红三叶异黄酮在刈割6 h内的变化规律

以豆科牧草红三叶(Trifolium pratense L.)为试验材料,研究6 h内连续刈割后‘炫丽’和‘海发’两品种的叶片和茎秆中抗逆物质异黄酮的含量变化。结果表明,叶片和茎秆的异黄酮总含量在刈割后均明显增加。4种异黄酮类化合物在不同品种和部位中表现出不同的变化趋势。鹰嘴豆素A、芒柄花素含量在‘炫丽’叶片、茎秆刈割3 h后显著增加,而在‘海发’的叶片中表现为下降趋势。大豆苷元含量除在‘炫丽’叶片中保持不变,在其余样品中增加,在茎秆中增加显著。染料木素含量最低,刈割后在‘海发’叶片中增加,‘炫丽’茎秆中显著增加,其余均呈下降趋势。综上可知,异黄酮是红三叶受到刈割后的主要应激响应物质之一,与植物体的再生和恢复密切相关。     

美拉德反应制备鹅肉风味液的研究

[目的]研究美拉德反应条件对鹅肉风味液的影响,为生产鹅肉风味香精提供理论参考。[方法]首先进行单因素试验,通过排序检验法筛选出适合进行响应面分析的美拉德反应参数,选择硫胺素添加量、半胱氨酸添加量、反应温度和反应时间4个因素进行BoxBehnken试验设计,通过响应面分析法获得最佳的美拉德反应条件。[结果]8个单因素中硫胺素添加量、鹅脂添加量、半胱氨酸添加量、反应时间等6个单因素对鹅肉风味有显著影响,根据F值排序,最终选择硫胺素添加量、半胱氨酸添加量、反应温度、反应时间4个单因素进行响应面分析试验。通过方差分析,确定所建立的二次回归模型为有效模型,通过该模型可求得美拉德反应制备鹅肉风味香精的最佳工艺条件为硫胺素1.09 g,半胱氨酸0.62 g,反应温度118.30℃,反应时间56.33 min。[结论]通过优化后的方法制备鹅肉风味液感官评价最高,达到4.186分。     

氧化还原酶辅因子的使用偏好与化学基础

为了探究氧化还原酶对不同辅因子的使用偏好性,使用生物信息学方法对40个物种体内氧化还原酶辅因子的使用频率进行了统计分析,发现古核生物和原核生物体内大约90%的氧化还原酶使用有机辅因子,真核生物体内约78%的氧化还原酶选择使用有机辅因子.为了进一步解释上述现象,一方面,对氧化还原反应方程式进行了分析,发现有机酶组约28.5%的反应需要氧气的参与;而金属酶组约63.2%的反应需要氧气的参与,由此我们推断氧气的出现有可能是导致金属辅因子使用频率升高的重要原因;另一方面,使用化学信息学方法对氧化还原反应涉及的小分子进行了化学性质的分析,发现有机酶组小分子的分子量和亲水性都比较高,由此我们推断金属辅因子更适于疏水的反应环境.     

烘烤过程中烟叶呼吸代谢的生理生化反应

从呼吸代谢的概念出发,介绍了烟叶在调制过程中呼吸代谢的类型,同时分析了影响烟叶呼吸代谢的因素及与烟叶调制过程中的生理生化变化的关系.     

猴头菌转化EGB发酵液提取物抗氧化及抑制非酶糖基化活性研究

猴头菌转化银杏叶粗提物发酵液具有清除体外自由基及抑制体外非酶糖基化反应的作用，对四氧嘧啶诱导的糖尿病模型小鼠具有显著的降血糖效果。但由于发酵液成分复杂，有效成分含量低，不便于直接服用，因而有必要对发酵液功能成分进行提取。笔者以抗氧化活性、体外非酶糖基化反应为指标，比较了、猴头菌转化EGB发酵液经AB-8吸附前后活性物质的活性变化，以期为发酵液的分离提取及提取产物的利用提供参考。     

A novel probe for harpin receptor in nonhost plants: Monoclonal anti-idiotypic antibodies as internal images of HarpinXoo active sites

