1株感染多种致病性大肠杆菌噬菌体的生物学特性研究

旨在测定此前从断奶前仔猪粪样中分离得到的1株大肠杆菌噬菌体C6在致病性大肠杆菌上的生物学特性,并比较该噬菌体在不同致病菌上的感染特性。利用电镜形态观察和基因组测序确定其分类,用点滴法和双层平板法测定其在致病性大肠杆菌上的宿主谱,通过噬菌斑形态、最佳感染复数（MOI）、成斑率（EOP）、吸附率、一步生长曲线以及抑菌曲线等来评价噬菌体在多株致病菌上的感染特性。结果显示：噬菌体C6可感染1株非致病性大肠杆菌和4株致病性大肠杆菌,包括大肠杆菌O157（E.coli W1）、2株产志贺毒素大肠杆菌（STEC W3、STEC W5）和1株肠致病性大肠杆菌（EPEC 143）。通过比较噬菌体C6在4株致病菌上的各项感染特性指标发现：噬菌斑大小和成斑率E.coli W1>EPEC 143>STEC W3>STEC W5;吸附率E.coli W1>EPEC 143、STEC W3、STEC W5;最佳MOI EPEC 143、STEC W3、STEC W5>E.coli W1;液体LB中生长能力和抑菌能力E.coli W1>STEC W3>EPEC 143、STEC W5。噬菌体C6为T4样噬菌体,可感染多株致病性大肠杆菌,在不同致病菌上的感染特性存在差异,但均能显著抑制致病菌的生长。     

干扰素刺激基因对羊口疮病毒在OFTu细胞中增殖的抑制效应

羊口疮病毒（ORFV）是重要的人兽共患病病原,不仅严重危害养羊业,而且威胁人类健康。干扰素刺激基因（stimulator of interferon genes,STING）作为细胞的DNA感受器,在机体天然免疫中起重要作用。为探索STING在ORFV感染中的作用及其对病毒复制的影响,本研究构建了ORFV感染羊胚胎鼻甲细胞（OFTu）的模型,分析了ORFV感染细胞后对STING及其相关基因的动态表达,探索了STING基因在干扰表达和过表达状态下对ORFV在细胞上增殖的影响。结果表明,ORFV感染OFTu细胞后,STING、cGAS、TBK1、IRF3、IRF7、IL-6、IFN-β、IL-1β和TNF-α的转录明显升高。OFTu细胞过表达STING可导致RIG-1、DDX41、IFI16、IRF3、IRF7、IL-6、TNF-α、IFN-α和IFN-β等基因转录上调。OFTu细胞在STING过表达状态下感染ORFV可介导TBK-1、IRF3、IFN-β和TNF-α的转录升高,抑制ORFV的复制;在STING表达干扰的状态下,ORFV感染OFTu细胞降低了TBK-1、IRF3、IFN-β和TNF-α的转录,增加了ORFV的复制。这表明STING蛋白能够增强抗病毒细胞因子的表达,抑制ORFV在OFTu细胞中的增殖,研究结果为深入理解STING在羊口疮病毒感染和复制中的作用提供了科学的理论依据,也为深入探索ORFV感染和致病的分子机制提供了基础数据。     

冰草属植物组织培养再生体系的建立

以适宜西北地区种植的优质牧草冰草属(AgropyronGaertn)中的三个不同种———蒙古冰草新品系(A.mongolicumKeng)、航道冰草(A.cristatumcv.Fairway)、诺丹冰草(A.desertorumcv.Nordan)和一个种间杂种冰草———蒙农杂种冰草(A.cristatum×A.desertorumcv.Mengnong)为材料,分别以幼穗为外植体建立了冰草组织培养再生体系。诱导愈伤组织的培养基为改良MS+2,4 D2.0mg/L,分化培养基为MS(无附加成分),在1/2MS培养基上生根后得到完整小植株。结果表明在本试验条件下,不同长度的幼穗在培养时,其愈伤组织发生的部位及其增殖速度不同;4种材料愈伤组织诱导率和分化率无明显差异,均可有效诱导愈伤组织并分化成再生植株,再生植株的产生主要通过直接器官发生途径。     

Optimal allocation of resources in evaluating current sunflower inbred lines for resistance to Sclerotinia

Sclerotinia sclerotiorum (Lib.) de Bary is a major limiting factor for sunflower (Helianthus annuus) production. This study was conducted to (1) evaluate a large number of current sunflower lines for their reaction to Sclerotinia, and (2) determine the optimum allocation of resources for their selection. A set of 85 inbred lines was screened under artificial leaf infection in three environments. The test revealed ample variation for all resistance traits in the current germplasm. A line selected from NDBLOS, an oilseed sunflower germplasm poo, and its derivatives were most resistant to Sclerotinia. Lines derived from interspecific crosses with the wild species Helianthus tuberosus and Helianthus argophyllus also showed satisfactory Sclerotinia resistance. The evaluation of five plants per plot in two replications and four environments appears to be a reasonable allocation of resources in order to optimize the selection response.     

