鸡胚内抗氧化物质的分布与变化

生物体内存在多种内源性抗氧化物质,在生命过程中发挥着基本的防御功能,是人们十分关注的研究领域。本文综述了近年来鸡胚内抗氧化物质的形成与来源等研究成果,分析了鸡胚孵育过程中维生素(A、C、E)、类胡萝卜素、硒、过氧化氢酶和超氧化物歧化酶等主要抗氧化物质的分布与变化,及内源性抗氧化系统的形成,旨在为今后的研究提供有益的科学依据。     

鸡ICV法的改建与NPY注射试验

目的：在参考Davis等建立的侧脑室注射（ICV）法的基础上,建立鸡ICV法。方法：利用改建的鸡ICV法研究梯度注射神经肽Y（NPY,2．5p．g／bird和5μg／bird）对鸡采食量的影响。结果：ICV套管安装手术的成功率为88％（37／42）,注射成功率为64％（23／36）;NPY可显著提高注射后1～4h和24h鸡的采食量（P〈0．05）,提高幅度在6．88%（5μg／bird,注射后24h）-138．95％（注射后1h）之间,注射后3h内,采食量随注射剂量增加而增加。结论：本研究建立的鸡ICV注射法是适用的,NPY是鸡重要的诱食因子之一,利用建立的ICV法,2．5μg／bird的外源性NPY就足以使鸡产生采食反应,为今后进一步开展鸡行为学研究提供方法和依据。     

鸡髓样分化因子88的原核表达及单克隆抗体制备

目的:克隆、表达、纯化鸡髓样分化因子88(MyD88),制备其单克隆抗体。方法:从脾脏cDNA中扩增857bp的MyD88基因片段,插入pMAL-c5X表达载体,转化大肠杆菌BL21(DE3)获得表达菌株,IPTG诱导表达,用SDS-PAGE分析MBP(麦芽糖结合蛋白)-MyD88重组融合蛋白的表达,切胶纯化目的蛋白;免疫BALB/c小鼠,制备针对MyD88的单克隆抗体,Western印迹检测抗体特异性,制备腹水并进行抗体亚型鉴定和效价测定。结果:构建了鸡MyD88原核表达载体pMAL-MyD88,并在大肠杆菌中获得高表达,目的蛋白以可溶性和包涵体两种形式存在;建立了3株抗鸡MyD88单克隆抗体细胞株,制备了腹水,亚型分别为IgG1、IgG1和IgG2a,轻链均为κ,腹水抗体的效价均为1∶2×105。结论:在原核表达系统中表达、纯化了重组鸡MyD88,制备了针对鸡MyD88的单克隆抗体,为后续的MyD88定量和功能研究奠定了基础。     

植物对土壤中铀的吸收与富集

核工业发展导致重金属铀排放和扩散,并造成了地表土壤的污染,对人类的生存环境产生了极其不利的影响。如何修复铀污染土壤成为亟待解决的问题。近年来发展起来的植物修复技术以其成本低廉、安全和环保的特点成为修复铀污染土壤的新选择。寻找理想的铀富集植物是这一技术的基础和关键。该文通过实验模拟铀污染的土壤（土壤中铀的浓度为100 mg.kg–1）,进行一次和二次铀污染土壤的植物修复后,从4个方面对植物修复铀污染土壤效果进行评估,即富集铀的浓度、生物提取量、生物富集系数（BFS）和转运系数（TFS）。实验结果表明：第1次修复时,四季香油麦菜（Lactuca dolichophylla）地上部富集铀的浓度为1.67×103 mg.kg–1,生物富集系数和转移系数均大于3;第2次修复时,麦冬（Ophiopogon japoni-cus）富集铀的浓度与第1次修复相比变化不大,而吊兰（Chlorophytum comosum）、四季豆（Phaseolus vulgaris）和艾蒿（Artemisia lavandulaefolia）富集铀的浓度与第1次修复相比均减少4–8倍;施加土壤改良剂鸡粪肥、海藻肥和柠檬酸后发现海藻肥和柠檬酸能够增强植物对铀污染土壤的修复;对两次修复土壤中铀的形态进行对比分析,发现二次修复时土壤中生物有效态铀的含量降低,造成第2次修复的难度增加。     

Dissection and Culture of Chick Statoacoustic Ganglion and Spinal Cord Explants in Collagen Gels for Neurite Outgrowth Assays

The sensory organs of the chicken inner ear are innervated by the peripheral processes of statoacoustic ganglion (SAG) neurons. Sensory organ innervation depends on a combination of axon guidance cues¹ and survival factors² located along the trajectory of growing axons and/or within their sensory organ targets. For example, functional interference with a classic axon guidance signaling pathway, semaphorin-neuropilin, generated misrouting of otic axons³. Also, several growth factors expressed in the sensory targets of the inner ear, including Neurotrophin-3 (NT-3) and Brain Derived Neurotrophic Factor (BDNF), have been manipulated in transgenic animals, again leading to misrouting of SAG axons⁴. These same molecules promote both survival and neurite outgrowth of chick SAG neurons in vitro^5,6.Here, we describe and demonstrate the in vitro method we are currently using to test the responsiveness of chick SAG neurites to soluble proteins, including known morphogens such as the Wnts, as well as growth factors that are important for promoting SAG neurite outgrowth and neuron survival. Using this model system, we hope to draw conclusions about the effects that secreted ligands can exert on SAG neuron survival and neurite outgrowth. SAG explants are dissected on embryonic day 4 (E4) and cultured in three-dimensional collagen gels under serum-free conditions for 24 hours. First, neurite responsiveness is tested by culturing explants with protein-supplemented medium. Then, to ask whether point sources of secreted ligands can have directional effects on neurite outgrowth, explants are co-cultured with protein-coated beads and assayed for the ability of the bead to locally promote or inhibit outgrowth. We also include a demonstration of the dissection (modified protocol⁷) and culture of E6 spinal cord explants. We routinely use spinal cord explants to confirm bioactivity of the proteins and protein-soaked beads, and to verify species cross-reactivity with chick tissue, under the same culture conditions as SAG explants. These in vitro assays are convenient for quickly screening for molecules that exert trophic (survival) or tropic (directional) effects on SAG neurons, especially before performing studies in vivo. Moreover, this method permits the testing of individual molecules under serum-free conditions, with high neuron survival⁸.     

