Pathogenesis and clinical signs of equine herpesvirus-1 in experimentally infected ponies in vivo.

Equine herpesvirus-1 (EHV-1) causes respiratory disease, neonatal death, abortion and neurologic disease. The main purpose of this study was to identify viral antigen in respiratory tract samples by immunoperoxidase staining. Six pony foals were selected on the basis of demonstrating seronegativity to EHV-1 by virus neutralization and housed in isolation. They were infected experimentally by administering EHV-1 nebulized ultrasonically through a face mask. Successful infection was clinically apparent as each of the foals had febrile responses, nasal discharge, and enlarged submandibular lymph nodes. Sporadic coughing was also heard. EHV-1 was isolated from nasopharyngeal swabs of 4/6 ponies and seroconversion was demonstrated in all foals. Bronchoscopic examination of the large airways revealed hyperemia. The incidence of recovery of Actinobacillus suis from nasopharyngeal swabs increased initially, with recovery of Streptococcus zooepidemicus isolates predominating at 3 wk post-infection. Cytology brushes were used to sequentially sample the respiratory tract of the infected ponies at the nasopharynx, mid-trachea and the mainstem bronchus. Bronchoalveolar lavage provided lung cells. Immunocytochemistry techniques were applied to both types of samples to locate EHV-1 antigen. Indirect immunoperoxidase staining of samples utilizing monoclonal antibodies specific for EHV-1 demonstrated viral antigen associated with cellular debris, primarily in the nasopharyngeal samples on days 3-9 post-infection.     

Proteoglycan-specific molecular switch for RPTPσ clustering and neuronal extension

Heparan and chondroitin sulfate proteoglycans (HSPGs and CSPGs, respectively) regulate numerous cell surface signaling events, with typically opposite effects on cell function. CSPGs inhibit nerve regeneration through receptor protein tyrosine phosphatase sigma (RPTPσ). Here we report that RPTPσ acts bimodally in sensory neuron extension, mediating CSPG inhibition and HSPG growth promotion. Crystallographic analyses of a shared HSPG-CSPG binding site reveal a conformational plasticity that can accommodate diverse glycosaminoglycans with comparable affinities. Heparan sulfate and analogs induced RPTPσ ectodomain oligomerization in solution, which was inhibited by chondroitin sulfate. RPTPσ and HSPGs colocalize in puncta on sensory neurons in culture, whereas CSPGs occupy the extracellular matrix. These results lead to a model where proteoglycans can exert opposing effects on neuronal extension by competing to control the oligomerization of a common receptor.     

天津市农业节水灌溉现状及发展方向

根据天津市农业节水灌溉的现状,分析了目前存在的农业节水工程建设速度缓慢、建设标准不高,管理体制和用水机制不健全,先进的节水技术和管理机制发展不平衡、不普及、不深入等主要问题,并根据山丘区、井灌区、混灌区和旱作区等不同节水类型区域,提出各类型区域发展节水灌溉的重点。     

The refractometric determination of the total protein concentration in some animal plasmas

Abstract

Extract

Refractometry has been used for serum or plasma total, protein determination since the beginning of this century and while at times the value and accuracy of the technique has been open to question (see Lines and Raine, 1970a Babul, J. and Stellwagen, E. 1969. Measurement of protein concentration with interference optics. Analyt. Biochem., 28: 216–221. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar],b Barry, K. G., McLaurin, A. W. and Parnell, B. L. 1960. A practical temperature-compensated hand refractometer (the TS-meter). Its clinical use and application in estimation of total serum proteins. J. lab. din. Med., 55: 803–808.  [Google Scholar]), many studies have shown close agreement between refractometric determination of serum total protein and estimation by such techniques as the Biuret method and the Kjeldahl nitrogen determination (Lines and Raine, 1970b Drickman, A. and McKeon, F. A. 1962. Determination of total serum protein by means of the refractive index of serum. Am. f. clin. Path., 38: 392–396.  [Google Scholar]; Barry et al., 1960 Harboe, M. 1959. A method for determination of haemoglobin in plasma by near-ultraviolet spec-trophotometry. Scand, J. clin. lab. Invest., 11: 66–70. [Taylor &; Francis Online] , [Google Scholar]; Drickman and McKeon, 1962 Henry, R. J. 1974. Clinical Chemistry, 177–177. New York, Evanston and London: Harper &; Row. John Weatherhill, Tokyo [Google Scholar]).     

