrode biofilms by applying voltage.

Identification and application of a novel patulin degrading enzyme from Cyberlindnera fabianii.

Patulin (PAT) is a mycotoxin commonly found in fruits and vegetables, prompting the need for effective removal and detoxification methods, which have garnered significant research attention in recent years. Among these methods, the utilization of microbial-derived enzymes stands out due to their mild operating conditions, specificity in targeted functional groups, and the production of non-toxic by-products, making it a preferred degradation approach. In this study, a novel PAT-degrading enzyme derived from Cyberlindnera fabianii (Cyfa-SDR) was identified, demonstrating its highest catalytic activity at pH 7.0 and 80 °C against PAT. This temperature tolerance level represents the highest reported for PAT-degrading enzymes to date. The enzyme was further characterized as a short-chain dehydrogenase through analysis of its amino acid composition, conserved GXXXGXG motif, and dependency on NADPH. Moreover, the study evaluated the efficiency of PAT degradation by Cyfa-SDR at varying substrate and enzyme concentrations, surpassing the performance of other PAT-degrading enzymes, thus highlighting its substantial potential for the biological control of PAT. In conclusion, the enzymatic treatment using the PAT-degrading enzyme Cyfa-SDR presents a viable and promising solution for enhancing the quality and safety of fruit juice.

[Dental treatment under general anesthesia among pediatric patients in 120 consecutive cases: a retrospective study].

PURPOSE： To investigate the clinical features of children who received treatment under dental general anesthesia (DGA). METHODS: The clinical records of dental patients below 18 years old who were treated under DGA at the Department of Pediatric Dentistry, Affiliated Dental Hospital of Kunming Medical University during June 2017 to November 2019 were obtained, including the baseline information, causes for DGA, anesthesia methods, intubation methods, treatment items, treatment time and follow-up visits. SPSS 26.0 software package was used to analyze the data. RESULTS: A total of 120 patients were included, 58.3% were males, and children aged 3 to 6 years showed the highest demand for DGA (85.0%). Fear of dental treatment, ineffective non-drug behavior management was the main causes for DGA in young children, while the most common causes for children over 6 years old to choose DGA were mental retardation (38.9%) and patients' needs(38.9%). The average number of teeth treated was (15.16±3.42) for each child, and the average time for treating one tooth was 12.26 min. Restoration, root canal treatment and primary teeth pre-forming crown(including anterior preformed resin transparent crown and posterior preformed metal crown) were the main treatment items. At 1-week follow-up visits, 98.3% of children had no discomfort. During 2017 to 2019, there was an increasing tendency in the number of patients who chose DGA in the authors' institute. CONCLUSIONS： The dental issues of children with fear of dental treatment, ineffectiveor non-drug behavior management or mental retardation can be treated under DGA conveniently, safely and efficiently. The acceptance rate of DGA among pediatric patients is on the rise. DGA training programs and related support projects are needed to meet the treatment demands among patients in less developed areas.

Synergism of ApoE4 and systemic infectious burden is mediated by the APOE-NLRP3 axis in Alzheimer's disease.

BACKGROUND: Systemic infections are associated with the development of AD, especially in individuals carrying the APOE4 genotype. However, the detailed mechanism through which APOE4 affects microglia inflammatory response remains unclear. METHODS: We obtained human snRNA-seq data from the Synapse AD Knowledge Portal and assessed the DEGs between APOE3 and APOE4 isoforms in microglia. To verify the interaction between ApoE and infectious products, we used ApoE to stimulate in vitro and in vivo models in the presence or absence of LPS (or ATP). The NLRP3 gene knockout experiment was performed to demonstrate whether the APOE-NLRP3 axis was indispensable for microglia to regulate inflammation and mitochondrial autophagy. Results were evaluated by biochemical analyses and fluorescence imaging. RESULTS: Compared with APOE3, up-regulated genes in APOE4 gene carriers were involved in pro-inflammatory responses. ApoE4-stimulation significantly increased the levels of NLRP3 inflammasomes and ROS in microglia. Moreover, compared with ApoE4 alone, the co-incubation of ApoE4 with LPS (or ATP) markedly promoted pyroptosis. Both NF-κB activation and mitochondrial autophagy dysfunction were contributed by the increased level of NLRP3 inflammasomes induced by ApoE4. Furthermore, the pathological impairment induced by ApoE4 could be reversed by NLRP3 KO. CONCLUSIONS: Our study highlights the importance of NLRP3 inflammasomes in linking ApoE4 with microglia innate immune function. These findings not only provide a molecular basis for APOE4-mediated neuroinflammatory but also reveal the potential reason for the increased risk of AD in APOE4 gene carriers after contracting infectious diseases.

