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1.
Cell Prolif ; : e12967, 2020 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-33300223

RESUMO

OBJECTIVES: The decidua is a tissue that contacts both maternal and foetal components and is pivotal to labour onset due to its location. Due to the heterogeneity of decidual tissue, it is challenging to study its role in the peripartum period. Herein, we analysed the transcriptomes of peripartum decidua at single-cell resolution. MATERIALS AND METHODS: Single-cell RNA sequencing was performed for 29 231 decidual cells before and after delivery to characterize the transcriptomes. RESULTS: Eight major cell types (including endothelial cells, fibroblasts) and subtypes of decidual stromal cells, extravillous trophoblasts and T cells were identified and found to have various functions. Compared with before delivery, the activation of decidual stromal cell, extravillous trophoblast and T-cell subtypes to different degrees was observed after delivery. Furthermore, the activation involved multiple functions, such as cell proliferation, and several pathways, such as the activator protein 1 pathway. The results of pseudotemporal ordering showed differentiation of decidual stromal cell and extravillous trophoblast subtypes, suggesting inhomogeneity of these subgroups in decidualization (decidual stromal cell) and invasion (extravillous trophoblast). CONCLUSIONS: The peripartum decidual tissue is heterogeneous. This study revealed changes in the decidua and its components at single-cell resolution; these findings provide a new perspective for the study of peripartum decidua.

2.
J Investig Med ; 2020 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-33372108

RESUMO

To investigate the heterogeneity of decidual stromal cells (DSCs) and their functional alterations during delivery, we conducted single-cell RNA sequencing analysis to characterize the transcriptomic profiles of DSCs before and after labor onset. According to their transcriptomic profiles, DSCs (6382 cells) were clustered into five subgroups with different functions. Similar to stromal cells, cells in cluster 1 were involved in cell substrate adhesion. On the other hand, cells in clusters 2 and 3 were enriched in signal transduction-related genes. Labor onset led to significant alterations in many pathways, including the activator protein 1 pathway (all clusters), as well as in the response to lipopolysaccharide (clusters 1-3). The downregulated genes were involved in coagulation, ATP synthesis, and oxygen homeostasis, possibly reflecting the oxygen and energy balance during delivery. Our findings highlight that peripartum DSCs are heterogeneous and play multiple roles in labor.

3.
PLoS One ; 15(10): e0240187, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33027312

RESUMO

Lignin, a characteristic component of terrestrial plants. Rivers transport large amounts of vascular plant organic matter into the oceans where lignin can degrade over time; however, microorganisms involved in this degradation have not been identified. In this study, several bacterial strains were isolated from marine samples using the lignin-derived compound vanillic acid (4-hydroxy-3-methoxybenzoic acid) as the sole carbon and energy source. The optimum growth temperature for all isolates ranged from 30 to 35°C. All isolates grew well in a wide NaCl concentration range of 0 to over 50 g/L, with an optimum concentration of 22.8 g/L, which is the same as natural seawater. Phylogenetic analysis indicates that these strains are the members of Halomonas, Arthrobacter, Pseudoalteromonas, Marinomonas, and Thalassospira. These isolates are also able to use other lignin-derived compounds, such as 4-hydroxybenzoic acid, ferulic acid, syringic acid, and benzoic acid. Vanillic acid was detected in all culture media when isolates were grown on ferulic acid as the sole carbon source; however, no 4-hydroxy-3-methoxystyrene was detected, indicating that ferulic acid metabolism by these strains occurs via the elimination of two side chain carbons. Furthermore, the isolates exhibit 3,4-dioxygenase or 4,5-dioxygenase activity for protocatechuic acid ring-cleavage, which is consistent with the genetic sequences of related genera. This study was conducted to isolate and characterize marine bacteria of degrading lignin-derived compounds, thereby revealing the degradation of aromatic compounds in the marine environment and opening up new avenues for the development and utilization of marine biological resources.

