奶牛MTT比色法的最佳条件探讨

为建立奶牛淋巴细胞增殖反应MTT比色法,对试验条件进行了研究。应用L16(45)正交试验,对影响MTT比色法的四个主要因素,包括ConA浓度、细胞浓度、培养液小牛血清浓度及培养时间进行了比较和探索。试验表明几个因素对其增殖反应都有显著影响(P<0.05),且最佳反应条件为:15μg/mL的ConA、1×106/mL细胞浓度、10%小牛血清及60h的培养时间;影响增殖反应的先后顺序为细胞浓度、ConA浓度、培养时间及血清浓度。     

鸡腿菇多酚氧化酶动力学特性

以邻苯二酚(C6H6O2)为底物,采用分光光度法在波长398nm下测定鸡腿菇Coprinus comaus多酚氧化酶(PPO)活性,分析其pH值、温度及底物浓度等因素对PPO活性的影响.结果表明,鸡腿菇PPO活性的最适pH值4.0～5.0,最适温度20℃,在沸水浴30s后酶基本被钝化.鸡腿菇酶促褐变反应的动力学符合米氏方程,米氏常数Km为0.64mol·L-1,最大反应速度vmax为0.08U·min-1.对鸡腿菇不同部位的PPO活性分析表明,菌盖PPO活性＞菌柄(上)＞菌柄(下).     

北京郊区猪戊型肝炎流行初步调查

用间接ELISA试剂盒对北京市郊区所采集的174份猪血清样品进行了抗体检测,结果显示,其抗体总阳性率达62.1%。针对戊型肝炎病毒(HEV)ORF2/ORF3重叠区设计了简并引物,采用巢式RT-PCR对随即采取的少量猪粪便样品进行了抗原检测。结果表明,部分粪便样品中存在HEV。     

山羊亚硝酸盐中毒口液,尿液,棉签偶氮显色快速诊断方法的研究

建立山羊亚硝酸盐中毒模型,用棉签分别蘸取口液、尿液立即滴加偶氮试剂均显粉红色,中毒后１０～２０ｍｉｎ显浅粉红色;６０ｍｉｎ显深粉红色,随中毒症状加重,棉签显色相应加深,甚致变为棕红色。同时棉签显色加深和血液褐变程度加重与ＭＨｂ／Ｈｂ比值升高同步。此种诊断方法是诊断亚硝酸盐中毒的动物可靠、灵敏和快速的诊断方法。     

套式反转录—聚合酶链反应检测恙螨及鼠肺内肾综合征出血热病毒RNA

选择覆盖肾综合征出血热病毒（ＨＦＲＳＶ）膜蛋白（ＭＰ）基因的保守区核苷酸序列合成２对引物,采用异硫氰酸胍一步抽提ＲＮＡ,建立了ＲＴ－ＰＣＲ检测鼠体恙螨及游离恙螨体内ＨＦＲＳＶ－ＲＮＡ的方法,扩增产物经凝胶电泳及斑点印迹杂交证实具有特异性。结果显示,ＨＦＲＳＶ抗原阳性鼠体恙螨５０只组、１０只组、游离螨５０只组,ＨＦＲＳＶ抗原阳性鼠肺１０００ｍｇ、５００ｍｇ组经ＲＴ－ＰＣＲ检测为阳性;ＨＦＲＳＶ抗原阳性鼠体恙螨５只组,ＨＦＲＳＶ抗原阴性鼠体恙螨５０只和１０只组,游离螨１０只和５只组,鼠肺ＨＦＲＳＶ抗原阳性１００ｍｇ组均未见有明显扩增带。进一步用套式反转录－聚合酶链反应（ＮｅｓｔｅｄＲＴ－ＰＣＲ）检测,在ＲＴ－ＰＣＲ未测出ＨＦＲＳＶ－ＲＮＡ的各组中均检测有ＨＦＲＳＶ－ＲＮＡ。结果表明ＮｅｓｔｅｄＲＴ－ＰＣＲ具有高特异、高敏感的特点,可用于检测恙螨体内微量ＨＦＲＳＶ－ＲＮＡ,为确认恙螨作为ＨＦＲＳＶ的传播媒介提供了分子生物学证据。     

