RESUMO
Solution plasma process (SPP) was used for sterilizing Staphylococcus aureus (S. aureus) in raw milk (RM). The sterilization efficacy analysis and kinetics analysis showed bacterial concentration and the distance between electrodes were negatively correlated with the sterilization effect, while discharge voltage was positive. The better sterilization effect was achieved at 4 kV. The electrochemical indices analysis indicated that pH value of RM had no changed. The DO content decreased. The conductivity increased with the increasing discharge voltage. The nutrient content analysis revealed that the content of acidity, lactose, fat, and protein decreased. RM after SPP treatment exhibited higher values of sourness and slightly lower values of astringency than the control. The higher discharge voltage and narrower distance between electrodes presented the stronger effect. The structural characterization of CMs and MFGs was carried out using a laser particle sizer, FTIR, 1H NMR, XRD, and AFM. The results showed that the main chemical structure of CMs was unchanged basically. The SPP with the narrower distance between electrodes and lower discharge voltage significantly reduced the size and aggregation of MFGs at the molecular level. At 4 kV/2 mm, the particle sizes of CMs and MFGs were reduced from 238 nm and 523 nm to 224 nm and 302 nm, respectively. The average diameter of MFGs was reduced from 45 nm to 18 nm. Therefore, SPP is a potential method in the milk industry and provides a new idea for the preservation and processing of beverage.
RESUMO
Radical scavengers were employed to evaluate the influence of various active species (â¢OH, â¢O, and H2O2) on the rheological properties, antioxidant activity, and molecular conformation of chitosan under solution plasma process (SPP) degradation. ESR analysis showed that â¢OH and â¢O radicals played important roles in SPP degradation. The results of rheological properties and antioxidant activity indicated that the â¢OH scavenger (tert-butanol), â¢O scavenger (1, 4-benzoquinone), and H2O2 scavenger (MnO2) remarkably inhibited the decrease of G' and G" of the degraded chitosan, the formation of gel structure, and the increase of antioxidant activity. The analysis of molecular conformation of the chitosan by particle size analysis, atomic force microscopy (AFM), and high performance size exclusion chromatography coupled with multi-angle laser light scattering (HPSEC-MALLS) revealed that the decrease of particle size, molecular aggregation, and molecular weight of chitosan was inhibited after the addition of radical scavengers. An evident effect of radical scavengers on the hard sphere conformation of chitosan was observed. It was found that the above effects were strongly dependent on the scavenger concentration. These results proved that â¢OH, â¢O, and H2O2 played important roles in SPP treatment. For the rheological properties and molecular conformation, H2O2 exhibited the greatest impact. For the antioxidant activity and molecular weight, â¢OH presented the biggest influence. Besides, â¢O expressed the weakest effect. This study will be beneficial to reveal the action mechanisms of SPP technology to the degradation of chitosan.
Assuntos
Antioxidantes , Quitosana , Antioxidantes/farmacologia , Antioxidantes/química , Quitosana/química , Peróxido de Hidrogênio/química , Compostos de Manganês , Óxidos , Radicais Livres , Conformação Molecular , Sequestradores de Radicais Livres/farmacologia , Sequestradores de Radicais Livres/químicaRESUMO
The effects of H2O2-assisted ultrasonic bath degradation technology on pectin were investigated. The degradation efficiency with different pectin concentrations, H2O2 concentrations, ultrasonic power, and ultrasonic time was analyzed. The results showed that pectin concentration was negatively correlated with the degradation efficiency of pectin, while, H2O2 concentration, ultrasonic power, and ultrasonic time were positive correlated with the degradation efficiency. Besides, the apparent viscosity and viscoelasticity of the degraded pectin decreased significantly. The antioxidant activity increased after the H2O2-assisted ultrasonic bath treatment. The results of FTIR, NMR, laser particle size, SEM, XRD, and AFM analysis indicated that the degradation treatment did not destroy the main structure of pectin. The average particle size and crystallinity of pectin decreased. The degree of aggregation and the height of the molecular chain decreased significantly. In conclusion, the H2O2-assisted ultrasonic bath degradation technique could effectively degrade pectin. This study provided a comprehensive analysis of the degradation of pectin under H2O2-assisted ultrasonic bath, which will be beneficial to further develop H2O2-assisted ultrasonic bath techniques for pectin degradation.
