Porcine reproductive and respiratory syndrome virus: morphological, biochemical and serological characteristics of Quebec isolates associated with acute and chronic outbreaks of porcine reproductive and respiratory syndrome.

Cytolytic and noncytolytic strains of the porcine reproductive and respiratory syndrome virus (PRRSV) were isolated in primary cultures of porcine alveolar macrophages (PAM) from lung homogenates of stillborn fetuses or blood samples of dyspneic piglets collected from Quebec pig farms having experienced acute or chronic outbreaks of PRRS. Serological identification of the virus was confirmed by indirect immunofluorescence and indirect protein A-gold immunoelectron microscopy using reference antiserum prepared from experimentally-infected specific pathogen free (SPF) piglets and monoclonal antibodies (MoAbs) directed against the p15 nucleocapsid (N) protein of the reference ATCC-VR2332 isolate. Intracytoplasmic enveloped viral particles that tended to accumulate into cytoplasmic vesicles were observed in the infected PAM; no budding was demonstrated at the level of the cytoplasmic membrane. The extracellular virions appeared as pleomorphic but mostly spherical enveloped particles, 50-72 nm in diameter (averaged diameter of 50 particles was 58.3 nm), with an isometric core about 25-30 nm. Buoyant density of the virus in CsCL density gradients was estimated to 1.18-1.20 g/mL. No hemagglutinating activity was demonstrated. Analysis of semipurified virions of isolate IAF-exp91 by radioimmunoprecipitation (RIPA) and Western immunoblotting experiments, using reference rabbit and porcine hyperimmune sera, revealed four major viral proteins, a predominant 15 kD N protein and three other proteins with predicted M(r_ of 19, 26 and 42 kD. Progeny viral particles produced in PRRSV-infected PAM in the presence of tunicamycin lacked the 42 kD protein, thus confirming its N-glycosylated nature. Immunoprecipitation experiments using the anti-ATCC-VR2332 MoAbs confirmed the close antigenic relationships between Quebec and American reference isolates of PRRSV.     

PEG诱导水分胁迫对柑桔幼苗细胞质膜透性及脯氨酸含量的影响

柑桔叶片相对含水量(RWC)随聚乙二醇(PEG)处理渗透势的降低而依次降低;叶片细胞质膜透性随PEG处理浓度的增加而依次增大;幼苗叶片累积脯氨酸的数量随水分胁迫时间和强度递增。     

如东县鸡腿病病因的调查研究

本文对如东县４０个养鸡户的鸡腿病进行了门诊与跟踪调查。从传染病、营养代谢病及饲养管理三个方面对发病原因进行了初步的探讨。结果表明：营养缺乏和代谢紊乱（特别是钙、磷）是该县鸡腿病的主要原因，传染性腿病如疑似病毒性关节炎、禽脑脊髓炎、葡萄球菌性关节炎等也不容忽视。     

敌百虫对国光、金冠苹果疏除幼果的效应

敌百虫对国光、金冠苹果疏果效应的研究结果表明,国光盛花后10d 喷布1125mg·1~(-1)敌百虫或加20mg·1~(-1)NAA;金冠盛花后12d 喷布900mg·1~(-1)敌百虫或加10mg·1~(-1)NAA,疏除幼果效应显著.果实单果重、翌年花量增加;果实品质、经济效益提高;大小年幅度降低.     

分子间的作用及其结构适应性

某些分子间的作用无法的用范德华力、氢键、介电常数、偶极矩等化学基本理论来加以解释，引入控制论的方法对这些分析间的作用进行研究后的结果表明，选择性分析间引力很可能是分子是最强的物理作用，而分子间的化学作用亦与分子间的结构适应性密切相关。     

应用热脉冲技术对小美旱杨耗水量的研究

应用热脉冲对河套灌区农田防护小美旱杨（Populus popular’s）日蒸腾耗水量进行了研究。结果表明：在正常生长状态下，小美旱杨的日蒸腾耗水量变化曲线呈宽峰状，随着林龄增加，日蒸腾耗水量逐渐增加，在不同水分条件下,灌水时日蒸腾耗水量：萌生苗日蒸腾耗水量大于扦插日蒸腾耗水量。     

两种一年生植物在替代试验中的相互竞争关系

（1）用替代试验研究了燕麦（Aneva sativa）和箭舌豌豆（Vicia sativa）在混播中的竞争相互作用。为了攻混播比例对两种植物在混播条件下的行为影响，田间试验设为5个混播总密度和5种混播比例，共了5次。（2）方差分析表明，相对总生物量（RYT）和竞争平衡指数（CBI）对总密度，混播比例和生长时间的反应敏感。总密度对RYT和CBI的影响高度显著，在大多数情况下，混播比例对RYT和CBI的影响不显著。（3）本文研究的结果表明，持续时间对RYT和CBI很强的影响，在第1次测定时，RYT值接近1而BI值接近0，这一事实表明，种间无竞争或互惠作用。而在生长旺盛期，种间竞争较为剧烈。（4）本研究结果表明，箭舌豌豆的生长严惩受到燕麦的抑制作用，这说明箭舌豌豆在与燕麦混播时表现为竞争上的弱者。