Author Report for: Fan XNo contact information in database for Fan X
Fan X, Zhao M, Wen H, Zhang Y, Zhang J, Liu X Ref: Chemosphere, 319:138021, 2023 : PubMed ESTHER: Fan_2023_Chemosphere_319_138021 PubMedSearch: Fan 2023 Chemosphere 319 138021 PubMedID: 36731665 Gene_locus related to this paper: 9bact-i6yrg4 Abstract The pervasive use of pyrethroids is seriously hazardous to the environment and even human health. Enzymatic bioremediation is potentially a rapid and environmentally friendly technology to combat the pollution of pyrethroid pesticides. The hydrolysis of ester linkages is the initial and critical enzymatic step in microbial degradation pathways. Here, the versatile and thermostable esterase Est816 was cloned and its new function, pyrethroid-hydrolysis activity, was expanded. To further improve its pyrethroid-hydrolysis ability, Est816 was modified by rational design. After two rounds of mutation, the best-performing mutant, Est816(A216V/K238N/M97V,) was obtained, which could completely degrade 1 mg/L lambda-cyhalothrin, cypermethrin, and deltamethrin within 20 min, and efficiently degrade fenvalerate, reaching over 80% conversion. Degradation activity analyses showed that three substitutions (A216V, K238 N and M97V) were beneficial for enhancing the activity of Est816. Enzymatic characterization showed that Est816(A216V/K238N/M97V) inherited broad substrate specificity and possessed excellent stability and adaptability over wide ranges of temperature and pH, which is essential for bioremediation in frequently changing conditions. Furthermore, Est816(A216V/K238N/M97V) had the best degradation effect on all four pyrethroid residues in Panax notoginseng root, with more than 87% conversion after 24 h. Pyrethroid residues in tea, cucumber, and soil were reduced by more than 76%, 80%, and 76%, respectively. Taken together, these findings highlight the great potential of Est816(A216V/K238N/M97V) in the bioremediation of pyrethroid-contaminated soil and agricultural products. Title: Strigolactone regulates adventitious root formation via the MdSMXL7-MdWRKY6-MdBRC1 signaling cascade in apple Fan X, Li Y, Deng CH, Wang S, Wang Z, Wang Y, Qiu C, Xu X, Han Z, Li W Ref: Plant J, 113:772, 2023 : PubMed ESTHER: Fan_2023_Plant.J_113_772 PubMedSearch: Fan 2023 Plant.J 113 772 PubMedID: 36575587 Abstract Propagation through stem cuttings is a popular method worldwide for species such as fruit tree rootstocks and forest trees. Adventitious root (AR) formation from stem cuttings is crucial for effective and successful clonal propagation of apple rootstocks. Strigolactones (SLs) are newly identified hormones involved in AR formation. However, the regulatory mechanisms underpinning this process remain elusive. In the present study, weighted gene co-expression network analysis, as well as rooting assays using stable transgenic apple materials, revealed that MdBRC1 served as a key gene in the inhibition of AR formation by SLs. We have demonstrated that MdSMXL7 and MdWRKY6 synergistically regulated MdBRC1 expression, depending on the interactions of MdSMXL7 and MdWRKY6 at the protein level downstream of SLs as well as the direct promoter binding on MdBRC1 by MdWRKY6. Furthermore, biochemical studies and genetic analysis revealed that MdBRC1 inhibited AR formation by triggering the expression of MdGH3.1 in a transcriptional activation pathway. Finally, the present study not only proposes a component, MdWRKY6, that enables MdSMXL7 to regulate MdBRC1 during the process of SL-controlled AR formation in apple, but also provides prospective target genes to enhance AR formation capacity using CRISPR (i.e. clustered regularly interspaced short palindromic repeats) technology, particularly in woody plants. Title: Immobilized lipase for sustainable hydrolysis of acidified oil to produce fatty acid Fan X, Zhang P, Fan M, Jiang P, Leng Y Ref: Bioprocess Biosyst Eng, :, 2023 : PubMed ESTHER: Fan_2023_Bioprocess.Biosyst.Eng__ PubMedSearch: Fan 2023 Bioprocess.Biosyst.Eng PubMedID: 37329348 Abstract Acidified oil is obtained from by-product of crops oil refining industry, which is considered as a low-cost material for fatty acid production. Hydrolysis of acidified oil by lipase catalysis for producing fatty acid is a sustainable and efficient bioprocess that is an alternative of continuous countercurrent hydrolysis. In this study, lipase from Candida rugosa (CRL) was immobilized on magnetic Fe(3)O(4)@SiO(2) via covalent binding strategy for highly efficient hydrolysis of acidified soybean oil. FTIR, XRD, SEM and VSM were used to characterize the immobilized lipase (Fe(3)O(4)@SiO(2)-CRL). The enzyme properties of the Fe(3)O(4)@SiO(2)-CRL were determined. Fe(3)O(4)@SiO(2)-CRL was used to catalyze the hydrolysis of acidified soybean oil to produce fatty acids. Catalytic reaction conditions were studied, including amount of catalyst, reaction time, and water/oil ratio. The results of optimization indicated that the hydrolysis rate reached 98% under 10 wt.% (oil) of catalyst, 3:1 (v/v) of water/oil ratio, and 313 K after 12 h. After 5 cycles, the hydrolysis activity of Fe(3)O(4)@SiO(2)-CRL remained 55%. Preparation of fatty acids from high-acid-value by-products through biosystem shows great industrial potential. Title: Functional mass spectrometry imaging maps phospholipase-A2 enzyme activity during osteoarthritis progression Fan X, Young RSE, Sun AR, Hamilton BR, Nedunchezhiyan U, Crawford R, Blanksby SJ, Prasadam I Ref: Theranostics, 13:4636, 2023 : PubMed ESTHER: Fan_2023_Theranostics_13_4636 PubMedSearch: Fan 2023 Theranostics 13 4636 PubMedID: 37649605 Abstract Background: Enzymes are central components of many physiological processes, and changes in enzyme activity are linked to numerous disease states, including osteoarthritis (OA). Assessing changes in enzyme function can be challenging because of difficulties in separating affected tissue areas that result in the homogenisation of healthy and diseased cells. Direct correlation between spatially-resolved enzyme distribution(s) and diseased cells/tissues can thus lead to advances in our understanding of OA pathophysiology. Herein, we present a method that uses mass spectrometry imaging (MSI) to visualise the distribution of lipase enzymes and their downstream lipid products in fresh bone and cartilage tissue sections. Immunohistostaining of adjacent tissue sections was then used to identify OA cells/tissues, which were then statistically correlated with molecular-level images. Methods: MSI was used to image lipase enzymes, their substrates, and their metabolic products to validate enzymatic activity and correlate to OA regions determined by immunohistochemistry (IHC). Based on the modified Mankin score, six non-OA and OA patient-matched osteochondral samples were analysed by matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI). Due to the involvement of phospholipase A2 (PLA(2)) in inflammatory pathways, explant tissues were treated with IL-1beta to mimic inflammation observed in OA. Bovine explant tissues were then subject to MSI methods to observe the spatial distribution of PLA(2). Results: Compared with non-OA samples, OA samples showed an elevated level of multiple arachidonic acid (AA)-containing phospholipids (P < 0.001), in which the elevation in the surface and deep layer cartilage