Assuntos
Pectinas , Ultrassom , Pectinas/química , Peróxido de Hidrogênio , Viscosidade , Concentração de Íons de HidrogênioRESUMO
Microwave was employed to enhance the degradation of polymeric proanthocyanidins from black chokeberry using the nucleophilic technique of sulfite/catechin. Based on the degradation effect and kinetics, it was found that increasing the microwave time, microwave power, microwave temperature, sulfite concentration, and mass ratio of raw material to catechins was favourable for the degradation reaction. The degradation kinetics conformed to a random first-order degradation model. The antioxidant activity of the degraded products was analysed using DPPH and O2- assay, which suggested that the scavenging effect of the products was improved. FT-IR and 1H NMR analyses showed that the main functional groups were not destroyed. Using MALDI-TOF/MS to study the components of the degradation products, it was found that the molecular weight distribution became narrower, and the compositions were more single. Polyproanthocyanidins were reduced to oligomers. This study suggested that microwave-assisted nucleophilic techniques could produce oligomeric proanthocyanidins with remarkably improved functionalities.
Assuntos
Catequina , Proantocianidinas , Antioxidantes , Proantocianidinas/análise , Catequina/química , Micro-Ondas , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Dried edible mushrooms have a unique flavor which is worth exploring to preserve and improve their flavor.Light can improve flavor for dried edible mushrooms, but there are few reports about monochromatic light. In this study, effects of red-light, yellow-light, green-light, blue-light and white-light on the umami taste and aroma of dried Suillus granulatus were investigated. The results showed that contents of umami amino acids and 5-nucleotides, equivalent umami concentration (EUC) and electronic tongue umami scores were higher under blue-light treatment. Principal component analysis (PCA) of volatiles showed that comprehensive scores under blue-light treatment were higher. The flavor was better under five light treatments at 6 and 9 days. Partial least squares-discrimination analysis (PLS-DA) further revealed the detailed differences between various light treatments, which were mainly caused by umami amino acids, alcohols, ketones and pyrazines. Collectively,blue-light treatment can be used as a processing technology to improve the flavor quality of dried edible mushrooms.
Assuntos
Agaricales , Odorantes , Odorantes/análise , Paladar , Nariz Eletrônico , Agaricales/química , Aminoácidos/análiseRESUMO
Synergistic degradation of chitosan by discrete ultrasonic and H2O2 was investigated. The effects of ultrasonic time, ultrasonic power, chitosan concentration, and H2O2 concentration were evaluated. The results revealed that ultrasonic power, H2O2 concentration and ultrasonic time were positively correlated with degradation rate, while chitosan concentration was negative. The results of degradation kinetics revealed that the synergistic degradation process was consistent with the first-order reaction. Changes of characterization of chitosan were analyzed by FTIR, 13C NMR, XRD, SEM, and AFM analysis. The results indicated that the synergistic degradation did not destroy the pyranose ring. The crystal structure of degraded chitosan was destroyed, and the molecular conformation changed significantly. The antioxidant activity of the original and degraded chitosan was determined by DPPH and reducing power assays. The degraded chitosan had higher antioxidant activity. All results showed that the synergistic degradation of discrete ultrasound and H2O2 was a feasible method for large-scale low molecular weight chitosan production.
Assuntos
Quitosana , Antioxidantes/química , Quitosana/química , Peróxido de Hidrogênio/química , Peso Molecular , UltrassomRESUMO
Solution plasma process (SPP) was employed to degrade chitosan. The effects of the initial pH value and the distance between the electrodes on the steady shear flow behavior, structural characterization, molecular conformation, and antioxidant activity of chitosan were investigated. The results revealed that a lower initial pH value and a narrower distance between the electrodes were beneficial to the decrease in viscosity and increase in shear-thinning capacity. Structural characterization of the chitosan by FT-IR and 1H NMR showed that chemical structure of chitosan was not destroyed at different process parameters. The results of XRD, HPSEC-MALLS, SEM, and AFM indicated that SPP degradation clearly decreased the crystallinity, molecular weight, molecular size, and molecular aggregation of chitosan. At initial pH values of 2.8 and 5.8, the molecular weight was 27.16 and 44.25 kDa, at the distance between the electrodes of 4 and 8 mm, it was 35.88 and 66.17 kDa, respectively. The results of DPPH and hydroxyl radical scavenging assays demonstrated that a lower initial pH value and a narrower distance between the electrodes enhanced the antioxidant activity.
