Susceptibility of apple clearwing moth larvae,Synanthedon myopaeformis (Lepidoptera: Sesiidae) to Beauveria bassiana and Metarhizium brunneum

Apple clearwing moth larvae, Synanthedon myopaeformis (Lepidoptera: Sesiidae) were found to be susceptible to infection by two entomopathogenic fungi: an indigenous fungus isolated from S. myopaeformis cadavers and identified as Metarhizium brunneum (Petch); and Beauveria bassiana isolate GHA. In laboratory bioassays, larvae exhibited dose related mortality after exposure to both the M. brunneum and Beauveria bassiana with 7 day LC₅₀'s of 2.9×10⁵ and 3.4×10⁵ spores/mL, respectively. Larval mortalities caused by the two isolates at 1×10⁶ spores/mL were not significantly different and 73% of the M. brunneum-treated, and 76% of the B. bassiana-treated larvae were dead 7 days post treatment, with LT₅₀'s of 5.5 and 5.1 days, respectively.     

The daily variations of airborne fungal spores in Mexico City

The daily and seasonal distribution of airborne fungal particles was recorded in a high altitude tropical zone. Sampling was carried out in the southern part of Mexico City. An Andersen air sampler was used over a period of six months. Ten minutes sampling for each set of plates was done at fixed schedule: 07:30, 14:00 and 19:00 hours. The sampler was placed 10 m above the ground. Daily variation was found to be associated with the season, weather and atmospheric stability. The highest value of mold counts (3195 CFU m⁻³) was recorded in the evening on October, a transitional month between the rainy and the dry seasons, the lowest (45 CFU m⁻³) at noon during the rainy season. Mold counts were significantly correlated with temperature, having negative signs both in the morning and at noon, and being positive in the evening. The abundance of only three genera was recorded.Cladosporium, was isolated more frequently, and its abundance at 14:00 h was of 38%;Alternaria represented 4.0%, at 14:00 h, andAspergillus 3.0% at 7:30 h. Fifteen species belonging to the latter genera were identified and most of them are considered as opportunistic molds of clinical significance.     

秦岭辛家山林区锐齿栎外生菌根真菌多样性

以秦岭辛家山林区锐齿栎为研究对象,通过野外调查结合形态学和分子生物学方法,观察和鉴定与其共生的外生菌根真菌。结果确定了3种子囊菌和48种担子菌,分属于10科14属,其中毛革菌属Tomentella是优势类群,丝伞盖属1 Inocybe 1、Russula persicina、毛革菌属1 Tomentella 1、毛革菌属2 Tomentella 2、块菌属Tuber、绒盖牛肝菌属Xerocomus是常见种,其余都为稀有种。两样地锐齿栎外生菌根真菌除丰富度指数外,Simpson指数、Shannon指数以及Pielou均匀度指数差异不显著;Jaccard相似性指数和Sorenson相似性指数分别为0.1154和0.2069。     

凉山州龙肘山锈红杜鹃与薄叶马银花根部真菌分子检测

【目的】为检验直接分子检测法用于揭示杜鹃花属(Rhododendron)植物根部真菌(Root-associated fungi,RAF)组成的有效性。【方法】采用不依赖于培养的分子检测技术直接从锈红杜鹃(R.bureavii)与薄叶马银花(R.leptothrium)的发根(Hair root)提取DNA,用真菌特异性引物扩增r DNA-ITS区、经克隆后测序,对获得的ITS序列进行分析;通过收集NCBI中与本研究的RAF相似性97%以上的所有序列对应的真菌来源(土壤或根系的身份)数据,分析真菌的生态学特性,并用FUNGuild软件提供的方法划分真菌的生态类型。【结果】从两种杜鹃花根部共检测到15种真菌,其中担子菌门(Basdiomycota)真菌3种,子囊菌门(Ascomycota)真菌12种。柔膜菌目(Helotiales)真菌在两种杜鹃花RAF群落中占据优势,并且在两种杜鹃花根系中均检测到该类真菌。此外,两种杜鹃花根部有多种生态类型的RAF共存,包括曾被频繁报道的杜鹃花类菌根菌Oidiodendron sp.和Rhizoscyphus sp.、内生真菌Phialocephala fortinii、共生一致病过渡型真菌Pezoloma ericae、外生菌根共生菌Meliniomyces sp.,以及腐生型真菌Myceana sp.、Lachnum virgineum、Herpotrichia sp.。【结论】直接分子检测法从两种杜鹃花属植物根部检测到的真菌谱系多样性较高、生态类型复杂,这一方法能较为全面地反映杜鹃花属植物RAF多样性。     

