High-intensity interval training stimulates remyelination via the Wnt/ß-catenin pathway in cuprizone-induced demyelination mouse model.

OBJECTIVES: This study aims to investigate the role of high-intensity interval training (HIIT) in promoting myelin sheath recovery during the remyelination phase in cuprizone (CPZ)-induced demyelination mice and elucidate the mechanisms involving the Wnt/ß-catenin pathway. METHODS: After 5 weeks of a 0.2% CPZ diet to induce demyelination, a 4-week recovery phase with a normal diet was followed by HIIT intervention. Mice body weight was monitored. Morris water maze (MWM) gauged spatial cognition and memory, while the open field test (OFT) assessed anxiety levels. Luxol fast blue (LFB) staining measured demyelination, and immunofluorescence examined myelin basic protein (MBP) and platelet-derived growth factor receptor-alpha (PDGFR-α). Western blotting analyzed protein expression, including MBP, PDGFR-α, glycogen synthase kinase-3ß (GSK3ß), ß-catenin, and p-ß-catenin. Real-time PCR detected mRNA expression levels of CGT and CST. RESULTS: HIIT promoted remyelination in demyelinating mice, enhancing spatial cognition, memory, and reducing anxiety. LFB staining indicated decreased demyelination in HIIT-treated mice. Immunofluorescence demonstrated increased MBP fluorescence intensity and PDGFR-α+ cell numbers with HIIT. Western blotting revealed HIIT reduced ß-catenin levels while increasing p-ß-catenin and GSK3ß levels. Real-time PCR demonstrated that HIIT promoted the generation of new myelin sheaths. Additionally, the Wnt/ß-catenin pathway agonist, SKL2001, decreased MBP expression but increased PDGFR-α expression. DISCUSSION: HIIT promotes remyelination by inhibiting the Wnt/ß-catenin pathway and is a promising rehabilitation training for demyelinating diseases. It provides a new theoretical basis for clinical rehabilitation and care programs.

Development of whole cell biocatalytic system for asymmetric synthesis of esomeprazole with enhancing coenzyme biosynthesis pathway.

Esomeprazole is the most popular proton pump inhibitor for treating gastroesophageal reflux disease. Previously, a phenylacetone monooxygenase mutant LnPAMOmu15 (LM15) was obtained by protein engineering for asymmetric synthesis of esomeprazole using pyrmetazole as substrate. To scale up the whole cell asymmetric synthesis of esomeprazole and reduce the cost, in this work, an Escherichia coli whole-cell catalyst harboring LM15 and formate dehydrogenase from Burkholderia stabilis 15516 (BstFDH) were constructed through optimized gene assembly patterns. CRISPR/Cas9 mediated insertion of Ptrc promoter in genome was done to enhance the expression of key genes to increase the cellular NADP supply in the whole cell catalyst, by which the amount of externally added NADP+ for the asymmetric synthesis of esomeprazole decreased to 0.05 mM from 0.3 mM for reducing the cost. After the optimization of reaction conditions in the reactor, the scalable synthesis of esomeprazole was performed using the efficient LM15-BstFDH whole-cell as catalyst, which showed the highest reported space-time yield of 3.28 g/L/h with 50 mM of pyrmetazole loading. Isolation procedure was conducted to obtain esomeprazole sodium of 99.55 % purity and > 99.9 % ee with 90.1 % isolation yield. This work provides the basis for production of enantio-pure esomeprazole via cost-effective whole cell biocatalysis.

Single-cell enzymatic cascade synthesis of testolactone enabled by engineering of polycyclic ketone monooxygenase and multi-gene expression fine-tuning.

The synthesis of steroids is challenging through multistep steroidal core modifications with high site-selectivity and productivity. In this work, a novel enzymatic cascade system was constructed for synthesis of testolactone by specific C17 lactonization/Δ1-dehydrogenation from inexpensive androstenedione using an engineered polycyclic ketone monooxygenase (PockeMO) and an appropriate 3-ketosteroid-Δ1-dehydrogenase (ReKstD). The focused saturation mutagenesis in the substrate binding pocket was implemented for evolution of PockeMO to eliminate the bottleneck effect. A best mutant MU3 (I225L/L226V/L532Y) was obtained with 20-fold higher specific activity compared to PockeMO. The catalytic efficiency (kcat/Km) of MU3 was 171-fold higher and the substrate scope shifted to polycyclic ketones. Molecular dynamic simulations suggested that the activity was improved by stabilization of the pre-lactonization state and generation of productive orientation of 4-AD mediated by distal L532Y mutation. Based on that, the three genes, MU3, ReKstD and a ketoreductase for NADPH regeneration, were rationally integrated in one cell via expression fine-tuning to form the efficient single cell catalyst E. coli S9. The single whole-cell biocatalytic process was scaled up and could generate 9.0 g/L testolactone with the high space time yield of 1 g/L/h without steroidal by-product, indicating the potential for site-specific and one-pot synthesis of steroid.