4.
Bioorg Med Chem Lett ; 30(21): 127504, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32827631

RESUMO

25-OH ginsenosides are potent and rare prodrugs in natural sources. However current strategies for such modification always end up in undesirable side products and unsatisfied yield that hinders them from further applications. Herein, ginsenoside Rg1 was thoroughly converted into 20(S/R)-Rh1 and 25-OH-20(S/R)-Rh1 by Cordyceps Sinensis in an optimum medium. The chemical correctness of either 25-OH-20(S/R)-Rh1 epimers was validated by LC-IT-TOF-MSn and 13C NMR spectrometry. The biocatalytic pathway was established as Rg1 â†’ 20(S/R)-Rh1 â†’ 25-OH-20(S/R)-Rh1. The molar bioconversion rate for total 25-OH-20(S/R)-Rh1 was calculated to be 82.5%, of which S-configuration accounted for 43.2% while R-configuration 39.3%. These two 25-OH derivatives are direct hydration products from 20(S/R)-Rh1 without other side metabolites, suggesting this is a highly regioselective process. In conclusion, this biocatalytic system could be harnessed to facilitate the preparation of diversified 25-OH ginsenosides with high yields of the target compound and simple chemical background in the reaction mixture.

5.
Genes (Basel) ; 11(7)2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32674393

RESUMO

As single-cell RNA sequencing technologies mature, massive gene expression profiles can be obtained. Consequently, cell clustering and annotation become two crucial and fundamental procedures affecting other specific downstream analyses. Most existing single-cell RNA-seq (scRNA-seq) data clustering algorithms do not take into account the available cell annotation results on the same tissues or organisms from other laboratories. Nonetheless, such data could assist and guide the clustering process on the target dataset. Identifying marker genes through differential expression analysis to manually annotate large amounts of cells also costs labor and resources. Therefore, in this paper, we propose a novel end-to-end cell supervised clustering and annotation framework called scAnCluster, which fully utilizes the cell type labels available from reference data to facilitate the cell clustering and annotation on the unlabeled target data. Our algorithm integrates deep supervised learning, self-supervised learning and unsupervised learning techniques together, and it outperforms other customized scRNA-seq supervised clustering methods in both simulation and real data. It is particularly worth noting that our method performs well on the challenging task of discovering novel cell types that are absent in the reference data.

6.
Front Genet ; 11: 295, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32362908

RESUMO

Single-cell RNA sequencing technologies have enabled us to study tissue heterogeneity at cellular resolution. Fast-developing sequencing platforms like droplet-based sequencing make it feasible to parallel process thousands of single cells effectively. Although a unique molecular identifier (UMI) can remove bias from amplification noise to a certain extent, clustering for such sparse and high-dimensional large-scale discrete data remains intractable and challenging. Most existing deep learning-based clustering methods utilize the mean square error or negative binomial distribution with or without zero inflation to denoise single-cell UMI count data, which may underfit or overfit the gene expression profiles. In addition, neglecting the molecule sampling mechanism and extracting representation by simple linear dimension reduction with a hard clustering algorithm may distort data structure and lead to spurious analytical results. In this paper, we combined the deep autoencoder technique with statistical modeling and developed a novel and effective clustering method, scDMFK, for single-cell transcriptome UMI count data. ScDMFK utilizes multinomial distribution to characterize data structure and draw support from neural network to facilitate model parameter estimation. In the learned low-dimensional latent space, we proposed an adaptive fuzzy k-means algorithm with entropy regularization to perform soft clustering. Various simulation scenarios and the analysis of 10 real datasets have shown that scDMFK outperforms other state-of-the-art methods with respect to data modeling and clustering algorithms. Besides, scDMFK has excellent scalability for large-scale single-cell datasets.

