摘要：
A simple, selective, highly sensitive, and label-free electrochemical immunosensor for atrazine detection was developed by immobilizing gold nanoparticles (GNPs) on the gold electrode surface. The modified gold electrode exhibited good electrochemical activity. The high sensitive detection was achieved by increased the surface area of work electrode resulting in capturing more anti-atrazine monoclonal antibodies. The whole immunosensor fabrication process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with the use of ferricyanide as an electrochemical redox indicator, respectively. The signal was triggered based on the interaction between anti-atrazine monoclonal antibody and atrazine via differential pulse voltammetry (DPV). Under the optimal conditions, a limit of detection for atrazine as low as 0.016 ng/mL was obtained in buffer, and the linear working range was between 0.05 ng/mL and 0.5 ng/mL. The recovery of 95.5-119.8% was obtained in maize. The proposed immunosensor has acceptable stability and reproducibility, thus could be applied to other pesticides analysis of crop samples in practice. (C) 2013 Elsevier B.V. All rights reserved.
关键词：
Fuzhuan brick-tea;Fungal community;Denaturing gradient gel electrophoresis;Eurotium cristatum;Debaryomyces hansenii;Anthraquinone
摘要：
Chinese Fuzhuan brick-tea is a unique microbial fermented tea characterized by a period of fungal growth during its manufacturing process. The aim of the present study was to characterize, both physicochemically and microbiologically, traditional industrial production processes of Fuzhuan brick-tea. Fermenting tea samples were collected from the largest manufacturer. Physicochemical analyses showed that the low water content in the tea substrates provided optimal growth conditions for xerophilic fungi. The fungal communities existing in tea materials, fermenting tea, and stored teas were monitored by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) targeting the D1 region of the 265 rRNA genes, followed by sequencing of the amplicons. Results revealed that the microorganisms were from, or closely related to, the genera Eurotium, Debaryomyces, Aspergillus, Verticillium, Pichia, Pestalotiopsis, Rhizomucor and Beauveria. This is the first report of Debaryomyces participating in the processing of Fuzhuan brick-tea. We concluded that the dominant genera Eurotium, Debaryomyces and Aspergillus are beneficial fungi associated with the fermentation of Fuzhuan brick-tea. The genus Beauveria was present in the stored Fuzhuan brick-tea, which may help protect tea products from insect spoilage. The remaining four genera were of minor importance in the manufacturing of Fuzhuan brick-tea. The predominant Eurotium species, a strain named Eurotium sp. FZ, was phenotypically and genotypically identified as Eurotium cristatum. High performance thin layer chromatography analysis of anthraquinones showed that emodin existed in all the dark tea samples, but physcion was only detectable in the tea fermented by E. cristatum. The PCR-DGGE approach was an effective and convenient means for profiling the fungal communities in Fuzhuan brick-tea. These results may help promote the use of microbial consortia as starter cultures to stabilize and improve the quality of Fuzhuan brick-tea products. (C) 2011 Elsevier B.V. All rights reserved.
通讯机构：
[Yin, Huaqun] Cent S Univ, Sch Minerals Proc & Bioengn, Changsha 410083, Peoples R China.
摘要：
Response of biological communities to environmental stresses is a critical issue in ecology, but how microbial communities shift across heavy metal gradients remain unclear. To explore the microbial response to heavy metal contamination (e.g., Cr, Mn, Zn), the composition, structure and functional potential of sedimentary microbial community were investigated by sequencing of 16S rRNA gene amplicons and a functional gene microarray. Analysis of 16S rRNA sequences revealed that the composition and structure of sedimentary microbial communities changed significantly across a gradient of heavy metal contamination, and the relative abundances were higher for Firmicutes, Chloroflexi and Crenarchaeota, but lower for Proteobacteria and Actinobacteria in highly contaminated samples. Also, molecular ecological network analysis of sequencing data indicated that their possible interactions might be enhanced in highly contaminated communities. Correspondently, key functional genes involved in metal homeostasis (e.g., chrR, metC, merB), carbon metabolism, and organic remediation showed a higher abundance in highly contaminated samples, indicating that bacterial communities in contaminated areas may modulate their energy consumption and organic remediation ability. This study indicated that the sedimentary indigenous microbial community may shift the composition and structure as well as function priority and interaction network to increase their adaptability and/or resistance to environmental contamination.
关键词：
Nisin-resistance;Cell wall;Membrane phospholipid;Two-component system
摘要：
Nisin is the most prominent lantibiotic and is used as a food preservative due to its high potency against certain Gram-positive bacteria. However, the effectiveness of nisin is often affected by environmental factors such as pH, temperature, food composition, structure, as well as food microbiota. The development of nisin resistance has been seen among various Gram-positive bacteria. The mechanisms under the acquisition of nisin resistance are complicated and may differ among strains. This paper presents a brief review of possible mechanisms of the development of resistance to nisin among Gram-positive bacteria.