Assuntos
Quitosana , Antioxidantes/química , Antioxidantes/farmacologia , Quitosana/química , Eletrodos , Concentração de Íons de Hidrogênio , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
This study investigated the role of various active species (OH, O, and H2O2) under solution plasma process (SPP) degradation based on the influence of different radical scavengers on the degradation effect and ESR spectra. The structures of oligochitosan with different radical scavengers were characterized by FT-IR, 1H NMR, and XRD analysis. The results indicated that OH, O, and H2O2 played important roles in SPP degradation. The degradation effect of the O was even higher than that of the OH. The physical effects (e.g. UV light and shockwaves) of SPP method or Fenton's reaction might contribute to the degradation treatment. Furthermore, the different scavengers could adjust the degradation effect of the corresponding free radicals. FT-IR, 1H NMR, and XRD analysis revealed that the primary chemical structure of chitosan was not changed by the scavengers. This study found that the controlled degradation by addition of a radical scavenger is feasible. Therefore, this study provided a straightforward analysis of the role of the free radicals and the controlled degradation of chitosan under SPP treatment, which will be beneficial to further develop SPP techniques for chitosan degradation.
RESUMO
The degradation effect of ultrasound (US)/hydrogen peroxide (H2O2) on Tremella fuciformis polysaccharide (TFP) were studied. The main process parameters of degradation were evaluated and the structural changes and antioxidant activities of TFP before and after US/H2O2 were analyzed. The results showed that the degradation effect of US/H2O2 was significantly higher than that of US or H2O2 alone, and the degradation of TFP was dependent on the duration of its exposure to US, the ultrasonic amplitude, and the H2O2 and TFP concentrations. US/H2O2 reduced the molecular weight (from 8.14 × 105 Da to 1.27 × 104 Da) and particle size (from 710 nm to 182 nm) of the TFP within 50 min and narrowed its molecular weight and particle size distribution. High performance liquid chromatography, Fourier-transform infrared spectroscopy, Carbon-13 nuclear magnetic resonance, scanning electron microscopy, atomic force microscopy, and Congo red results indicated that the treatment could break down the polysaccharide chains, hinder the aggregation, and improve the conformation flexibility of the TFP molecules without changing the primary structure and monosaccharide composition of TFP. Additionally, the degraded TFPs with low molecular weight exhibited a higher antioxidant activity than the original TFP. These findings suggest that the US/H2O2 treatment is a simple and effective method to prepare a TFP of low molecular weight and high bioactivity.
Assuntos
Basidiomycota/química , Polissacarídeos Fúngicos/química , Peróxido de Hidrogênio/química , Ondas Ultrassônicas , Algoritmos , Antioxidantes/química , Antioxidantes/farmacologia , Sequestradores de Radicais Livres/química , Polissacarídeos Fúngicos/farmacologia , Espectroscopia de Ressonância Magnética , Modelos Químicos , Peso Molecular , Monossacarídeos , Tamanho da Partícula , Sonicação , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
SCOPE: This study investigates the modulatory effects of Lonicera caerulea L. polyphenols (LCPs) on the intestinal environment and lipopolysaccharide (LPS)-induced liver injury via the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (HO-1)/NQO1 and mitogen-activated protein kinase (MAPK) pathways in a rat model of oxidative stress damage (OSD). METHODS AND RESULTS: To examine the prebiotic properties of LCP, a model of high-fat-diet-induced OSD is established using Sprague Dawley rats. In the colon, treatment with LCP for 8 weeks ameliorates enhanced intestinal permeability (glucagon-like peptide-2 content and occludin protein increase, whereas claudin-2 protein decreases), intestinal inflammation (levels of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nuclear factor kappa-B p65 (NF-κB p65), decrease), and intestinal OSD (through regulation of the Nrf2/HO-1/NQO1 pathway). Moreover, LCP alleviates LPS-induced liver injury by suppressing the nuclear translocation of NF-κB p65 and activation of the MAPK signaling pathway. Additionally, Bacilli, Lactobacillales, Lactobacillaceae, Lactobacillus, Akkermansia, Actinobacteria, Proteobacteria, Rothia, and Blautia are found to be the key intestinal microbial taxa related to intestinal OSD and LPS-induced liver injury in rats. CONCLUSION: LCP treatment potentially modulates the intestinal environment and alleviates liver injury by suppressing oxidative-stress-related pathways and altering the composition of the intestinal microbiota.