of OA tissues is correlated to elevated PLA(2) activity (P < 0.001). Bovine explant tissues treated with IL-1beta to mimic OA pathophysiology validated these results and displayed elevated PLA(2) levels in OA mimic samples relative to the controls (P < 0.001). It was established that the PLA(2)G(2)A isoform specifically was responsible for PLA(2) enzyme activity changes in OA tissues (P < 0.001). Conclusion: Our results present a reliable method for imaging enzyme dynamics in OA cartilage, which sets up the foundation for future spatial enzyme dynamics in the OA field. We demonstrated that OA patients exhibit increased expression of PLA(2)G(2)A at the superficial and deep cartilage zone that degrades cartilage differently at the spatial level. A tissue-specific PLA(2)G(2)A precision inhibition may be the potential target for OA. Title: Ecological risk assessment of environmentally relevant concentrations of propofol on zebrafish (Danio rerio) at early life stage: Insight into physiological, biochemical, and molecular aspects Jiang N, Li X, Wang Q, Baihetiyaer B, Fan X, Li M, Sun H, Yin X, Wang J Ref: Chemosphere, :137846, 2023 : PubMed ESTHER: Jiang_2023_Chemosphere__137846 PubMedSearch: Jiang 2023 Chemosphere 137846 PubMedID: 36646180 Abstract Propofol is an intravenous anesthetic injection extensively used in clinic, which has been proved to be neurotoxic in humans. Improper use and disposal of propofol may lead to its release into the aquatic environment, but the potential ecological risk of propofol to aquatic organisms remains poorly understood. For this study, we comprehensively explored the ecotoxicological effects and potential mechanisms of propofol (0.04, 0.2 and 2 mg L(-1)) on 120 hpf zebrafish (Danio rerio) embryos from physiological, biochemical, and molecular perspectives. The results showed that propofol has moderate toxicity on zebrafish embryos (96 h LC(50) = 4.260 mg L(-1)), which could significantly reduce the hatchability and delay the development. Propofol can trigger reactive oxygen species (ROS) generation, lipid peroxidation (Malondialdehyde, MDA) and DNA damage (8-hydroxy-2-deoxyguanosine, 8-OHdG). The glutathione peroxidase (GPX) activity of zebrafish embryos in 0.04 and 0.2 mg L(-1) propofol treatment group was activated in response to oxidative damage, while activities of superoxide dismutase (SOD), catalase (CAT) and GPX in zebrafish treated with 2 mg L(-1) was significant inhibited compared with the control group (p0.05). Moreover, the expression of antioxidant genes and related pathways was inhibited. Apoptosis was investigated at genes level and histochemistry. Molecular docking confirmed that propofol could change in the secondary structure of acetylcholinesterase (AChE) and competitively inhibited acetylcholine (ACh) binding to AChE, which may disturb the nervous system. These results described toxic response and molecular mechanism in zebrafish embryos, providing multiple aspects about ecological risk assessment of propofol in water environment. Title: Acute toxicity of tire wear particles and leachate to Daphnia magna Liu J, Feng Q, Yang H, Fan X, Jiang Y, Wu T Ref: Comparative Biochemistry & Physiology C Toxicol Pharmacol, :109713, 2023 : PubMed ESTHER: Liu_2023_Comp.Biochem.Physiol.C.Toxicol.Pharmacol__109713 PubMedSearch: Liu 2023 Comp.Biochem.Physiol.C.Toxicol.Pharmacol 109713 PubMedID: 37544637 Abstract Tire wear particles (TWP) are a new pollutant widely present in the environment, and have been identified as microplastics (MPs), which are receiving increasing attention due to their toxic effects on aquatic organisms. In this study, D. magna was used as test organism, and the leachate from TWP was prepared by hot water extraction for 30 (30-E) and 120 min (120-E). The acute toxic effects of particles and leachate on D. magna were studied under different exposure concentrations. The results showed that zinc and pyrene were the highest detected contaminants in the leachate. The 48 h-LC(50) values for particles and leachate were determined to be 56.99, 461.30 (30-E), and 153.00 mg/L (120-E), respectively. Following a 48 h exposure period, the immobilization of D. magna exposed to the particles and their leachate were increased with the concentration increase. The physical damage of the gut was found to be a possible mechanism for particle-induced biotoxicity. The compounds leached from TWP were responsible for the acute toxicity of leachate. Particles usually demonstrated a greater degree of toxicity in comparison to their leachate, especially at environmentally relevant concentrations. Exposure to particles and leachate resulted in the inhibition of swimming speed, swimming acceleration, filtration rate, and ingestion rate in D. magna. Furthermore, thoracic limb activity was observed to be inhibited. The heart rate of D. magna was significantly increased by the presence of particles at a concentration of 200 mg/L and leachate at concentrations of 400 and 800 mg/L (120-E). The observed alterations in behavior and physiological endpoints may be related to oxidative stress and neurotoxicity in the organism. Reduced superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) activities indicated that D. magna may suffer from excessive oxidative stress, whereas the increase of acetylcholinesterase (AChE) activity may serve as a biomarker of susceptibility to evaluate the environmental risks of TWP and corresponding leachates as potential aquatic pollutants.. Therefore, a more comprehensive risk assessment of TWP in the environment is necessary. Title: Major biotransformation of phthalic acid esters in Eisenia fetida: Mechanistic insights and association with catalytic enzymes and intestinal symbionts Fan X, Gu C, Jin Z, Cai J, Bian Y, Wang F, Chen H, Jiang X Ref: Environ Int, 171:107712, 2022 : PubMed ESTHER: Fan_2022_Environ.Int_171_107712 PubMedSearch: Fan 2022 Environ.Int 171 107712 PubMedID: 36577298 Abstract Phthalic acid esters (PAEs) are an important group of organic pollutants that are widely used as plasticizers in the environment. The PAEs in soil organisms are likely to be biotransformed into a variety of metabolites, and the combined toxicity of PAEs and their metabolites might be more serious than PAEs alone. However, there are only a few studies on PAE biotransformation by terrestrial animals, e.g. earthworms. Herein, the key biotransformation pathways of PAEs and their association with catalytic enzymes and intestinal symbionts in earthworms were studied using in vivo and in vitro incubation approaches. The widely distributed PAE in soil, dibutyl phthalate (DBP), was proven to be biotransformed rapidly together with apparent bioaccumulation in earthworms. The biotransformation of PAE congeners with medium or long side chains appeared to be faster compared with those with short side chains. DBP was biotransformed into butyl methyl phthalate (BMP), monobutyl phthalate (MBP), and phthalic acid (PA) through esterolysis and transesterification. Besides, the generation of small quantities of low-molecular weight metabolites via beta-oxidation, decarboxylation or ring-cleavage, was also observed, especially when the appropriate proportion of NADPH coenzyme was applied to transfer electrons for oxidases. Interestingly, the esterolysis of PAEs was mainly regulated by the