7.
J Sep Sci ; 43(12): 2436-2446, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32227667

RESUMO

Four types of middle-pressure chromatogram isolated gels are evaluated for adsorption or desorption characteristics of ginsenosides from Panax ginseng. Among them, SP207SS and SP2MGS were selected for dynamic investigations based on their static adsorption or desorption capacity of total ginsenoside. Their adsorption kinetics was better explained by pseudosecond-order model and isotherms were preferably fitted to Langmuir model. Dynamic breakthrough experiments indicated an optimum sample loading speed of 4 bed volume/h for either SP207SS or SP2MGS. Desorption speed was determined to be 2 bed volume/h according to desorption amount of total ginsenoside in their effluents. Eight ginsenosides were identified and quantified by high performance liquid chromatography-triple quadropole-mass spectrometry in total ginsenoside extract and different fractions during stepwise dynamic elution. For SP207SS, 27.62% of loaded ginsenosides was detected in 40% ethanol fraction, while 59.12% of them were found in 60% ethanol fraction. As on SP2MGS, the number went to 53.71 and 44.43%, respectively. Recovery rate of ginsenosides were calculated to 78.65% for SP207SS and 89.53% for SP2MGS, respectively. Intriguingly, content of Rg1 and Re in 40% ethanol fraction from SP207SS became 20.1 and 18.6 times higher than that in total ginsenoside extract by one-step elution, which could be leveraged for the facile enrichment of these two ginsenosides from natural sources.

8.
Glob Chang Biol ; 26(3): 1697-1713, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31479179

RESUMO

Global dimming, a decadal decrease in incident global radiation, is often accompanied with an increase in the diffuse radiation fraction, and, therefore, the impact of global dimming on crop production is hard to predict. A popular approach to quantify this impact is the statistical analysis of historical climate and crop data, or use of dynamic crop simulation modelling approach. Here, we show that statistical analysis of historical data did not provide plausible values for the effect of diffuse radiation versus direct radiation on rice or wheat yield. In contrast, our field experimental study of 3 years demonstrated a fertilization effect of increased diffuse radiation fraction, which partly offset yield losses caused by decreased global radiation, in both crops. The fertilization effect was not attributed to any improved canopy light interception but mainly to the increased radiation use efficiency (RUE). The increased RUE was explained not only by the saturating shape of photosynthetic light response curves but also by plant acclimation to dimming that gradually increased leaf nitrogen concentration. Crop harvest index slightly decreased under dimming, thereby discounting the fertilization effect on crop yields. These results challenge existing modelling paradigms, which assume that the fertilization effect on crop yields is mainly attributed to an improved light interception. Further studies on the physiological mechanism of plant acclimation are required to better quantify the global dimming impact on agroecosystem productivity under future climate change.


Assuntos
Oryza , Fotossíntese , Produção Agrícola , Produtos Agrícolas , Triticum
9.
Chem Asian J ; 14(19): 3251-3254, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31400067

RESUMO

Circular single-stranded DNA (c-ssDNA) has significant applications in DNA detection, the development of nucleic acid medicine, and DNA nanotechnology because it shows highly unique features in mobility, dynamics, and topology. However, in most cases, the efficiency of c-ssDNA preparation is very low because polymeric byproducts are easily formed due to intermolecular reaction. Herein, we report a one-pot ligation method to efficiently prepare large c-ssDNA. By ligating several short fragments of linear single-stranded DNA (l-ssDNA) in one-pot by using T4 DNA ligase, longer l-ssDNAs intermediates are formed and then rapidly consumed by the cyclization. Since the intramolecular cyclization reaction is much faster than intermolecular polymerization, the formation of polymeric products is suppressed and the dominance of intramolecular cyclization is promoted. With this simple approach, large-sized single-stranded c-ssDNAs (e.g., 200-nt) were successfully synthesized in high selectivity and yield.