河北屠宰场高致病性猪蓝耳病带毒情况调查

为了了解河北省屠宰场猪只高致病性猪蓝耳病的带毒情况,采用RT-PCR方法对2006～2009年采自全省11个地市228个县级屠宰场1565份商品猪的肺脏或肺门淋巴结进行高致病性猪繁殖与呼吸综合征病毒(HP-PRRSV)病原学检测,结果4年间猪场的阳性比率分别为55.56％、72.50％、44.62％和28.74％;4年样品阳性检出率分别为28.45％、40.74％、12.01％和7.31％.HP-PRRSV同伪狂犬病病毒(PRV)、圆环病毒2型(PCV-2)和猪瘟病毒(CSFV)混合感染所占的比率为61.66％,多以PCV-2和PRV的二重或三重混合感染为主.总之,HP-PRRSV在河北省猪群中污染面积较大,值得高度重视.     

复方硫氰酸红霉素可溶性粉对人工感染鸡慢性呼吸道病的疗效试验

用复方硫氰酸红霉素可溶性粉以每升水中加0.5、0.6、0.7、0.8、0.9 g 5个剂量对人工感染鸡慢性呼吸道病的鸡群混饮治疗,同时设立硫氰酸红霉素可溶性粉对照组.试验结果表明,用药5d后,复方硫氰酸红霉素可溶性粉每升水加0.6、0.7、0.8、0.9g剂量组的有效率和治愈率皆高于硫氰酸红霉素可溶性粉组.     

不同基质接种不同丛植菌根真菌对黄檗幼苗侵染及生长的影响

通过盆栽接种试验,用4种丛枝菌根真菌(Arbuscular mycorrhizae,AM)接种黄檗1 a生实生苗,探索不同接种基质、不同菌种以及混合菌种条件下,内生丛枝菌根(Vesicalar-Arbuscular,VA)真菌对黄檗(Phellodendron amurense Rupr.)幼苗的侵染效果及对其生长量的影响.结果表明:不同基质条件下接种丛枝菌根真菌对寄主植物的生长发育的影响差异很大,就该试验菌种接种黄檗而言,以草炭∶蛭石∶沙子=1∶0.5∶1基质接种效果良好;通过混合接种与单独接种的侵染特性比较,凡是含G.mosseae和G.diaphanum菌种的接种处理侵染率高,显著提高了苗木的生长量,而含有G.versiforme和G.diaphanum的组合侵染率一直比较低,而且降低了G.mosseae和G.diaphanum的侵染效率.     

Temporal association of potato tuber development with susceptibility to common scab and Streptomyces scabiei‐induced responses in the potato periderm

Using hydroponics and novel non‐destructive pot culture systems which enable inoculation at specific tuber development stages, the dynamics of common scab infection patterns in potato were studied in order to provide more precise identification of tuber physiological factors associated with susceptibility. At the whole‐tuber level, infection percentages were greatest when Streptomyces scabiei inoculation occurred early; at 2 weeks after tuberization (WAT) 68% of tubers became infected, contrasting with late inoculation (8 WAT), when only 4% infection occurred. The first‐formed internodes were most susceptible to infection, whilst later‐forming and slower‐expanding internodes were less susceptible. Detailed tuber physiological examination of internode 2 showed that pathogen‐induced changes, including increased phellem (periderm) thickness, cell layers and phellem suberization (key physiological features believed critical to S. scabiei infection) were promoted through S. scabiei inoculation. Sequential harvesting showed enhanced phellem suberization (28% greater than the control) within 7 days of pathogen exposure, while phellem thickness and layer responses were also initiated early in the infection process (10–14 days after pathogen exposure) and these responses were independent of symptom expression. Differences in cultivar response were observed, with greater phellem suberization observed 10 days after tuberization (DAT) in the common‐scab‐tolerant cv. Russet Burbank than in the susceptible cv. Desiree. Likewise, Russet Burbank had thicker and more numerous cell layers in the phellem (up to eight cell layers) during early tuber growth (20–30 DAT) than Desiree (up to six cell layers).     

山核桃溃疡病与营养元素的关系

调查并分析了安徽省宁国市不同种植区山核桃溃疡病与土壤因子、树皮中营养元素等之间的关系,结果表明:山核桃林分中土壤条件与溃疡病的发生与发展的关系十分密切,其感病指数与土壤密度,树皮中P、Fe的含量呈正相关关系;与土层深度,土壤中N、P、K元素的含量和土壤中有机质的含量及树皮中N、K、M g的含量等呈负相关关系。     

油茶根腐病发生规律和综合防治研究

油茶根腐病是油茶林的新病害，植株自发病至死亡为２～３年，其病菌为根际土壤习居菌，喜酸性和较低温度，病菌侵入植株的途径主要是伤口，潜育期２０ｄ左右．防治本病的关键是保护幼树根颈部及主根不受伤害，加强管理，增强树势．此外，用熟石灰在根际处与表土层拌匀覆盖和用多菌灵、退菌特等杀菌剂及时进行防治，并辅以营林技术措施治理，可收到良好的防治效果．