植物病原镰刀菌产生的毒素种类及其危害

镰刀菌(Fusarium spp.)是多种重要农作物的病原体,不仅可造成农作物产量和品质的严重损失还可在离体培养条件下或植物寄主体内产生一系列被称为镰刀菌毒素的次生代谢产物.这些毒素一方面作为致病因子与镰刀菌对宿主植物的致病力密切相关,另一方面可导致家畜生产性能下降和相关病症的出现,进而影响农业生态系统并对人类健康造成...     

镰刀菌毒素对动物毒性作用的研究进展

镰刀菌是污染粮食和饲料的主要真菌菌属之一,可产生多种高毒性、低分子量的代谢产物,如玉米赤霉烯酮、脱氧雪腐镰刀菌烯醇、T-2毒素等,这些毒素严重威胁动物和人类的健康.摄入镰刀菌毒素可对动物造成多种毒性作用,包括生殖毒性、免疫毒性、肠道毒性、肝肾毒性、细胞毒性及致癌性等.不同类型镰刀菌毒素引起的毒性作用不尽一致,且不同毒素...     

饲料中镰刀菌毒素对家畜的危害性

在世界温带地区,与食用谷物一样,饲用谷物中也普遍存在镰刀菌属霉菌。若收割前存在这种霉菌,收割后贮藏条件差,就会进一步增殖。谷粒有机械性损伤,附着在表面的镰刀菌会乘虚而入。     

饲料中镰刀菌毒素的研究进展

镰刀菌产生的镰刀菌毒素是污染饲料的主要毒素之一,对畜禽的健康危害极大,本文就镰刀菌的特征分类、产生毒素的条件及其对动物的危害等进行综述.     

猪类镰刀菌毒素中毒病的临床诊疗报告

镰刀菌是自然界分布很广的真菌。同其他霉菌一样,极易侵染谷物和牧草。饲草(麦草、稻草、各种秸杆)被霉菌,尤其是镰刀菌产生的毒素污染引起的中毒,国内有多处报道。国外曾报道某些镰刀菌引起耕牛的“烂蹄病”,与国内不少省区报道耕牛发生霉饲草中毒的症状基本一致。病牛体表末稍器官(四肢下部、耳、尾等处)的皮肤和     

猪镰刀菌毒素中毒

2003年秋冬季节，菏泽市及其周边地区，不少养猪场(养猪户)反映，猪生长缓慢，光吃不长；有的猪食欲下降或呕吐；有的仔猪食欲正常，但出现肛门、外阴红肿，脱肛，甚至反复脱肛，多次整复不能康复而淘汰：雌性小猪出现阴户红肿，假发情或阴户脱出，乳房肿大等现象。笔者对此进行了病因调查，经过对病猪的症状、病因、剖检等多项综合诊断，确定为镰刀菌毒素中毒，现报告如下。     

饲料中镰刀菌毒素的危害和控制

在饲料的生物性污染中以霉菌及霉菌毒素的危害最大．目前已明确能造成人和动物毒害的有300多种,主要有曲霉菌属、镰刀菌属和青霉菌属。镰刀菌可分泌多种毒素,包括单端孢霉烯族化合物、烟曲霉菌毒素、玉米赤霉烯酮等,其产生的毒素在全球危害最大。它们是谷类饲料和青贮料中最普遍存在的霉菌毒素。可以降低家畜的采食量,导致生长速度下降、免疫抑制、繁殖障碍等。以拒食和繁殖障碍为观察的标准,通常认为猪是对饲料中霉菌毒素最敏感的动物。     

植物病原真菌对土壤种子库的影响

植物病原真菌对土壤种子库的影响是国际新兴的研究领域之一。本研究回顾与综述了近20年来该领域的研究进展。大多数已报道的研究均采用“种子袋埋藏+杀菌剂处理”的方法。应用杀菌剂处理埋藏种子能提高多种生境下土壤种子库的存活或降低其损失,其效果因生境或植物种而异。小粒种子与老龄种子更易受到病原真菌的威胁,种子内的化学防御物质有助于种子抵御病原真菌的侵袭而延长其寿命。病原真菌对种子库的影响亦与土壤水分、温度及种子埋深等土壤非生物因素及生物因素有关:在湿润条件下病原真菌作用增强,浅土层或高密度的种子库受其影响更甚,食真菌动物与非致病性细菌能够保护种子免于受害。分析了现有研究方法的特点并提出了改进的意见,建议了该领域的研究思路与方法及尚需加强研究的内容。     

The occurrence of Fusarium toxins in feed

Fusariotoxins can be found in imported feed as well as in crops from the Middle-Europe-Region. Concerning frequency of contamination, zearalenone is most important in the Federal Republic of Germany. From the grains, maize and oats are mainly affected. Frequency and intensity of contamination however, variates, depending on several factors as climate or genetical resistance. Typical districts with high frequency of contamination cannot be found in the FRG at the present status of knowledge. Feed-intoxications by zearalenone predominantly can be seen in pigs, cases with ruminants, horses or fowl rarely can be found. As imported feeds--especially those of the by-products of the wet-milling technique of maize--can be contaminated with zearalenone, a consequent control is demanded. Additionally culture techniques, genetical selection, seed treatment and harvesting should be optimized. A scientific-based tolerable limit till now cannot be stated. There are however some hints, that female pigs show cystic degenerations of the ovary receiving 50 microgram per kg diet. Naturally contaminated feed with 100 microgram fed for several weeks to growing female pigs induced signs of hyperestrogenism. Trichothecene contamination was found with lower frequency in the Federal Republic especially with DON, which dominates in Austria and some districts of the USA. From the contaminated feeds, maize and oats should be mentioned with priority. Ensiled products of the maize plant show some degradation during the ensiling process. Husks contain higher levels than the endosperm. No differences between conventionally and alternatively (biologic dynamic) grown crops could be found. A value for a tolerable daily intake cannot be stated at the present status of knowledge.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vacuolating cytotoxin produced by avian pathogenic Escherichia coli

