Deduced Amino Acid Sequences Surrounding the Fusion Glycoprotein Cleavage Site and of the Carboxyl-terminus of Haemagglutinin–Neuraminidase Protein of the Avirulent Thermostable Vaccine Strain I-2 of <Emphasis Type="Italic">Newcastle disease virus</Emphasis>

A single-tube RT-PCR technique generated a 387 bp or 300 bp cDNA amplicon covering the F₀ cleavage site or the carboxyl (C)-terminus of the HN gene, respectively, of Newcastle disease virus (NDV) strain I-2. Sequence analysis was used to deduce the amino acid sequences of the cleavage site of F protein and the C-terminus of HN protein, which were then compared with sequences for other NDV strains. The cleavage site of NDV strain I-2 had a sequence motif of ¹¹² RKQGRLIG¹¹⁹, consistent with an avirulent phenotype. Nucleotide sequencing and deduction of amino acids at the C-terminus of HN revealed that strain I-2 had a 7-amino-acid extension (VEILKDGVREARSSR. This differs from the virulent viruses that caused outbreaks of Newcastle disease in Australia in the 1930s and 1990s, which have HN extensions of 0 and 9 amino acids, respectively. Amino acid sequence analyses of the F and HN genes of strain I-2 confirmed its avirulent nature and its Australian origin.     

2种钙肥对菜心生长及品质的影响

采用73.0 mg/L的果蔬钙肥及1.25 g/L、2.5 g/L和3.75 g/L 3种浓度的氯化钙溶液对菜心进行叶面喷施,研究不同钙肥处理对菜心生长及品质的影响。试验结果表明,不同的钙肥处理均可促进菜心的生长发育,提高叶绿素含量、增加菜心的产量、改善菜心品质,但存在差异,73.0 mg/L的果蔬钙肥处理效果最好,低浓度氯化钙处理对菜心产量和品质影响很小,中浓度氯化钙处理影响比较大,高浓度氯化钙处理比中浓度处理效果差。在不同的生长发育期,作用效应有所不同,在菜心生长的初期各钙肥处理影响不大,生长中后期影响比较大。     

白菜叶和茎中微量元素Cu、Mn含量的测定

为研究白菜的食品应用及工业应用价值,采用HNO3-HCl O4(4∶1)湿法消解样品,火焰原子吸收光谱法(FAAS)测定白菜叶和茎中微量元素Cu、Mn的含量。试验结果表明,白菜叶和茎中Mn、Cu含量存在明显差异,Mn的含量均大于Cu的含量,且这两种元素在叶中的含量均高于茎。     

小白菜潮汐式栽培专用基质的筛选

对3种不同栽培基质和常规栽培基质（市场销售）在潮汐式灌溉模式下进行小白菜栽培试验,比较小白菜的植物学性状,筛选出适用于潮汐式灌溉的小白菜专用型栽培基质。研究结果表明,处理2（40%茶渣蚓粪、20%泥炭、20%蛭石、20%珍珠岩）培育的小白菜株高、生物量、株幅、SPAD 值均显著优于其他处理,栽培效果显著提高,可推荐作为潮汐式灌溉小白菜栽培的专用型基质。     

中国生态农业与面源污染减排

2007年世界环境日中国的主题为"污染减排与环境友好型社会",农业污染减排是其中一个无法回避的问题。农业污染即面源污染,或称非点源污染,主要有过量施用化肥和农药造成的土壤和水体污染、农业生产废弃物造成的污染和农业温室气体排放等三大类。当前中国严重的面源污染问题是由农业生产方式决定的。中国生态农业是具有中国特色的可持续农业,因充分利用废弃物、综合效益提高、减施化肥和农药等特征,而具备实现面源污染减排的功能。中国生态农业是中国解决面源污染减排和农业可持续发展的最重要途径。针对中国生态农业发展中的问题,应该提高认识、建立和完善支撑体系并积极推广中国生态农业经典模式,加快中国农业发展,推进面源污染减排。     

光敏、温敏核不育水稻核不育基因等位性及基因对数的研究

以光敏核不育系农垦58S及其衍生的光敏核不育系7001S、温敏核不育系W6154S、增矮64S，以及温敏核不育系安农S－1及其衍生的温敏核不育系810S、安湘S、香125S为材料进行相互杂交，在长日高温条件下观察F1的育性，根据其可育性和不育性确定核不育基因的等位性。结果表明：7001S、W6154S、培矮64S与核不育基因供体农垦58S之间有等位点的核不育基因；但温敏核不育系W6154S与培矮64S之间，不具等位点的温敏核不育基因。该结果说明光敏核不育系农垦58S至少存在一对光敏核不育基因和两对温敏核不育基因，而且各对温敏核不育基因可独立遗传，在夏季高温条件下其不育性得到充分表达。安农S－1与其衍生的不育系之间以及衍生的不育系与不育系之间都具有等位点的温敏核不育基因。农垦58S及衍生的核不育系与安农S－1及衍生的核不育系之间没有等位点的核不育基因。     

Determination of the genetic variation in the effect of temperature and daylength on bolting of Brassica campestris L.

Summary Effects of temperature and daylength on the bolting of a number of B. campestris accessions were investigated both in the open and in the IVT phytotron. From the results it was concluded that low temperature and genotype are the predominant factors with respect to bolting. Daylength has rather limited influence. One cultivar bolted more than 12 weeks earlier at 10 and 14°C than at 18°C. On the other hand some cultivars did not require vernalization at all.At 14°C and short daylength, depending on genotype, the period of time between sowing and 50% bolting ranged from 8 to 30 weeks. At this temperature the stimulating effect of long day (24 h), depending again on the genotype, ranged from 0 to 4 weeks. The genotypes most resistant to bolting appeared to be the stubble turnips (B. campestris ssp. rapa).In terms of seed(ling) vernalization at 5°C the cold requirement ranged from 0 to more than 3 weeks, depending on the genotype. The required vernalization periods at 5°C can be used as a criterion in screening for resistance to bolting.     

中药细胞级粉碎及其发展趋势

细胞级粉碎是一项新兴的物料加工技术。介绍了中药细胞级粉碎的概念、原理、特点、设备及其发展趋势。     

基本培养基和蔗糖浓度在大白菜花药培养中对胚状体诱导的影响

以6个大白菜品种为试材进行花药培养,研究了不同基本培养基和蔗糖浓度对胚状体诱导的影响。结果表明,B5和Keller培养基为适适宜的基本培养基;培养基适宜的蔗糖浓度为8％-12％,最适浓度为10％。     

久保桃湿冷贮藏过程中生理生化指标的变化

研究了久保桃在温度1℃±1℃,相对湿度(RH)90%的湿冷保鲜贮藏条件下的几种生理生化指标的变化。试验结果表明,复合保鲜剂在湿冷贮藏条件下能有效地保持久保桃果实的采后品质,可明显抑制桃果实的可溶性固形物含量的增加和果实硬度的下降,降低果实褐变率,从而延缓大桃的成熟。