Genome and metabolome analysis of Bacillus sp. Hex-HIT36: A newly screened functional microorganism for the degradation of 1-hexadecene in industrial wastewater.

1-Hexadecene has been detected at a level of mg/L in both influent and effluent of wastewater treatment plants situated in chemical/pharmaceutical industrial parks, which poses a potential threat to the environment. However, few reports are available on aerobic metabolic pathways and microorganisms involved in 1-Hexadecene degradation. In this study, a new strain of 1-Hexadecene-degrading bacteria, Bacillus sp. Hex-HIT36 (HIT36), was isolated from the activated sludge of a wastewater treatment plants located in an industrial park. The physicochemical properties and degradation efficacy of HIT36 were investigated. HIT36 was cultured on a medium containing 1-Hexadecene as a sole carbon source; it was found to remove ∼67% of total organic carbon as confirmed by mass spectrometric analysis of intermediate metabolites. Metabolomic and genomic analysis showed that HIT36 possesses various enzymes, namely, pyruvate dehydrogenase, dihydropolyhydroxyl dehydrogenase, and 2-oxoglutarate-2-oxoiron oxidoreductase (subunit alpha), which assist in the metabolization of readily available carbon source or long chain hydrocarbons present in the growth medium/vicinity. This suggests that HIT36 has efficient long-chain alkane degradation efficacy, and understanding the alkane degradation mechanism of this strain can help in developing technologies for the degradation of long-chain alkanes present in wastewater, thereby assisting in the bioremediation of environment.

Clinical Significance of Long Non-Coding RNA SNHG5 in the Diagnosis and Prognosis of Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is preventable and requires early screening. The study aimed to examine the clinical values of long non-coding RNA (lncRNA) SNHG5 in COPD diagnosis and prognosis. Out of 160 COPD patients, 80 were in the stable stage and 80 were in the acute exacerbation of COPD stage (AECOPD). SNHG5 expression was detected via qRT-PCR. The survival analysis was conducted using Cox regression analysis and K-M curve. SNHG5 levels significantly reduced in both stable COPD and AECOPD groups compared with the control group, with AECOPD group recording the lowest values. SNHG5 levels were negatively correlated with GOLD stage. Serum SNHG5 can differentiate stable COPD patients from healthy individuals (AUC = 0.805), and can screen AECOPD from stable ones (AUC = 0.910). SNHG5 negatively influenced the release of inflammatory cytokines. For AECOPD patients, those with severe cough and wheezing dyspnea symptoms exhibited the lowest values of SNUG5. Among the 80 AECOPD patients, 16 cases died in the one-year follow-up, all of whom had low levels of SNHG5. SNHG5 levels independently influenced survival outcomes, patients with low SNHG5 levels had a poor prognosis. Thus, lncRNA SNHG5, which is downregulated in patients with COPD (especially AECOPD), can potentially protect against AECOPD and serve as a novel prognostic biomarker for AECOPD.

[Establishment and evaluation of a premenstrual syndrome rat model induced by progesterone-withdrawal and emotional-stimulation].

