宁夏部分地区奶牛场犊牛腹泻病原调查分析

为了明确宁夏地区奶牛犊牛腹泻的发病情况及引起腹泻的病原微生物种类,随机采集宁夏地区10个规模化奶牛场有腹泻症状的132头0～60日龄奶牛犊牛腹泻粪便样品,采用抗原快速检测试剂盒对轮状病毒、冠状病毒、隐孢子虫、大肠埃希氏菌K99、贾第鞭毛虫进行病原检测;采用麦克马斯特氏法进行艾美耳球虫检测.结果显示,132份样品中共检出...     

Vertical transmission and concurrent infection of multiple bacterial pathogens in naturally infected red tilapia (Oreochromis spp.)

Horizontal transmission of various bacterial pathogens in tilapia is well described, but there is scant information regarding their vertical transmission. This study aimed to determine the possibility of vertical transmission of two commonly reported bacterial pathogens (Francisella noatunensis subsp. orientalis and Shewanella putrefaciens) in natural stocks of red tilapia (Oreochromis spp.). Vertical transmission of these pathogens via gametes was evaluated using in vitro fertilization from 10 different families and analysing for the presence of bacteria in milt, unfertilized eggs, fertilized eggs and offspring at various ages (1‐day‐old larvae, 10‐day‐old fry and 30‐day‐old fingerlings), as well as water samples using colorimetric LAMP assay. The study revealed that both F. n. orientalis (6/10) and S. putrefaciens (4/10) was transmitted vertically to the fertilized eggs. Analysis of the water samples from different water sources (brood stock tanks, hatching chamber and larval rearing tanks) showed that both the pathogens were present in water samples with highest prevalence for F. n. orientalis followed by S. putrefaciens. Analyses for the presence of two pathogens in various organs (gonads, gill, liver, spleen, kidney and brain) of the healthy tilapia broodstock without any clinical symptoms of disease demonstrated they were carriers of S. putrefaciens and F. n. orientalis. This is the first documented evidence that vertical transmission via the broodstock of tilapia may also play an important role in transmitting these problematic pathogens to their progeny and underlines the necessity to modify the current disease management strategies in tilapia aquaculture.     

Identification and characterization of pathogens associated with fin erubescence and ulceration of cultured Scophthalmus maximus

Scophthalmas maximus is a precious and main aquacultural species in northern China with an annual output value of more than 1.5 billion yuan. However, with the expansion of breeding range, increased stocking density and variety degradation, a variety of bacterial, parasitic and viral diseases have often occurred and worsened. Among them, bacterial disease is the most serious in farmed S. maximus. Since 2010, an epidemic bacterial disease with primary symptoms of lighter colour of lateral and caudal fins, spotty bleeding, fin base bleeding, abdominal swelling and redness and lesions of internal organs has put broken in S. maximus cultured in Weihai, Longkou and Haiyang, Shandong Province, China. The disease occurred mostly at the seedling and early development stages and propagated very fast, resulting in high mortality. These S. maximus died with obvious surface ulceration in only 3–4 days, causing great economic losses to the aquaculture industry. Beginning in 2010, we conducted epidemiological investigation in farmed S. maximus and isolated two different pathogens from the body of the diseased S. maximus from different farms. In this paper, we observed their morphology, conducted phylogenetic analysis based on their physiological and conventional biochemical characteristics and 16S rRNA gene sequences, preliminarily analysed their pathogenesis and investigated the histopathological changes of the diseased S. maximus. We believed that Vibrio anguillarum and V. parahaemolyticus were the pathogenic bacteria for the epidemic disease in S. maximus.     

蘘荷叶枯病病原菌的分离鉴定与生物学特性

从发病严重田块采集蘘荷叶枯病病叶,采用组织分离法进行病原菌分离、纯化,获得代表性致病菌株RH–1,对RH–1进行鉴定,并测定其生物学特性。结合病原菌形态学特征和分子生物学鉴定,构建真菌内转录间隔区(ITS)、β–微管蛋白基因(β–Tubulin)和TEF–1α系统发育树,鉴定该菌为尖孢镰刀菌(Fusarium oxysporum)。分别在温度(5、10、15、20、25、30、35℃)、pH(4、5、6、7、8、9、10)和光照时间(连续光照、连续黑暗、12h光照/12 h黑暗、24 h光照/24 h黑暗)条件下用PDA培养基培养RH–1,结果在30℃、pH 9和连续光照下菌丝生长较快。分别用葡萄糖、α–乳糖和麦芽糖以及酵母膏、牛肉膏、(NH4)₂SO₄、NH₄Cl、蛋白胨和NH₂CH₂COOH等量替代Czapek基础培养基中的碳源和氮源,发现菌丝生长的较适碳源为葡萄糖或麦芽糖,最适氮源为牛肉膏或蛋白胨。将RH–1分别接种于红蘘荷和绿蘘荷,发现绿蘘荷的抗病性强于红蘘荷的。     