摘要：
This work compares the polyphenolics composition, antioxidant activity and contents of selected nutrients in the leaves from seven cultivars of Moringa oleifera ('Tumu', 'Sunyaw', 'Kumasi', 'Techiman', 'China', 'Pakistan Black', and 'Pakistan White') representing the variety in Pakistan. Both the non-enzymatic (DPPH free radical and linoleic acid peroxidation inhibition assays) and enzymatic (superoxide dismutase, peroxidase, and catalase activities) antioxidant capacity was appraised. Regarding,the nutritional value, in terms of protein and minerals contents, minor differences were recorded among cultivars. HPLC-PDA-ESI-MSn analysis of the hydro-methanolic extracts of Moringa leaves revealed a wide range of phenolics, highlighting their content in kaempferol derivatives, caffeoylquinic acid, and feruloylquinic acid. The antioxidant capacity of the tested leaves was correlated with the individual phenolics composition in order to identify which compounds were responsible for this beneficial power. The varying (p < 0.05) concentration of phenolics together with the antioxidant capacity of the tested leaves established 'Pakistan Black' and 'Techiman' as the most nutritive cultivar among others to be grown in the local area. Moreover, these data support the relevance of genetic variability of Moringa for determining the aptitude as a source of beneficial phenolics and nutrients, allowing to identify the optima cultivars to be grown in southern Asia. (c) 2015 Elsevier B.V. All rights reserved.
摘要：
The chlorogenic acids of Gardeniae Fructus used traditionally as a Chinese herbal medicine (zhizi) have been investigated qualitatively by liquid chromatography/multi-stage mass spectrometry (LC/MS4). Twenty-nine chlorogenic acids were detected and twenty-five characterised to regioisomer level on the basis of their fragmentation, twenty-four for the first time from this source. Assignment to the level of individual regioisomers was possible for three caffeoylquinic acids, three dicaffeoylquinic acids, three sinapoylquinic acids, four caffeoyl-sinapoylquinic acids, two feruloyl-sinapoylquinic acids, one p-coumaroyl-sinapoylquinic acid, three (3-hydroxy, 3-methyl)glutaroyl-quinic acids, two (3-hydroxy, 3-methyl)glutaroyl-feruloylquinic acids, one (3-hydroxy, 3-methyl)glutaroyl-dicaffeoylquinic acid, and one (3-hydroxy, 3-methynglutaroyl-caffeoyl-feruloylquinic acid. Six (3-hydroxy, 3-methyl)glutaroyl-caffeoylquinic acids were detected and two were tentatively assigned as 3-caffeoyl-4-(3-hydroxy, 3-methyl)glutaroylquinic acid and 3-caffeoyl-5-(3-hydroxy, 3-methyl)glutaroylquinic acid. The (3-hydroxy, 3-methyl)glutaroyl residue modifies the mass spectral fragmentation behavior and elution sequence compared with the chlorogenic acids that contain only a cinnamic acid residue(s). Fourteen of these twenty-nine chlorogenic acids have not previously been reported from any source. Copyright (C) 2010 John Wiley & Sons, Ltd.
通讯机构：
[Jiang, Bimei] Cent S Univ, Xiangya Sch Med, Dept Pathophysiol, Changsha 410000, Hunan, Peoples R China.
关键词：
B cell translocation gene 2 (BTG-2);cardiotoxicity;doxorubicin (DOX);microRNA-21 (miR-21)
摘要：
Doxorubicin (DOX) is an anthracycline drug with a wide spectrum of antineoplastic activities. However, it causes cardiac cytotoxicity, and this limits its clinical applications. MicroRNA-21 (miR-21) plays a vital role in regulating cell proliferation and apoptosis. While miR-21 is preferentially expressed in adult cardiomyocytes and involved in cardiac development and heart disease, little is known regarding its biological functions in responding to DOX-induced cardiac cytotoxicity. In this study, the effects of DOX on mouse cardiac function and the expression of miR-21 were examined in both mouse heart tissues and rat H9C2 cardiomyocytes. The results showed that the cardiac functions were more aggravated in chronic DOX injury mice compared with acute DOX-injury mice; DOX treatment significantly increased miR-21 expression in both mouse heart tissue and H9C2 cells. Over-expression of miR-21 attenuated DOX-induced apoptosis in cardiamyocytes whereas knocking down its expression increased DOX-induced apoptosis. These gain- and loss- of function experiments showed that B cell translocation gene 2 (BTG2) was a target of miR-21. The expression of BTG2 was significantly decreased both in myocardium and H9C2 cells treated with DOX. The present study has revealed that miR-21 protects mouse myocardium and H9C2 cells against DOX-induced cardiotoxicity probably by targeting BTG2.