Assuntos
Colo/efeitos dos fármacos , Fígado/efeitos dos fármacos , Lonicera/química , Estresse Oxidativo/efeitos dos fármacos , Polifenóis/farmacologia , Animais , Peso Corporal/efeitos dos fármacos , Colo/patologia , Dieta Hiperlipídica/efeitos adversos , Microbioma Gastrointestinal/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Heme Oxigenase (Desciclizante)/metabolismo , Lipopolissacarídeos/toxicidade , Fígado/metabolismo , Fígado/patologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , NAD(P)H Desidrogenase (Quinona)/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Ratos Sprague-DawleyRESUMO
Synergistic degradation of water-soluble Auricularia auricula polysaccharide (AAP) by solution plasma process (SPP) in the presence of hydrogen peroxide (H2O2) was investigated. The effects of H2O2 concentration, AAP concentration and the distance between the electrodes on the degradation of AAP were evaluated. The results showed that higher H2O2 concentration, lower AAP concentration and narrower distance between the electrodes were favorable for the degradation effect. Particle size, congo red (CR), scanning electron micrographs (SEM) and atomic force microscopy (AFM) results confirmed that SPP irradiation with H2O2 improved significantly the flexibility of the conformation. The degraded AAPs exhibited greater metal chelating effects and DPPH radical scavenging effect than the original AAP. It concluded that the combined SPP/ H2O2 method could be used for preparation of low-molecular-weight AAP.
Assuntos
Antioxidantes/química , Basidiomycota , Polissacarídeos Fúngicos/química , Peróxido de Hidrogênio/química , Compostos de Bifenilo/química , Compostos Ferrosos/química , Picratos/química , Solubilidade , Soluções , Água/químicaRESUMO
Solution plasma process (SPP) in combination with hydrogen peroxide (H2O2) were adopted to the degradation of Auricularia auricula polysaccharide (AAP). The results showed that SPP irradiation with H2O2 was effective for the AAP degradation. The intrinsic viscosity ([η]) of AAP solution decreased exponentially with increase in irradiation time. The degradation reaction closely fitted to the first order kinetics. The degradation rate constant after SPP irradiation with H2O2 was approximately 4.2 times that with SPP irradiation alone. GPC analysis showed that the molecular weight distribution of AAP was narrowed during degradation. FTIR and 13C NMR analysis revealed that primary structure of APP was not changed by the combination method. In vitro antioxidant activity of the polysaccharides was evaluated by determining their reducing power and radical (ABTS radical and superoxide radical) scavenging abilities. It was found that the degraded AAP possessed the higher antioxidant activity. The results suggested that SPP with H2O2 was an effective means for AAP degradation.
Assuntos
Antioxidantes/química , Basidiomycota/química , Peróxido de Hidrogênio/química , Polissacarídeos/química , Espectroscopia de Ressonância Magnética , Peso Molecular , Espectroscopia de Infravermelho com Transformada de Fourier , ViscosidadeRESUMO
Schisantherin A (SinA), one of the most abundant active ingredients of Schisandra chinensis, was reported to protect and benefit the liver, however, its effect on alcohol-induced liver injury (ALI) was still not clear. In the present study, an ALI mice model was induced by feeding mice an alcohol-containing liquid diet for four weeks. Then, 100 mg/kg or 200 mg/kg SinA was administered to mice every day by gavage for the last two weeks. Histopathological analysis showed that alcohol-induced liver lipid vacuoles were reduced by SinA. The activities of aspartate aminotransferase (AST, 61.90 ± 14.65 vs. 93.65 ± 20.50, 50.46 ± 13.21 vs. 93.65 ± 20.50) and alanine transaminase (ALT, 41.29 ± 9.20 vs. 64.04 ± 18.13, 36.52 ± 7.71 vs. 64.04 ± 18.13) in the serum of ALI mice were significantly reduced by 100 mg/kg or 200 mg/kg SinA when compared with control mice. Alcohol-induced oxidative stress and the inflammatory response in the liver were suppressed by SinA in a dose-dependent manner. Meanwhile, treatment with SinA decreased alcohol dehydrogenase (ADH) activity and increased acetaldehyde dehydrogenase (ALDH) activity in ALI mice. Alcohol-induced upregulation of CYP2E1 and CYP1A2 in the liver was inhibited by SinA. Further, SinA suppressed activation of the NF-kB pathway in ALI mice. In conclusion, our findings demonstrate that SinA is able to protect against ALI, and this may be, at least in part, caused by regulation of alcohol metabolism and the NF-kB pathway. Our data suggest a therapeutic potential of SinA in the treatment of ALI.
