重要虫生真菌莱氏野村菌芽生孢子的形态发生

经对比,萨氏麦芽糖-酵母浸粉培养液(SMY)较适合制备莱氏野村菌Nomuraea rileyi芽生孢子。以菌株Nr09接种该培养基,在130r/min、25℃全光照下震荡培养,观察芽生孢子在不同时期发育的形态变化。结果表明,分生孢子萌发产生芽管;24h萌发率为42%,36h时达84%。芽管迅速伸长形成菌丝。在48h前芽生孢子通过菌丝顶端及分枝末端缢缩的方式形成,后期则主要通过芽生孢子继续出芽的方式大量形成,78h芽生孢子数量达到最大值。芽生孢子的形成方式可为一端、两端或多端芽殖。芽生孢子的形成过程可分为5个阶段:(I)分生孢子膨大期;(II)芽管萌发期;(III)芽管延长期;(IV)芽生孢子形成初期;(V)芽生孢子指数生长期。30h后培养液中有少量草酸钙结晶出现并逐渐增多。到84h时有31%的芽生孢子细胞内液泡聚集增大,表明芽生孢子已开始进入衰老阶段。使用指数生长期制备的Nr09芽生孢子进行几丁质酶基因转化,转化效率达79个转化子/μgDNA。     

Lipid composition of the entomopathogenic fungus Nomuraea rileyi

The total lipid content, neutral and polar lipid composition, and fatty acid profiles were determined for the different developmental stages of the entomopathogenic fungus, Nomuraea rileyi. In general, the lipid composition of N. rileyi was found to be very similar to that of other Fungi Imperfecti. Triacylglycerides and sterols were the major neutral lipids and phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the major polar lipids. Phosphatidylcholine, resolved in conidial and mycelial samples, was not detected in hyphal body samples. The major fatty acids were palmitic, oleic, and linoleic. Stearic acid was detected as a minor component of hyphal body samples. During conidiogenesis the overall lipid composition was altered in (1) a reduction in total lipid content, (2) an increase in the polar/neutral lipid ratio, and (3) an increase in the degree of fatty acid unsaturation.     

Susceptibility of Heliothis zea larvae to Nomuraea rileyi at various temperatures

Laboratory studies were conducted to determine the susceptibility of various larval instars of Heliothis zea to different spore doses of Nomuraea rileyi at constant and variable temperatures. The fungus was most effective at 20° and 25°C, with a mortality of 80% and 71%, respectively. At 15°C the disease progressed very slowly with larval mortality occurring in 12–28 days post-treatment. Conversely, at temperature ranges above 15°C, the mortality of the larvae occurred in 6–12 days. Three different combinations of variable temperatures included 20–30°, 25–30°, and 20–35°C, but mortality did not exceed 46%. Larvae in the third to fifth instars were more susceptible to infection than were those in the first and second instars.     

Optimization of extracellular lipase production from the biocontrol fungus Nomuraea rileyi

Lipases are important cuticle-degrading enzymes that hydrolyze the ester bonds of waxes, fats and lipoproteins during the infection of insects by the fungus Nomuraea rileyi. Lipase production by the N. rileyi strain MJ was optimized by varying environmental and nutritional conditions in culture medium containing different vegetable oils at various concentrations with shaking at 150 rpm for 8 days at 25°C. The maximum lipase production was obtained using castor oil (30.5±0.6 U mL^?1), followed in order by coconut oil (20.8±0.4 U mL^?1), olive oil (20.8±0.4 U mL^?1) and cottonseed oil (20.6±0.4 U mL^?1). The highest lipase activity (37.7±0.4 U mL^?1) was obtained when castor oil was used at a concentration of 4% (v/v) of basal medium. When the surfactant Tween 80 was added at the fourth day rather than at the beginning of incubation, a maximum lipase activity of 44.9±3.5 U mL^?1 was obtained. The optimal temperature and pH for lipase production were 25°C and pH 8.0, respectively. This is the first report on lipase production by the biocontrol fungus N. rileyi.     

莱氏野村菌紫外线诱变抗敌敌畏菌株的生理特性

[背景]夜蛾科害虫易对化学杀虫剂产生高抗性,但一些化学农药可以对部分虫生真菌的毒力作用效果起增幅作用,目前缺乏对莱氏野村菌(Nomuraea rileyi)的该方面研究.[目的]探究对常用有机磷杀虫剂敌敌畏具有较强耐药性的紫外线诱变莱氏野村菌突变菌株的生理特性,包括菌丝生长、产孢情况和产几丁质酶活性.[方法]在紫外线诱...     