The purpose of this study was to determine whether avian pathogenic Escherichia coli produced cytotoxic activity. Culture supernatants of 20 E. coli strains isolated from cellulitis lesions in chickens, five E. coli strains from avian septicemia, five from swollen head syndrome, and five from the feces of healthy chickens were incubated with primary chicken embryo fibroblast (CEF) cells, primary chicken kidney (PCK) cells, a quail fibroblast cell line (QT-35), and four mammalian cell lines (human epithelioid cervical carcinoma, African green monkey kidney, Chinese hamster ovary, and human larynx epidermoid carcinoma). Cytotoxicity was observed with supernatants from the 30 avian pathogenic strains on the two primary chicken cells (CEF and PCK). The highest dilution of culture supenatant that induced cytotoxic changes in 50% of the cells was 1/64. Supernatants from the five strains from normal feces were noncytotoxic, and none of the supernatants was cytotoxic for the QT-35 or the four mammalian cell lines. The cytotoxic effect, which was observed as early as 2 hr after exposure of the cells, was maximal at 6 hr and was evident as vacuolation, morphologically indistinguishable from that previously reported for culture supernatants of Helicobacter pylori. Like the activity in H. pylori, the cytotoxicity of the avian pathogenic strains was destroyed by heating at 70 C for 30 min and by exposure to proteolytic enzymes and was retained by filtration with a 100,000 molecular weight cut-off ultrafilter. Supernatants of two vacuolating cytotoxin-positive cultures of H. pylori failed to induce vacuolation of the CEF and PCK cells but caused the characteristic vacuolation in HeLa and Vero cells. The observations suggest that avian pathogenic E. coli produce a cytotoxin that is similar to the cytotoxin of H. pylori but may be specific for avian cells.     

一株能拮抗3种土传病害病原真菌的长枝木霉

为了丰富生防木霉菌(Trichodermaspp.)种资源,在园林植物八宝景天(Sedum spectabile)根际土壤中分离得到一株优势木霉。根据该菌株菌落的形态特征、形态学显微观察、菌株rDNA-ITS序列分析以及邻接法同源性比对等结果判定木霉菌株种类。采用平板对峙法将该菌株与3种土传病害病原菌[(Sclerotinia sclerotiorum)、立枯丝核菌(Rhizoctonia solani)和细链格孢菌(Alternaria alternata)]进行对峙培养。并用该木霉诱导山新杨(Populus davidiana×P.albavar.Pyramidalis)组培苗,观察离体叶片抵抗细链格孢菌侵染的能力。结果表明,此木霉为长枝木霉(Trichoderma longibrachiatum),命名为Tl-70。该菌株对3种土传病害病原真菌均有较明显的拮抗作用。对核盘菌的抑菌率最高为77.71%,显著高于对细链格孢菌和立枯丝核菌的抑制率(P0.05);对立枯丝核菌的抑菌率为58.56%,显著高于对细链格孢菌的抑制率(P0.05);对细链格孢菌的抑菌率最低,为53.32%。并且,该木霉能提高山新杨组培苗叶片拮抗细链格孢菌侵染的能力。说明此菌株是具有潜力的生防菌株。     

丛枝菌根真菌与个体植物的关系及其对群落生产力和物种多样性的影响

丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)是陆地生态系统的重要组成部分,能够与大约80%的陆地植物种类形成AMF-植物共生体。AMF能够影响个体植物的养分吸收,调节物种间的相互作用和植被更新,进而对群落生产力和物种多样性产生重要影响。为了把握AMF与个体植物、植物种间作用以及植物群落关系的研究现状,阐明AMF对群落生产力和物种多样性的作用机制,本研究拟从以下几个方面进行论述。首先,分析了物种水平上AMF与植物间的共生关系及其影响因素,提出预测AMF在不同土壤磷水平下对植物生长影响的概念模型。其次,总结了AMF对植物种间相互作用关系以及幼苗定植的影响。最后,分析了AMF对群落生产力和物种多样性的作用机制,提出相应的预测模型。对于实际生产,本文的研究结果能够应用到牧草生产和草地管理中,为利用人工草地土壤中AMF的养分吸收功能和天然草地的多样性保育及稳定性维持提供了科学根据。对于学术研究,本文综合了国内外最新研究进展,分析了当前研究中存在的科学问题,并对今后的研究方向进行了展望。     

Characterisation of haemolytic RTX toxins produced by Australian isolates of Actinobacillus pleuropneumoniae

The haemolytic RTX toxins of 27 isolates of Actinobacillus pleuropneumoniae, representing all serovars that have been isolated in Australia, were characterised. The quantity of protein secreted by these isolates into the media was not significantly different between serovars, but haemolytic activity was detected only in the unconcentrated supernatants from cultures of serovar 1 and 5 isolates. Haemolytic activity in supernatants of serovar 2, 3 and 7 isolates was detected only after the supernatants were concentrated. On Southern hybridisation blots, genomic DNA of serovar 1 and 5 isolates contained regions that were similar to the cloned structural genes for Apxl (apxIA) and for ApxII (apxIIA). In contrast, genomic DNA of serovar 2,3 and 7 isolates only contained regions similar to, if not identical with, the cloned apxIIA gene. The haemolytic activity of the culture supernatant depends on the type or composition of media and adaptability of the bacteria to in-vitro cultivation. Low passage cultures of A pleuropneumoniae, which were characterised by waxy colonies, produced significantly weaker haemolytic activity than A pleuropneumoniae after several passages in vitro.