Assuntos
Ciclo-Octanos/administração & dosagem , Dioxóis/administração & dosagem , Etanol/metabolismo , Lignanas/administração & dosagem , Hepatopatias Alcoólicas/tratamento farmacológico , Hepatopatias Alcoólicas/metabolismo , Fígado/metabolismo , NF-kappa B/metabolismo , Fitoterapia , Transdução de Sinais/efeitos dos fármacos , Alanina Transaminase/sangue , Álcool Desidrogenase/sangue , Aldeído Oxirredutases/sangue , Animais , Aspartato Aminotransferases/sangue , Ciclo-Octanos/isolamento & purificação , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP2E1/metabolismo , Dioxóis/isolamento & purificação , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Lignanas/isolamento & purificação , Fígado/patologia , Hepatopatias Alcoólicas/patologia , Masculino , Camundongos Endogâmicos C57BL , Estresse Oxidativo/efeitos dos fármacos , Schisandra/químicaRESUMO
Synthesis of chitosan-Cu(II) complex by solution plasma process (SPP) irradiation was investigated. The effects of the distance between the electrodes, initial Cu(II) concentration, and initial pH on the Cu(II) adsorption capacity were evaluated. The results showed that narrower distance between the electrodes, higher initial Cu(II) concentration and higher initial pH (at pH<6) were favourable for the adsorption capacity of Cu(II). Characterization of the chitosan-Cu(II) complex by ultraviolet-visible (UV-vis), fourier transform infrared (FT-IR) and electron spin resonance (ESR) spectroscopy revealed that the main structure of chitosan was not changed after irradiation. Thermogravimetry (TG) analysis indicated that Cu(II) ions were well incorporated into the chitosan. The antioxidant activity of the chitosan-Cu(II) complex was evaluated by DPPH, ABTS, and reducing power assays. The chitosan-Cu(II) complex exhibited greater antioxidant activity than the original chitosan. Thus, SPP could be used for preparation of chitosan-Cu(II) complexes.
Assuntos
Antioxidantes/química , Antioxidantes/síntese química , Quitosana/química , Cobre/química , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Gases em Plasma/química , Adsorção , Benzotiazóis/química , Compostos de Bifenilo/química , Técnicas de Química Sintética , Eletrodos , Concentração de Íons de Hidrogênio , Picratos/química , Soluções , Ácidos Sulfônicos/químicaRESUMO
In the present work, solution plasma process (SPP) with bubbling gas was used to prepare oligochitosan. The effect of SPP irradiation with bubbling gas on the degradation of chitosan was evaluated by the intrinsic viscosity reduction rate and the degradation kinetic. The formation of OH radical was studied. Changes of the physicochemical properties of chitosan were measured by scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, as well as ultraviolet-visible, Fourier-transform infrared, and 13C nuclear magnetic resonance spectroscopy. The results indicated an obvious decrease in the intrinsic viscosity reduction rate after SPP irradiation with bubbling gas, and that the rate with bubbling was higher than that without. The main chemical structure of chitosan remained intact after irradiation, but changes in the morphology, crystallinity, and thermal stability of oligochitosan were observed. In particular, the crystallinity and thermal stability tended to decrease. The present study indicated that SPP can be effectively used for the degradation of chitosan.
Assuntos
Fenômenos Químicos , Quitosana/química , Gases em Plasma/química , Ar , Radical Hidroxila/química , Solubilidade , SoluçõesRESUMO
BACKGROUND: Broccoli (Brassica oleracea var. italica), a member of Cruciferae, is an important vegetable containing high concentration of various nutritive and functional molecules especially the anticarcinogenic glucosinolates. The sprouts of broccoli contain 10-100 times higher level of glucoraphanin, the main contributor of the anticarcinogenesis, than the edible florets. Despite the broccoli sprouts' functional importance, currently available genetic and genomic tools for their studies are very limited, which greatly restricts the development of this functionally important vegetable. RESULTS: A total of â¼85 million 251 bp reads were obtained. After de novo assembly and searching the assembled transcripts against the Arabidopsis thaliana and NCBI nr databases, 19,441 top-hit transcripts were clustered as unigenes with an average length of 2,133 bp. These unigenes were classified according to their putative functional categories. Cluster analysis of total unigenes with similar expression patterns and differentially expressed unigenes among different tissues, as well as transcription factor analysis were performed. We identified 25 putative glucosinolate metabolism genes sharing 62.04-89.72% nucleotide sequence identity with the Arabidopsis orthologs. This established a broccoli glucosinolate metabolic pathway with high colinearity to Arabidopsis. Many of the biosynthetic and degradation genes showed higher expression after germination than in seeds; especially the expression of the myrosinase TGG2 was 20-130 times higher. These results along with the previous reports about these genes' studies in Arabidopsis and the glucosinolate concentration in broccoli sprouts indicate the breakdown products of glucosinolates may play important roles in the stage of broccoli seed germination and sprout development. CONCLUSION: Our study provides the largest genetic resource of broccoli to date. These data will pave the way for further studies and genetic engineering of broccoli sprouts and will also provide new insight into the genomic research of this species and its relatives.
