农业生产上几种重要的赤霉属真菌研究进展

赤霉属真菌大多是农业生产上具有破坏性的植物病原真菌。选取几种在农业生产上重要的赤霉属真菌来阐述该属在系统发生,生物学和化学上的多样性,并且比较了它们在分类学、遗传学、植物病理学和真菌毒理学方面的差异。虽然它们是非常近缘的赤霉属各种,但在繁殖方式、地理分布、寄主范围、植物致病机理、毒素和其他生物活性代谢物的产生方面都有所不同。     

Pleurotus ostreatus对线虫作用机理的研究

 本文详细地研究了粗皮侧耳(Pleurotus ostreatus)对线虫(Panagrellus redivivus)的致病过程、线虫感病症状及菌丝与线虫的相互作用。探明了粗皮侧耳对线虫致病的实质是杀主寄生,菌丝分泌的毒素首先将线虫击倒并杀死,然后菌丝从线虫体孔侵入,或靠酶和机械力的作用从表皮侵入,最后消解、吸收和利用线虫。一般菌丝与线虫接触1~5min线虫被击倒,20~30min卵和幼虫解体,4~6h成虫死亡,12h后菌丝侵入虫体营腐生生活。菌丝也可不侵染线虫,仅靠毒素将线虫杀死,在酶的协同作用下将线虫分解,直接吸收利用线虫。若菌丝分泌的毒素不足以杀死线虫,纵然菌丝与线虫充分接触也不能侵染活线虫。试验还表明,该菌平板培养产生的毒素,除去菌丝也能杀死线虫。     

Herpesviral abortion in domestic animals

Abortion or neonatal disease may follow infection with several α, β and γ-herpesviruses. The α-herpesvirus, equid herpesvirus-1 (EHV-1), causes single or epizootic abortions or neonatal deaths in equids, and the closely related virus EHV-4 causes sporadic equine abortions. In cattle, the α-herpesviruses, bovine herpesvirus-1 (infectious bovine rhinotracheitis virus) and bovine herpesvirus-5 (bovine encephalitis virus), and a γ-herpesvirus, bovine herpesvirus-4, have all been implicated as causes of abortion. In pigs, suid herpesvirus-1 (SHV-1: pseudorabies virus), an α-herpesvirus, and SHV-2 (porcine cytomegalovirus), a β-herpesvirus, each cause abortion or neonatal piglet losses. Caprine herpesvirus-1, canine herpesvirus and feline herpesvirus-1, all α-herpesviruses, cause abortions or neonatal deaths in goats, dogs and cats, respectively. This review discusses the pathogenesis, pathology and laboratory diagnosis of these herpesviral abortions and neonatal diseases, with an emphasis on experimental studies of each disease. Alternative reviews covering other aspects of each infection, such as the genetic and antigenic structure of the viruses, host immune responses and approaches to vaccination and disease control are indicated at appropriate points in the text. nts in the text.     

Inclination and Anteversion of Collum Femoris in Hip Dysplasia and Coxarthritis

Madsen, J.S. and E. Svalastoga: Inclination and anteversion of collum femoris in hip dysplasia and coxarthritis. Acta vet. scand. 1994, 35, 115-119.–Femoral neck angles were measured radiographically in 41 dogs examined for hip dysplasia. Steep femoral neck inclination was found to be a phenomenon of hip dysplasia and coxofemoral joint laxity. The altered biomechanics of a steep femoral neck inclination may be a factor in the pathogenesis of hip dysplasia and secondary osteoarthritis.     

