鸡腿菇多酚氧化酶动力学特性

以邻苯二酚(C6H6O2)为底物,采用分光光度法在波长398nm下测定鸡腿菇Coprinus comaus多酚氧化酶(PPO)活性,分析其pH值、温度及底物浓度等因素对PPO活性的影响.结果表明,鸡腿菇PPO活性的最适pH值4.0～5.0,最适温度20℃,在沸水浴30s后酶基本被钝化.鸡腿菇酶促褐变反应的动力学符合米氏方程,米氏常数Km为0.64mol·L-1,最大反应速度vmax为0.08U·min-1.对鸡腿菇不同部位的PPO活性分析表明,菌盖PPO活性＞菌柄(上)＞菌柄(下).     

中华鳖同工酶研究

采用垂直淀粉胶电泳对中华鳖脑、眼、心、肌、肝、肾和卵巢七种组织中的六种同工酶系统（ＬＤＨ、ＡＤＨ、ＩＤＨ、ＭＥ、Ｇ６ＰＤＨ、ＥＳＴ）进行研究，构建了中华鳖同工酶酶谱，并利用草鱼ＬＤＨ－Ｂ４抗体对中华鳖ＬＤＨ酶谱进行了免疫化学分析，确定了中华鳖ＬＤＨ同工酶酶谱和亚基组成，揭示了鱼类ＬＤＨ与爬行类ＬＤＨ在进化上的保守性     

Degradation and effect of hydrogen peroxide in small‐scale recirculation aquaculture system biofilters

From an environmental point of view, hydrogen peroxide (HP) has beneficial attributes compared with other disinfectants in terms of its ready degradation and neutral by‐products. The rapid degradation of HP can, however, cause difficulties with regard to safe and efficient water treatment when applied in different systems. In this study, we investigated the degradation kinetics of HP in biofilters from water recirculating aquaculture systems (RAS). The potential effect of HP on the nitrification process in the biofilters was also examined. Biofilter elements from two different pilot‐scale RAS were exposed to various HP treatments in batch experiments, and the HP concentration was found to follow an exponential decay. The biofilter ammonia and nitrite oxidation processes showed quick recuperation after exposure to a single dose of HP up to 30 mg L^?1. An average HP concentration of 10–13 mg L^?1 maintained over 3 h had a moderate inhibitory effect on the biofilter elements from one of the RAS with relatively high organic loading, while the nitrification was severely inhibited in the pilot‐scale biofilters from the other RAS with a relatively low organic loading. A pilot‐scale RAS, equipped with two biofilter units, both a moving‐bed (Biomedia) and a fixed‐bed (BIO‐BLOK^®) biofilter, was subjected to an average HP concentration of ～12 mg L^?1 for 3 h. The ammonium‐ and nitrite‐degrading efficiencies of both the Biomedia and the BIO‐BLOK^® filters were drastically reduced. The filters had not reverted to pre‐HP exposure efficiency after 24 h, suggesting a possible long‐term impact on the biofilters.     

二元共沉淀体系去除沼液有机物及机理分析

针对猪场沼液有机质含量高,其他处理工艺周期长、成本高、难去除的问题。采用包含氧化钙水溶液和AlCl3的二元共沉淀体系去除沼液有机污染物。探究了沉淀剂配比、投加量、反应时间、沼液初始pH等因素对有机物去除效果的影响。结果表明:当共沉淀剂体积比为1∶2.5、投加量为1∶1(体积比)、反应时间60 min、pH为9时有机质最大去除率达到93%。通过对反应前后沉淀物XRD、FITR和SEM分析,表明共沉淀剂可与沼液中带负电有机质通过电荷吸引以及与正价金属离子的络合作用絮凝沉淀有机物。沉淀反应迅速且去除有机质较为彻底,在养殖场废水处理中具有良好的工业应用前景。     

Characterization and expression of SLO1 potassium channels during spermatogenesis in Eriocheir sinensis

