香蕉枯萎病拮抗菌的筛选及盆栽防效的测定

从香蕉根围土壤中分离得到了六株对香蕉枯萎病具有较强抑制作用的拮抗菌,其中真菌2株(F1、F2)、细菌3株(B1、B2、B3)、放线菌1株(A1).利用土壤接种法和蘸根接种法分别测定了这6株拮抗菌对香蕉枯萎病的盆栽防治效果.结果表明:这6株拈抗菌对香蕉枯萎病均具有一定的防效,其中真菌F2菌株对香蕉枯萎病的防治效果最好,在接种其发酵液60 d后,两种接种方法的平均防效分别达60.54%和67.84%,这为利用生物防治方法控制香蕉枯萎病提供了潜在的资源.     

3株非致病性镰刀菌Fusarium oxysporum菌株对番茄枯萎病的生物防治效果

对3株非致病镰刀菌Fusariumoxysporum菌株IF 23、251/2和MSA35对于番茄枯萎病的生物防治效果进行了初步研究。温室盆栽试验表明:3株菌株对番茄枯萎病均有一定的抑制作用,其中105CFU/g浓度的IF 23菌株的防治效果最好;基质灭菌对于番茄枯萎病也有一定的抑制作用。     

甜瓜枯萎病拮抗菌的筛选及鉴定

[目的]筛选对甜瓜枯萎病菌有较强拮抗活性的菌株,并对拮抗菌株进行分类鉴定,为丰富热带地区甜瓜枯萎病生防菌资源库及田间应用提供参考.[方法]以前期筛选获得的82株菌株为试验材料,通过平板对峙、继代培养、发芽率及盆栽试验筛选出对甜瓜枯萎病菌有较强拮抗活性的菌株,并通过形态特征、生理生化特征及16S rDNA序列分析对筛选获得的菌株进行分类鉴定.[结果]筛选出一株对甜瓜枯萎病菌有较强拮抗活性的放线菌菌株D2,其对枯萎病的防治效果达73.53%.D2菌株可形成气生菌丝和孢子丝,孢子丝呈螺旋形,孢子卵呈圆形,且与利迪链霉菌(Streptomyces lydicus)聚于同一分支中,其同源性达99.6%;综合D2菌株的形态特征及生理生化特性,可鉴定其为利迪链霉菌( S. lydicus ).[结论]D 2菌株对甜瓜枯萎病有较好的防治效果,具有开发成生物农药或生物肥料的潜力.     

含短小芽孢杆菌的种衣剂对棉花枯萎病防治效果的研究

用自鉴定分离的短小芽孢杆菌(Bacillus pumilus)KX-33株为有效成分配制种衣剂,对8种感枯萎病棉花种子和2种抗枯萎病棉花种子包衣。将含不同浓度KX-33菌液种衣剂包衣的棉花种子、含8%宁南霉素及含50%多菌灵种衣剂包衣的棉花种子在室内分别盆栽种植,分析各种衣剂组合对棉花发芽率的影响;将含不同浓度KX-33种衣剂包衣的棉花种子分别在大田种植,比较接种棉花枯萎病菌(Fusarium oxysporum)后不同时期病情指数和防治效果。结果表明,盆栽试验中含不同浓度KX-33菌液的种衣剂与对照比棉种发芽率差异不显著(P0.05),含8%宁南霉素和50%多菌灵的种衣剂与对照比发芽率差异显著(P0.05);大田试验中棉花接枯萎病菌第10天时,短小芽孢杆菌菌液浓度为1×10~8 CFU/mL种衣剂包衣的8种感病及2种抗病棉花品种(系)的防治效果普遍较好,分别为41.67%～72.22%和50.00%～55.56%。使用短小芽孢杆菌菌液浓度为1×10~8 CFU/mL的种衣剂,对棉花枯萎病防治具有较好的应用价值。     

枯草芽胞杆菌R31在香芽蕉根部的定殖能力测定

枯草芽胞杆菌R31在田间和温室对香蕉枯萎病表现出一定防效,为探索其防效产生的机制,利用耐受300 μg/mL利福平和遗传稳定的突变株R31*测定其在巴西蕉和广粉一号粉蕉根际的定殖能力,进行盆栽灌根接种试验.结果显示,每株苗接种50 mL 1.78×108 CFU/mL的菌液,接种后60d,标记菌株在香蕉根际土、根表、根内和球茎中的含量分别为4.14×106 CFU/g(干土)、1.09×107CFU/g(鲜重)、4.66× 104 CFU/g(鲜重)、1.23×103 CFU/g(鲜重);同样处理的粉蕉40d后,根际土和根表的菌量分别为9.87×105 CFU/g(干土),7.9× 104 CFU/g(鲜重).表明突变株R31*在根际土和根表能成功定殖,但在根内和球茎的定殖量则较少,且根际土和根表的定殖量与接种浓度和每天最高气温有关.     

