抗生素微生物检定法测定黄霉素预混剂的含量

采用抗生素微生物检定法测定黄霉素预混剂的含量,方法的线性范围为1.832～8.736黄霉素单位/mL,r=0.999 3,加样回收率为99.3%,RSD为0.8%(n=10).本方法具有专属性、准确性、重现性好等优点.     

Biochar impact on the estimation of the colorimetric‐based enzymatic assays of soil

This study was carried out in order to assess the influence of biochar applications on the estimation of colorimetric‐based enzymatic assays and to verify the effectiveness of the most common methods. Since most methods used to determine enzymatic activities in the soil are based on colorimetry, biochar may absorb substrates and/or coloured products thereby distorting the analytical result. Biochar was added to two soils, with different textures and cation exchangeable capacities, at a rate of 2% (w/w), and seven enzyme activities were determined following standard methods. The biochar amendment lowered the spectrophotometer reading of the activity of FDAase and dehydrogenase in the sandy soil. In the three enzymatic activities based on p‐nitrophenol production (β‐glucosidase, phosphatase and arylsulphatase), the addition of biochar did not change the enzyme assays. The biochar led to an overestimation in terms of the protease and urease activities in the sandy soil. In the clay loamy soil, biochar did not change the response of any of the enzyme activities tested. A biochar dose of up to 2% only guarantees the effectiveness of the most common spectrophotometric methods for not excessively sandy soils.     

河北农业大学农药残留工作20年

农药残留研究是农业环境保护的重要内容。本文综述了我校２０年来农药残留研究内容及成绩，其中包括农药残留动态及安全使用评价；农药残留分析方法的改进提高；环境、食品中农药残留的调查与检测等。     

水稻rbcs基因启动子的克隆及结构功能分析

利用PCR法克隆了水稻日本晴来源的核酮糖-1、5-二磷酸羧化酶小亚基基因（rbcS）5’上游调控区，命名为Posrbcs。将Posrbcs与gus基因融合，并通过农杆菌介导转入水稻中。对转基因水稻植株中GUS活性进行定性与定量分析，结果表明，Posrbcs启动子可驱动gus基因在转基因水稻植株的叶片、叶鞘、茎杆及颖壳中特异性表达，在胚乳中不表达。然后构建不同长度片断的Posrbcs的5’端缺失体，分别与gus构建融合基因，转入水稻中。对转基因植株GUS活性定量分析结果显示， Posrbcs片段愈短，GUS活性愈低；进一步的光诱导试验结果显示，光能明显提高gus基因表达活性，并且随着Posrbcs片段缩短，Posrbcs中的I box、GT1结合位点、GATA box、T box 等光诱导相关元件的缺失会造成在不同时间段的光诱导活性降低以及光诱导表达时间后移。凝胶阻滞试验证实Posrbcs序列中的这些光诱导相关元件有相应的核蛋白的结合。     

Cholinesterase (ChE) inhibition in pumpkinseed (Lepomis gibbosus) as environmental biomarker: ChE characterization and potential neurotoxic effects of xenobiotics

Inhibition of cholinesterases (ChEs) has been widely used as an environmental biomarker of exposure to organophosphates (OP) and carbamate (CB) pesticides. More recently, this biomarker has been suggested as a putative biomarker for exposure to detergents. The use of cholinesterase inhibition as effect criterion in Ecotoxicology requires the previous characterization of the specific enzymatic forms that may be present in different tissues or organs. Different ChEs isoforms may be present in the same tissue and may exhibit distinct sensitivities towards environmental contaminants. This work intended to characterize the soluble ChEs present in pumpkinseed sunfish (Lepomis gibbosus) total head and dorsal muscle homogenates, through the use of different substrates and selective inhibitors of cholinesterasic activity. Also, the in vitro effects of sodium dodecylsulphate (SDS - anionic detergent) and chlorfenvinphos (organophosphate pesticide) on the enzymatic activity of the mentioned species were investigated. In general terms, the predominant cholinesterasic form present in both tissues was acetylcholinesterase. Chlorfenvinphos was responsible for inhibitory effects on AChE activity, while SDS did not cause any significant effect. These results suggest that in environmental monitoring programs, L. gibbosus head and dorsal muscle AChE can be an adequate diagnostic tool for exposure to OP pesticides; this conclusion however is not applicable to detergent residues. We also discuss the usefulness of L. gibbosus as an alternative model system and valuable option for freshwater ecotoxicological monitoring programs.     