Multienzymatic Cascade for Synthesis of Hydroxytyrosol via Two-Stage Biocatalysis.

Hydroxytyrosol, a naturally occurring compound with antioxidant and antiviral activity, is widely applied in the cosmetic, food, and nutraceutical industries. The development of a biocatalytic approach for producing hydroxytyrosol from simple and readily accessible substrates remains a challenge. Here, we designed and implemented an effective biocatalytic cascade to obtain hydroxytyrosol from 3,4-dihydroxybenzaldehyde and l-threonine via a four-step enzymatic cascade composed of seven enzymes. To prevent cross-reactions and protein expression burden caused by multiple enzymes expressed in a single cell, the designed enzymatic cascade was divided into two modules and catalyzed in a stepwise manner. The first module (FM) assisted the assembly of 3,4-dihydroxybenzaldehyde and l-threonine into (2S,3R)-2-amino-3-(3,4-dihydroxyphenyl)-3-hydroxypropanoic acid, and the second module (SM) entailed converting (2S,3R)-2-amino-3-(3,4-dihydroxyphenyl)-3-hydroxypropanoic acid into hydroxytyrosol. Each module was cloned into Escherichia coli BL21 (DE3) and engineered in parallel by fine-tuning enzyme expression, resulting in two engineered whole-cell catalyst modules, BL21(FM01) and BL21(SM13), capable of converting 30 mM 3,4-dihydroxybenzaldehyde to 28.7 mM hydroxytyrosol with a high space-time yield (0.88 g/L/h). To summarize, the current study proposes a simple and effective approach for biosynthesizing hydroxytyrosol from low-cost substrates and thus has great potential for industrial applications.

Probing Energy-Funneling Kinetics in Nanocrystal Sublattices for Superior X-Ray Imaging.

Long-lasting radioluminescence scintillators have recently attracted substantial attention from both research and industrial communities, primarily due to their distinctive capabilities of converting and storing X-ray energy. However, determination of energy-conversion kinetics in these nanocrystals remains unexplored. Here we present a strategy to probe and unveil energy-funneling kinetics in NaLuF4:Mn2+/Gd3+ nanocrystal sublattices through Gd3+-driven microenvironment engineering and Mn2+-mediated radioluminescence profiling. Our photophysical studies reveal effective control of energy-funneling kinetics and demonstrate the tunability of electron trap depth ranging from 0.66 to 0.96 eV, with the corresponding trap density varying between 2.38×105 and 1.34×107 cm-3. This enables controlled release of captured electrons over durations spanning from seconds to 30 days. It allows tailorable emission wavelength within the range of 520-580 nm and fine-tuning of thermally-stimulated temperature between 313-403 K. We further utilize these scintillators to fabricate high-density, large-area scintillation screens that exhibit a 6-fold improvement in X-ray sensitivity, 22 lp/mm high-resolution X-ray imaging, and a 30-day-long optical memory. This enables high-contrast imaging of injured mice through fast thermally-stimulated radioluminescence readout. These findings offer new insights into the correlation of radioluminescence dynamics with energy-funneling kinetics, thereby contributing to the advancement of high-energy nanophotonic applications.

An artificial biocatalytic cascade for efficient synthesis of norepinephrine by combination of engineered L-threonine transaldolase with multi-enzyme expression fine-tuning.