10.
J Am Chem Soc ; 141(19): 7758-7764, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30844265

RESUMO

Z-DNA, a left-handed duplex, has been shown to form in vivo and regulate expression of the corresponding gene. However, its biological roles have not been satisfactorily understood, mainly because Z-DNA is easily converted to the thermodynamically favorable B-DNA. Here we present a new idea to form stable Z-DNA under normal physiological conditions and achieve detailed analysis on its fundamental features. Simply by mixing two complementary minicircles of single-stranded DNA with no chemical modification, the hybridization spontaneously induces topological constraint which twines one-half of the double-stranded DNA into stable Z-DNA. The formation of Z-conformation with high stability has been proved by using circular dichroism spectroscopy, Z-DNA-specific antibody binding assay, nuclease digestion, etc. Even at a concentration of MgCl2 as low as 0.5 mM, Z-DNA was successfully obtained, avoiding the use of high salt conditions, limited sequences, ancillary additives, or chemical modifications, criteria which have hampered Z-DNA research. The resultant Z-DNA has the potential to be used as a canonical standard sample in Z-DNA research. By using this approach, further developments of Z-DNA science and its applications become highly promising.


Assuntos
DNA Forma Z/química , DNA Forma Z/genética , Sequência de Bases , DNA de Forma B/química , DNA de Forma B/genética , Termodinâmica
11.
J Biol Chem ; 293(25): 9662-9673, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29610274

RESUMO

In mammalian cells, autophagy plays crucial roles in restricting further spread of invading bacterial pathogens. Previous studies have established that the Salmonella virulence factors SseF and SseG are required for intracellular bacterial survival and replication. However, the underlying mechanism by which these two effectors facilitate bacterial infection remains elusive. Here, we report that SseF and SseG secreted by Salmonella Typhimurium (S. Typhimurium) inhibit autophagy in host cells and thereby establish a replicative niche for the bacteria in the cytosol. Mechanistically, SseF and SseG impaired autophagy initiation by directly interacting with the small GTPase Rab1A in the host cell. This interaction abolished Rab1A activation by disrupting the interaction with its guanine nucleotide exchange factor (GEF), the TRAPPIII (transport protein particle III) complex. This disruption of Rab1A signaling blocked the recruitment and activation of Unc-51-like autophagy-activating kinase 1 (ULK1) and decreased phosphatidylinositol 3-phosphate biogenesis, which ultimately impeded autophagosome formation. Furthermore, SseF- or SseG-deficient bacterial strains exhibited reduced survival and growth in both mammalian cell lines and mouse infection models, and Rab1A depletion could rescue these defects. These results reveal that virulence factor-dependent inactivation of the small GTPase Rab1A represents a previously unrecognized strategy of S Typhimurium to evade autophagy and the host defense system.


Assuntos
Proteínas de Bactérias/metabolismo , Interações Hospedeiro-Patógeno , Infecções por Salmonella/microbiologia , Salmonella typhimurium/patogenicidade , Virulência , Proteínas rab1 de Ligação ao GTP/fisiologia , Animais , Autofagia , Proteínas de Bactérias/genética , Complexo de Golgi/metabolismo , Complexo de Golgi/microbiologia , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Células HeLa , Humanos , Camundongos , Camundongos Knockout , Salmonella typhimurium/crescimento & desenvolvimento , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
12.
Biomed Rep ; 7(6): 527-531, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29188056

RESUMO

Cyclophilins (CyPs), a member of peptidyl-prolyl cis-trans isomerases (PPIases), are ubiquitously distributed in organisms such as bacteria, yeast, plants and animals. CyPs have diverse biological functions, with some exhibiting antifungal and antiviral activities. In this study, Panax ginseng cyclophilin (pgCyP), a novel gene encoding an antifungal protein from Panax ginseng, was cloned, and its protein product was expressed in Escherichia coli, and then fractionated by affinity chromatography. The open reading frame of the pgCyP full-length coding sequence was found to encode a single-domain CyP-like protein of 174 amino residues with a calculated molecular weight of 18.7 kDa. The pGEX system was used to express pgCyP fused to glutathione S-transferase. After affinity purification, the protein showed a strong fungal resistance effect on Phytophthora cactorum. In addition, pgCyP showed high PPIase activity. To the best of our knowledge, the present study is the first successful effort to clone and characterize a CyP-like protein gene from Panax ginseng.