非致病性尖镰孢FO47的原生质体融合改良研究

【目的】改良非致病性尖镰孢FO47的综合性状,获得具有较好防效的生防菌株。【方法】利用原生质体融合技术,将非致病性尖镰孢FO47和生防放线菌153进行融合,通过形态特征和菌落直径生长情况对融合菌株进行初筛,并采用西瓜苗期生长发育、防病效果和抗药性试验对所获得的初筛菌株进行复筛。【结果】筛选出14株菌落直径较FO47生长快的再生菌株,其中菌株F1-35、F1-38、F1-1和F1-41能够促进幼苗生长,菌株F1-35处理西瓜幼苗后单株鲜质量较FO47提高了36.93%,根长较FO47增加了19.07%。菌株F1-35、F1-38和F1-4对西瓜枯萎病的防治效果超过50%,其中菌株F1-35的防治效果最好,达到59.04%。菌株F1-4对多菌灵表现出较高的抗性,说明菌株F1-4可以与低质量浓度多菌灵混合使用防治西瓜枯萎病。【结论】筛选出3株综合性状得到提高的再生菌株,说明原生质体融合是改良生防菌株的有效手段。     

3株植物内生细菌对番茄灰霉病的防治效果

从中草药透骨草、白鲜皮和番茄植株体内筛选出3株对灰霉菌有较强抑制作用的内生拮抗细菌,离体番茄果实灰霉病防治和盆栽防治试验结果表明,3个菌株对番茄灰霉病均有较好的防治效果,先接种拮抗内生细菌24 h后再接种灰霉菌的防效优于同时接种拮抗菌和病原菌的防效;拮抗菌株T15对番茄灰霉病的防治效果优于菌株B2和F8的防治效果。     

木霉菌诱导甜瓜抗枯萎病相关防御反应酶系的研究

测定了木霉菌对甜瓜枯萎病的室内及田间防效。分析了应用木霉菌后，甜瓜根组织中部分防御酶系比活力的变化。结果表明：木霉菌对甜瓜枯萎病有较好的防治效果，室内防效和田间防效分别为72．73％和79．00％，接种木霉菌后β-1，3-葡聚糖酶活性升高，挑战接种尖孢镰孢菌，苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）、多酚氧化酶（PPO）酶活性有明显的增强，表明木霉菌能明显诱导甜瓜对枯萎病的抗性反应。     

拮抗甜瓜枯萎病链霉菌D2菌株发酵条件的优化

[目的]优化甜瓜枯萎病拮抗链霉菌D2菌株的发酵条件,为该菌发酵方法的建立及工业化生产提供科学依据.[方法]以D2菌株有效活菌数为考察指标,玉米粉含量、豆饼粉含量、pH、摇床转速、接种量和温度为影响因素,利用响应面法对D2菌株的发酵条件进行优化.[结果]豆饼粉含量、玉米粉含量和温度对D2菌株有效活菌数有显著影响(P<0.05).D2菌株有效活菌数回归模型为:Y=8.28757+0.12344X1+0.21477X2+0.06184X3-0.05929X12-0.09817X22-0.14942X32(式中,Y为有效活菌数对数,X1、X2和X3分别为玉米粉含量、豆饼粉含量和温度的编码值),理论有效活菌数为2.99×108 CFU/mL.D2菌株最优发酵条件为:玉米粉含量39.08 g/L、豆饼粉含量39.19 g/L、培养温度37.4℃,在此条件下D2菌株有效活菌数为3.01×108 CFU/mL,与理论值接近,但极显著高于未经优化采用培养基Ⅱ得到的有效活菌数(1.0×106 CFU/mL)(P<0.01).[结论]采用响应面法优化得到的D2菌株发酵条件可有效提高该菌株有效活菌数,且回归模型推算出的理论活菌数与优化条件发酵的有效活菌数接近,可用于指导D2菌株的实际规模化生产.     