Cost-effective multiplication of the entomopathogenic fungus Nomuraea rileyi (F) Samson

Cost-effective and rapid multiplication of Nomuraea rileyi is reported. The spore yields in semi-synthetic media were comparable or significantly higher to the standard medium. Maltose and peptone, carbon and nitrogen sources could be effectively replaced with 2% barley extract and 1% soybean extract respectively. However, replacement of yeast extract with dry yeast resulted in lower spore yields. Sporulation of the fungus multiplied on solid substrate was possible only when the bags used had a 0.2 m filter to facilitate passive exchange of sterile air. A high spore yield of 2.8 × 10⁹/g of substrate was realized on crushed sorghum.This revised version was published online in October 2005 with corrections to the Cover Date.     

几种植物油对莱氏野村菌分生孢子萌发的影响

【目的】研究从银纹夜蛾(鳞翅目:夜蛾科)[Argyrogramma agnata Staudinger(Lepidoptera:Noctuidae)]幼虫上分离得到的莱氏野村菌菌株Nr0815分生孢子,于不同温度下在8种植物油中萌发率和萌发速率的差异。【方法】采用紫外分光光度计测定了Nr0815分生孢子在8种植物油中的吸光度,并用载玻片萌发法测定了72 h内不同温度下分生孢子在不同植物油中的萌发率以及不同观察时间段的萌发速率。【结果】莱氏野村菌分生孢子在供试植物油中分散良好。在10–30°C内,莱氏野村菌分生孢子在各植物油中均能正常萌发,其中在大豆油中累积萌发率均最高。从孢子萌发速率来看,23°C时除大豆油和菜籽油外,其他植物油中孢子的萌发速率在72 h内均随着时间的延长而上升,在48–72 h时的萌发速率最大。10°C时的萌发速率最小,48 h后才开始萌发。从孢子萌发后芽管生长来看,23°C下孢子萌发后72 h时大豆油中的芽管长度最大,为(24.89±1.04)μm,葵花籽油中芽管最短,仅为(9.10±1.00)μm。【结论】明确了温度和植物油对莱氏野村菌孢子萌发的影响,也为该菌油剂开发利用提供理论基础。     

Molecular phylogeny of asexual entomopathogenic fungi with special reference to Beauveria bassiana and Nomuraea rileyi

The phylogenetic lineage, taxonomic affiliation and interrelationships of important asexual entomopathogenic fungal genera were studied using the sequences of partial regions of β-tubulin and rRNA genes. The species structures of Beauveria bassiana and Nomuraea rileyi were also investigated. A total of 147 fungal entries covering 94 species were analysed. Phylogenetic analysis placed all the asexual entomopathogenic fungal species analysed, in the family Clavicipitaceae of the order Hypocreales of Ascomycota. Deep phylogenetic lineages were observed in B. bassiana iterating the complex nature of this species. Some of the isolates assigned to this species separated out more distinctly than morphologically distinguishable genera. Cryptic speciation was also evident in N. rileyi. It is concluded that the asexual fungi with entomopathogenic habit arose from a single lineage in sexual Clavicipitaceae.     

Use of lectins to investigate the carbohydrate determinants of cholinergic receptors of various subtypes in molluscan neurons

The chemical nature of the carbohydrate determinants of the plasma membrane that affect the responses of identified neurons of the molluskHelix pomatia, induced by application of acetylcholine (ACh), was studied using D-mannose-specific (ConA), D-galactose-specific (RCA), N-acetyl-D-glucosamino-specific (WGA), and sialo-specific (LPA) lectins. Differences in the change in the Ach-induced chloride and sodium-potassium currents under the action of ConA and in the time and temperature dependences of the effects of ConA for these currents are evidence of the presence of different mechanisms of the influence of carbohydrate determinants containing mannose residues on the functional properties of the cholinergic receptors. On the basis of the time and temperature dependences of the inhibiting effects of WGA and RCA on the ACh-induced currents, it was suggested that endocytosis of the lectin-receptor complexes containing N-acetyl-D-glucosamine residues occurs.A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 2, pp. 161–169, March–April, 1992.     

Susceptibility of larvae of Trichoplusia ni and Anticarsia gemmatalis to intrahemocoelic injections of conidia and blastospores of Nomuraea rileyi

The LD₅₀ for larvae of Trichoplusia ni injected with blastospores of Nomuraea rileyi was 4.30 ± 1.16 hyphal bodies/larva; the LD₅₀ for injected conidia was ca. 25,000 conidia/larva. The dose-mortality regression line for blastospores was Y = 4.6504 + 0.5487 X. Larval mortalities of Anticarsia gemmatalis and T. ni at 100 blastospores/larva were 0.4 ± 0.5% and 96.7 ± 1.9%, respectively. At a dosage of 25,000 conidia/larva, larval mortalities for A. gemmatalis and T. ni were 0.4 ± 0.5% and 43.1 ± 8.7%, respectively. Thus, larvae of A. gemmatalis were > 100 times and >200 times more resistant to injected conidia and blastospores, respectively, than were larvae of T. ni. Resistance of A. gemmatalis to N. rileyi may not be solely at the integumental barrier, as is often believed, but may also be a function of an internal physiological response.