Norepinephrine, a kind of ß-adrenergic receptor agonist, is commonly used for treating shocks and hypotension caused by a variety of symptoms. The development of a straightforward, efficient and environmentally friendly biocatalytic route for manufacturing norepinephrine remains a challenge. Here, we designed and realized an artificial biocatalytic cascade to access norepinephrine starting from 3, 4-dihydroxybenzaldehyde and L-threonine mediated by a tailored-made L-threonine transaldolase PsLTTA-Mu1 and a newly screened tyrosine decarboxylase ErTDC. To overcome the imbalance of multi-enzymes in a single cell, engineering of PsLTTA for improved activity and fine-tuning expression mode of multi-enzymes in single E.coli cells were combined, leading to a robust whole cell biocatalyst ES07 that could produce 100 mM norepinephrine with 99% conversion, delivering a highest time-space yield (3.38 g/L/h) ever reported. To summarized, the current study proposed an effective biocatalytic approach for the synthesis of norepinephrine from low-cost substrates, paving the way for industrial applications of enzymatic norepinephrine production.

Identification and expression analysis of ATP-binding cassette (ABC) transporters revealed its role in regulating stress response in pear (Pyrus bretchneideri).

BACKGROUND: ATP-binding cassette (ABC) transporter proteins constitute a plant gene superfamily crucial for growth, development, and responses to environmental stresses. Despite their identification in various plants like maize, rice, and Arabidopsis, little is known about the information on ABC transporters in pear. To investigate the functions of ABC transporters in pear development and abiotic stress response, we conducted an extensive analysis of ABC gene family in the pear genome. RESULTS: In this study, 177 ABC transporter genes were successfully identified in the pear genome, classified into seven subfamilies: 8 ABCAs, 40 ABCBs, 24 ABCCs, 8 ABCDs, 9 ABCEs, 8 ABCFs, and 80 ABCGs. Ten motifs were common among all ABC transporter proteins, while distinct motif structures were observed for each subfamily. Distribution analysis revealed 85 PbrABC transporter genes across 17 chromosomes, driven primarily by WGD and dispersed duplication. Cis-regulatory element analysis of PbrABC promoters indicated associations with phytohormones and stress responses. Tissue-specific expression profiles demonstrated varied expression levels across tissues, suggesting diverse functions in development. Furthermore, several PbrABC genes responded to abiotic stresses, with 82 genes sensitive to salt stress, including 40 upregulated and 23 downregulated genes. Additionally, 91 genes were responsive to drought stress, with 22 upregulated and 36 downregulated genes. These findings highlight the pivotal role of PbrABC genes in abiotic stress responses. CONCLUSION: This study provides evolutionary insights into PbrABC transporter genes, establishing a foundation for future research on their functions in pear. The identified motifs, distribution patterns, and stress-responsive expressions contribute to understanding the regulatory mechanisms of ABC transporters in pear. The observed tissue-specific expression profiles suggest diverse roles in developmental processes. Notably, the significant responses to salt and drought stress emphasize the importance of PbrABC genes in mediating adaptive responses. Overall, our study advances the understanding of PbrABC transporter genes in pear, opening avenues for further investigations in plant molecular biology and stress physiology.

Production of mannooligosaccharides from orange peel waste with ß-mannanase expressed in Trichosporonoides oedocephalis.

A large quantity of orange peel waste (OPW) is generated per year, yet effective biorefinery methods are lacking. In this study, Trichosporonoides oedocephalis ATCC 16958 was employed for hydrolyzing OPW to produce soluble sugars. Glycosyl hydrolases from Paenibacillussp.LLZ1 which can hydrolyze cellulose and hemicellulose were mined and characterized, with the highest ß-mannanase activity of 39.1 U/mg at pH 6.0 and 50 ℃. The enzyme was overexpressed in T. oedocephalis and the sugar production was enhanced by 16 %. The accumulated sugar contains 57 % value-added mannooligosaccharides by the hydrolysis of mannans. The process was intensified by a pretreatment combining H2O2 submergence and steam explosion to remove potential inhibitors. The mannooligosaccharides yield of 6.5 g/L was achieved in flask conversion and increased to 9.7 g/L in a 5-L fermenter. This study improved the effectiveness of orange peel waste processing, and provided a hydrolysis-based methodology for the utilization of fruit wastes.

Solifenacin promotes remyelination in cuprizone mouse model by inhibiting the Wnt/ß-catenin signaling pathway.