Premenstrual syndrome(PMS) lacks a highly consistent and feasible animal model that aligns with diagnostic and therapeutic standards in both traditional Chinese medicine(TCM) and western medicine, resulting in a lack of reliable experimental carriers for studying its pathogenesis and pharmacological effects. This study aims to systematically analyze the biological implications of PMS from the perspective of the "disease-syndrome-symptom" correlation and establish preparation and evaluation methods for an improved animal model of this disease. Firstly, clinical symptom gene sets related to the Qi stagnation syndromes due to liver depression and blood stasis in PMS in both modern medicine and TCM diagnostic standards were collected through GeneCards, DisGeNET, Mala-Cards, and the System of Foundational Diagnostic Association(SoFDA) database, as well as published literature. Based on the interaction information between genes, a "disease-syndrome-symptom" correlation network of PMS was established. Based on data mining results, an improved rat model of PMS was prepared by combining chronic restraint stress with the classical progesterone-withdrawal mo-del to simulate emotional depression caused by external environmental stimuli during the clinical onset process, inducing pathological damage from both physiological and emotional dimensions. The evaluation of the improved model before and after modification included open field experiment scores, organ indices, ovarian pathological changes, serum levels of estradiol(E_2), follicle-stimulating hormone/luteinizing hormone(FSH/LH), 5-hydroxytryptamine(5-HT), dopamine(DA), norepinephrine(NE), as well as coagulation parameters and hemorheology indexes. By calculating the degree, betweenness, and closeness centrality of nodes in the "disease-syndrome-symptom" correlation network, 163 core genes with topological importance were identified. Further biological function mining results indicated that core genes in PMS mainly participated in the regulation of the "nervous-endocrine-immune" system and pathways related to circulatory disorders. Mapping analysis of clinical phenotype symptom gene sets suggested significant correlations between core genes in PMS and depressive symptoms and pain symptoms caused by blood stasis. Compared with the simple progesterone withdrawal model, rats subjected to combined injections and restraint stress showed more significant abnormalities in open field experiment scores, ovarian tissue pathology, serum neurotransmitter levels of 5-HT and DA, as well as serum hormone levels of E_2 and FSH/LH. The modified modeling conditions exacerbated the pathological changes in blood rheology, coagulation function, and red blood cell morphology in model rats, confirming that the improved rat model could characterize the "nervous-endocrine-immune" system disorder and circulatory system disorders in the occurrence and progression of PMS, consistent with the clinical diagnostic and therapeutic standards of both TCM and western medicine. The establishment of the improved rat model of PMS can provide a reliable experimental carrier for elucidating the pathogenesis of PMS and discovering and evaluating therapeutic drugs. It also provides references for objectively reflecting the clinical characteristics of PMS in TCM and western medicine and precision treatment.

PTX promotes breast cancer migration and invasion by recruiting ATF4 to upregulate FGF19.

BACKGROUND: Widely-spread among women, breast cancer is a malignancy with fatalities, and chemotherapy is a vital treatment option for it. Recent studies have underscored the potential of chemotherapeutic agents such as paclitaxel, adriamycin, cyclophosphamide, and gemcitabine, among others, in facilitating tumor metastasis, with paclitaxel being extensively researched in this context. The molecular mechanism of these genes and their potential relevance to breast cancer is noteworthy. METHOD: Clinical tissue specimens were used to analyze the expression and clinical significance of FGF19 or P-FGFR4 in patients with breast cancer before and after chemotherapy. qRT-PCR, ELISA, immunofluorescence and Western blotting were used to detect the expression level of FGF19 in breast cancer cells. The biological impacts of paclitaxel, FGF19, and ATF4 on breast cancer cells were assessed through CCK8, Transwell, and Western blot assays. The expression of ATF4 in breast cancer cells was determined through database analysis, Western blot analysis, qRT-PCR, and immunofluorescence. The direct interaction between FGF19 and ATF4 was confirmed by a luciferase assay, and Western blotting was used to assess the levels of key proteins in the stress response pathway. To confirm the effects of PTX and FGF19 in vivo, we established a lung metastasis model in nude mice. RESULTS: FGF19 expression was increased in breast cancer patients after chemotherapy. Paclitaxel can boost the migration and invasion of breast cancer cells, accompanied by an increase in FGF19 expression. ATF4 might be involved in facilitating the enhancing effect of FGF19 on breast cancer cell migration. Finally, stimulation during paclitaxel treatment could trigger a stress response, influencing the expression of FGF19 and the migration of breast cancer cells. CONCLUSION: These data suggest that paclitaxel regulates FGF19 expression through ATF4 and thus promotes breast cancer cell migration and invasion.