13.
Appl Biochem Biotechnol ; 180(8): 1524-1533, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27387957

RESUMO

Fumaric acid as a four-carbon unsaturated dicarboxylic acid is widely used in the food and chemical industries. Food waste (FW), rich in carbohydrates and protein, is a promising potential feedstock for renewable bio-based chemicals. In this research, we investigated the capability of Rhizopus arrhizus RH7-13 in producing fumaric acid from FW. The liquid fraction of the FW (L-FW) was proven to be the best seed culture medium in our research. When it was however used to be fermentation medium, the yield of fumaric acid reached 32.68 g/L, at a volumetric production of 0.34 g/L h. The solid fraction of FW mixed with water (S-FW) could also be used as fermentation medium when a certain amount of glucose was added, and the yield of fumaric acid reached 31.26 g/L. The results indicated that both fractions of FW could be well utilized in fermentation process and it could replace a part of common carbon, nitrogen, and nutrient. The process has an application potential since reducing the costs of raw materials.


Assuntos
Fermentação , Alimentos , Fumaratos/metabolismo , Rhizopus/metabolismo , Resíduos/análise , Biodegradação Ambiental/efeitos dos fármacos , Biomassa , Fermentação/efeitos dos fármacos , Glucose/farmacologia , Rhizopus/efeitos dos fármacos
14.
Artigo em Inglês | MEDLINE | ID: mdl-27213000

RESUMO

Propolis, a traditional medicine, has been widely used for a thousand years as an anti-inflammatory and antioxidant drug. The flavonoid fraction is the main active component of propolis, which possesses a wide range of biological activities, including activities related to heart disease. However, the role of the flavonoids extraction from propolis (FP) in heart disease remains unknown. This study shows that FP could attenuate ISO-induced pathological cardiac hypertrophy (PCH) and heart failure in mice. The effect of the two fetal cardiac genes, atrial natriuretic factor (ANF) and ß-myosin heavy chain (ß-MHC), on PCH was reversed by FP. Echocardiography analysis revealed cardiac ventricular dilation and contractile dysfunction in ISO-treated mice. This finding is consistent with the increased heart weight and cardiac ANF protein levels, massive replacement fibrosis, and myocardial apoptosis. However, pretreatment of mice with FP could attenuate cardiac dysfunction and hypertrophy in vivo. Furthermore, the cardiac protection of FP was suppressed by the pan-PI3K inhibitor wortmannin. FP is a novel cardioprotective agent that can attenuate adverse cardiac dysfunction, hypertrophy, and associated disorder, such as fibrosis. The effects may be closely correlated with PI3K/AKT signaling. FP may be clinically used to inhibit PCH progression and heart failure.

15.
Chin J Nat Med ; 14(1): 61-5, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26850348

RESUMO

In order to determine the chemical constituents of Cistanche deserticola cultured in Tarim desert, a systematically phytochemical investigation was carried out. The constituents were isolated by silica gel, Sephadex LH-20, MCI gel, ODS column chromatography, and semi-preparative HPLC. Their structures were determined on the basis of MS and NMR spectroscopic analyses, by chemical methods, and/or comparison with literature data. The anti-inflammatory activities of the isolates were evaluated for their inhibitory effects on the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV-2 mouse microglial cells. Nine iridoids were isolated and identified as cistadesertoside A (1), cistanin (2), cistachlorin (3), 6-deoxycatalpol (4), gluroside (5), kankanoside A (6), ajugol (7), bartsioside (8), and 8-epi-loganic acid (9). Compound 9 exhibited potent inhibition on the NO production with an IC50 value being 5.2 µmol·L(-1), comparable to the positive control quercetin (4.3 µmol·L(-1)). Compound 1 was a new iridoid, and compounds 5, 6, and 8 were isolated from this species for the first time.