Demyelinating diseases are a type of neurological disorder characterized by the damage to the myelin sheath in the central nervous system. Promoting the proliferation and differentiation of oligodendrocyte precursor cells (OPCs) is crucial for treatment. Non-selective muscarinic receptor (MR) antagonists have been shown to improve remyelination in rodent models, although the mechanisms are still unclear. In this study, we treated cuprizone (CPZ)-induced demyelination mouse model with different concentrations of Solifenacin (Sol), a selective M3 receptor antagonist, to determine the optimal concentration for promoting remyelination. Behavioral tests and Luxol fast blue (LFB) staining were used to observe the extent of remyelination, while immunofluorescence was used to measure the expression levels of myelin-related proteins, including myelin basic protein (MBP) and platelet-derived growth factor receptor alpha (PDGFR-α). Western blot analysis was employed to analyze the expression levels of molecules associated with the Wnt/ß-catenin signaling pathway. The results showed that Sol treatment significantly promoted myelin regeneration and OPCs differentiation in CPZ-induced demyelination mouse model. Additionally, Sol treatment inhibited the Wnt/ß-catenin signaling pathway and reversed the effects of CPZ on OPCs differentiation. In conclusion, Sol may promote the differentiation of OPCs by inhibiting the Wnt/ß-catenin signaling pathway, making it a potential therapeutic option for central nervous system demyelinating diseases.

Engineering extracellular vesicles with macrophage membrane fusion for ameliorating imiquimod-induced psoriatic skin inflammation.

INTRODUCTION: Herein, we developed an engineered extracellular vehicle (EV)-based method for ameliorating inflammatory responses in psoriasis. METHODS: EVs, derived from annexin A1 (ANXA1) overexpressing T cells, were co-extruded with M2 macrophage membrane to obtain engineered EVs. In vitro, the effect of engineered EVs on macrophage polarization was evaluated by real-time PCR. In imiquimod (IMQ)-induced psoriasis-like mouse model, the efficacy of engineered EVs in ameliorating psoriatic inflammation was evaluated by Psoriasis Area and Severity Index (PASI) score and immunohistochemistry staining after subcutaneous injection of EVs. RESULTS: The engineered EVs not only preserved the high stability of M2 macrophage membrane but also retained the macrophage reprogramming potential of ANXA1 overexpressed in T cells. In the psoriasis-like mouse model, subcutaneous injection of engineered EVs successfully reduced the PASI score and the levels of pro-inflammatory cytokines, including IL-1ß, IL-6, and TNF-α. Along with high biosafety, the administration of EVs also rescued the histomorphological changes of spleen, liver, and kidney. CONCLUSIONS: The engineered EVs exhibited the potential to alleviate inflammation of psoriasis, providing new insights and potential strategies for the immunotherapies of psoriasis.

Microplastics exposure promotes the proliferation of skin cancer cells but inhibits the growth of normal skin cells by regulating the inflammatory process.

Cutaneous squamous cell carcinoma (CSCC) is one of the most common malignant tumors of the skin, occurring primarily in the elderly population. CSCC is the second most common nonmelanoma skin malignancy in humans. The development of cutaneous squamous cell carcinoma is closely linked to environmental factors. Microplastics, as a new pollutant, are currently being intensively studied for their potential health effects. However, the effect of microplastics on skin cancer is not yet known and is an important scientific question that needs to be addressed. To this end, in the current study, two skin squamous cell carcinoma cell lines (SCL-1 and A431) were utilized to investigate the effects of microplastics on skin cancer, and cell behavior experiments showed that microplastics were internalized into the skin squamous cell carcinoma cell line in a time- and dose-dependent manner. Further experiments showed that microplastics promoted the proliferation of skin cancer cells by MTT, flow cytometry, laser confocal microscopy, Western blotting and other experimental techniques. Mechanistic studies showed that microplastics could lead to increased mitochondrial ROS in skin cancer cells, which in turn caused a change in mitochondrial membrane potential, thus opening mPTP, which in turn caused the release of mt-DNA from mitochondria into the cytoplasm, thus activating NLRP3 and ultimately causing skin cancer cell proliferation. We further evaluated the effect of microplastics on HaCaT cells in a normal skin cell model and showed that microplastics caused damage to normal skin cells through NLRP3-mediated inflammation and scorch death. The current study suggests that microplastics, as a new contaminant, may promote tumor cell proliferation while causing damage to normal skin.

Multiplex metabolic pathway engineering of Monascus pilosus enhances lovastatin production.