Antibody-drug conjugates targeting DDR1 as a novel strategy for treatment of breast cancer.

Antibody-drug conjugates (ADCs) have emerged as a novel class of targeted cancer therapies and been successfully applied in the treatment of breast cancer (BC). Discoidin domain receptor 1 (DDR1) is a single transmembrane receptor tyrosine kinase and has been identified as a possible target for cancer. In this study, we explored the potential of an anti-DDR1 ADC, named T4H11-DM4, for the treatment of DDR1-positive BC. We demonstrated that high protein expression and RNA expression of DDR1 in BC tissues. In vitro, T4H11-DM4 was potently cytotoxic to DDR1-expressing BC cells, with IC50 in the nanomolar range. In mice BC xenograft models, T4H11-DM4 dramatically eliminated BC tumours, without observable toxicity. Taken together, our findings demonstrated that DDR1 can serve as a promising therapeutic target for BC.

NLRP3-mediated autophagy dysfunction links gut microbiota dysbiosis to tau pathology in chronic sleep deprivation.

Emerging evidence indicates that sleep deprivation (SD) can lead to Alzheimer's disease (AD)-related pathological changes and cognitive decline. However, the underlying mechanisms remain obscure. In the present study, we identified the existence of a microbiota-gut-brain axis in cognitive deficits resulting from chronic SD and revealed a potential pathway by which gut microbiota affects cognitive functioning in chronic SD. Our findings demonstrated that chronic SD in mice not only led to cognitive decline but also induced gut microbiota dysbiosis, elevated NLRP3 inflammasome expression, GSK-3ß activation, autophagy dysfunction, and tau hyperphosphorylation in the hippocampus. Colonization with the "SD microbiota" replicated the pathological and behavioral abnormalities observed in chronic sleep-deprived mice. Remarkably, both the deletion of NLRP3 in NLRP3 -/- mice and specific knockdown of NLRP3 in the hippocampus restored autophagic flux, suppressed tau hyperphosphorylation, and ameliorated cognitive deficits induced by chronic SD, while GSK-3ß activity was not regulated by the NLRP3 inflammasome in chronic SD. Notably, deletion of NLRP3 reversed NLRP3 inflammasome activation, autophagy deficits, and tau hyperphosphorylation induced by GSK-3ß activation in primary hippocampal neurons, suggesting that GSK-3ß, as a regulator of NLRP3-mediated autophagy dysfunction, plays a significant role in promoting tau hyperphosphorylation. Thus, gut microbiota dysbiosis was identified as a contributor to chronic SD-induced tau pathology via NLRP3-mediated autophagy dysfunction, ultimately leading to cognitive deficits. Overall, these findings highlight GSK-3ß as a regulator of NLRP3-mediated autophagy dysfunction, playing a critical role in promoting tau hyperphosphorylation.

Comparative study of antifungal susceptibility testing methods for clinical Candida albicans isolates.

