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采用MTT法、Cometassay(彗星实验)和流式细胞分析法研究了表没食子儿茶素没食子酸酯(EGCG)对卡莫司汀引起的张氏肝细胞DNA损伤的保护作用及其机制。结果表明:EGCG能阻止卡莫司汀所致张氏肝细胞的生长抑制,卡莫司汀单用对张氏肝细胞的IC50为43.31μg/ml,当用无毒浓度25μg/ml和50μg/ml的EGCG与卡莫司汀联用时,对张氏肝细胞的IC50分别提高至52.46μg/ml和46.65μg/ml。彗星分析结果表明EGCG还能减小卡莫司汀引起的张氏肝细胞DNA损伤,彗星Olive尾矩值由单用时的9.07±5.48降为联用时的6.02±2.46。EGCG还能减小卡莫司汀所致张氏肝细胞的早期凋亡率,25μg/ml的EGCG和20μg/ml的卡莫司汀联合处理4、6h和24h时,早期凋亡率分别从4.53±0.64(%)、6.01±0.14(%)、2.27±0.32(%)降至3.04±0.47(%)、5.61±0.10(%)、1.14±0.23(%)。说明EGCG能保护卡莫司汀对正常肝细胞的杀伤,其机理是它能减少这类药物引起的细胞DNA损伤,降低卡莫司汀所致细胞早期凋亡。 相似文献
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采用MTT法及Comet assay(彗星实验分析方法)研究了表没食子儿茶素没食子酸酯（EGCG）与卡莫司汀联用对人肺癌细胞A549的生长抑制率及DNA损伤的影响,结果表明：联合应用EGCG能降低卡莫司汀对人肺癌细胞A549的IC50。卡莫司汀单用对人肺癌细胞A549的IC50为187.46βμg/ml,当用无毒浓度25βμg/ml和50βμg/ml的EGCG与卡莫司汀联用时,卡莫司汀对人肺癌细胞A549的IC50分别下降为139.56βμg/ml和154.02βμg/ml。EGCG还能增强卡莫司汀引起的人肺癌细胞A549 DNA的损伤,彗星尾矩值由单用时的19.02±14.60上升为联用时的33.07±10.47。结果说明EGCG能增强卡莫司汀对人肺癌细胞A549造成的DNA损伤,从而增强其抗肿瘤活性。 相似文献
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HPLC法同时测定茶叶中4种儿茶素类成分 总被引：3，自引：0，他引：3
采用高效液相色谱（HPLC）分析4种儿茶素类化合物EC、EGC、EGCG、ECG。色谱柱为Hypersil ODS C18（5μm,150mm×4．6mm）,流动相为甲醇、水、冰醋酸（25：74：1）混合液,流速为1mL／min,检测波长270nm,进样量：10μL。线性方程分别为EGCG：Y=24．254X＋464．34,R=0．9993;EC：Y=669．55X＋19．14,R=0．9947;EGC：Y=5196．80X-65．17,R=0．9984;ECG：Y=518．76X＋71．53,R=0．9991。结果显示,本法操作简便,能同时用于4种儿茶素的含量测定;线性关系好;精密度RSD在1．0％左右;可在8h内测定;EC、EGC、EGCG、ECG的回收率分别为99．6％、98．7％、98．7％、99．4％。 相似文献
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油菜菌核病菌对多菌灵的抗药性 总被引：2，自引：0，他引：2
从江苏句容市丘陵山区从未施用多菌灵（MBC）的白菜型油菜苗核病株上，采集了49个Sclerotiniasclerotiorum野生菌株，MBC抑制这些菌株的菌丝生长，平均EC50为0．2198±0．1083μg／ml，最低抑制生长浓度（MIC）值为5．0μg／ml。从镇江农科所油菜育种试验田中采集的S．selerotiorum菌核标样中，发现6个抗MBC的抗性菌株，其EC50值均大于2000μg／ml。抗性菌株对离体油菜叶片的致病力与野生的敏感菌株没有差异。油菜叶片经1000μg／mlMBC溶液浸渍后，敏感菌株对其不能侵染，而抗性菌株对这些叶片的致病力与对未浸药叶片的致病力无明显差异。 相似文献
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本文研究了黄品种茶树对元素硒的生物积累特征。结果表明，黄各器官对元素硒的生物积累呈中等与强积累程度，生物积累系数BAC在n×10°～n×10－1之间，其中细根（5．53）居首位，其次是皮（4．43）与叶（3．69）；各器官含硒量为0，006～0．148μg／g，其中，皮（0．148μg／g）最高，其次是叶与细根，都为0．140μg／g；而对硬的积累量，则以叶最高，可达37．97μg。 相似文献
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本研究建立了一种同时测定大豆低聚糖粉中棉子糖和水苏糖含量的高效液相色谱分析方法（HPLC）。采用示差折光检测器（RID）,色谱柱为Agilent Zorbax carbohydrate柱（4．6mm&;#215;150mm,5μm）,流动相为乙腈-水（75：25,V：V）,流速1．0mL／min,柱温30℃。实验结果表明：棉子糖和水苏糖分别在1～10mg／mL、1～10mg／mL范围内线性良好,相关系数分别为0．9925、0．9971;2种糖的相对标准偏差（RSD）分别为1．57％、1．81％（n=5）,平均回收率分别为95．8％、96．0％。该分析方法适用于大豆低聚糖粉中棉子糖和水苏糖含量的检测。 相似文献
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甜菜SSR-PCR反应体系的优化 总被引：3，自引：0，他引：3
为了建立适宜甜菜的SSR反应体系,笔者以甜菜不育系TB005A为试验材料,研究了甜菜SSR技术中PCR反应体系的主要成分对SSR扩增结果的影响。对SSR反应体系中的DNA模板浓度、引物浓度、Taq聚合酶浓度、dNTPs浓度以及退火温度进行了探索,确立了适合甜菜的SSR反应体系为;在20μL反应体系中,模板DNA为60ng,引物（50ng／μL）1．2μL,Taq DNA聚合酶1．0U,dNTPs（2、5mM／L）0．6μL。并利用该反应体系对30个甜菜不同品系进行SSR反应,用6％的变性聚丙烯酰胺凝胶电泳检测,不同品系间DNA谱带多态性丰富,证实该体系稳定可靠。 相似文献
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Composite films based on EVA with CMF were prepared and characterized for their solvent transport nature. CMF were derived from Hibiscus sabdariffa by steam explosion technique and incorporated in the EVA matrix by extrusion. Solvent transport by the composites was analyzed using hexane, heptane and octane as penetrant molecules. The solvent uptake behavior of EVA/CMF composites is explained on the basis of the penetrant size, temperature and the filler loading. The composite had improved barrier property compared with unfilled EVA. This in turn is an indication of good fiber-matrix interaction in the composite system. Diffusion parameters such as diffusion coefficient, permeation coefficient and Arrhenius activation parameters and thermodynamic parameters such as enthalpy and entropy were evaluated in detail. The mode of transport was found to be Fickian. 相似文献
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Xiansheng Zhang Xiaoning Tang Ran Wang Rui Wang Xiong Yan Meiwu Shi 《Fibers and Polymers》2017,18(8):1421-1430