High-Throughput Measurement and Classification of Organic P in Environmental Samples

Many types of organic phosphorus (P) molecules exist in environmental samples¹. Traditional P measurements do not detect these organic P compounds since they do not react with colorimetric reagents^2,3. Enzymatic hydrolysis (EH) is an emerging method for accurately characterizing organic P forms in environmental samples^4,5. This method is only trumped in accuracy by Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy (³¹P-NMR) -a method that is expensive and requires specialized technical training⁶. We have adapted an enzymatic hydrolysis method capable of measuring three classes of phosphorus (monoester P, diester P and inorganic P) to a microplate reader system⁷. This method provides researchers with a fast, accurate, affordable and user-friendly means to measure P species in soils, sediments, manures and, if concentrated, aquatic samples. This is the only high-throughput method for measuring the forms and enzyme-lability of organic P that can be performed in a standard laboratory. The resulting data provides insight to scientists studying system nutrient content and eutrophication potential.     

Comparative fecundity and survival rates of Phlebotomus papatasi sandflies membrane fed on blood from eight mammal species

Female sandflies, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae), were fed via chicken membrane on heparinized blood from eight species of mammal (human, horse, cow, pig, dog, rabbit, guinea-pig, hamster) and their reproductive success rates were compared. No appreciable differences between those fed on human and animal blood were detected with respect to the proportion of flies that fed successfully, mortality-rate within 24h, number of eggs laid per blood-fed female or egg viability. When mass-rearing sandflies for research purposes, membrane-feeding avoids practical difficulties encountered if sandflies are allowed to feed on live hosts (i.e. anaesthesia, distress from handling and postfeeding inflammation) and reduction of sandfly fecundity due to host antibody interference. Use of animal blood also eliminates risks of accidental transmission of human blood-borne pathogens, e.g. hepatitis B and human immunodeficiency virus (HIV), and is less expensive than maintenance of animals and their preparation for sandfly feeding.     

Life-Cycle Assessment of Biosolids Processing Options

Biosolids, also known as sewage sludge, are reusable organic materials separated from sewage during treatment. They can be managed in a variety of ways. Different options for biosolids handling in Sydney, Australia, are compared in this study using life-cycle assessment. Two key comparisons are made: of system scenarios (scenario 1 is local dewatering and lime amendment; scenario 2 is a centralized drying system) and of technologies (thermal drying versus lime amendment). The environmental issues addressed are energy consumption, global warming potential (GWP), and human toxicity potential (HTP).
Scenario 2 would consume 24% more energy than scenario 1. This is due to the additional electricity for pumping and particularly the petrochemical methane that supplements biogas in the drier. A centralized system using the same technologies as scenario 1 has approximately the same impacts. The GWP and HTP of the different scenarios do not differ significantly.
The assessment of technology choices shows significant differences. The ample supply of endogenous biogas at North Head sewage treatment plant for the drying option allows reductions, relative to the lime-amendment option, of 68% in energy consumption, 45% in GWP, and 23% in HTP.
Technology choices have more significant influence on the environmental profile of biosolids processing than does the choice of system configurations. Controlling variables for environmental improvement are the selection of biogas fuel, avoidance of coalsourced electrical energy, minimization of trucking distances, and raising the solids content of biosolids products.     

Factors affecting the pressure resistance of some Campylobacter species

AIMS: To compare pressure resistance between strains of Campylobacter jejuni, Campylobacter coli, Campylobacter lari and Campylobacter fetus, and to investigate the effect of suspending medium on pressure resistance of sensitive and more resistant strains. METHODS AND RESULTS: Six strains of C. jejuni and four each of C. coli, C. lari and C. fetus were pressure treated for 10 min at 200 and 300 MPa. Individual strains varied widely in pressure resistance but there were no significant differences between the species C. jejuni, C. coli and C. lari. Campylobacter fetus was significantly more pressure sensitive than the other three species. The pressure resistance of C. jejuni cultures reached a maximum at 16-18 h on entry into stationary phase then declined to a minimum at 75 h before increasing once more. Milk was more baroprotective than water, broth or chicken slurry but did not prevent inactivation even of a resistant strain at 400 MPa. CONCLUSIONS: Pressure resistance varies considerably between species of Campylobacter and among strains within a species, and survival after a pressure challenge will be markedly influenced by culture age and food matrix. SIGNIFICANCE AND IMPACT OF THE STUDY: Despite the strain variation in pressure resistance and protective effects of food, Campylobacter sp. do not present a particular problem for pressure processing.