Evaluation of guar meal detoxification by bioassay with rat and tetrahymena pyriformis W

Attempts were made to detoxify guar meal by autoclaving and dilute acid extraction. Upgrading achieved was evaluated by proximate analysis. The extent of detoxification achieved by autoclaving and acid extraction was compared and evaluated by bioassay with male weanling Wistar rats andTetrahymena pyriformis W. Supplementation with tryptophan, methionine and threonine significantly improved the PER of the detoxified guar meal.     

Bluetongue: Laboratory diagnosis

Definitive diagnosis of bluetongue virus (BTV) infection, often subclinical in domestic and wild ruminant relies heavily on laboratory techniques for BTV isolation and demonstration of BTV antigens, viral nucleic acids and antibodies. The virus can be isolated from blood components, mainly the erythrocyte fraction, collected from affected animals during the period of febrile response. Semen collected from male animals at the peak of viremia and tissues from affected animals and fetuses may also be used for BTV isolation. The primary procedure for BTV isolation is inoculation of embryonated chicken eggs with a subpassage onto cell cultures (e.g. BKH-21, Vero cell lines). In addition to the conventional techniques such as fluorescent antibody staining and virus neutralization procedures for sero-grouping and serotyping of BTV isolates, immunohistochemical, immunoenzymatic and immunoelectron microscopic techniques, using monoclonal antibodies (MAb), offer more rapid, specific and sensitive approaches for BTV identification and antigen detection. The progress of molecular biology, especially the development of genetic probes for hybridization analysis and polymerase chain reaction techniques for detection of BTV nucleic acids hold the promise of most efficient diagnostic assays. Among the various serogroup-specific assays for antibody detection, the agar gel immunodiffusion (AGID) and competitive (C) ELISA are the most widely used tests. Because of its limitations (i.e. anticomplementary serum and complexity of the procedure) the complement fixation (CF) test is virtually abandoned and is used in only a few laboratories. Although the AGID test is simple to perform and rapid, it is not highly sensitive or quantitative and has limitations in its specificity. Sera containing antibodies to other group of Orbiviruses (e.g. epizootic hemorrhagic disease) may result in non-specific reaction in the AGID test. Among several ELISAs that have recently been developed, the C.ELISA in which a group-specific MAb to BTV is used, has proved to be the most sensitive and specific assay for detection of antibodies to BTV. Following extensive national and international validation, the C.ELISA is gradually replacing the AGID as a universal test to certify ruminants for trade purposes and to diagnose BT infection in domestic and wild animals. The cell culture-based microtiter serum neutralization (MTSN) is the most commonly used assay for the detection of serotype-specific antibodies to the recognized BTVs in animal sera. The MTSN may be used to type virus isolates and also to monitor animal population for specific serotypes of BTV in epidemiological investigations.     

锶对蚕豆根尖细胞的遗传毒性效应

为探讨Sr²⁺污染对蚕豆根尖细胞的生态毒性效应和对植物生长影响的毒理机制,以蚕豆为试材,通过急性毒性实验、微核实验和彗星实验,以ρ(Sr²⁺)0.01 mmol·L^-1处理为CK,分析了Sr²⁺处理浓度[ρ(Sr²⁺)]为0.05~10 mmol·L^-1对蚕豆根(芽)生长、干重、根尖细胞染色体结构及根尖细胞DNA断裂损伤的影响。结果显示,Sr²⁺对蚕豆的根尖细胞的生态毒性效应具有双重性。当ρ(Sr²⁺)<0.05 mmol·L^-1时可促进蚕豆根、芽生长;ρ(Sr²⁺)>0.25 mmol·L^-1时,蚕豆发芽率下降了17.93%~36.32%,根茎、生物量及总生物量分别降低了42.15%、48.69% 和46.75%。同时,Sr²⁺抑制了蚕豆根尖细胞有丝分裂,促进DNA链发生断裂,导致有丝分裂指数(MI)降低,出现染色体断片和微核,其微核率(MCN)是CK的200%~400%;彗星尾长(TL)、尾部DNA含量(TD)和彗星尾矩(TM)也显著高于CK(P<0.05),表明DNA出现了明显的断裂损伤。     

动物蛋白源抗氧化肽的研究进展

氧化不仅影响食品的质量而且危害人体健康,因此抗氧化一直是生命科学领域的研究热点之一。动物蛋白源抗氧化肽在食品和生物体中表现出了有效的抗氧化活性（如清除自由基、抑制油脂氧化和螯合金属离子等）;当它作为功能性原料时还具有增强人体健康的作用,因此动物蛋白源抗氧化肽被认为是一种安全的抗氧化物质,得到越来越多的关注。文中介绍了动物蛋白源抗氧化肽的研究状况,阐述了影响抗氧化肽抗氧化能力的因子和抗氧化能力的测定方法,并预测了抗氧化肽的应用前景与面临的挑战。