番茄黄化曲叶病毒病研究进展

论文从研究现状、植株症状、致病机理、检测方法、防治措施、抗病育种方法、鉴定手段等多方面阐述番茄黄化曲叶病毒病研究进展,对番茄黄化曲叶病毒病研究方向、防治工作等提出展望。     

Flavobacterium psychrophilum infections in salmonid fish

Flavobacterium psychrophilum is the causative agent of bacterial cold water disease and rainbow trout fry syndrome, disease entities responsible for substantial economic losses in salmonid aquaculture. Problems associated with epizootics include high mortality rate, increased susceptibility to other diseases, high labour costs of treatment and the enormous expenditure on chemotherapy. Despite the increasing significance of the disease, the pathogenesis of F. psychrophilum infections has only been partially elucidated, hampering the development of preventive measures to efficiently combat this disease condition. This literature review discusses the agent and the disease it causes, with emphasis on the bacterium-host interactions.     

浅谈附红细胞体病的研究概况

附红细胞体病是由附红细胞体感染机体引起的一种人畜共患的传染病。而附红细胞体则是寄生于红细胞表面、血浆、及骨髓中的一类微生物。近年来随着我国养猪业的蓬勃发展,该病的流行已有越来越烈之势,并逐渐成为危害养猪业的传染病之一。本文就猪附红细胞体的病原特点、流行病学、发病机理、临床症状、病理变化、诊断及防治对策作一综述。     

Phytogard® and DL-β-amino Butyric Acid (BABA) Induce Resistance to Downy Mildew (Bremia Lactucae) in Lettuce (Lactuca sativa L)

Downy mildew of lettuce (Bremia lactucae) is a serious disease. An alternative to chemicals is the application of disease resistance inducers. The aim of this study was to test whether DL--amino butyric acid (BABA) and Phytogard® (K₂HPO₃) could induce resistance in downy mildew susceptible plants. Aqueous solutions of BABA (0, 10, 20, 30, 50, 80, 100mM) and Phytogard® (0.0, 5.8, 29.0, 40.6, 58.0 and 87.0ppm) were sprayed on seven-day-old seedlings 0, 3, 7 and 15 days before or 1–3 days after inoculation with B. lactucae. Results obtained showed that Phytogard®- and BABA-induced resistance was dose-dependent. At 40.6ppm for Phytogard® and 10mM for BABA, complete protection was obtained. Both compounds had a curative effect and the induced resistance lasted for at least 15 days. It was also shown that both compounds induced systemic resistance in lettuce against downy mildew. Phytogard® at 40.6ppm completely inhibited spore germination while BABA at 20mM did not. Pathogenesis related (PR) protein analysis showed that BABA induced weak accumulation of PR-2, but not PR-1, PR-5 and PR-9. Phytogard® induced none of these proteins. The use of these two compounds to protect lettuce from B. lactucae is discussed.     

Ultrastructural and cell wall modifications during infection of <Emphasis Type="Italic">Eucalyptus viminalis</Emphasis> roots by a pathogenic <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> strain

Fusarium species are soil-borne fungal pathogens that produce a variety of disease symptoms when attacking crop plants. The mode of root colonization of Eucalyptus viminalis seedlings by a pathogenic F. oxyporum strain (Foeu1) at the ultrastructural level and changes in cell wall pectin during host pathogen interactions are described. Root systems of E. viminalis plants were inoculated with F. oxysporum in an in vitro model system. Hyphae of F. oxysporum adhered to the outer epidermal cell walls through fibrillar material, and after penetration they spread into the internal tissues. They developed intercellularly and intracellularly in the root cortex and invaded vascular tissues. Papillae were induced, and the host plasma membrane ruptured in colonized cells, causing rapid host tissue and cell damage. Changes in distribution and occurrence of nonesterified and methyl-esterified pectins were evaluated after root colonization by F. oxysporum using two monoclonal antibodies, JIM 5 and JIM 7, respectively. Nonesterified pectin in control roots was mainly localized in the epidermal cell walls and middle lamellae in parenchymal cortex, whereas methyl-esterified pectin accumulated more in primary cell walls of the cortex and phloem. Decreases in immunodetected nonesterified and methyl-esterified pectins were associated with extensive plant tissue degradation after root colonization by the pathogenic fungus.