cytoplasmic carboxylesterase (CarE) in earthworms, with a Michaelis constant (K(m)) of 0.416smM in the catalysis of DBP. The stronger esterolysis in non-intestinal tissues indicated that the CarE was primarily secreted by non-intestinal tissues of earthworms. Additionally, the intestinal symbiotic bacteria of earthworms could respond to PAE stress, leading to the changes in their diversity and composition. The enrichment of some genera e.g. Bacillus and Paracoccus, and the enhancement of metabolism function, e.g. amino acids, energy, lipids biosynthesis and oxidase secretion, indicated their important role in the degradation of PAEs. Title: Improved Aitongxiao prescription (I-ATXP) induces apoptosis, cell cycle arrest and blocks exosomes release in hepatocellular carcinoma (HCC) cells Huang MB, Gao Z, Xia M, Zhao X, Fan X, Lin S, Zhang L, Huang L, Wei A and Leng J <4 more author(s)> Huang MB, Gao Z, Xia M, Zhao X, Fan X, Lin S, Zhang L, Huang L, Wei A, Zhou H, Wu JY, Roth WW, Bond VC, Leng J (- 4) Ref: Int Journal de Physiologie Pathophysiol Pharmacol, 14:90, 2022 : PubMed ESTHER: Huang_2022_Int.J.Physiol.Pathophysiol.Pharmacol_14_90 PubMedSearch: Huang 2022 Int.J.Physiol.Pathophysiol.Pharmacol 14 90 PubMedID: 35619665 Abstract BACKGROUND: Hepatocellular carcinoma (HCC) is the second most common malignancy globally, after lung cancer, accounting for 85-90% of primary liver cancer. Hepatitis B virus (HBV) infection is considered the leading risk factor for HCC development in China. HCC is a highly malignant cancer whose metastasis is primarily influenced by the tumor microenvironment. The role of exosomes in cancer development has become the focus of much research due to the many newly described contents of exosomes, which may contribute to tumorigenesis. However, the possible role exosomes play in the interactions between HCC cells and their surrounding hepatic milieu is mainly unknown. We discovered an Improved Aitongxiao Prescription (I-ATXP): an 80% alcohol extract from a mix of 15 specific plant and animal compounds, which had been shown to have an anticancer effect through inducing apoptosis and cell cycle arrest and blocking exosomes release in HCC cells. However, the anticancer mechanism of I-ATXP on human liver carcinoma is still unclear. OBJECTIVE: Due to its inhibitory effects on chemical carcinogenesis and inflammation, I-ATXP has been proposed as an effective agent for preventing or treating human liver carcinoma. In this study, we aimed to explore the effect of I-ATXP on proliferation, apoptosis, and cell cycles of different HCC cell lines. We investigated the impact of I-ATXP on exosomes' secretion derived from these HCC cells. METHODS: The inhibitory effect of I-ATXP on proliferation and cytotoxicity of HepG2, SMMC7721, HKCL-C3 HCC cell lines, and MIHA immortalized hepatocyte cell line was assessed by CCK-8 assay. The cell cycle distribution and cell apoptosis were determined by flow cytometry using Annexin V-FITC/PI staining. The expression of Alix and CD63 of exosome marker proteins was detected by western blotting. The exosome protein concentration was measured by a fluorescent plate reader. The exosome-specific enzyme activity was measured by acetylcholinesterase (AchE) assay, and exosome morphological characteristics were identified by transmission electron microscopy (TEM). RESULTS: I-ATXP inhibited the growth of HCC cells in a dose and time-dependent manner. Flow cytometry analysis showed that I-ATXP induced G0/G1 phase arrest and cell apoptosis. The I-ATX reduced HepG2, SMMC7721, and HKCI-C HCC cell lines exosomes release and low-dose I-ATXP significantly enhanced the growth inhibition induced by 5-Fu. Western blot analysis shows that after HCC cell lines were treated with various concentrations of I-ATXP (0.125-1 mg/ml) for 24 h, exosomes derived from three different HCC cells expressed exosome-specific proteins Alix and CD63. Compared with the untreated group, with the increment of the concentration of I-ATXP, the expression of exosome-specific proteins Alix and CD63 were reduced. These results suggest that I-ATXP can inhibit the release of exosomes with Alix and CD63 protein from HCC cells. CONCLUSIONS: I-ATXP is a traditional Chinese medicine that acts as an effective agent for preventing or treating human liver carcinoma. (i) I-ATXP can effectively inhibit cell proliferation of different HCC cells in a time and dose-dependent manner. Compared with 5-Fu, I-ATXP exhibited more selective proliferation inhibition in HCC cells, displaying traditional Chinese medicine advantages on tumor therapy and providing the experimental basis for I-ATXP clinical application. (ii) I-ATXP can induce apoptosis and cell cycle arrest in HCC cells. The CCK-8 assay results indicated that I-ATXP could inhibit HCC cell proliferation mediated by apoptosis and cell cycle arrest. (iii) I-ATXP can inhibit both the exosome releases and expression of CD63, and Alix derived from HCC cells, but the exosomes derived from liver cancer cells affect liver cancer cells' biological properties such as proliferation, invasion, and migration. These suggest that I-ATXP may affect HCC cells via regulation of exosomes of HCC cells, further indicating the potential clinical values of I-ATXP for the prevention or treatment of human liver carcinoma. Title: The Relationship Between Zinc Deficiency and Hepatocellular Carcinoma Associated with Hepatitis B Liver Cirrhosis: A 10-year Follow-up Study Wang S, Fan X, Gao Y, Zuo L, Hong M, Xu Y Ref: Biol Trace Elem Res, :, 2022 : PubMed ESTHER: Wang_2022_Biol.Trace.Elem.Res__ PubMedSearch: Wang 2022 Biol.Trace.Elem.Res PubMedID: 35247138 Abstract Our aim is to evaluate the serum zinc levels in Hepatitis B liver cirrhosis patients and clarify the relationship between the serum zinc levels and the development of hepatocellular carcinoma (HCC). From January 2009 to December 2019, 295 included patients diagnosed with Hepatitis B liver cirrhosis received nucleos(t)ide analogues (NUCs) therapy at China-Japan Union Hospital of Jilin University. Their comprehensive medical records were retrospectively analyzed, and to analyze the relationship between hypozincemia and hepatitis B-related HCC. Twenty-eight of 295 patients (9.49%) developed HCC during an observation period of the median follow-up time was 42 months. Compared with the non-zinc deficiency group, the zinc deficiency group is older, has a higher proportion of hepatic encephalopathy, higher levels of aspartate aminotransferase(AST), international normalized ratio(INR) and TB, and lower levels of cholinesterase (CHE), creatinine, and platelet counts (P< 0.05). Multivariate analysis showed that zine (HR=0.854, 95%CI 0.725-1.007; P=0.061), zinc is not significant for reducing the incidence of HCC, as liver disease progresses, the proportion of zinc deficiency is getting higher and higher, Child-Pugh C. The proportion of grade zinc deficiency accounted for 64.86%. Child-Pugh grade C was more than Child-Pugh grade B and A, p<0.001. Zinc deficiency is associated with hepatic encephalopathy, and other complications related to hepatitis B and liver cirrhosis. But the relationship with hepatocellular carcinoma still needs further study. Title: Mechanistic insights into primary biotransformation of diethyl phthalate in earthworm and significant SOD inhibitory