影响微生物接种剂发挥作用的因素

大量施用化肥不仅造成了环境污染, 而且也是一个能源消耗的问题。在生态农业中, 通过向土壤中接种有益微生物部分替代化肥已是科学家研究的热点。微生物通过活化土壤养分、抑制病原菌、降解有毒污染物等方式发挥作用, 然而, 微生物要发挥功效必须在土壤中能够定殖。本文主要针对国内外在影响微生物根际定殖的因素以及影响引入微生物活性的因素两方面的研究进行综述, 同时强调对接种剂引入所引起的生物种群及生态环境变化应予以重视。     

土壤有益细菌在植物根际竞争定殖的影响因素

在土壤有益微生物应用于生物肥料、生物杀虫剂、植物生长刺激剂和生物处理剂的过程中,根际定殖具有重要作用。细菌在植物根际定殖是一个比较复杂的过程,影响定殖能力的因素也是复杂多样的。本文综述了参与根部竞争定殖的生物因素,包括受细菌遗传控制的某些特性如鞭毛/运动性、趋化性、多糖、位点特异重组酶/菌落阶段变异、NADH脱氢酶,植物根的分泌物和植物种类等;影响微生物根际定殖的非生物因素如土壤类型、土壤特性和土壤温度等,探讨了影响微生物根际定殖的主要研究方向。     

Factors which Affect Efficiency of Autoradiography with Tritiated Thymidine

The overall efficiency of autoradiography with tritium-labeled thymidine has been found to be influenced by the following conditions: (1) exposure in an atmosphere of CO₂ and the use of the stripping-film technique, both of which increase the autoradiographic efficiency when compared to exposure in air or to dip-coating technique; (2) latent image fading, which increases with increasing exposure. Up to 2 wk of exposure, however, this disadvantage is counterbalanced by the fading of the mechanical background produced during stripping or dip-coating; (3) the thickness of the inert coating interposed between the labeled locus and the sensitized emulsion. A layer of inert coating can be obtained that will arrest all beta particles from tritium, while having no effect on more energetic emitters like C¹⁴; (4) the amount of tritiated thymidine given, with relatively large amounts producing an increase in the mean grain count per labeled cell but not in the percentage of cells identifiable as labeled; and (5) the type of fixative and the staining procedure used. Feulgen stain reduces the mean grain count in cells labeled with radioactive thymidine, while fixation with acetic alcohol (1:3) reduces the grain count in cells labeled with precursors of ribonucleic acid.     

Effect of VA Mycorrhizal Inoculation on Growth of Asparagus Seedlings

Experiments on asparagus (Asparagus of)icinalis L.) inoculated with VA mycorrhizal fungi were conducted under two fluvo-aquatic phosphorus deficient soils. This study was to examine the growth response of VA mycorrhizae and fertilizer effects on the growth of mycorrhizal and non-mycorrhizal asparagus seedlings in pots and under field conditions. Inoculation with VA mycorrhizal fungi significantly increased mycorrhizal infection and enhanced seedling growth. In treatments of fertilization by different batches of NPK or by different amount of application it was shown that phosphorus was most favourable to VAM activity. Both the prevalance of mycorrhizal infection and the dry weight of seedlings in treatment with NPK in 1:0:1 was similar to that in 1:1:1 and 1:2:1 after inoculation. Further more the prevalance of infection, plant growth and P content in the treatment of 1/2 an amount of NPK in 1:1:1 were even higer than those in full amount of NPK and in non-fertilization. It is indicated that phosphorus uptake and plant growth benefit greatly by mycorrhizal inoculation. Mycorrhizal plant requires only about half as much phosphorus to achieve maximum growth as the uninoculated plants.     

管花肉苁蓉与柽柳试管苗离体接种的研究

用去果皮的种子对柽柳长根实生苗和试管苗进行接种,建立管花肉苁蓉种子与柽柳的离体接种体系,用体视显微镜观察接种情况并用整体透明方法观察侵染情况.结果表明,寄主柽柳的试管苗与管花肉苁蓉种子的共培养能够建立管花肉苁蓉-柽柳接种复合体,这将为研究寄主-寄生物相互关系提供有效的实验体系.     