Monascus sp. is an important food microbial resource with the production of cholesterol-lowering agent lovastatin and other healthy metabolites. However, the mycotoxin citrinin naturally produced by Monascus sp. and the insufficient productivity of lovastatin limit its large-scale use in food industry. The aim of this paper is to modify a lovastatin-producing strain Monascus pilosus GN-01 through metabolic engineering to obtain a citrinin-free M. pilosus strain with higher yield of lovastatin. The citrinin synthesis regulator gene ctnR was firstly disrupted to obtain GN-02 without citrinin production. Based on that, the lovastatin biosynthesis genes (mokC, mokD, mokE, mokF, mokH, mokI, and LaeA) were, respectively, overexpressed, and pigment-regulatory gene (pigR) was knocked out to improve lovastatin production. The results indicated ctnR inactivation effectively disrupted the citrinin release by M. pilosus GN-01. The overexpression of lovastatin biosynthesis genes and pigR knockout could lead higher contents of lovastatin, of which pigR knockout strain achieved 76.60% increase in the yield of lovastatin compared to GN-02. These studies suggest that such multiplex metabolic pathway engineering in M. pilosus GN-01 is promising for high lovastatin production by a safe strain for application in Monascus-related food. KEY POINTS: • Disruption of the regulator gene ctnR inhibited citrinin production of M. pilosus. • Synchronous overexpression of biosynthesis gene enhanced lovastatin production. • pigR knockout enhanced lovastatin of ΔctnR strain of M. pilosus.

A chemoenzymatic process for preparation of highly purified dehydroepiandrosterone in high space-time yield.

Dehydroepiandrosterone (DHEA) is an important neurosteroid hormone to keep human hormonal balance and reproductive health. However, DHEA was always produced with impurities either by chemical or biological method and required high-cost purification before the medical use. To address this issue, a novel chemoenzymatic process was proposed and implemented to produce DHEA. An acetoxylated derivate of 4-androstene-3,17-dione (4-AD) was generated by chemical reaction and converted into DHEA by an enzyme cascade reaction combining a hydrolysis reaction with a reduction reaction. The hydrolysis reaction was catalyzed by a commercial esterase Z03 while the reduction reaction was catalyzed by E. coli cells co-expressing a 3ß-hydroxysteroid dehydrogenase SfSDR and a glucose dehydrogenase BtGDH. After the condition optimization, DHEA was synthesized at a 100 mL scale under 100 mM of substrate loading and purified as white powder with the highest space-time yield (4.80 g/L/h) and purity (99 %) in the biosynthesis of DHEA. The successful attempt in this study provides a new approach for green synthesis of highly purified DHEA in the pharmaceutical industry.

Ro25-6981 alleviates neuronal damage and improves cognitive deficits by attenuating oxidative stress via the Nrf2/ARE pathway in ischemia/reperfusion rats.

OBJECTIVES: Oxidative stress plays a crucial role in the initiation and progression of cerebral ischemia‒reperfusion injury (CIRI). Therefore, ameliorating oxidative damage is considered to be a beneficial strategy for the treatment of CIRI. NMDAR NR2B subunit antagonists have been reported to be beneficial for synaptic plasticity, neuropathic pain, epilepsy, and cerebral ischemia. However, it remains unclear whether the NR2B subunit antagonist Ro25-6981 has any effect on CIRI. METHODS: In this study, the Morris water maze test and passive avoidance test were used to detect spatial learning and memory. Neuronal loss was measured by Nissl staining. The expression of NSE was assayed by immunohistochemistry. The activities of MDA, 8-OHdG, SOD, GSH-Px, GST and CAT were detected by assay kits. Real-time PCR was used to detect the mRNA levels of hippocampal SOD, GSH-Px and HO-1. Western blotting was used to measure the activation of the Nrf2/ARE pathway by Ro25-6981. RESULTS: Ro25-6981 ameliorated cognitive deficits and neuronal damage induced by ischemia‒reperfusion (I/R). Neuronal injury was decreased and the expression of NSE was increased in the CA1 regions of the hippocampus of I/R rats after Ro25-6981 treatment. Moreover, Ro25-6981 alleviated the levels of MDA and 8-OHdG by elevating the activities of SOD, GSH-Px, GST and CAT. Meanwhile, the mRNA levels of SOD, GSH-Px and HO-1 were increased in I/R rats after Ro25-6981 treatment. Furthermore, Ro25-6981 promoted the translocation of Nrf2 to the nucleus, promoting the expression of the Nrf2 downstream genes HO-1 and NQO1. CONCLUSION: The present study indicated that the improvement in the antioxidant properties of Ro25-6981 is mediated by the Nrf2/ARE pathway. This is the first study to demonstrate a favorable effect of Ro25-6981 on cognitive impairment in a CIRI rat model, rendering this NR2B subunit antagonist a promising agent for the treatment or prevention of CIRI.

