运用致病毒素筛选抗烟草黑胫病细胞突变体Ⅱ 抗毒素愈伤组织的再生植株及其后代的抗病性鉴定

用黑胫病粗毒素作为选择压力, 结合辐射诱变技术, 从烟草花粉植株叶片的愈伤组织中筛选出抗毒素的愈伤组织, 并对其再生植株及其 Ｍ２ 代进行抗病性鉴定、选育． 目前已获得６ 个高抗黑胫病的细胞突变株系, 且抗病性状表现稳定, 并建立了一套烤烟抗黑胫病突变体的筛选和鉴定体系． 研究结果表明, 在细胞水平上筛选抗病突变体是开发新抗源的有效途径．     

茶鲜叶摊放过程中脂质过氧化作用特点初探

对新鲜茶叶在摊放过程中的失水率、细胞膜透性、三种保护酶（ＳＯＤ,ＣＡＴ,ＰＯＤ）活性及脂质过氧化产物丙二醛（ＭＤＡ）含量的变化及其相互关系进行了研究．结果表明,随着摊放时间的延长和叶片失水程度的增加,鲜叶内ＳＯＤ,ＣＡＴ活性先增强然后迅速减弱,ＰＯＤ活性则一直保持增强的趋势,叶片细胞膜透性和ＭＤＡ含量则不断上升．反映出茶鲜叶在摊放过程中脂质过氧化作用不断加剧,并且其增加速率与保护酶活性变化有一定相关,这在一定程度上意味着茶鲜叶适度摊放的化学实质与脂质过氧化作用有关     

水稻白叶枯病菌拮抗细菌B56菌株的拮抗活性研究

B56 菌株经30 ℃振荡培养去菌体,其上清液经2 m ol/L 硫酸铵沉淀获得对水稻白叶枯病菌有拮抗活性的初提液。该初提液具有耐热性,经一定强度热处理后仍保持强的抑菌能力;抑菌效果在pH3～9 之间无明显差异;用胰蛋白酶、蛋白酶K 等处理后拮抗活性无明显变化。利用PhenylSepharose CL-4B疏水色谱柱和DEAE-Sephacel阴离子交换柱分离B56 菌株初提液, 得到一个具有拮抗活性的洗脱峰。该洗脱峰经SDS-PAGE检测发现具有一条分子量约为36 kD 的蛋白带。质粒提取和检测发现B56菌株存在一个稳定的内源质粒。     

Autumn bloom of antarctic pack-ice algae

An autumn bloom of sea-ice algae was observed from February to June of 1992 within the upper 0.4 meter of multiyear ice in the Western Weddell Sea, Antarctica. The bloom was reliant on the freezing of porous areas within the ice that initiated a vertical exchange of nutrient-depleted brine with nutrient-rich seawater. This replenishment of nutrients to the algal community allowed the net production of 1760 milligrams of carbon and 200 milligrams of nitrogen per square meter of ice. The location of this autumn bloom is unlike that of spring blooms previously observed in both polar regions.     

有机化合物构性相关分析的解析程序

根据有机化合物的构性相关规则 ,用演绎推理的方法建立了有机化合物构性相关分析的解析程序。这一解析程序把有机化合物的构性相关分析归纳成 5个步骤 ,即写出靶结构式 ,找出官能团 ,分析官能团和烃基中所含的每 1根化学键 ,考察分子中各结构单元之间产生的相互影响 ,最后分类总结出有机化合物的全部性能。     

泸州地区白背飞虱种群动态及预测预报

随着杂交稻的广泛种植,白背飞虱已成为泸州地区水稻的重要害虫。通过对泸州市叙永,合江,泸县和古蔺县１９８３￣１９９８年白背飞虱灯诱测报资料和田间系统调查资料的分析,结合异地虫情信息交流,天气资料分析,明确了泸州地区白背飞虱虫源主要由黔南,桂北及以南稻区经东南气流迁飞而来。分析了其主要降落范围、害虫田间消长规律和影响其大发生的主要气候因子。建立了预测预报模型,为指导泸州地区白背飞虱防治提供了科学依据。     

Recombinant gene expression in vivo within endothelial cells of the arterial wall

A technique for the transfer of endothelial cells and expression of recombinant genes in vivo could allow the introduction of proteins of therapeutic value in the management of cardiovascular diseases. Porcine endothelial cells expressing recombinant beta-galactosidase from a murine amphotropic retroviral vector were introduced with a catheter into denuded iliofemoral arteries of syngeneic animals. Arterial segments explanted 2 to 4 weeks later contained endothelial cells expressing beta-galactosidase, an indication that they were successfully implanted on the vessel wall.     

A high-resolution radiation hybrid map of the human genome draft sequence

We have constructed a physical map of the human genome by using a panel of 90 whole-genome radiation hybrids (the TNG panel) in conjunction with 40,322 sequence-tagged sites (STSs) derived from random genomic sequences as well as expressed sequences. Of 36,678 STSs on the TNG radiation hybrid map, only 3604 (9.8%) were absent from the unassembled draft sequence of the human genome. Of 20,030 STSs ordered on the TNG map as well as the assembled human genome draft sequence and the Celera assembled human genome sequence, 36% of the STSs had a discrepant order between the working draft sequence and the Celera sequence. The TNG map order was identical to one of the two sequence orders in 60% of these discrepant cases.     

Effects of size and temperature on metabolic rate

We derive a general model, based on principles of biochemical kinetics and allometry, that characterizes the effects of temperature and body mass on metabolic rate. The model fits metabolic rates of microbes, ectotherms, endotherms (including those in hibernation), and plants in temperatures ranging from 0 degrees to 40 degrees C. Mass- and temperature-compensated resting metabolic rates of all organisms are similar: The lowest (for unicellular organisms and plants) is separated from the highest (for endothermic vertebrates) by a factor of about 20. Temperature and body size are primary determinants of biological time and ecological roles.     

芦苇作为环保型有机基质的可能性研究

20世纪80年代以来，岩棉一直是蔬菜无土栽培的主要栽培基质。但由于用后的岩棉条成为大量的不可降解的废物，于是科学家们开始寻找可多年重复利用的无机基质如海绵，以及环保型有机基质如椰子壳丝等。90年代以后，瑞士等国家将芦苇作为有机无土栽培基质应用于蔬菜无土栽培。本文分析比较了芦苇、松木、椰子壳基质使用前的物理和化学特性，并通过栽培樱桃番茄（品种EVITA）的试验，与椰子壳基质和海绵基质栽培性能进行了比较研究。结果表明，芦苇可作为很有应用价值的环保型有机基质在生产中推广与应用。而且由于芦苇生产适应性好，分布广泛，来源充足，基质生产成本低等特点，而显示出很好的应用前景。