effect of esterolytic products Fan X, Gu C, Cai J, Zhong M, Bian Y, Jiang X Ref: Chemosphere, 288:132491, 2021 : PubMed ESTHER: Fan_2021_Chemosphere_288_132491 PubMedSearch: Fan 2021 Chemosphere 288 132491 PubMedID: 34624352 Abstract Phthalic acid esters (PAEs) are used as plasticizer or modifier in artificially-manufactured products. Though the rapid biotransformation of phthalates in microbes and plants have been well documented, it is less studied yet in terrestrial animals, e.g. earthworm. In this study, the major biotransformation of diethyl phthalate (DEP) in Eisenia fetida was illustrated using in vitro incubation of earthworm crude enzymes. DEP could be substantially biotransformed into phthalate monoester (MEP) and a small amount of phthalic acid (PA) through esterolysis, which was verified to be driven by endogenous carboxylesterase. Despite the inferior contribution, the oxidation of DEP might also occur under the initiated electron transfer by NADPH coenzyme. The dominant metabolite MEP showed a higher inhibition of superoxide dismutase (SOD) activity than DEP with EC(50) of 0.0082 +/- 0.0016 mmol/L, so the higher ecological risks of MEP would be marked. The inhibition effect of PA was validated to be even stronger than MEP though it was slightly generated. The direct binding interaction with SOD was proved to be an important molecular event for regulation of SOD activity. Besides the static quenching mechanism, the caused conformational changes including despiralization of alpha-helix and spatial reorientation of tryptophan were spectrally believed to affect binding and underlie inhibition efficiency of SOD activity. Title: The Role of Cholinesterase in Differential Diagnosis between Gastric Cancer and Benign Gastric Diseases Gao H, Wan Y, Fan X, Dong Y, Ji X, Song W Ref: Clin Lab, 67:, 2021 : PubMed ESTHER: Gao_2021_Clin.Lab_67_ PubMedSearch: Gao 2021 Clin.Lab 67 PubMedID: 33616318 Abstract BACKGROUND: Gastric cancer is the fifth most common malignancy worldwide. In early stages, no obvious symptoms are usually observed in gastric cancer patients, and it is especially hard to distinguish gastric cancer from benign gastric diseases, resulting in delayed diagnosis and poor prognosis. Common biomarkers of gastric cancer, such as CEA and CA19-9, are also elevated in benign diseases. There is an urgent need to develop a convenient and reliable biomarker for differentiating between gastric cancer and benign gastric diseases. METHODS: This study retrospectively analyzed the data of 126 patients, including 73 gastric cancer patients and 53 benign gastric disease patients. Patient characteristics collected for analysis included age, gender, laboratory data, and clinical staging. Unpaired t-test was used to check the difference of cholinesterase level between the gastric cancer group and the benign gastric disease group. Kruskal Wallis H test and Mann-Whitney U test were used to check the difference of cholinesterase level among different stage groups. Receiver operating characteristic (ROC) curve was used to assess whether cholinesterase level can be used as a biomarker for differentiating between gastric cancer and benign gastric diseases. RESULTS: Serum cholinesterase level was decreased significantly in the gastric cancer group in comparison to that of the benign gastric disease group (p < 0.001). In addition, cholinesterase level of stage IV patients was significantly lower than stage I patients. ROC curve analysis revealed that with a cutoff of 5,969.00 U/L, cholinesterase level showed an area under the curve of 0.819 (95% CI 0.732 - 0.905, p < 0.001) in differentiating between gastric cancer and benign gastric diseases. No significant difference in the levels of CEA and CA19-9 was observed between gastric cancer patients and benign gastric disease patients. CONCLUSIONS: This study indicated that serum cholinesterase level could be considered as a potential biomarker for differentiating between gastric cancer and benign gastric diseases. Title: Enhanced Production of (S)-2-arylpropionic Acids by Protein Engineering and Whole-Cell Catalysis Liu X, Zhao M, Fan X, Fu Y Ref: Front Bioeng Biotechnol, 9:697677, 2021 : PubMed ESTHER: Liu_2021_Front.Bioeng.Biotechnol_9_697677 PubMedSearch: Liu 2021 Front.Bioeng.Biotechnol 9 697677 PubMedID: 34307324 Gene_locus related to this paper: 9zzzz-Est924 Abstract Esterases are important biocatalysts for chemical synthesis. Several bHSL family esterases have been used to prepare (S)-2-arylpropionic acids with stronger anti-inflammatory effects via kinetic resolution. Here, we presented the discovery of key residues that controlled the enantioselectivity of bHSL family esterases to ethyl 2-arylpropionates, through careful analysis of the structural information and molecular docking. A new bHSL family esterase, Est924, was identified as a promising catalyst for kinetic resolution of racemic ethyl 2-arylpropionates with slight (R)-stereopreference. Using Est924 as the starting enzyme, protein engineering was conducted at hotspots, and the substitution of A203 was proved to enhance the enantioselectivity. The stereopreference of the mutant M1 (A203W) was inverted to ethyl (S)-2-arylpropionates, and this stereopreference was further improved in variant M3 (I202F/A203W/G208F). In addition, the optimal variant, M3, was also suitable for the resolution of ibuprofen ethyl ester and ketoprofen ethyl ester, and their efficient (S)-isomers were synthesized. Next, the whole-cell catalyst harboring M3 was used to prepare (S)-ketoprofen. (S)-ketoprofen with 86%ee was produced by whole-cell catalyst with a single freeze-thaw cycle, and the cells could be reused for at least five cycles. Our results suggested that Est924 variants could kinetically resolve economically important racemates for industrial production and further offer the opportunity for the rational design of enzyme enantioselectivity. Moreover, it is an economical process to prepare optically pure (S)-ketoprofen and (S)-naproxen by using an engineered strain harboring M3 as the catalyst. Title: Repurposing an Ancient Protein Core Structure: Structural Studies on FmtA, a Novel Esterase of Staphylococcus aureus Dalal V, Kumar P, Rakhaminov G, Qamar A, Fan X, Hunter H, Tomar S, Golemi-Kotra D Ref: Journal of Molecular Biology, 431:3107, 2019 : PubMed ESTHER: Dalal_2019_J.Mol.Biol_431_3107 PubMedSearch: Dalal 2019 J.Mol.Biol 431 3107 PubMedID: 31260692 Abstract FmtA is a penicillin-recognizing protein (PRP) with novel hydrolytic activity toward the ester bond between d-Ala and the backbone of teichoic acids. Teichoic acids are polyol-phosphate polymers found in the Staphylococcus aureus cell wall, and they play important roles in antibiotic resistance and pathogenesis. Two of the PRPs conserved motifs, namely, SXXK and Y(S)XN, are involved in the hydrolysis by FmtA, but the catalytic mechanism remains elusive. Here we determined the crystal structure of FmtA. FmtA shares the core structure of PRPs: an all alpha-helical domain and alpha/beta domain sandwiched together. However, it does not have the typical PRPs active-site cleft. Its active site is shallow, solvent-exposed, and enlarged. Furthermore, our mutagenesis and kinetic studies suggest that the SXXK and Y(S)XN motifs of FmtA offer all that is necessary for catalysis, and more: