Identification and Characterisation of Bacteria Causing Soft-rot in Agave tequilana

Agave tequilana is the raw material for the production of the alcoholic beverage tequila. A bacterial disease has affected the A. tequilana crop in recent years. Previous reports based on colony and cell morphology, Gram stain and potato rot indicated that Erwinia sp. is the main pathogen. We isolated a several bacterial isolates capable of producing soft-rot symptoms in greenhouse pathogenicity assays. An extensive characterisation involving pathogenicity tests, fatty acid profile, metabolic and physiological properties, ribosomal DNA sequence and intergenic transcribed spacer amplification (ITS-PCR) and restriction banding pattern (ITS-RFLP) was made of each isolate. Three different species: Erwinia cacticida, Pantoea agglomerans and Pseudomonas sp. were identified. Fatty acid and metabolic profiles gave low similarity values of identification but 16S rDNA sequence, ITS-PCR and ITS-RFLP confirmed the identification of E. cacticida. In the phylogenetic tree, E. cacticida from blue agave was grouped neither with E. cacticida type strains nor with Erwinia carotovora. This is the first report that associates E. cacticida with A. tequilana soft-rot symptoms.     

Evaluation of Olive Cultivars for Resistance to Verticillium dahliae

Resistance of 23 important olive cultivars to Verticillium dahliae has been evaluated in four experiments under controlled conditions. Nine-month-old nursery olive plants were inoculated with a cotton non-defoliating (ND) (V4) or a cotton defoliating (D) (V117) isolate of V. dahliae. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale and estimating the area under disease progress curves. The percentage of plants killed and of those which recovered from the disease were used as additional parameters for including a particular cultivar into a defined category. Most of the evaluated cultivars were susceptible, although at different levels, to both isolates of V. dahliae. All cultivars were more susceptible to the D pathotype than to the ND one. A group of 11 cultivars, including several important Spanish cultivars, were susceptible or extremely susceptible to both pathotypes of V. dahliae. A second group showed differences of resistance depending on the pathotype used. They were susceptible or extremely susceptible to the D pathotype but resistant or moderately susceptible to the ND one. Finally, 'Frantoio', 'Oblonga' and 'Empeltre' were moderately susceptible to the D isolate of V. dahliae and resistant to the ND one. The resistance of 'Empeltre' was evident by the plant ability to recover from infection with either isolates. 'Empeltre' is considered to be a valuable cultivar for inclusion in breeding programmes for resistance to Verticillium wilt.     

草地螟和黄草地螟危害苜蓿产量损失及防治指标的研究

采用人工接虫的方法,研究了草地螟的虫口密度与苜蓿产量损失之间的关系和防治指标.结果表明,苜蓿干草产量损失率(y)与20枝条虫量(x)的关系为y=4.936 6x-0.850 9,相关系数r为0.994 3,二者相关性极显著.按照防治的直接收益与直接成本,确定了宁夏旱地苜蓿和水地苜蓿草地螟的防治指标,旱地苜蓿刈割2和3次的草地螟的防治指标分别是10和14头/100枝,水地苜蓿草地螟的防治指标是7头/100枝.依据同样的试验方法,制定了黄草地螟危害苜蓿的防治指标,旱地苜蓿刈割2和3次的黄草地螟的防治指标分别是45和60头/100枝,水地苜蓿黄草地螟的防治指标是36头/100枝.     

中草药饲料添加剂提高奶牛产奶量效果研究

选取同一胎次,健康正常的黑白花奶牛共36头随机分三组,对照组饲喂基础日粮,中草药Ⅰ组饲喂含5%黄芪日粮,中草药Ⅱ组饲喂党参-黄芪复合中药添加剂日粮,进行产奶量比对分析试验.结果证明,在奶牛的日粮中适当添加一定量的中草药添加剂 ,可以明显提高奶牛的奶产量(P＜0.01),产奶量可提高约12.88%左右,并能有效减少奶牛乳房炎的发病率.试验结果还证明,在日粮中添加单味中药添加剂,对奶产量的提高也有一定的影响,但实际效果不如中草药Ⅱ组显著.     