经营强度对毛竹林植物多样性的影响

对由天然针阔混交林或天然阔叶林经过人为改造和抚育转变成的4类毛竹林(即成林原因相同的4种林型—强度干扰下的毛竹纯林,较强干扰下的竹杉混交林,较弱干扰下的竹阔混交林,弱度干扰下的竹杉阔混交林)的层次结构、物种组成、物种丰富度、α多样性及群落相似性经营强度对毛竹林植物多样性的影响进行了对比分析。结果表明:这4种人工毛竹林随着经营强度的加大,层次结构逐渐简单化,乔木层、灌木层和草本层的物种丰富度迅速下降,且物种组成发生显著变化。乔木层、灌木层和草本层的生物多样性总体也呈下降趋势,但灌木层和草本层的生物多样性竹阔混交林类型反倒略高于经营强度最弱的竹杉阔混交林类型。而且不同经营强度下所形成的这4种类型毛竹林的群落相似性也随着经营强度的增加而降低,其中毛竹纯林与其他3类的相似性最低。     

农副产品及废弃物化感抑藻作用的研究与机理

农副产品废弃物作为可再生性、可降解性的生物质资源,在农村被大量的丢弃和焚烧,给环境造成了极大地危害.通过一系列技术处理,可以从农副产品和废弃物中提取化感物质,应用于海水和淡水中藻类的抑制,以有效利用废物资源.文章对化感作用的概念、20种农副产品及废弃物对19种藻类的化感抑制作用以及化感作用抑藻机理等进行了较系统的论述,对今后植物化感作用抑藻技术的研究方向进行了展望.提出应多学科结合,利用化感物质对不同藻类的影响及其选择性抑制机理做更深入的研究.     

溴虫腈与哒螨灵对朱砂叶螨的联合作用

为明确溴虫腈与哒螨灵的联合杀螨活性,采用玻片浸渍法测定了溴虫腈与哒螨灵不同配比混剂对朱砂叶螨雌成螨的杀螨活性,并以共毒因子法和共毒系数法评价混剂的增效作用。结果表明,溴虫腈和哒螨灵对朱砂叶螨雌成螨处理后24 h的致死中质量浓度(LC50)分别为8.80、17.69mg/L;溴虫腈与哒螨灵的质量比为49∶51、47∶53、45∶55时增效最明显,对朱砂叶螨处理后24 h的共毒系数分别为177.94、178.49、173.73,LC50分别为6.65、6.72、7.00 mg/L,其毒力分别是哒螨灵的2.66倍、2.63倍、2.53倍。因此,45%~49%溴虫腈与51%~55%哒螨灵混合具有显著的增效作用。     

Transformation of the nitrogen cycle: recent trends, questions, and potential solutions

Humans continue to transform the global nitrogen cycle at a record pace, reflecting an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food production in some parts of the world is nitrogen-deficient, highlighting inequities in the distribution of nitrogen-containing fertilizers. Optimizing the need for a key human resource while minimizing its negative consequences requires an integrated interdisciplinary approach and the development of strategies to decrease nitrogen-containing waste.     

响应面法对金银花中绿原酸提取工艺的优化

为优化金银花中绿原酸提取率的最佳工艺条件,在单因素试验的基础上,应用Box-Behnken中心组合设计研究了乙醇质量分数、水浴时间、微波温度3个独立因子对金银花中绿原酸提取率的影响,再利用响应面分析法优化提取工艺条件。结果表明:绿原酸微波辅助提取最佳工艺条件为微波功率400W,微波温度58℃处理70 s,料液比1∶25,乙醇质量分数72%,60℃水浴加热51 min。经实际提取验证,绿原酸提取率为4.643 mg/g。