the active-site nucleophile (serine), the general base (lysine) required for the acylation step and the deacylation step, and an anchor (tyrosine) to hold the active-site serine, and possibly the substrate, in an optimum conformation for catalysis. Our study establishes that the FmtA esterase activity represents an expansion of the catalytic activity repertoire of the PRPs core structure, which typically displays peptidase activity. This finding points toward a novel mechanism of ester bond hydrolysis by a PRP. The structure of FmtA provides insights to the design of inhibitor molecules with the potential to serve as leads in the development of novel antibacterial chemotherapeutic agents. Title: Trihexyphenidyl rescues the deficit in dopamine neurotransmission in a mouse model of DYT1 dystonia Downs AM, Fan X, Donsante C, Jinnah HA, Hess EJ Ref: Neurobiol Dis, 125:115, 2019 : PubMed ESTHER: Downs_2019_Neurobiol.Dis_125_115 PubMedSearch: Downs 2019 Neurobiol.Dis 125 115 PubMedID: 30707939 Abstract Trihexyphenidyl, a nonselective muscarinic receptor antagonist, is the small molecule drug of choice for the treatment of DYT1 dystonia, but it is poorly tolerated due to significant side effects. A better understanding of the mechanism of action of trihexyphenidyl is needed for the development of improved treatments. Because DTY1 dystonia is associated with both abnormal cholinergic neurotransmission and abnormal dopamine regulation, we tested the hypothesis that trihexyphenidyl normalizes striatal dopamine release in a mouse model of DYT1 dystonia using ex vivo fast scan cyclic voltammetry and in vivo microdialysis. Trihexyphenidyl increased striatal dopamine release and efflux as assessed by ex vivo voltammetry and in vivo microdialysis respectively. In contrast, L-DOPA, which is not usually effective for the treatment of DYT1 dystonia, did not increase dopamine release in either Dyt1 or control mice. Trihexyphenidyl was less effective at enhancing dopamine release in Dyt1 mice relative to controls ex vivo (mean increase WT: 65% vs Dyt1: 35%). Trihexyphenidyl required nicotinic receptors but not glutamate receptors to increase dopamine release. Dyt1 mice were more sensitive to the dopamine release decreasing effects of nicotinic acetylcholine receptor antagonism (IC50: WT=29.46nM, Dyt1=12.26nM) and less sensitive to acetylcholinesterase inhibitors suggesting that nicotinic acetylcholine receptor neurotransmission is altered in Dyt1 mice, that nicotinic receptors indirectly mediate the differential effects of trihexyphenidyl in Dyt1 mice, and that nicotinic receptors may be suitable therapeutic targets for DYT1 dystonia. Title: The development of 2-acetylphenol-donepezil hybrids as multifunctional agents for the treatment of Alzheimer's disease Zhu G, Wang K, Shi J, Zhang P, Yang D, Fan X, Zhang Z, Liu W, Sang Z Ref: Bioorganic & Medicinal Chemistry Lett, 29:126625, 2019 : PubMed ESTHER: Zhu_2019_Bioorg.Med.Chem.Lett_29_126625 PubMedSearch: Zhu 2019 Bioorg.Med.Chem.Lett 29 126625 PubMedID: 31444085 Abstract A series of 2-acetylphenol-donepezil hybrids was designed and synthesized based on multi-target-directed ligands strategy. The biological activities were evaluated by AChE/BChE inhibition and MAO-A/MAO-B inhibition. The results revealed that the tertiary amines and methylene chain length significantly affected the eeAChE inhibitory potency, in particular, compound TM-14 showed the best eeAChE inhibitory activity with IC(50) value of 2.9 microM, in addition, both kinetic analysis of AChE inhibition and docking study displayed that TM-14 could simultaneously bind to the catalytic active site and peripheral anionic site of AChE. Moreover, compound TM-14 was a selective metal chelator and could form 1:1 TM-14-Cu(2+) complex. The structure-active-relationship also indicated that the O-alkylamine fragment remarkably decreased hMAO-B inhibitory activity, compound TM-2 exhibited potent hMAO-B inhibitory activity (IC(50) = 6.8 microM), which was supported by the molecular docking study. More interestingly, compounds TM-14 and TM-2 could cross the blood-brain barrier in vitro. Therefore, the structure-active-relationship of 2-acetylphenol-donepezil hybrids could encourage the development of multifunction agents with selective AChE inhibition or selective MAO-B inhibition for the treatment of Alzheimer's disease. Title: Combined toxicity of organophosphate flame retardants and cadmium to Corbicula fluminea in aquatic sediments Li D, Wang P, Wang C, Fan X, Wang X, Hu B Ref: Environ Pollut, 243:645, 2018 : PubMed ESTHER: Li_2018_Environ.Pollut_243_645 PubMedSearch: Li 2018 Environ.Pollut 243 645 PubMedID: 30219590 Abstract Organophosphate flame retardants (OPFRs), as alternatives to polybrominated biphenyl ethers (PBDEs), are frequently detected in various environmental matrices. Owing to urbanization and industrial pollution, co-contamination of OPFRs and heavy metals is ubiquitous in the environment. The toxicity of OPFRs in aqueous phase is a significant concern, but uncertainty still exists regarding the co-toxicity to benthic organisms of OPFRs and metals in sediments. Hence, we explored the physiological response of Corbicula fluminea to OPFRs and Cd in sediments. The results indicated that the antioxidant system in the clams was stimulated in the presence of OPFRs and Cd, and the oxidative stress increased with increasing concentrations of OPFRs. In contrast, the cytochrome P450 (CYP450) content and acetylcholinesterase (AChE) activity were reduced by exposure to both OPFRs and Cd. The cytochrome P450 4 family (CYP4) mRNA expression and OPFR toxicity were lower than those in previously reported experiments conducted in the water phase. Moreover, the expression levels of metallothionein (MT) and AChE mRNA decreased when OPFRs and Cd were present together. The highest integrated biomarker response (IBR) index (IBR=15.41) was observed in the presence of 45mgkg(-1) Cd + 200 mg kg(-1) OPFRs, rather than the 45mgkg(-1) Cd + 400 mg kg(-1) OPFRs treatment (IBR=9.48). In addition, CYP450 and AChE in the digestive glands of C. fluminea exhibited significant correlations with the concentration of the OPFR/Cd mixture (p<0.01) and could be effective biomarkers for OPFR and Cd co-contamination. The results potentially contribute to more realistic predictions and evaluations of the environmental risks posed by OPFRs in aquatic sediments contaminated with heavy metals, particularly with respect to the risk to benthic organisms. Title: Biosynthetic and antimicrobial potential of actinobacteria isolated from bulrush rhizospheres habitat in Zhalong Wetland, China Li Y, Li Q, Gao J, Wang J, Luo Y, Fan X, Gu P Ref: Arch Microbiol, 200:695, 2018 : PubMed ESTHER: Li_2018_Arch.Microbiol_200_695 PubMedSearch: Li 2018 Arch.Microbiol 200 695 PubMedID: 29368168 Gene_locus related to this paper: 9actn-a0a2s3y543 Abstract The wetland ecosystem is known to possess unique vegetation and serves multiple functions within the environment. In this study, bacterial bioprospecting of bulrush rhizospheres in the Zhalong Wetland, China, was performed using comprehensive methods, including strain isolation and phylogenetic analysis, PCR detection of biosynthetic gene clusters, assessment of antimicrobial activity, metabolite profiling and genome analysis. A total of 27 