Assuntos
Anti-Inflamatórios/farmacologia , Cistanche/química , Iridoides/farmacologia , Animais , Anti-Inflamatórios/isolamento & purificação , Iridoides/química , Iridoides/isolamento & purificação , Camundongos , Caules de Planta/química
16.
Molecules ; 20(10): 19291-309, 2015 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-26512632

RESUMO

Compound K (CK), a highly active and bioavailable derivative obtained from protopanaxadiol ginsenosides, displays a wide variety of pharmacological properties, especially antitumor activity. However, the inadequacy of natural sources limits its application in the pharmaceutical industry. In this study, we firstly discovered that Cordyceps sinensis was a potent biocatalyst for the biotransformation of ginsenoside Rb1 into CK. After a series of investigations on the biotransformation parameters, an optimal composition of the biotransformation culture was found to be lactose, soybean powder and MgSO4 without controlling the pH. Also, an optimum temperature of 30 °C for the biotransformation process was suggested in a range of 25 °C-50 °C. Then, a biotransformation pathway of Rb1→Rd→F2→CK was established using high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS). Our results demonstrated that the molar bioconversion rate of Rb1 to CK was more than 82% and the purity of CK produced by C. sinensis under the optimized conditions was more than 91%. In conclusion, the combination of C. sinensis and the optimized conditions is applicable for the industrial preparation of CK for medicinal purposes.


Assuntos
Cordyceps/metabolismo , Ginsenosídeos/biossíntese , Ginsenosídeos/metabolismo , Micélio/metabolismo , Biotransformação , Cordyceps/crescimento & desenvolvimento , Meios de Cultura , Ginsenosídeos/isolamento & purificação , Concentração de Íons de Hidrogênio , Hidrólise , Redes e Vias Metabólicas , Micélio/crescimento & desenvolvimento
17.
Zhong Nan Da Xue Xue Bao Yi Xue Ban ; 40(7): 748-53, 2015 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-26267687

RESUMO

OBJECTIVE: To identify the screening time and prepare a screening schedule for outpatients with acute fatty liver of pregnancy (AFLP).
 METHODS: AFLP patients who admitted to Xiangya Hospital and the Second Xiangya Hospital, Central South University, Hunan, China between November, 2006 and December, 2013, were retrospectively studied. The diagnosis of 78 AFLP patients met the domestic clinical and laboratory criteria and the Swansea criteria. Clinical and laboratory data obtained on admission were used for analysis. Contrastive analysis was conducted within our data and other large medical centers or general hospitals. 
 RESULTS: The difference between domestic clinical and laboratory criteria and Swansea criteria in diagnosing AFLP patients in the 2 hospitals mentioned above was significant (P<0.05). The maternal mortality was 14.10% (11/78) and perinatal mortality was 17.95 % (14/78). The mean gestational age at delivery was 35.6 weeks. Based on the clinical and laboratory data, more than 85% of AFLP patients showed abnormal levels of transaminase, bilirubin, and white blood cells, as well as coagulation dysfunction. Gastrointestinal symptoms, such as abdominal pain and vomiting, jaundice, renal impairment and ascites or bright liver on ultrasound scan, were showed in 50%-85% of AFLP patients. Less than 50% of patients suffered from low blood sugar, high blood ammonia or hepatic encephalopathy.
 CONCLUSION: The 34th gestation week might be important time for screening AFLP outpatients. Gastrointestinal symptoms, blood routine, liver function, and coagulant function tests are recommended as the first grade screening indicators. Renal function, blood sugar test, and abdominal ultrasound could be the second grade screening indicators for AFLP outpatients.