金华地区牧草引种试验研究初报

对从国外和北京引进的13个牧草品种在金衢盆地进行了栽培及品比试验。结果表明：籽粒苋、苏丹草、俄罗斯饲料菜、甜高梁等鲜草产量高；紫花苜蓿、白三叶、鲁梅克斯、欧洲菊苣、籽粒苋等牧草粗蛋白含量较高，在20％以上；冬牧70黑麦草出苗后可在严寒的冬季生长，且产量高；特早熟二倍体和意大利四倍体黑麦草生育期长，可延长黑麦草利用期1个月左右。     

雏鸡服用益生素后免疫器官指数及局部体液免疫球蛋白相对含量的动态变化

用商品益生素和自制益生素分别灌服1日龄雏鸡，灌服益生素后1、4、7、10、18d测定胸腺、脾脏、法氏囊的器官指数动态变化，用间接酶联免疫吸附试验(ELISA)方法测定泪液、气管液、胆汁和肠液的IgA、IgM、IgG相对含量的动态变化，结果发现服用商品益生素的雏鸡免疫器官指数在第7天高于未服用益生素的对照雏鸡，上述4种体液的IgA、IgM、IgG相对含量在服用益生素后7～10d高于未服用益生素的对照雏鸡，服用自制益生素的雏鸡上述4种体液的IgA、IgM、IgG相对含量在服用益生素后4～7d高于未服用益生素的对照雏鸡。表明益生素对雏鸡的免疫系统有一定的影响，能够促进免疫器官的生长发育，提高雏鸡呼吸道和消化道局部体液的免疫球蛋白相对含量。     

鸡传染性喉气管炎油乳剂灭活疫苗的研究

分别将3株鸡传染性喉气管炎病毒(标准强毒株J株、山东分离株N株和L株)经甲醛灭活后制成油乳剂灭活疫苗。免疫效力试验结果表明，以N株鸡传染性喉气管炎病毒制备的油乳剂灭活疫苗免疫效果较其它几种疫苗好，免疫鸡AGP抗体阳性率高达83％，免疫保护率高达100％。     

北京油鸡胚胎成纤维细胞系建立与生物学特性研究

采取组织块直接培养法，对北京油鸡胚胎组织进行原代和继代培养，成功地建立了成纤维细胞系。并对培养细胞进行了形态学、细胞生长动力学观察，以及核型和乳酸脱氢酶、苹果酸脱氢酶的同工酶分析。结果表明，该细胞系的群体倍增时间(PDT)为24h；细胞染色体中二倍体占主体，为76％～88％；乳酸脱氢酶、苹果酸脱氢酶同工酶电泳图谱与本室其它细胞系有明显差别；细菌、真菌、病毒、支原体检测呈阴性。该细胞系的建立，使北京油鸡这一国家重要种质资源在细胞水平上保存下来，也为基因组文库和体细胞克隆等研究提供了理想的生物材料。     

实时荧光定量PCR构建绵羊PrP基因标准品质粒和标准曲线

羊痒病是一种传染性的致死性神经退行性疾病,常引起绵羊和山羊发病,该病在欧洲流行了大约250年,但是它的流行病学和传播机制还不是很清楚.正常的朊蛋白（PrPc）不能引起神经退行性病变,虽然目前已经对许多组织的PrP mRNA进行了检测,但是对它的生物学功能还知之甚少,对PrP基因表达的机制尚不清楚.研究显示,不同组织来源的细胞中朊蛋白的表达程度差异很大,主要出现于神经细胞中.PrPc在细胞中的高水平表达可促使PrPc向PrPsc转变,目前的研究中,对绵羊PrP mRNA的转录机制尚未阐释清楚.因此,对绵羊外周和中枢系统PrP mRNA的表达进行定量,有助于探讨各组织器官中的PrP在羊痒病的发生过程中的作用.