山楂多酚类物质的提取及其抗氧化活性研究

[目的]研究山楂中多酚类物质的提取和体外抗氧化作用,为山楂作为抗氧化、抗衰老的保健食品的开发提供理论依据。[方法]通过70%乙醇提取与D101大孔吸附树脂纯化制备山楂多酚;采用铁离子还原/抗氧化能力测定法、邻苯三酚自氧化法、二苯代苦味酰基自由基(DPPH.)分析法及油脂过氧化值测定法,测定山楂多酚的体外抗氧化能力。[结果]纯化制备的山楂多酚含量为60.24%;山楂多酚对羟自由基(.OH)的50%清除率(IC50)为53.4μg/ml;对O2-.的50%清除率(IC50)为42.3μg/ml;对DPPH.的50%清除率(IC50)为63.3μg/ml;山楂多酚有较强的抗猪油氧化作用,能显著抑制猪油POV的增加。[结论]山楂多酚的提取工艺比较简单,有较强的体外抗氧化能力。     

姬松茸加工过程中防褐变的研究

根据姬松茸酶促褐变的机理,研究了姬松茸加工过程中防褐变的有效方法。以处理后菇片中多酚氧化酶的残存活性及视觉观察菇片放置8h不褐变为指标,确定每种方法的最适参数。结果表明,防止姬松茸褐变有四种方法:沸水热烫10min,0.7％亚硫酸钠溶液浸泡,直接添加0.7％VC或添加0.5％亚硫酸钠与0.3％VC。     

Characteristics of citrus fruits in relation to granulation

A study was conducted in different citrus cultivars to observe the incidence and degree of granulation, and to measure polyphenol oxidase (PPO) activity and phenolic content pattern in relation to granulation. Standard procedures were followed to observe the incidence and degree of granulation, phenolic content pattern, PPO activity and pheno-physicochemical fruit characteristics of citrus fruits. Across all citrus cultivars studied, 25% of the fruit were affected by granulation to the degree of about 10%. In general, granulated fruit were larger in size than normal fruit, and were inferior in quality characteristics. Among different citrus cultivars, ‘Kaula’ mandarin had highest incidence of granulation (62.5%), followed by ‘Mosambi’ sweet orange (43.6%) and the least in ‘Kagzi’ lime (12.2%). Phenolic content and polyphenol oxidase activity also varied widely among different citrus types, and were significantly higher in normal fruit than granulated fruit. Thus, it appears from the study that PPO plays some role in the occurrence of granulation in citrus.     

酶活性与黄瓜对霜霉病抗性的关系

研究了多酚氧化酶和过氧化物酶活性与黄瓜对霜霉病抗性的关系。结果表明黄思苗在感病期间,不同品种叶片质膜透性的增大与这两种酶活性有密切关系,抗病性强的,质膜透性增幅增低,酶活性高;反之,抗病性弱的,质膜透性增效大酶活性低。     

树脂法吸附分离苹果汁中多酚物质的研究

通过树脂的筛选、吸附和解吸条件的优化等对树脂法分离提取苹果汁中多酚物质进行了研究。结果表明,XDA-5树脂为吸附分离苹果汁中多酚物质的优良材料,其吸附最适温度为40℃,适宜的洗脱剂为80%乙醇溶液。在此基础上结合苹果浓缩汁加工工艺提出了一条分离提取苹果多酚的新途径。根据该方法制备的苹果多酚提取物中总酚含量可达到96.72%。该方法既能提高苹果浓缩汁的品质和稳定性,又实现了资源的充分利用。     

微型薯多酚氧化酶的特性研究

对分离纯化后的微型薯的多酚氧化酶性质进行研究,以邻苯二酚为作用底物,用分光光度计在波长420 nm处测定不同pH值、反应温度、底物条件下微型薯的多酚氧化酶(PP0)活性,以讨论微型薯的褐变机理.结果表明,微型薯的PPO最适pH值约为5.5,最适反应温度为35℃左右.该酶热稳定性差;最适作用底物为绿原酸、原儿茶酸和咖啡酸;FeSO4和抗坏血酸等化合物可以抑制PPO活性,CaCl2和CuS04等则起促进作用.适度高温、强酸性或碱性条件、FeSO4或抗坏血酸等处理都可以抑制该酶活性.     