伤寒Vi多糖菌苗接种反应观察

本文报告了对我国首次成功的伤寒Ｖｉ多糖菌苗进行人体接种反应观察结果,接种对象为２０至５４岁无伤寒病史,近年无伤寒菌苗接种史的健康人,共６０名,以完全随机的方法分为两组,实验组注射３０μｇＶｉ多糖菌苗,对照组注射Ｖｉ多糖菌苗的稀释液。其结果３０名Ｖｉ多糖菌苗接种者注射后体温无中重反应发生,局部红肿仅有１例中反应。注射后对血压、心律没有影响。红细胞计数,白细胞计数均在正常范围,与接种前相比,无显著差异     

Nutrient Constraints on Metabolism Affect the Temperature Regulation of Aquatic Bacterial Growth Efficiency

Inorganic nutrient availability and temperature are recognized as major regulators of organic carbon processing by aquatic bacteria, but little is known about how these two factors interact to control bacterial metabolic processes. We manipulated the temperature of boreal humic stream water samples within 0–25°C and measured bacterial production (BP) and respiration (BR) with and without inorganic nitrogen?+?phosphorus addition. Both BP and BR increased exponentially with temperature in all experiments, with Q ₁₀ values varying between 1.2 and 2.4. The bacterial growth efficiency (BGE) showed strong negative relationships with temperature in nutrient-enriched samples and in natural stream water where community-level BP and BR were not limited by nutrients. However, there were no relationships between BGE and temperature in samples where BP and BR were significantly constrained by the inorganic nutrient availability. The results suggest that metabolic responses of aquatic bacterial communities to temperature variations can be strongly dependent on whether the bacterial metabolism is limited by inorganic nutrients or not. Such responses can have consequences for both the carbon flux through aquatic food webs and for the flux of CO₂ from aquatic systems to the atmosphere.     

Inoculation of millet with azospirillum

Summary Millet plants (Pennisetum glaucum) were grown at three levels of nitrogen fertilization with and without an inoculum of live nitrogen-fixing Azospirillum cells. The highest average rate of nitrogen fixation as estimated from acetylene reduction by excised preincubated roots was only 23g N₂ fixed per ha per day and occurred after treatment with low levels of nitrogen amendment. The average rates of acetylene reduction for intact plants at all treatments were also low. The lack of significant nitrogen fixation due to an Azospirillum-millet association in this study was substantiated by plant dry weight analysis, and determination of the nitrogen content of plants, pot leachate, and soil. There was significant correlation between the total nitrogen content of the plants per pot at the termination of the experiment and the amount of nitrogen fertilizer added initially, but there was no effect of inoculum on final total nitrogen content.     

电转染效率影响因素的探讨

目的:探讨影响电转染效率的因素。方法:将CHO细胞和DNA(携带标志基因的质粒)混和后进行电转染,观察电转染前孵育温度、渗透压、电转染参数、细胞周期等对细胞存活率和电转染效率影响。结果:孵育温度不影响细胞的存活率,而影响基因的转染效率;电转染前后低渗条件有利于电转染;延长电转染持续时间和频率而不加大电压有利于电转染;最好选用处于G2/M期的细胞进行电转染。结论:初步认为温度、渗透压、电转染参数、细胞周期等对细胞存活率和电转染效率有一定的影响。     

介绍一种兔VX2肿瘤的传代和接种方法及其应用经验和体会

目的:介绍一种兔VX2肿瘤的传代和接种方法及其应用经验和体会,从而更好的利用此模型进行生物医学研究。方法:从荷瘤新西兰大白兔取活性良好的肿瘤组织块,制备肿瘤细胞悬液,过滤后接种于健康成年新西兰兔左后肢肌肉内。通过一般观察、MRI和大体及病理学切片对肿瘤进行验证。结果:肿瘤传代和接种后生长良好,MRI、大体及组织学验证保持了VX2的肿瘤特点。结论:本研究介绍的兔VX2肿瘤的传代与接种方法稳定、可靠,值得大家推广和应用。     

10种绿化苗木对VA菌根的依赖性及其接种效应

研究了10种绿化树对VA菌根的依赖性、感染率及其接种效应。结果表明:各参试树种对VA菌根都有不同程度的感染率及依赖性;其中黑金刚(Ficus elastica cv.Deocora Burgundy)接种感染率最高,达90%,巴西榕(Ficus elastica cv. Variegaa)、竹节树(Carallia brachiata)的接种感染率大于80%,接种感染率大于60%的有花金刚(Ficus elastica cv. Decora Tricolor)、红关公(Ficus elastica cv. Decora)、扭纹铁(Dracaena deremensis)、红桂木(Artocarpus nitidus subsp. lingnanensis),小于35%的有红楣(Anneslea fragrans)、伞花木(Eurycorymbus cavaleriei)、石楠(Photinia serrulata);黑金刚、巴西榕对VA菌根的依赖度最高,都超过了300%,红关公、花金刚对VA菌根的依赖度中等,分别为213.3%、203.5%;红桂木、竹节树、扭纹铁、石楠、红楣、伞花木对VA菌根依赖性偏弱,依赖度都在200%以下。参试树种菌根感染率和依赖度的排序基本一致。VA菌根对各参试树种均有不同程度的接种效应,对黑金刚、花金刚、红关公、巴西榕和竹节树的接种效应最为明显,对扭纹铁、红桂木的接种效应较好,而对石楠、红楣和伞花木则稍差。