Assuntos
Fígado Gorduroso/diagnóstico , Programas de Rastreamento/métodos , Complicações na Gravidez/diagnóstico , China , Feminino , Idade Gestacional , Humanos , Pacientes Ambulatoriais , Gravidez , Estudos Retrospectivos , Fatores de Tempo
18.
Bioresour Technol ; 186: 348-350, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25862014

RESUMO

Fumaric acid, as an important material for polymerization, is highly expected to be produced by fermentation of lignocellulosic biomass which is composed of cellulose, hemicellulose and lignin. Xylose as the main component of hemicellulose cannot be efficiently utilized by most of the common fermentation. In this study, a new strain Rhizopus arrhizus RH 7-13-9# was selected from the R. arrhizus RH 7-13 through a novel convenient and efficient selection method. Efficient production of fumaric acid (45.31 g/L) from xylose was achieved by the new strain, and the volumetric productivity was still 0.472 g/L h. Moreover, the conversion of xylose reached 73% which is close to the theoretic yield (77%). The production of fumaric acid was increased approximate by 172%, compared with the initial strain counterpart. These results indicated that xylose, as the main component of hemicellulose, has a promising application for the production of fumaric acid on an industrial-scale.


Assuntos
Fumaratos/isolamento & purificação , Rhizopus/metabolismo , Xilose/metabolismo , Células Imobilizadas/metabolismo , Cromatografia Líquida de Alta Pressão , Fermentação
19.
Langmuir ; 30(24): 7168-76, 2014 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-24920223

RESUMO

Microgel particles of cross-linked poly(NIPAM-co-acrylic acid) with different acrylic acid contents are investigated in solution and in the adsorbed state. As a substrate, silicon with a poly(allylamine hydrochloride) (PAH) coating is used. The temperature dependence of the deswelling of the microgel particles was probed with atomic force microscopy (AFM). The inner structure of the adsorbed microgel particles was detected with grazing incidence small angle neutron scattering (GISANS). Small angle neutron scattering (SANS) on corresponding microgel suspensions was performed for comparison. Whereas the correlation length of the polymer network shows a divergence in the bulk samples, in the adsorbed microgel particles it remains unchanged over the entire temperature range. In addition, GISANS indicates changes in the particles along the surface normal. This suggests that the presence of a solid surface suppresses the divergence of internal fluctuations in the adsorbed microgels close to the volume phase transition.

20.
Food Chem ; 152: 539-45, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24444972

RESUMO

Phytochemical investigation of the aqueous extract of pu-erh tea afforded eight novel 8-C N-ethyl-2-pyrrolidinone substituted flavan-3-ols (puerins I-VIII) by (1)H, (13)C, two-dimensional nuclear magnetic resonance (NMR) and high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS) analysis. Comparative chemical analysis of green tea, black tea and Chinese dark teas confirmed that these compounds were the marker compounds of Chinese dark teas. Furthermore, fungal fermentation was indispensable for the biosynthesis of these novel compounds. Through single fungal fermentation, it was proved that catechins and theanine were the precursors of puerins I-VIII. HPLC-DAD-ESI/MS analysis elucidated the biosynthetic pathway for puerins I-VIII. Puerins I-IV have potential protective effects for the human micro-vascular endothelial cells (HMEC) injury induced by hydrogen dioxide compared to other tea polyphenols. 8-C N-ethyl-2-pyrrolidinone substituted flavan-3-ols could be used in the quality control and authentication of Chinese dark teas.


Assuntos
Antioxidantes/análise , Camellia sinensis/química , Flavonoides/análise , Pirrolidinonas/análise , Antioxidantes/metabolismo , Biomarcadores/análise , Biomarcadores/metabolismo , Camellia sinensis/microbiologia , Catequina/análise , Catequina/metabolismo , Fermentação , Flavonoides/metabolismo , Fungos/metabolismo , Pirrolidinonas/metabolismo , Chá
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