固定化酶膜催化茶多酚形成茶黄素反应条件优选

用SAS统计软件中的响应面分析法探讨了固定化多酚氧化酶酶膜催化儿茶素生产茶黄素的最佳反应条件,确定了酶膜法生产高纯度茶黄素的五个重要因素及最佳组合。五个因素包括反应时间、酶与底物之比、通气量、底物浓度和pH值。最佳反应条件为：反应时间49βmin、酶与底物之比为1:128.7、通气量为23.81L/min 、底物浓度5.95βmg/ml和pH值4.3。该条件下产物茶黄素浓度的理论值为0.766βmg/ml,实测值为0.754±0.017βmg/ml,表明优化模型合理,条件筛选结果准确。     

杀雄剂SQ 1诱导的小麦生理型雄性不育系交替氧化酶基因(AOX1)的表达分析

为了揭示小麦生理型雄性不育败育过程与交替氧化酶（AOX1）基因表达的关系,利用荧光定量技术分析了小麦交替氧化酶基因家族AOX1基因（AOX1a和AOX1c）在K型遗传型不育系[ms（Kots）-90-110]、K型不育系和恢复系杂交后经多代回交选育的可育系（BC5F1）以及杀雄剂SQ-1诱导的BC5F1小麦生理型雄性不育系的旗叶和花药（单核期、二核期、三核期）中的表达情况。结果表明,AOX1a基因在供试可育系（BC5F1）和遗传型不育系[ms（Kots）-90-110]中的表达规律一致,都表现为旗叶中的表达量较少,花药单核期表达量最高,二核期和三核期表达量下降;SQ-1诱导的生理型不育系中AOX1a基因在旗叶中表达量也最少,花药单核期表达量最高,二核期表达量减少,但三核期略呈上升;与其他2个材料相比较,生理型不育系的单核期AOX1a基因的表达量极显著增加,二核期极显著降低。AOX1c基因在3个材料各时期的表达规律一致,都表现为先升后降;但在表达量上,可育系与生理型不育系各时期的表达量两者几乎没有差异,遗传型不育系中的单核期表达量极显著低于可育系和生理型不育系。推测,AOX1a基因在生理型不育系单核期和二核期的异常表达,可能影响了花药发育过程中抗氰呼吸途径,导致呼吸代谢紊乱,引起花药败育;AOX1c基因没有参与生理型不育的代谢调节。     

基于线粒体COⅠ序列比较长江口中华绒螯蟹放流与野生群体的遗传多样性

为探讨长江口中华绒螯蟹(Eriocheir sinensis)放流亲蟹与野生群体的遗传多样性和遗传结构的差异,对77个放流和野生亲蟹个体进行了线粒体细胞色素氧化酶亚基Ⅰ(COⅠ)基因序列的比较分析,结果表明:所检测的样本共计77个COⅠ基因序列(630 bp)中,变异位点(V)41个,简约信息位点(P)37个,A+T(61.7%)的含量明显高于C+G(38.3%),表现出较为明显的碱基组成偏倚性;两个群体共检测出15种单倍型,其中单倍型Hap-1出现频率最大,为两个群体所共享,放流和野生群体各具有5种独有单倍型;两个群体的单倍型多样性指数(H)为0.825,核苷酸多样性指数(π)为0.004 66,平均核苷酸变异数(K)为2.910,其中野生群体的单倍型多样性指数(0.833)和核苷酸多样性指数(0.007 70)均高于放流群体(0.810和0.002 11)。AMOVA分子方差分析表明,长江口中华绒螯蟹放流与野生群体总的遗传变异主要来自群体内,其中96.53%遗传变异来自各群体内部,3.47%遗传变异来自群体间。群体内遗传分化指数(FST)野生群体(0.034 75)高于放流群体(0.034 57),两个群体间遗传分化指数(FST)为0.034 66(P0.05),两个群体遗传分化不显著。两个群体间的基因流(Nm)为13.93(Nm1),表明放流群体和野生群体的基因交流较为频繁。     

Short-term biochar-induced increase in soil CO2 release is both biotically and abiotically mediated

The application of biochar to soil has been shown to cause an apparent increase in soil respiration. In this study we investigated the mechanistic basis of this response. We hypothesized that increased CO₂ efflux could occur by: (1) Biochar-induced changes in soil physical properties (bulk density, porosity, moisture content); (2) The biological breakdown of organic carbon (C) released from the biochar; (3) The abiotic release of inorganic C contained in the biochar; (4) A biochar-induced stimulation of decomposition of native soil organic matter (SOM) which could occur both biotically or abiotically; (5) The intrinsic biological activity of the biochar results in the liberation of CO₂. Our results show that most of the extra CO₂ produced after biochar addition to soil came from the equal breakdown of organic C and the release of inorganic C contained in the biochar. Using long-term ¹⁴C-labelled SOM, we show that biochar repressed native SOM breakdown, counteracting the release of CO₂ from the biochar. A range of mechanisms to describe this negative priming response is presented. Although biochar-induced significant changes in the physical characteristics of the soil, overall this made no contribution to changes in soil respiration. Similarly, the evidence from our study suggests that changes in soluble polyphenols do not help explain the respiration response. In summary, biochar induced a net release of CO₂ from the soil; however, this C loss was very small relative to the amount of C stored within the biochar itself (ca. 0.1%). This short-term C release should therefore not compromise its ability to contribute to long-term C sequestration in soil environments.