PURPOSE: Candida albicans is the second most common cause of candidemia in Malaysia. The Clinical and Laboratory Standards Institute (CLSI) broth microdilution method is the gold standard for determining its minimum inhibitory concentration (MIC); however, it is laborious and time-consuming. This study was conducted to evaluate the usefulness of alternative methods, namely Sensititre YeastOne (SYO), VITEK 2 system, and E-test for determining the MIC of clinical C. albicans isolates. MATERIALS AND METHODS: The susceptibilities of 95 C. albicans isolates were compared between SYO, VITEK 2 system, and E-test with CLSI broth microdilution method. The categorical agreement (CA), essential agreement (EA), very major errors (VME), major errors (ME) and minor errors (MiE) were calculated. RESULTS: Our finding showed the CA varied for SYO from 96.8% to 100%, while the EA ranged from 91.6% to 100%. The SYO method showed 1.1% of VME and ME, and up to 3.2% of MiE. Next, the CA and EA ranges for the VITEK 2 system were 97.8%-100% and 23.2%-100%, respectively. In the VITEK 2 technique, 1.1% of VME were found. For the E-test, the CA varied from 83.2% to 100% while the EA ranged from 64.2% to 98.9%. The E-test method showed 1.1% of VME and up to 16.8% of MiE. CONCLUSIONS: In conclusion, SYO and VITEK 2 (except flucytosine) could be potential alternatives to the CLSI broth microdilution method in determining the MIC of C. albicans.

Arginine-Proline Metabolism as a Mediator in the Association Between Coal Dust Exposure and Lung Function: A Retrospective Analysis.

OBJECTIVES: To investigate the mediating role of the activation degree of arginine-proline metabolism in the association of coal dust and decreased lung function. METHODS: CDE represented coal dust exposure, while the Hyp/Arg in BALF gauged arginine-proline metabolism activation. Pulmonary function indicators, including FVC%pred, FEV1/FVC%, and FEV1%pred, DLCO%pred, P(A-a) O2 and 6MWT, were assessed. RESULTS: Findings revealed a significant association between elevated CDE and increased Hyp/Arg, increased P(A-a) O2, decreased 6MWT, DLCO%pred, and decreased FVC%pred. However, no statistically significant association was found between CDE and FEV1%pred or FEV1/FVC%. The mediating effect of Hyp/Arg was significant for CDE's impact on P(A-a) O2 and DLCO%pred but not on 6MWT and FVC%pred. CONCLUSIONS: These results highlight the role of Hyp/Arg in mediating the association between CDE and lung function parameters, shedding light on potential therapeutic avenues for mitigating coal dust-induced lung function impairment.

Retracing from Outcomes to Causes: NRF2-Driven GSTA4 Transcriptional Regulation Controls Chronic Inflammation and Oxidative Stress in Atopic Dermatitis Recurrence.

Atopic dermatitis (AD), a chronic and recurrent inflammatory skin disorder, presents a high incidence and imposes a substantial economic burden. Preventing its recurrence remains a significant challenge in dermatological therapy owing to poorly understood underlying mechanisms. In our study, we adopted a strategy of tracing the mechanisms of recurrence from clinical outcomes. We developed a mouse model of recurrent AD and applied clinically validated treatment regimens. Transcriptomic analyses revealed a pronounced enrichment in the glutathione metabolic pathway in the treated group. Through integrated bioinformatics and in vivo validation, we identified glutathione S-transferase alpha 4 (GSTA4) as a pivotal mediator in AD recurrence. Immunohistochemical analysis demonstrated decreased GSTA4 expression in lesions from patients with AD. Functionally, in vitro overexpression of GSTA4 significantly curtailed AD-like inflammatory responses and ROS production. Moreover, we discovered that NRF2 transcriptional activity regulates GSTA4 expression and function. Our treatment notably augmented NRF2-mediated GSTA4 transcription, yielding pronounced anti-inflammatory and ROS-neutralizing effects. Conclusively, our findings implicate GSTA4 as a critical factor in the recurrence of AD, particularly in the context of oxidative stress and chronic inflammation. Targeting the NRF2-GSTA4 axis emerges as a promising anti-inflammatory and antioxidative strategy for preventing AD recurrence.

The two-step strategy for enhancing the specific activity and thermostability of alginate lyase AlyG2 with mechanism for improved thermostability.