Quantitative evaluation of impacts of the steadiness and duration of urban surface wind patterns on air quality.

The complexity and heterogeneity of urban land surfaces result in inconsistencies in near-surface winds, which in turn influence the diffusion and dispersion of air pollutants. In this study, we classified urban surface wind fields, quantified their steadiness, duration, and influence on air quality using hourly wind observations from 50 meteorological stations, as well as hourly PM2.5 and NO2 concentrations from 18 monitoring stations during 2017-2018 in Shenzhen, a mega city in southern China. We found that the K-means clustering technique was reliable for distinguishing surface wind patterns within the city. Urban surface-wind patterns greatly affected pollutant concentrations. When dominated by calm, northerly wind, high PM2.5/NO2 concentration episodes occurred more frequently than those during other surface wind patterns. The urban surface transport index (USTI) was used to quantify the steadiness of surface wind classes. High pollutant concentrations were present during both high wind speed periods with a large USTI, indicating external pollutant transport, and during low wind speed periods with a small USTI, indicating pollutant accumulation. The threshold durations for surface wind fields (TDSWF) was proposed to quantify the impacts of surface wind persistence on air quality. We found that poor air quality occurred during the first several hours of a dominant wind pattern, indicating that transitions between wind patterns should be a particular focus when assessing air-quality deterioration. USTI and TDSWF are potentially applicable to other urban areas, owing to their clear definitions and simple calculation. In combination with wind speeds, these indices are likely to improve air quality forecasting and strategic decisions on air pollution emergencies, based on long time series of multiple wind and pollutant concentration observations.

Enhancement of L-ribulose Production from L-ribose Through Modification of Ochrobactrum sp. CSL1 Ribose-5-phosphate Isomerase A.

L-ribulose, a kind of high-value rare sugar, could be utilized to manufacture L-form sugars and antiviral drugs, generally produced from L-arabinose as a substrate. However, the production of L-ribulose from L-arabinose is limited by the equilibrium ratio of the catalytic reaction, hence, it is necessary to explore a new biological enzymatic method to produce L-ribulose. Ribose-5-phosphate isomerase (Rpi) is an enzyme that can catalyze the reversible isomerization between L-ribose and L-ribulose, which is of great significance for the preparation of L-ribulose. In order to obtain highly active ribose-5-phosphate isomerase to manufacture L-ribulose, ribose-5-phosphate isomerase A (OsRpiA) from Ochrobactrum sp. CSL1 was engineered based on structural and sequence analyses. Through a rational design strategy, a triple-mutant strain A10T/T32S/G101N with 160% activity was acquired. The enzymatic properties of the mutant were systematically investigated, and the optimum conditions were characterized to achieve the maximum yield of L-ribulose. Kinetic analysis clarified that the A10T/T32S/G101N mutant had a stronger affinity for the substrate and increased catalytic efficiency. Furthermore, molecular dynamics simulations indicated that the binding of the substrate to A10T/T32S/G101N was more stable than that of wild type. The shorter distance between the catalytic residues of A10T/T32S/G101N and L-ribose illuminated the increased activity. Overall, the present study provided a solid basis for demonstrating the complex functions of crucial residues in RpiAs as well as in rare sugar preparation.

"Nonpolarity paving" in substrate tunnel of a Limnobacter sp. Phenylacetone monooxygenase for efficient single whole-cell synthesis of esomeprazole.

Baeyer-Villiger monooxygenase (BVMO) mediated sulfoxidation is a sustainable approach for the synthesis of esomeprazole. In this work, a novel phenylacetone monooxygenase from Limnobacter sp. (LnPAMO) was found to have trace activity for synthesis of enantiopure esomeprazole. Through engineering in the substrate tunnel using a mutagenesis strategy called "nonpolarity paving" and some modifications in cofactor binding domains, a mutant harboring 15 mutations (LnPAMO Mu15) was obtained with 6.6 × 103-fold higher activity to convert omeprazole sulfide into esomeprazole. The activities of the mutant for synthesis of (S)-methyl phenyl sulfoxide and (S)-pantoprazole also increased much, indicating the versatility of the mutant for sulfoxide synthesis. Importantly, no over-oxidation byproduct omeprazole sulfone was detected in the sulfoxidation products by both mass spectrometry and HPLC analysis. Then NADP-dependent Burkholderia stabili formate dehydrogenase was ligated behind Mu15 along with a ribosome binding site sequence in pET-28a for co-expression. By single whole-cell of recombinant Escherichia coli BL21 coexpressing Mu15 and formate dehydrogenase, omeprazole sulfide was efficiently converted into esomeprazole without production of sulfone (16 g/L substrate, enantiomeric excess > 99.9% (S) and > 99% conversion) and the space-time-yield reached 1.67 g product/L/h.