actinobacterial strains were isolated, and their biosynthetic gene clusters (NRPS, PKS-I and PKS-II) were investigated; all of the tested strains had at least one of the three aforementioned biosynthetic gene clusters. Furthermore, fermentation broth extracts produced by these strains showed antimicrobial activities against certain pathogens, and ten of the extracts exhibited broad-spectrum antimicrobial activity. Liquid chromatography-mass spectrometry (LC-MS) analysis indicated chemical diversity of secondary metabolites from these extracts. Among these strains, ZLSD-24 generated the largest amounts and types of secondary metabolites. Subsequent genome analysis showed that 41 secondary metabolite biosynthetic gene clusters were present in the strain ZLSD-24, which was in accordance with the LC-MS data. Taken together, the results of this study reveal that bulrush rhizosphere habitat in the Zhalong wetland is a promising source of novel natural products. Title: Inhibition of Soluble Epoxide Hydrolase 2 Ameliorates Diabetic Keratopathy and Impaired Wound Healing in Mouse Corneas Sun H, Lee P, Yan C, Gao N, Wang J, Fan X, Yu FS Ref: Diabetes, 67:1162, 2018 : PubMed ESTHER: Sun_2018_Diabetes_67_1162 PubMedSearch: Sun 2018 Diabetes 67 1162 PubMedID: 29615440 Abstract EPHX2 (encoding soluble epoxide hydrolase [sEH]) converts biologically active epoxyeicosatrienoic acids (EETs), anti-inflammatory and profibrinolytic effectors, into the less biologically active metabolites, dihydroxyeicostrienoic acids. We sought to characterize the expression and the function of EPHX2 in diabetic corneas and during wound healing. The expression of EPHX2 at both mRNA and protein levels, as well as sEH enzymatic activity, was markedly upregulated in the tissues/cells, including corneal epithelial cells as well as the retina of human type 2 and mouse type 1 (streptozotocin [STZ] induced) and/or type 2 diabetes. Ephx2 depletion had no detectable effects on STZ-induced hyperglycemia but prevented the development of tear deficiency. Ephx2(-/-) mice showed an acceleration of hyperglycemia-delayed epithelium wound healing. Moreover, inhibition of sEH increased the rate of epithelium wound closure and restored hyperglycemia-suppressed STAT3 activation and heme oxygenase-1 (HO-1) expression in the diabetic corneas. Treatment of diabetic corneas with cobalt protoporphyrin, a well-known HO-1 inducer, restored wound-induced HO-1 upregulation and accelerated delayed wound healing. Finally, Ephx2 depletion enhanced sensory innervation and regeneration in diabetic corneas at 1 month after epithelial debridement. Our data suggest that increased sEH activity may be a contributing factor for diabetic corneal complications; targeting sEH pharmacologically or supplementing EETs may represent a new, adjunctive therapy for treating diabetic keratopathy. Title: Aii810, a Novel Cold-Adapted N-Acylhomoserine Lactonase Discovered in a Metagenome, Can Strongly Attenuate Pseudomonas aeruginosa Virulence Factors and Biofilm Formation Fan X, Liang M, Wang L, Chen R, Li H, Liu X Ref: Front Microbiol, 8:1950, 2017 : PubMed ESTHER: Fan_2017_Front.Microbiol_8_1950 PubMedSearch: Fan 2017 Front.Microbiol 8 1950 PubMedID: 29067011 Gene_locus related to this paper: 9bact-Aii810 Abstract The pathogen Pseudomonas aeruginosa uses quorum sensing (QS) to control virulence and biofilm formation. Enzymatic disruption of quorum sensing is a promising anti-infection therapeutic strategy that does not rely on antibiotics. Here, a novel gene (aii810) encoding an N-acylhomoserine lactonase was isolated from the Mao-tofu metagenome for the first time. Aii810 encoded a protein of 269 amino acids and was expressed in Escherichia coli BL21 (DE3) in soluble form. It showed the highest activity at 20 degrees C, and it maintained 76.5% of activity at 0 degrees C and more than 50% activity at 0-40 degrees C. The optimal pH was 8.0. It was stable in both neutral and slightly alkaline conditions and at temperatures below 40 degrees C. The enzyme hydrolyzed several rho-nitrophenyl esters, but its best substrate was rho-nitrophenyl acetate. Its kcat and Km values were 347.7 S(-1) and 205.1 muM, respectively. It efficiently degraded N-butyryl-L-homoserine lactone and N-(3-oxododecanoyl)-L-homoserine lactone, exceeding hydrolysis rates of 72.3 and 100%, respectively. Moreover, Aii810 strongly attenuated P. aeruginosa virulence and biofilm formation. This enzyme with high anti-QS activity was the most cold-adapted N-acylhomoserine lactonase reported, which makes it an attractive enzyme for use as a therapeutic agent against P. aeruginosa infection. Title: Chlorogenic acid protects against aluminium-induced cytotoxicity through chelation and antioxidant actions in primary hippocampal neuronal cells Wang X, Fan X, Yuan S, Jiao W, Liu B, Cao J, Jiang W Ref: Food Funct, 8:2924, 2017 : PubMed ESTHER: Wang_2017_Food.Funct_8_2924 PubMedSearch: Wang 2017 Food.Funct 8 2924 PubMedID: 28745369 Abstract Chlorogenic acid (CGA), a major polyphenolic component of many plants, displays antioxidant and neuroprotective properties in neurodegenerative diseases. To investigate whether CGA may influence aluminium (Al) induced cytotoxicity, aluminium chloride (50 muM Al) was administered in primary hippocampal neuronal cells presupplemented with CGA (10, 50 and 100 muM). Our study shows that the exposure to Al caused cell death, Al(3+) accumulation, reactive oxygen species generation and mitochondrial damage in cells. The administration of CGA (50 muM) increased cell viability by 37.5%, decreased the levels of Al(3+) by 26.0%, together with significantly weakening the oxidative damage compared with Al treatment alone. CGA protected neurons against Al-induced oxidative stress by increasing the expression of nuclear factor-E2-related factor 2 and its target phase 2 enzymes. The administration of CGA remarkably promoted the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, creatine kinase and acetylcholinesterase and attenuated the rate of ATP hydrolysis. Our finding shows that CGA has neuroprotective effects against Al-induced cytotoxicity by chelation and antioxidant activation. Title: Transcriptome of the GSH-Depleted Lens Reveals Changes in Detoxification and EMT Signaling Genes, Transport Systems, and Lipid Homeostasis Whitson JA, Zhang X, Medvedovic M, Chen J, Wei Z, Monnier VM, Fan X Ref: Invest Ophthalmol Vis Sci, 58:2666, 2017 : PubMed ESTHER: Whitson_2017_Invest.Ophthalmol.Vis.Sci_58_2666 PubMedSearch: Whitson 2017 Invest.Ophthalmol.Vis.Sci 58 2666 PubMedID: 28525556 Abstract Purpose: To understand the effects of glutathione (GSH)-deficiency on genetic processes that regulate lens homeostasis and prevent cataractogenesis. Methods: The transcriptome of lens epithelia and fiber cells was obtained from C57BL/6 LEGSKO (lens GSH-synthesis knockout) and buthionine sulfoximine (BSO)-treated LEGSKO mice and compared to C57BL/6 wild-type mice using RNA-Seq. Transcriptomic data were confirmed by qPCR and Western blot/ELISA on a subset of genes. Results: RNA-Seq results were in excellent agreement with qPCR (correlation coefficients 0.87-0.94 and P < 5E-6 for a subset of 36 mRNAs). Of 24,415 transcripts mapped to the mouse genome, 441 genes showed significantly modulated expression. Pathway analysis indicated major changes in