Thermal degradation behaviors and fire retardant properties of poly(1,3,4-oxadiazole)s (POD) and poly(m-phenylene isophthalamide) (PMIA) fibers were investigated. The thermal gravimetric analysis (TGA) demonstrated that POD exhibited higher onset thermal degradation temperature (Tonset) than PMIA, exceeding nearly 80 °C. The thermal degradation kinetics, evaluated by the modified Coats-Redfern method, displayed that the apparent activation energy (Ea) of POD and PMIA fibers was similar when the conversion rate (α) ranges from 0.2 to 0.5, while with the α from 0.6 to 0.8, the Ea of POD was significantly lower than that of PMIA. The fire retardant performance of POD and PMIA fibers were evaluated by cone calorimeter under heat fluxes of 35, 50 and 75 kW/m2, during which the temperature of the fibers were monitored by a thermocouple. Surprisingly, POD fibers showed inferior fire retardant performance in comparison with PMIA, with lower time to ignition (TTI) and higher peak heat release rate (PHRR). The origin of the different fire retardant properties of both fibers was revealed by analyzing the residual chars and gaseous products during thermal pyrolysis. The morphology confirmed that stable and compact chars can be formed in PMIA. In addition, the Fourier Transform Infrared Spectroscopy (FTIR) characterization of the residual char revealed that POD can form carbonaceous chars at the heat flux of 50 kW/m2, while the heat flux of PMIA was 75 kW/m2. The pyrolysis products characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that POD can be pyrolyzed completely at 600 °C, while the temperature of PMIA was 700 °C. 相似文献
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《Journal of Crop Improvement》2013,27(2):287-298
Summary It is well known that C4 crops have a lower water requirement than C3 crops. Reasons for the difference are not well understood. Therefore, hydraulic resistance of sorghum [Sorghum bicolor (L.) Moench] (C4) and sunflower (Helianthus annuus L.) (C3) was determined to see if it might be one explanation for the lower water use of crops with the C4 photosynthetic pathway. Plants were grown under greenhouse conditions in pots with soil, which was well watered (soil matric potential of ～0 MPa) or allowed to dry (soil matric potential of ?0.038 MPa and ?0.065 MPa for sorghum and sunflower, respectively). Hydraulic resistance was calculated in two ways: (1) using the classic Ohm's law analogue, which assumes that the relation between flux (transpiration) and difference in water potentials of the soil and plant is linear and (2) using an equation that considers diurnal changes in leaf water content along with transpiration and difference in water potentials. Because change in leaf-water content during a day was small, hydraulic resistances calculated by the two methods resulted in similar values. Sorghum had a linear relationship between flux and difference in potentials (constant hydraulic resistance), but sunflower had a nonlinear one (variable hydraulic resistance). The hydraulic resistance of watered sunflower increased only slightly during a day and averaged about 40 MPa m2 s mol?1, which was 3.5 times less than that of watered or water-stressed sorghum (-140 MPa m2 s mol?1). The hydraulic resistance of water-stressed sunflower increased steeply during a day and by the end of the day it had a hydraulic resistance that approached that of sorghum. 相似文献
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茶叶多糖铁的合成及其铁含量的测定 总被引：8，自引：0，他引：8
用热水浸泡法从粗老茶叶中提取茶叶多糖,在碱性条件下,茶叶多糖水溶液与三氯化铁反应合成茶叶多糖铁配合物(TPC),并用邻菲罗啉分光光度法和原子吸收光谱法测定TPC中铁(Ⅲ)的含量。实验结果表明:TPC是深棕红色无定型粉末,易溶于水,在pH值3~12范围内不沉淀,不水解。TPC中铁(Ⅲ)的含量:邻菲罗啉分光光度法测定结果为20.71%,原子吸收光谱法测定结果为20.13%。 相似文献