镰刀菌属真菌毒素在植物和病原菌互作中的研究进展

镰刀菌是世界上最重要的植物病原菌之一,可影响植物的生长发育,严重威胁全球粮食安全和生物多样性。几乎所有的镰刀菌都会产生真菌毒素,其毒素种类多、毒性强,一方面可以作为致病因子之一参与镰刀菌的致病过程,另一方面可污染粮食和饲料,进而引起人类和动物的相关病症。已有研究表明,镰刀菌侵染植物后产生的不同种类真菌毒素不仅毒害植物细胞,引起植物组织的坏死,还会加速病原菌的侵染;同时,针对病原菌产生的毒素,植物会激活防御酶并启动防御相关基因的表达,或将致病毒素转化为无毒或低毒物质并转运到胞外,或通过分泌次生代谢物直接抑制病原菌毒素的生物合成。为全面解析镰刀菌毒素在病原菌侵染植物中的作用,提高植物对病原菌的抗性,该文综述了镰刀菌属真菌毒素的种类、毒性机理以及毒素在植物和病原菌互作中的作用,并讨论了植物对真菌毒素的防御反应策略,以期为镰刀菌毒素致病机制和病原菌防治策略研究提供参考。     

Rationally Designed Guanidine and Amidine Fungicides

A previous investigation established that compounds containing a guanidinium or amidinium grouping are effective inhibitors of sterol Δ⁸–Δ⁷ isomerase and/or Δ¹⁴ reductase activity in plant pathogenic fungi. A binding model for known fungicidal inhibitors of this enzyme has now been used to rationally design further guanidinium or amidinium inhibitors. Three novel classes of chemistry were investigated. The results of biochemical testing against ergosterol biosynthesis in Ustilago maydis (DC) Corda and of in-vivo testing for fungicidal activity against Erysiphe graminis DC f. sp. hordei Marchal (powdery mildew of barley), do much to support the binding model, and compounds with significant fungicidal activity have been found. © 1997 SCI.     

纳米抗体的制备与临床应用研究进展

抗体是一类能特异性识别并结合抗原的免疫球蛋白，也是机体体液免疫的主要成分。随着科学技术的发展及对抗体研究的深入，抗体的应用领域不断扩展，可作为亲和配体或探针用于蛋白互相作用、蛋白与核酸相互作用、生物大分子定位与分布等研究，也可作为免疫抑制剂或治疗药物用于免疫性疾病、肿瘤、感染等疾病的治疗，还可结合各种标记技术用于疾病诊断、食品安全检测和环境监测。但传统抗体生产成本高、组织穿透力差、免疫排斥反应等缺点限制了其在疾病治疗等领域的广泛应用。近年来，科学家们致力于新型小分子抗体的寻找和研究，先后研制出嵌合抗体、小分子抗体、双特异性抗体等新型抗体。其中，纳米抗体（nanobody，Nb）又称重链可变区（variable heavy chain domain，VHH）抗体，是一种仅由一个重链可变区组成的单域抗体。纳米抗体保留了重链抗体完整的抗原结合能力，且具有分子质量小、组织穿透性强、抗原亲和力高、能识别隐藏表位、免疫原性低、结构稳定、水溶性好、生产成本低、易于产业化等优点，在疾病诊断、癌症和感染性疾病治疗、小分子药物及毒素残留检测等领域展现出巨大的应用前景。作者首先介绍了纳米抗体的特点，然后简述了纳米抗体的制备流程，重点综述了纳米抗体在疾病诊断、疾病治疗、食品安全和环境监测等领域的应用，最后对纳米抗体在兽医临床的应用前景进行了分析和展望。     

基于PCR技术的植物病原菌分子定量检测技术研究进展

植物病原菌的菌源量是病害发生和流行的重要因子之一,对其精准的定量测定或检测可大大提高植物病害预测的准确性,本文对实时荧光定量PCR (qPCR)与数字PCR在植物病原菌定量检测、以及基于RNA水平的real-time PCR和基于核酸染料(EMA/PMA)与qPCR相结合的技术在植物病原菌活体定量检测中的应用进行了综述,并展望其在植物病害流行和预测中的应用前景。     

茭白胡麻叶斑病病原菌分离与鉴定

茭白胡麻叶斑病发生普遍且严重,已成为茭白的常见病害。为了明确病原菌,先后从茭白主产区采集胡麻叶斑病病叶,各产区分离纯化5～10株病原菌。通过对菌株DNA的内转录间隔区ITS基因、3-磷酸甘油醛脱氢酶GPDH基因、延伸因子EF-1α基因的序列进行分析。结合形态学观察、致病力测定等方法对茭白胡麻叶斑病病菌进行鉴定。结果表明,茭白胡麻叶斑病病原菌为稻平脐蠕孢Bipolaris oryzae,与水稻胡麻叶斑病病原菌一致。本文的研究成果可为茭白胡麻叶斑病的防治提供一种新的思路。     

番茄灰叶斑病原菌的鉴定及抗性种质资源的筛选

<正>番茄灰叶斑病是一种世界性病害,近年来,该病在北京、台湾、海南、山东和浙江等地均有发生,极大地限制了我国番茄生产的竞争力~([1])。该病害主要由Stemphylium spp.不同的4个种引起~([2])。本研究采用形态观察法、ITS和gpd序列分析法对从番茄病株分离得到的病原菌进行鉴定,并对番茄灰叶斑病抗性鉴定方法进行研究,以期为番茄灰叶斑病的抗病育种研究及其利用提供理论依据。