Harpins constitute one group of effector proteins which elicit a hypersensitive response in nonhost plants, but the subcellular localization and tissue distribution of harpin receptors are still controversial. Antigen mimicry by anti-idiotypic antibodies is employed as a reliable strategy to probe receptors that are present in very low concentrations in the organism. In this study, a monoclonal anti-idiotypic antibody (Ab2), named 6B2, was elicited by F(ab′)₂ fragments digested from the purified polyclonal antibody specific for Harpin_Xoo (Ab1). 6B2 competed with Harpin_Xoo for binding to Ab1 and the total protein extracted from tobacco leaves indicated its anti-idiotypic character and internal image property. The relevance of antigen mimicry was further confirmed by eliciting a third generation antibody (Ab3), which was shown not only to bind to Ab2 competing with Ab1 but also to react with the original antigen, Harpin_Xoo. Taken together, these results demonstrate functional and biochemical mimicry of Harpin_Xoo by Ab2 and suggest that 6B2 can be a useful tool in probing its receptor in nonhost plants and other downstream studies.     

反胶束体系中的酶催化反应

反胶束是新的酶催化反应的介质工程,酶在反胶束体系中的性质与在水溶液中相比有较大区别。综述了含酶反胶束体系的制备、反胶束体系中影响酶催化化学反应的因素,以及在反胶束体系中酶的活性及动力学特性,介绍了反胶束体系下酶催化反应的优点及应用,并展望了其发展前景。     

Sensitivity of seven PCRs for early detection of koi herpesvirus in experimentally infected carp,Cyprinus carpio L., by lethal and non-lethal sampling methods

Koi herpesvirus (KHV) causes an economically important, highly infectious disease in common carp and koi, Cyprinus carpio L. Since the occurrence of mass mortalities worldwide, highly specific and sensitive molecular diagnostic methods have been developed for KHV detection. The sensitivity and reliability of these assays have essentially focused at the detection of low viral DNA copy numbers during latent or persistent infections. However, the efficacy of these assays has not been investigated with regard to low-level viraemia during acute infection stages. This study was conducted to compare the sensitivity of seven different polymerase chain reaction (PCR) assays to detect KHV during the first hours and days post-infection (hpi; dpi), using lethal and non-lethal sampling methods. The results highlight the limitations of the assays for detecting virus during the first 4 dpi despite rapid mortality in experimentally infected carp. False-negative results were associated with time post-infection and the tissue sampled. Non-lethal sampling appears effective for KHV screening, with efficient detection in mucus samples obtained from external swabs during this early infection period (<5 dpi), while biopsies from gills and kidney were negative using the same PCR assays. Non-lethal sampling may improve the reliability of KHV detection in subclinical, acutely infected carp.     

基于辐照场糖基化改性的大豆蛋白冻融稳定性提高研究

为了提高大豆蛋白的冻融稳定性，在辐照场下采用湿法糖基化改性大豆分离蛋白，以接枝度和冻融后的乳析指数为指标进行优化改性工艺试验。结果表明：在大豆分离蛋白(SPI)与麦芽糖(M)质量比为4、SPI质量浓度为40mg/mL、辐照剂量为7.5kGy的条件下，制备的SPI冻融稳定性显著提高；与未改性SPI相比，改性SPI 3次冻融循环后乳液乳析指数分别降低了22.98、28.40、30.70个百分点，出油率分别降低了9.7、21.2、26.4个百分点；乳化活性指数和乳化稳定性指数比未改性的SPI分别提高了9.26m2/g和376min；红外光谱分析表明，麦芽糖分子以共价键的形式与大豆分离蛋白结合；扫描电镜表明，辐照SPI-M微观结构呈蜂窝状，呈现出良好的持水性；光学显微镜分析表明，与未改性的SPI乳液相比，冻融处理后的辐照SPI-M乳液只出现部分小油滴，乳液状态更稳定。     

AFLP技术流程的改进及其在种子研究中的应用

概述了扩增片段长度多态性（AFLP）在模板、酶切、扩增体系、检测和分析方法等方面的技术流程,并探讨了近年来AFLP在种子研究中的应用。