epithelial-mesenchymal transition (EMT) signaling, visual cycle, small molecule biochemistry, and lipid metabolism. GSH-deficient lenses showed upregulation of detoxification genes, including Aldh1a1, Aldh3a1 (aldehyde dehydrogenases), Mt1, Mt2 (metallothioneins), Ces1g (carboxylesterase), and Slc14a1 (urea transporter UT-B). Genes in canonical EMT pathways, including Wnt10a, showed upregulation in lens epithelia samples. Severely GSH-deficient lens epithelia showed downregulation of vision-related genes (including crystallins). The BSO-treated LEGSKO lens epithelia transcriptome has significant correlation (r = 0.63, P < 0.005) to that of lens epithelia undergoing EMT. Protein expression data correlated with transcriptomic data and confirmed EMT signaling activation. Conclusions: These results show that GSH-deficiency in the lens leads to expression of detoxifying genes and activation of EMT signaling, in addition to changes in transport systems and lipid homeostasis. These data provide insight into the adaptation and consequences of GSH-deficiency in the lens and suggest that GSH plays an important role in lenticular EMT pathology. Title: Thyroglobulin gene mutations in Chinese patients with congenital hypothyroidism Hu X, Chen R, Fu C, Fan X, Wang J, Qian J, Yi S, Li C, Luo J and Shen Y <9 more author(s)> Hu X, Chen R, Fu C, Fan X, Wang J, Qian J, Yi S, Li C, Luo J, Su J, Zhang S, Xie B, Zheng H, Lai Y, Chen Y, Li H, Gu X, Chen S, Shen Y (- 9) Ref: Mol Cell Endocrinol, 423:60, 2016 : PubMed ESTHER: Hu_2016_Mol.Cell.Endocrinol_423_60 PubMedSearch: Hu 2016 Mol.Cell.Endocrinol 423 60 PubMedID: 26777470 Gene_locus related to this paper: human-TG Abstract Mutations in Thyroglobulin (TG) are common genetic causes of congenital hypothyroidism (CH). But the TG mutation spectrum and its frequency in Chinese CH patients have not been investigated. Here we conducted a genetic screening of TG gene in a cohort of 382 Chinese CH patients. We identified 22 rare non-polymorphic variants including six truncating variants and 16 missense variants of unknown significance (VUS). Seven patients carried homozygous pathogenic variants, and three patients carried homozygous or compound heterozygous VUS. 48 out of 382 patients carried one of 18 heterozygous VUS which is significantly more often than their occurrences in control cohort (P < 0.0001). Unique to Asian population, the c.274+2T>G variant is the most common pathogenic variant with an allele frequency of 0.021. The prevalence of CH due to TG gene defect in Chinese population was estimated to be approximately 1/101,000. Our study uncovered ethnicity specific TG mutation spectrum and frequency. Title: An upp-based markerless gene replacement method for genome reduction and metabolic pathway engineering in Pseudomonas mendocina NK-01 and Pseudomonas putida KT2440 Wang Y, Zhang C, Gong T, Zuo Z, Zhao F, Fan X, Yang C, Song C Ref: J Microbiol Methods, 113:27, 2015 : PubMed ESTHER: Wang_2015_J.Microbiol.Methods_113_27 PubMedSearch: Wang 2015 J.Microbiol.Methods 113 27 PubMedID: 25828098 Abstract A markerless gene replacement method was adapted by combining a suicide plasmid, pEX18Tc, with a counterselectable marker, the upp gene encoding uracil phosphoribosyltransferase (UPRTase), for the medium-chain length polyhydroxyalkanoates (PHAMCL)-producing strain Pseudomonas mendocina NK-01. An NK-01 5-fluorouracil (5-FU) resistant background strain was first constructed by deleting the chromosomal upp gene. The suicide plasmid pEX18Tc, carrying a functional allele of the upp gene of P. mendocina NK-01, was used to construct the vectors to delete the algA (encoding mannose-1-phosphate guanylyltransferase) and phaZ (encoding PHAMCL depolymerase) genes, and a 30kb chromosomal fragment in the 5-FU resistant background host. The genes were removed efficiently from the genome of P. mendocina NK-01 and left a markerless chromosomal mutant. In addition, two exogenous genes were inserted into the phaC1 (PHAMCL polymerase) loci of Pseudomonas putida KT-UPP simultaneously. Thus, we constructed a genetically stable and marker-free P. putida KT2440 mutant with integrated mpd (encoding methyl parathion hydrolase (MPH)) and pytH (encoding a pyrethroid-hydrolyzing carboxylesterase (PytH)) gene on the chromosome. The upp-based counterselection system could be further adapted for P. mendocina NK-01 and P. putida KT2440 and used for genome reduction and metabolic pathway engineering. Title: Newly Identified Thermostable Esterase from Sulfobacillus acidophilus: Properties and Performance in Phthalate Ester Degradation Zhang XY, Fan X, Qiu YJ, Li CY, Xing S, Zheng YT, Xu JH Ref: Applied Environmental Microbiology, 80:6870, 2014 : PubMed ESTHER: Zhang_2014_Appl.Environ.Microbiol_80_6870 PubMedSearch: Zhang 2014 Appl.Environ.Microbiol 80 6870 PubMedID: 25149523 Abstract EstS1, a newly identified thermostable esterase from Sulfobacillus acidophilus DSM10332, was heterologously expressed in Escherichia coli and shown to enzymatically degrade phthalate esters (PAEs) to their corresponding monoalkyl PAEs. The optimal pH and temperature of the esterase were found to be 8.0 and 70 degrees C, respectively. The half-life of EstS1 at 60 degrees C was 15 h, indicating that the enzyme had good thermostability. The specificity constant (kcat/Km) of the enzyme for p-nitrophenyl butyrate was as high as 6,770 mM(-1) s(-1). The potential value of EstS1 was demonstrated by its ability to effectively hydrolyze 35 to 82% of PAEs (10 mM) within 2 min at 37 degrees C, with all substrates being completely degraded within 24 h. At 60 degrees C, the time required for complete hydrolysis of most PAEs was reduced by half. To our knowledge, this enzyme is a new esterase identified from thermophiles that is able to degrade various PAEs at high temperatures. Title: A novel protocol for ultra-trace detection of pesticides: Combined electrochemical reduction of Ellman's reagent with acetylcholinesterase inhibition Dong J, Fan X, Qiao F, Ai S, Xin H Ref: Anal Chim Acta, 761:78, 2013 : PubMed ESTHER: Dong_2013_Anal.Chim.Acta_761_78 PubMedSearch: Dong 2013 Anal.Chim.Acta 761 78 PubMedID: 23312317 Abstract This paper proposed a novel method for ultra-trace detection of pesticides combining electrochemical reduction of Ellman's reagent with acetylcholinesterase (AChE) inhibition. The amperometric biosensor, fabricated by immobilizing AChE on multi-walled carbon nanotubes-chitosan (MWCNTs-Chi) nanocomposites modified glassy carbon electrode, enjoyed high sensitivity owing to the excellent conductivity and favourable biocompatibility of MWCNTs-Chi nanocomposites. Meanwhile, the sensitivity of the biosensor was further enhanced using the electrochemical reduction signal of DTNB for determination. Under optimum conditions, methyl parathion was detected based on its inhibition effect on AChE activity and the subsequent change in electrochemical reduction response of DTNB. Good relationship was obtained between the reduction current and pesticide concentration in the ranges of 5.0x10(-7) to 1.0x10(-12)M with a detection limit of 7.5x10(-13)M (S/N=3). Moreover, the proposed protocol was successfully employed for the determination of methyl parathion in water and soil samples. Title: Determination of neonicotinoid insecticides residues in eels using subcritical