SLO1 potassium channels are pivotal to many aspects of spermatogenic cell. Experiments were conducted to assess physiology and function of SLO1 potassium channels in different developmental stages of spermatogenic cell in Eriocheir sinensis. First, the expression of SLO1 protein was examined via Western blot, RT‐PCR, immunohistochemistry and immunofluorescence assays. The results showed that the expression of the SLO1 protein was not uniform in the spermatogenic cells of E. sinensis. Second, whole‐cell patch clamp technique was used to record the potassium current of spermatogenic cells and to analyse the electrophysiological characteristics of the potassium channels with the aid of inhibitors. It is proved that the potassium current in E. sinensis germ cells is associated with intracellular Ca²⁺, and the calcium‐activated potassium channel mediated by SLO1 protein is mainly large‐conductance Ca²⁺‐activated K⁺ channels (BK_Ca). Based on these researches, the cDNA of SLO1 from testis was cloned and sequenced. The SLO1 protein contained domains bound to calcium ions, and the spatial structure formed by its tetramers constituted potassium channels. Phylogenetic analysis revealed that SLO1 was much closer to Scylla paramamosain than other examined species. Finally, iberiotoxin (IbTX) and CdCl₂ were used to inhibit the acrosome reaction (AR) induced by A23187 and to explore the role of SLO1 potassium channels in the AR of E. sinensis. The experimental results showed that SLO1 potassium channels were expressed in E. sinensis spermatogenic cells and played an important role in the AR of crab sperm (SP).     

液相色谱-串联质谱法测定水产品中孔雀石绿的残留量

建立了液相色谱-串联质谱测定水产品中孔雀石绿及其代谢物残留的检测方法。样品经乙酸铵盐溶液和乙腈提取,经二氯甲烷萃取,PRS阳离子交换柱净化,然后选用电喷雾离子源,在正离子、多反应监测方式模式下进行定性,以内标法进行定量。方法的检出限为0.10μg·kg-1,工作曲线的线性范围为0.10~4.00μg·kg-1。在添加浓度为0.10~4.00μg·kg-1的范围内,孔雀石绿和隐色孔雀石绿的平均回收率均分别为83.4%和95.0%,相对标准偏差分别为6.23%和6.74%。     

Need for flagella for complete virulence of Pseudomonas syringae pv. tabaci: genetic analysis with flagella-defective mutants ?fliC and ?fliD in host tobacco plants

The flagellins purified from Pseudomonas syringae pv. tabaci induce a hypersensitive reaction in nonhost tomato cells. To investigate the role of flagella and flagellin in the compatible interaction, we generated two types of flagella-defective mutant. The fliC mutant lost the fliC gene that encodes flagellin protein, whereas the fliD mutant lost the fliD gene that encodes HAP2-capping protein. The two mutants had markedly reduced ability to cause disease symptoms in tobacco leaves. Furthermore, propagation of the mutants in tobacco leaves was less than that in wild-type pv. tabaci. Compared to the inoculation with wild-type pv. tabaci, inoculation with the two mutants did not markedly induce the expression of typical defense response-related genes such as PAL and hsr203J. Complementation of each fliC and fliD gene to the corresponding deficient mutant restored motility and virulence. These results indicate that flagella of P. syringae pv. tabaci are indispensable organelles for complete virulence on host tobacco plants.     

棕色化反应调控技术在烟草中的应用现状及展望

棕色化反应影响着烟叶及其烟草制品的外观和内在品质.对酶促褐变和非酶促褐变的反应杌理、调控技术研究和在烟草中的应用现状进行了综述,探讨了棕色化反应调控技术的发展前景.     

水溶剂红花油合成共轭亚油酸研究——(I) 工艺优化研究

传统油脂共轭反应制备共轭亚油酸多采用有机溶剂,这种工艺存在溶剂残留等潜在问题。研究了红花油以水为溶剂的碱性异构化合成共轭亚油酸反应,考察了反应温度、时间、水油比、油碱比对共轭反应的影响,得到工艺条件的数学模型。反应的最佳条件为反应温度214℃,反应时间4.9h,水油比=4.3,油碱比=1.3。在此条件下,反应转化率可达到97.64%。