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The population density of Closterotomus trivialis (Costa) and its damage potential were studied in citrus and olive orchards of Crete. C. trivialis was found to be most abundant in wild radish Raphanus raphanistrum L., annual mercury Mercurialis annua L., Urtica sp. and upright pellitory Parietaria officinalis L. compared to mallow Malva sylvestris L., prickly goldenfleece Uropermum picroides (L.), sowthistle Sonchus oleraceus L., citrus or olive trees. Its damage potential on the setting of olive fruit was investigated at the early inflorescence stage. When 1, 5 or 10 adults of C. trivialis were enclosed with stems at the 55th and 57th phenological growth stages, the number of fruits was significantly reduced compared to controls.The developmental biology of individuals of C. trivialis was studied on R. raphanistrum at seven constant temperatures 15, 20, 25, 30, 32.5, 35 and 37 °C, under laboratory conditions. No nymphs survived above 35 °C. The highest nymph to adult survival (89.6%) was found at 20 °C and the lowest (40.6%) at 32.5 °C. Mean developmental time as well as adult longevity decreased with increasing temperature. The developmental time from 1st nymphal instar to adult ranged from at least 9.0 at 32.5 °C to 27.8 days at 15 °C. The adults lived from 2.9 days at 32.5 °C to 45.3 days at 15 °C. It required 212.7 degree-days to complete development above a minimum threshold of 7.72 °C as estimated by linear regression and 8 °C as estimated by nonlinear model. The importance of these findings in the management of this species through the prediction of its seasonal appearance is discussed. 相似文献
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In this present study, an organic-inorganic hybrid membrane was prepared by embedding yttrium(III) into chitosan matrix for the removal of Cr(VI) from aqueous solutions. Several techniques, including fourier infrared spectrum (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) are employed to characterize the properties of the membrane. The mechanical properties of the membrane were also examined. The chitosan/poly(vinyl alcohol) containing yttrium(III) (CY) membrane was experimentally used for the removal of Cr(VI) ions from aqueous solution under the optimized conditions. The results showed that the adsorption capacity for the removal of Cr(VI) ions was enhanced when yttrium(III) was introduced. The adsorption data from the experiment were fit well by Langmuir isotherm. Based on Langmuir model, q m was calculated to be 38.48 mg g?1. Kinetic study results indicated that the adsorption process followed a pseudo-second-order kinetics. 相似文献
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The oriental (invasive) fruit fly Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae) has invaded Africa and is currently established in over 30 countries and has caused in massive fruit losses. Avocado (Persea americana Miller) is among the fruit with which the pest is associated. The aim of the study was to determine the host status of a ‘black-skinned’ cultivar “Hass” and two ‘green-skinned’ cultivars “Pinkerton” and “Fuerte” to B. (invadens) dorsalis. In the laboratory study conducted in Kenya in 2012 and 2013, punctured and unpunctured recently-harvested fruit were exposed to sexually-mature fruit fly in ‘no-choice’ experiments. B. (invadens) dorsalis readily developed in the punctured fruit but not in the uncompromised fruit (fruit not damaged by insects or handling). This result was confirmed in Tanzania in 2013 where flies were introduced to unpunctured fruit. In the field studies the fruit of each cultivar were caged in situ with flies for 72 h. On dissection only fruit damaged by false codling moth (Thaumatotibia leucotreta (Meyrick)) were found to harbor B. (invadens) dorsalis. In the light of these results the risk imposed for “Hass”, “Pinkerton” and “Fuerte” by B. (invadens) dorsalis is negligible under standard export conditions. The findings of this study and the implications to regional and international trade are discussed. 相似文献