water extraction and ultra-performance liquid chromatography-tandem mass spectrometry Xiao Z, Yang Y, Li Y, Fan X, Ding S Ref: Anal Chim Acta, 777:32, 2013 : PubMed ESTHER: Xiao_2013_Anal.Chim.Acta_777_32 PubMedSearch: Xiao 2013 Anal.Chim.Acta 777 32 PubMedID: 23622962 Abstract A rapid, sensitive, and environmental-friendly multi-residue method has been developed for the simultaneous determination of seven neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, imidacloprid, clothianidin, acetamiprid, and thiacloprid) residues in eel samples. Subcritical water extraction was investigated as a novel and alternative technology for the extraction of neonicotinoids from eel matrices and the results were compared with the conventional ultrasonic and shaking extraction. The target compounds were identified and quantitatively determined by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-MS/MS) operated in multiple reaction monitoring mode. Under the current optimized chromatographic conditions, each LC run was completed in 5 min. Average recoveries of the seven analytes from fortified samples ranged between 84.6% and 102.0%, with relative standard deviations (RSD) lower than 10.8%. The limits of detection (LODs) and quantification (LOQs) for neonicotinoids were in the ranges of 0.12-0.36 mug kg(-1) and 0.42-1.12 mug kg(-1), respectively. The proposed method is fast, sensitive, easy to perform, water-based thus more environmentally acceptable, making it applicable for high-throughput monitoring of insecticides residues in aquatic products. Title: Identification and characterization of a novel thermostable pyrethroid-hydrolyzing enzyme isolated through metagenomic approach Fan X, Liu X, Huang R, Liu Y Ref: Microb Cell Fact, 11:33, 2012 : PubMed ESTHER: Fan_2012_Microb.Cell.Fact_11_33 PubMedSearch: Fan 2012 Microb.Cell.Fact 11 33 PubMedID: 22409882 Gene_locus related to this paper: 9bact-Sys410 Abstract BACKGROUND: Pyrethroid pesticides are broad-spectrum pest control agents in agricultural production. Both agricultural and residential usage is continuing to grow, leading to the development of insecticide resistance in the pest and toxic effects on a number of nontarget organisms. Thus, it is necessary to hunt suitable enzymes including hydrolases for degrading pesticide residues, which is an efficient "green" solution to biodegrade polluting chemicals. Although many pyrethroid esterases have consistently been purified and characterized from various resources including metagenomes and organisms, the thermostable pyrethroid esterases have not been reported up to the present. Title: The cloning and characterization of one novel metagenome-derived thermostable esterase acting on N-acylhomoserine lactones Fan X, Liu X, Liu Y Ref: J Mol Catal B Enzym, 83:29, 2012 : PubMed ESTHER: Fan_2012_J.Mol.Catal.B.Enzym_83_29 PubMedSearch: Fan 2012 J.Mol.Catal.B.Enzym 83 29 Gene_locus related to this paper: 9bact-i6yrg4 Abstract A novel gene (designated as est816) encoding an esterase was isolated from a Turban Basin metagenomic library with a functional screening method. Sequence analysis revealed that est816 encoded a protein of 271 amino acids with a predicted molecular mass (Mr) of 29.9 kDa and was expressed in Escherichia coli BL21 (DE3) in soluble form. The optimum pH and temperature of the recombinant Est816 were 7.5 and 60 degC, respectively. The enzyme was stable in the pH range of 5.0-9.0 and at temperatures below 50 degC. The residual activity of Est816 was 47.7% when stored at 25 degC for 5 months. The enzyme could hydrolyze a wide range of n-nitrophenyl esters, but its best substrate is n-nitrophenyl acetate with the highest activity (364 U/mg). It could also degrade medium to long-chain AHLs at the concentration of 1 mM in half an hour with more than 90% degradation efficiency. This is the first report to construct one metagenomic library from Turban Basin to obtain one esterase, which belongs to family V esterases/lipases and has AHL-lactonase activity. The recombinant enzyme displayed broad substrate spectrum, high activity and thermostability. These excellent properties make it an attractive enzyme for quorum quenching. Title: Lipases as biocatalyst for biodiesel production Fan X, Niehus X, Sandoval G Ref: Methods Mol Biol, 861:471, 2012 : PubMed ESTHER: Fan_2012_Methods.Mol.Biol_861_471 PubMedSearch: Fan 2012 Methods.Mol.Biol 861 471 PubMedID: 22426735 Abstract The global shortages of fossil fuels, significant increase in the price of crude oil, and increased environmental concerns have stimulated the rapid growth in biodiesel production. Biodiesel is generally produced through transesterification reaction catalyzed either chemically or enzymatically. Enzymatic transesterification draws high attention because that process shows certain advantages over the chemical catalysis of transesterification and it is "greener." This paper reviews the current status of biodiesel production with lipase-biocatalysis approach, including sources of lipases, kinetics, and reaction mechanism of biodiesel production using lipases, and lipase immobilization techniques. Factors affecting biodiesel production and economic feasibility of biodiesel production using lipases are also covered. Title: [Prostaglandin E(2) and omeprazole in treating poisoning related acute mucosal lesion] Fan X, Xu Y, Zhang H Ref: Zhong Nan Da Xue Xue Bao Yi Xue Ban, 34:1036, 2009 : PubMed ESTHER: Fan_2009_Zhong.Nan.Da.Xue.Xue.Bao.Yi.Xue.Ban_34_1036 PubMedSearch: Fan 2009 Zhong.Nan.Da.Xue.Xue.Bao.Yi.Xue.Ban 34 1036 PubMedID: 19893258 Abstract OBJECTIVE: To determine the effects of prostaglandin E(2) alone and the combination with omeprazole for poisoning related acute mucosal lesion. METHODS: Forty-two healthy SD rats were randomly divided into 7 groups: control group (control) , methamidophos poisoning model group (intox), 10 mg/kg omeprazole group (ome1), 50 mg/kg omeprazole group (ome2), 10 microg/kg prostaglandin E(2) group (PG1), 50 microg/kg prostaglandin E(2) group (PG2), 10 microg/kg prostaglandin E(2) combined with 10 mg/kg omeprazole group (union). The gastric ulcer index was counted and the content of serum cholinesterase, endothelin, and tumor necrosis factor were measured, and dependability was analyzed. RESULTS: There was no obvious difference between the prostaglandin group and the poisoning model group in gastric ulcer index, endothelin, and tumor necrosis factor. The omeprazole alone and the combination treatment could improve the acute gastric mucosa lesion induced by methamidophos poisoning. CONCLUSION: Prostaglandin E(2) alone can not obviously improve the acute gastric mucosa lesion by methamidophos poisoning. The combination with omeprazole may be a promising treatment. Title: [Construction and immunogenicity of DNA vaccine encoding secreted form of Ag85B protein of Mycobacterium tuberculosis] Fan X, Xu Z, Li Y Ref: Zhonghua Jie He He Hu Xi Za Zhi, 24:548, 2001 : PubMed ESTHER: Fan_2001_Zhonghua.Jie.He.He.Hu.Xi.Za.Zhi_24_548 PubMedSearch: Fan 2001 Zhonghua.Jie.He.He.Hu.Xi.Za.Zhi 24 548 PubMedID: 11758171 Abstract OBJECTIVE: To construct the recombinant eukaryotic plasmid DNA expression vector encoding Mycobacterium tuberculosis antigen 85B (Ag85B) and to investigate its immunogenicity. | |||||||
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