微生物有机肥能有效防治黄瓜枯萎病

从生长健康的黄瓜根际土壤中分离筛选得到1株对黄瓜枯萎病病原菌——尖孢镰刀菌黄瓜专化型具有较强拮抗作用的细菌菌株B,菌株B对棉花黄萎病、甜瓜枯萎病、辣椒疫病等病原菌有较强的拮抗作用。盆栽试验表明:拮抗菌B与有机肥发酵制成的微生物有机肥(BIO)对黄瓜枯萎病有显著的防治作用,发病率降低66.7%,病情指数下降67%,防治效果达80.7%;而单     

带杠杆千斤顶的设计

带杠杆千斤顶是基于地震、矿难、车祸等场合的救援或自救而自主研发的一种新型、简便、实用、高效的救援装置。由于其构造简单、携带方便,对于空间狭小且地表复杂的救援非常实用,亦可民用或作为工厂维修工具。本文对设计的原理方案、产品优点及使用进行了系统的说明。     

一类生化开关模型的定性分析

本文研究一类生化开关模型其中ｘ≥０，ｙ≥０；ａｉ，ｂｉ，ｃｉ（ｉ＝１，２）为正参数、给出了系统（１）具有开关行为的充要条件．     

Transformation of a star into a planet in a millisecond pulsar binary

Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719-1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction.     

一类p-Ginzburg—Landau泛函的C^1,a口收敛

研究了一类p-Ginzburg-Landau（p〉0）模型的渐近性态.通过局部分析的技巧,推出了泛函的正则性估计.在此基础上,利用Euler方程解的正则性估计及渐近行为,得到了极小元的C1,α收敛.     

Identification of a sex pheromone from a spider

The compounds (R)-3-hydroxybutyric acid and its dimer, (R)-3-[(R)-3-hydroxybutyryloxy]-butyric acid, have been identified as sex pheromones of a spider. These compounds elicit web reduction behavior by males of Linyphia triangularis (Clerck) on the webs of unmated adult females.     

Capture of a single molecule in a nanocavity

We describe a heptameric protein pore that has been engineered to accommodate two different cyclodextrin adapters simultaneously within the lumen of a transmembrane beta barrel. The volume between the adapters is a cavity of approximately 4400 cubic angstroms. Analysis of single-channel recordings reveals that individual charged organic molecules can be pulled into the cavity by an electrical potential. Once trapped, an organic molecule shuttles back and forth between the adapters for hundreds of milliseconds. Such self-assembling nanostructures are of interest for the fabrication of multianalyte sensors and could provide a means to control chemical reactions.     

Conversion of a peroxiredoxin into a disulfide reductase by a triplet repeat expansion

Pathways for the reduction of protein disulfide bonds are found in all organisms and are required for the reductive recycling of certain enzymes including the essential protein ribonucleotide reductase. An Escherichia coli strain that lacks both thioredoxin reductase and glutathione reductase grows extremely poorly. Here, we show that a mutation occurring at high frequencies in the gene ahpC, encoding a peroxiredoxin, restores normal growth to this strain. This mutation is the result of a reversible expansion of a triplet nucleotide repeat sequence, leading to the addition of one amino acid that converts the AhpC protein from a peroxidase to a disulfide reductase. The ready mutational interconversion between the two activities could provide an evolutionary advantage to E. coli.     

Development of a receptor on a foreign nerve fiber in a Pacinian corpuscle

When the sensory fiber of a Pacinian corpuscle (in cat mesentery) is transected (at the inferior mesenteric nerve) transduction fails within 30 hours: the nerve ending produces no generator potentials in response to mechanical stimulation. Electrically elicited nerve impulse conduction continues for at least another 18 hours. A transducer mechanism develops on a regenerating nerve fiber when this fiber enters the denervated corpuscle. Such transducer development takes place on myelinated fibers from the inferior mesenteric nerve, which normally supplies corpuscles, as well as on myelinated hypogastric nerve fibers, which normally do not go to corpuscles, including fibers larger than the original corpuscle afferents.     

湖南省一种刀腹茧蜂学名的订正

订正湖南省一种刀腹茧蜂暗翅刀腹茧蜂Xiphozele obscuripennis You et Zhou 的学名.