杨盘二孢激发子的分离及稳定性研究

 从杨盘二孢的培养滤液和菌丝中获得2种激发子粗提物,分别测定其糖和蛋白质的含量,发现滤液激发子粗提物(CFE)糖和蛋白质的含量分别为41.07和40mg/mL,菌丝激发子粗提物(CME)糖和蛋白质含量分别为48.07和55mg/mL。滤液激发子粗提物对温度不敏感而对碱性条件敏感;菌丝激发子粗提物对酸碱不敏感而对温度敏感。用Sephadex G-100柱层析的方法初步纯化2种激发子,并且菌丝激发子粗提物过柱后得到2个活性组分J14和J25;滤液激发子粗提物过柱后获得2个活性组分L9和L16。将4个组分进行烟草叶片过敏反应和I-895杨酶活性的诱导,结果表明,菌丝激发子强活性物质集中在J14组分;而滤液激发子强活性物质集中在L9组分。     

Need for flagella for complete virulence of Pseudomonas syringae pv. tabaci: genetic analysis with flagella-defective mutants ?fliC and ?fliD in host tobacco plants

The flagellins purified from Pseudomonas syringae pv. tabaci induce a hypersensitive reaction in nonhost tomato cells. To investigate the role of flagella and flagellin in the compatible interaction, we generated two types of flagella-defective mutant. The fliC mutant lost the fliC gene that encodes flagellin protein, whereas the fliD mutant lost the fliD gene that encodes HAP2-capping protein. The two mutants had markedly reduced ability to cause disease symptoms in tobacco leaves. Furthermore, propagation of the mutants in tobacco leaves was less than that in wild-type pv. tabaci. Compared to the inoculation with wild-type pv. tabaci, inoculation with the two mutants did not markedly induce the expression of typical defense response-related genes such as PAL and hsr203J. Complementation of each fliC and fliD gene to the corresponding deficient mutant restored motility and virulence. These results indicate that flagella of P. syringae pv. tabaci are indispensable organelles for complete virulence on host tobacco plants.     

吉林省烟草野火病菌群体分子多态性分析

为研究烟草野火病菌的群体遗传多样性,采用正交试验方法,对5个多态性引物(REP,ERIC,BOX,J3,IS1112)的Rep-PCR反应体系分别进行了优化,同时优化了体系中的Mg2+、dNTP、rTaq酶等几个因素,并在此基础上对来源于吉林省不同地区的70株烟草野火病菌进行了分子多态性分析。结果表明:优化的PCR反应体系电泳图谱清晰,多态性丰富,重复性好,适合烟草野火病菌群体分子标记研究。通过聚类分析发现,吉林省烟草野火病菌群体存在分子多态性,在遗传相似系数为0.9时,70个菌株被聚为4个类群(G1~G4),其中G1类群最大(39个菌株,占55.71%),而G3类群最小,仅包括2个菌株。G1和G2类群分别包含了5个和3个亚群。不同类群和亚群的菌株地理来源存在多样性。     

Chemical changes of kenaf core binderless boards during hot pressing (I): influence of the pressing temperature condition

Self-bonding is the main factor of the performance expression of binderless boards, and therefore its clarification is considered to be an important issue. For this purpose, a series of chemical analyses were conducted on kenaf core binderless boards and their chemical changes during the hot-pressing process are discussed in this article. First of all, binderless boards were prepared from kenaf core powder at different pressing temperatures (without steam-explosion process) and were used for chemical analyses after they were reduced into powders and extracted with methanol. To investigate their chemical changes, lignin, holocellulose, and neutral sugar contents were determined, Fourier transform infrared (FTIR) spectra were recorded, and the nitrobenzene oxidation procedure was applied. As a result, it was found that parts of lignin and hemicelullose were decomposed during the hot-pressing process; however, the contribution of the resulting fractions to selfbonding was not observed. In addition, progress of condensation reactions in lignin and the formation of chemical bonds by low molecular weight conjugated carbonyl compounds in methanol extractives were observed. Thermal softening of lignin is also suggested to play an important role in the expression of board performance.