To overcome the trade-off challenge encountered in the engineering of alginate lyase AlyG2 from Seonamhaeicola algicola Gy8T and to expand its potential industrial applications, we devised a two-step strategy encompassing activity enhancement followed by thermal stability engineering. To enhance the specific activity of efficient AlyG2, we strategically substituted residues with bulky steric hindrance proximal to the active pocket with glycine or alanine. This led to the generation of three promising positive mutants, with particular emphasis on the T91S mutant, exhibiting a 1.91-fold specific activity compared to the wild type. To mitigate the poor thermal stability of T91S, mutants with negative ΔΔG values in the thermal flexibility region were screened out. Notably, the S72Ya mutant not only displayed 17.96 % further increase in specific activity but also exhibited improved stability compared to T91S, manifesting as a remarkable 30.97 % increase in relative activity following a 1-hour incubation at 42 °C. Furthermore, enhanced kinetic stability was observed. To gain deeper insights into the mechanism underlying the enhanced thermostability of the S72Ya mutant, we conducted molecular dynamics simulations, principal component analysis (PCA), dynamic cross-correlation map (DCCM), and free energy landscape (FEL) analysis. The results unveiled a reduction in the flexibility of the surface loop, a stronger correlation dynamic and a narrower motion subspace in S72Ya system, along with the formation of more stable hydrogen bonds. Collectively, our findings suggest amino acids substitutions resulting in smaller side chains proximate to the active site can positively impact enzyme activity, while reducing the flexibility of surface loops emerges as a pivotal factor in conferring thermal stability. These insights offer valuable guidance and a framework for the engineering of other enzyme types.

Genomics and transcriptomics reveal ß-carotene synthesis mechanism in Dunaliella salina.

Dunaliella salina is by far the most salt-tolerant organism and contains many active substances, including ß-carotene, glycerol, proteins, and vitamins, using in the production of dried biomass or cell extracts for the biofuels, pharmaceutical formulations, food additives, and fine chemicals, especially ß-carotene. We report a high-quality genome sequence of D. Salina FACHB435, which has a 472 Mb genome size, with a contig N50 of 458 Kb. A total of 30,752 protein-coding genes were predicted. The annotation results evaluated by BUSCO was shown that completeness was 91.0% and replication was 53.1%. The fragments were 6.3% and the deletions were 2.6%. Phylogenomic and comparative genomic analyses revealed that A. thaliana diverged from Volvocales about 448 million years ago, then Volvocales C. eustigma, D. salina, and other species diverged about 250 million years ago. High light could promote the accumulation of ß-carotene in D. salina at a 13 d stage of culture. The enrichment of DEGs in KEGG, it notes that the predicted up-regulated genes of carotenoid metabolic pathway include DsCrtB, DsPDS, DsZ-ISO, DsZDS, DsCRTISO, DsLUT5, DsCrtL-B, and DsCCD8, while the predicted down-regulated genes include DsCrtF, and DsLUT1. The four genes that were both up-regulated and down-regulated were DsZEP, DsCrtR-b, DsCruA/P and DsCrtZ 4. The research results can provide scientific basis for the industrialization practice of D. salina.

Photocatalytic NO x removal and recovery: progress, challenges and future perspectives.

The excessive production of nitrogen oxides (NO x ) from energy production, agricultural activities, transportation, and other human activities remains a pressing issue in atmospheric environment management. NO x serves both as a significant pollutant and a potential feedstock for energy carriers. Photocatalytic technology for NO x removal and recovery has received widespread attention and has experienced rapid development in recent years owing to its environmental friendliness, mild reaction conditions, and high efficiency. This review systematically summarizes the recent advances in photocatalytic removal, encompassing NO x oxidation removal (including single and synergistic removal and NO3 - decomposition), NO x reduction to N2, and the emergent NO x upcycling into green ammonia. Special focus is given to the molecular understanding of the interfacial nitrogen-associated reaction mechanisms and their regulation pathways. Finally, the status and the challenges of photocatalytic NO x removal and recovery are critically discussed and future outlooks are proposed for their potential practical application.