关键词：
Fish gelatin;Acid pretreatment;Protein yield;Molecular weight distribution;Viscosity;Film
摘要：
Tilapia production is growing worldwide and to better utilize wastes from the processing industry, one important application is production of high quality fish gelatin to meet the needs of markets that are not amenable to beef or porcine gelatin. The extraction process from tilapia skin gelatin was optimized through the use of a combination of alkali (0.3 M NaOH) with different types and concentrations of acids before thermal hydrolysis. The effects of acid pretreatments on the protein yields and the physicochemical properties of tilapia gelatin were investigated. Acid concentrations (0.01-0.20 M) influenced gelatin protein recovery: 10.52%-22.40% for citric acid, 1.92%-21.55% for acetic acid, and 4.47%-24.35% for HCl. It was possible to increase gelatin yield for each of the tested acids by adjusting the acid concentration. Gelatin viscosity and the molecular weight distribution of gelatin proteins were related to the acid concentration used. Gelatin prepared using too low a concentration (e.g. 0.01 M acetic acid or HCl) or too high a concentration (e.g. >0.05 M HCl or citric acid) yielded an extract with a smaller ratio of large molecule components, such as beta-chains, and exhibited lower viscosity. The film forming properties of gelatins extracted from three acid-optimized pretreatments showed no significant difference in transparency, tensile strength and elongation at break; though the gelatin film made from 0.03 M citric acid pretreated gelatin had somewhat better water barrier property than those made with HCl or acetic acid. (C) 2013 Elsevier Ltd. All rights reserved.
摘要：
The influence of protein phosphorylation on meat color stability was investigated in this study. Phosphatase and protein kinase inhibitors were added to minced ovine Longissimus thoracis et lumborum (LTL) muscle to manipulate the global phosphorylation of sarcoplasmic proteins. The data obtained show that the rate and extent of pH decline, along with lactate accumulation in postmortem muscle, were related to protein phosphorylation. Analysis of meat color and the relative content of myoglobin redox forms revealed that meat color stability was inversely related to the phosphorylation of sarcoplasmic proteins. Thus, this study suggests that protein phosphorylation may be involved in meat color development by regulating glycolysis and the redox stability of myoglobin. (C) 2016 Elsevier Ltd. All rights reserved.
关键词：
GAB;Guggenheim-Anderson-de Boer;M0;monomolecular layer moisture content;K;multilayer heat of sorption;C;monolayer heat of sorption;SEE;standard error of estimate;P;mean relative deviation modulus;qst;net isosteric heat of sorption;Qst;isosteric heat of sorption;heat of vaporization of pure water;∆H;differential enthalpy;∆S;differential entropy;∆G;Gibbs free energy;Tβ;isokinetic temperature;Thm;harmonic mean temperature;spreading pressure;∆Hin;net integral enthalpy;∆Sin;net integral entropy;aw*;geometric mean water activity at constant spreading pressure;Pullulan;Sodium alginate;Thermodynamic properties;Moisture isotherms;Enthalpy–entropy compensation theory
摘要：
Moisture sorption isotherms of pure pullulan, alginate and blend films were determined using the gravimetric method at 25, 35 and 45 degrees C. The five-parameter Guggenheim-Anderson-de Boer (GAB) model was used to fit the isotherm data from the experiments by nonlinear regression. Additionally, the experimental data were used to determine the thermodynamic parameters for pullulan-alginate based films. Net isosteric heat values for the films decreased exponentially with increasing moisture content, and approached to zero after around 025 g/H2O g dry basis. Pure pullulan films exhibited lowest differential entropy values at a high moisture content range, whereas pure alginate films showed the lowest differential entropy values with increasing moisture content from 0.05 to 0.17 g/H2O g dry basis. Net integral entropy values for pullulan, alginate and blend films were observed to decrease to each minimum value, and then increase with moisture content increases. Moreover, according to the enthalpy-entropy compensation theory, the sorption mechanism for all tested films was enthalpy-controlled. The thermodynamic information obtained from this study is essential for designing equipment and standardized drying process for pullulan-sodium alginate based edible films. (C) 2013 Elsevier Ltd. All rights reserved.
摘要：
Baicalein, a major component of Scutellaria baicalensis Georgi (Huang Qin), is widely used in the traditional Chinese medicine. However, the mechanisms underlying cancer chemoprevention are still not clear. The present study aimed to clarify how baicalein modulate Nrf2/Keap1 system to exert its cytoprotection and cancer chemoprevention. In the upstream cellular signaling, baicalein stimulated the phosphorylation of MEK1/2, AKT and JNK1/2, which were demonstrated to be essential for baicalein-induced Nrf2 expression by their inhibitors. Immunoprecipitation with Nrf2 found that baicalein increased the amount of phosphorylated MEK1/2, AKT and JNK1/2 bound to Nrf2, and also stabilized Nrf2 protein by inhibiting the ubiquitination and proteasomal turnover of Nrf2. Simultaneously, baicalein down-regulated Keap1 by stimulating modification and degradation of Keap1 without affecting the dissociation of Keap1-Nrf2. Silencing Nrf2 using Nrf2 siRNA markedly reduced the ARE activity under both baseline and baicalein-induced conditions. Thus, baicalein positively modulate Nrf2/Keap1 system through both Keap1-independent and -dependent pathways. These finding provide an insight to understand the mechanisms of baicalein in cytoprotection and cancer chemoprevention. (C) 2014 Elsevier Inc. All rights reserved.