A cold front induced co-occurrence of O3 and PM2.5 pollution in a Pearl River Delta city: Temporal variation, vertical structure, and mechanism.

In this study, the spatiotemporal variabilities and characteristics of ozone (O3) and fine particulate matter (PM2.5) were reconstructed, and the interaction between meteorological conditions and the co-occurrence of O3 and PM2.5 in Zhuhai, a city in the Pearl River Delta (China), was analysed. The vertical distributions of lower tropospheric O3, aerosol extinction coefficient, and wind velocity were measured using a ground-based LiDAR system. The diurnal variations in air pollutant concentrations and meteorological conditions at ground level were examined from 28 November to December 8, 2020 considering the weather conditions in Zhuhai. Heavy pollution episodes with increased concentrations of O3 and PM2.5 were observed from 6 to 7 December after a period of cold air invasion. The maximum hourly average concentrations of O3 and PM2.5 at the ground level reached up to 190 µg/m3, 98 µg/m3, respectively. The horizontal wind speed rapidly decreased to less than 2 m/s during the heavy pollution episodes driven by O3 and PM2.5, whereas the vertical wind velocity was dominated by the downdraught. When the large-scale synoptic winds were weak, a strengthening sea breeze in the afternoon could promote the landward propagation of warm marine air masses, and a lower surface wind speed was driven by the convergence of cold air from the north and warm air from the south. In turn, this increased the residence time of air pollutants and promoted their conversion to secondary pollutants. Regarding the pollution sources, the results indicated that the Pearl River Estuary represented a 'pool' of O3 and PM2.5 pollution. In addition, the contribution of regional pollutant transport could not be ignored when considering the accumulative increase in air pollution. Overall, the relatively weak synoptic winds, low mixing height, and high generation of pollution around Zhuhai collectively resulted in high concentrations of O3 and PM2.5.

Characterization and substrate-accelerated thermal inactivation kinetics of a new serine-type arylsulfatase.

Arylsulfatase is useful in industrial agar processing by removing sulfate groups. A full-length arylsulfatase gene, designated ArySMA1, was obtained from marine bacteria Serratia sp. SM1. The ArySMA1 gene encoded a novel serine-type arylsulfatase and the enzymatic properties were characterized. The enzyme presented notable capacity of removing sulfate groups from natural algae substrates. Kinetic study suggested that the microscopic thermal inactivation rate of ArySMA1 in free form was smaller than that of the enzyme-substrate complex. The presence of substrate could unexpectedly accelerate ArySMA1 to deactivate at high temperature. Such phenomenon was opposite to many findings that substrate could stabilize enzymes against heat. Molecular dynamics simulation and ANS fluorescent assay indicated the substrate led the hydrophobic regions of the active site more flexible and the sulfate group of the substrate could retard the processivity of ArySMA1 catalysis. This study provides guidance for agar desulfation and down-stream processing industry.

Histone methylation in pancreatic cancer and its clinical implications.

Pancreatic cancer (PC) is an aggressive human cancer. Appropriate methods for the diagnosis and treatment of PC have not been found at the genetic level, thus making epigenetics a promising research path in studies of PC. Histone methylation is one of the most complicated types of epigenetic modifications and has proved crucial in the development of PC. Histone methylation is a reversible process regulated by readers, writers, and erasers. Some writers and erasers can be recognized as potential biomarkers and candidate therapeutic targets in PC because of their unusual expression in PC cells compared with normal pancreatic cells. Based on the impact that writers have on the development of PC, some inhibitors of writers have been developed. However, few inhibitors of erasers have been developed and put to clinical use. Meanwhile, there is not enough research on the reader domains. Therefore, the study of erasers and readers is still a promising area. This review focuses on the regulatory mechanism of histone methylation, and the diagnosis and chemotherapy of PC based on it. The future of epigenetic modification in PC research is also discussed.