Assuntos
Brassica/genética , Brassica/metabolismo , Glucosinolatos/metabolismo , Sementes/genética , Sementes/metabolismo , Transcriptoma , Análise por Conglomerados , Biologia Computacional , Bases de Dados Genéticas , Perfilação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Redes e Vias Metabólicas , Anotação de Sequência Molecular , Fatores de Transcrição/genéticaRESUMO
The radioprotective effect of anthocyanin extracted from Lonicera caerulea var. edulis (ALC), was studied in ICR mice. Different doses of ALC were intragastrically administered to mice once a day, prior to radiation. After two weeks, the mice received a one-time 5 Gy whole body (60)Coγ radiation. The spleen index, thymus index, activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), malondialdehyde (MDA) content, and glutathione (GSH) content in liver tissue were measured. Compared with the radiation control group, the levels of MDA in all ALC treated groups decreased significantly (p < 0.05). Moreover, the GSH content, activities of SOD and GSH-Px in liver tissue were enhanced significantly (p < 0.05) in all ALC groups. These results demonstrate that ALC may be a potential radioprotector, and a further study of the molecular mechanism is needed for further application.
Assuntos
Antocianinas/farmacologia , Raios gama/efeitos adversos , Lonicera/química , Lesões Experimentais por Radiação/prevenção & controle , Protetores contra Radiação/farmacologia , Animais , Antocianinas/química , Glutationa Peroxidase/metabolismo , Fígado/metabolismo , Fígado/patologia , Malondialdeído/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Lesões Experimentais por Radiação/metabolismo , Lesões Experimentais por Radiação/patologia , Protetores contra Radiação/química , Baço/metabolismo , Baço/patologia , Superóxido Dismutase/metabolismo , Timo/metabolismo , Timo/patologia , Irradiação Corporal TotalRESUMO
The depolymerization of chitosan by plasma in the presence of hydrogen peroxide (H(2)O(2)) was investigated. The efficiency of the depolymerization was demonstrated by means of determination of viscosity-average molecular weight and gel permeation chromatography (GPC). The structure of the depolymerized chitosan was characterized by Fourier-transform infrared spectra (FT-IR), ultraviolet spectra (UV) and X-ray diffraction (XRD). The results showed that chitosan can be effectively degradated by plasma in the presence of H(2)O(2). The chemical structure of the depolymerized chitosan was not obviously modified. The combined plasma/H(2)O(2) method is significantly efficient for scale-up manufacturing of low molecular weight chitosan.
Assuntos
Quitosana/química , Peróxido de Hidrogênio/químicaRESUMO
Wheat (Triticum aestivum L.) stem rust caused by Puccinia graminis f. sp. tritici is one of the main diseases of wheat worldwide. Wheat mutant line D51, which was derived from the highly susceptible cultivar L6239, shows resistance to the prevailing races 21C3CPH, 21C3CKH, and 21C3CTR of P. graminis f. sp. tritici in China. In this study, we used the cDNA-AFLP technology to identify the genes that are likely involved in the stem rust resistance. EcoRI/MseI selective primers were used to generate approximately 1920 DNA fragments. Seventy five differentially transcribed fragments (3.91%) were identified by comparing the samples of 21C3CPH infected D51 with infected L6239 or uninfected D51. Eleven amplified cDNA fragments were sequenced. Eight showed significant similarity to known genes, including TaLr1 (leaf rust resistance gene), wlm24 (wheat powdery mildew resistance gene), stress response genes and ESTs of environment stress of tall fescue. These identified genes are involved in plant defense response and stem rust resistance and need further research to determine their usefulness in breeding new resistance cultivars.