Interactions of Cu (II) and Fe (III) with mangal humic substances studied by synchronous fluorescence spectroscopy and potentiometric titration

Humic (HA) and fulvic (FA) acids isolated from mangrove sediments of Sundarban, the largest delta on earth in the estuarine phase of the river Ganges, were studied and attempts were made to characterize their binding sites by quenching of Synchronous fluorescence (SyF) bands with Fe (III) and Cu (II). A modified Stern-Volmer relationship applicable for static quenching was applied for the determination of conditional stability constants and the data were compared with those determined by potentiometric titration. In the excited state HA and FA showed different acidity constant compared to the ground state. Values of the conditional stability constant (log K_c) for Fe (III) and Cu (II) indicated that binding sites were bidentate in nature. FA were better chelators than the HA fractions. High energy binding sites of both FA & HA were occupied by Fe(III) and the low energy binding sites, mainly responsible for mobilization and immobilization of metal, were occupied by Cu(II).     

Fungal ribotoxins: molecular dissection of a family of natural killers

RNase T1 is the best known representative of a large family of ribonucleolytic proteins secreted by fungi, mostly Aspergillus and Penicillium species. Ribotoxins stand out among them by their cytotoxic character. They exert their toxic action by first entering the cells and then cleaving a single phosphodiester bond located within a universally conserved sequence of the large rRNA gene, known as the sarcin-ricin loop. This cleavage leads to inhibition of protein biosynthesis, followed by cellular death by apoptosis. Although no protein receptor has been found for ribotoxins, they preferentially kill cells showing altered membrane permeability, such as those that are infected with virus or transformed. Many steps of the cytotoxic process have been elucidated at the molecular level by means of a variety of methodological approaches and the construction and purification of different mutant versions of these ribotoxins. Ribotoxins have been used for the construction of immunotoxins, because of their cytotoxicity. Besides this activity, Aspf1, a ribotoxin produced by Aspergillus fumigatus, has been shown to be one of the major allergens involved in allergic aspergillosis-related pathologies. Protein engineering and peptide synthesis have been used in order to understand the basis of these pathogenic mechanisms as well as to produce hypoallergenic proteins with potential diagnostic and immunotherapeutic applications.     

Quantification of Alternaria,Cladosporium, Fusarium and Penicillium verrucosum in Conventional and Organic Grains by qPCR

We analysed the levels of Alternaria, Cladosporium, Fusarium and Penicillium verrucosum in grain samples harvested in 2011 and 2012 from conventional and organic farms using qPCR. In general, both Alternaria and Cladosporium occurred in all cereal grains in the highest quantities, followed by P. verrucosum and Fusarium. Alternaria, Cladosporium and P. verrucosum had the highest levels in crop mixtures, barley and rye and lower levels in wheat, while Fusarium levels were the highest in crop mixtures and wheat. The levels of Alternaria and P. verrucosum were higher in organic rye and wheat than conventional grains. Although the level of Fusarium was higher in conventional than organic rye, opposite results were obtained for crop mixtures. A positive correlation was found between Alternaria, Cladosporium and P. verrucosum, indicating that similar factors might affect the distribution of these fungi in grains.     

Temporal variation of Bistorta vivipara‐associated ectomycorrhizal fungal communities in the High Arctic

Ectomycorrhizal (ECM) fungi are important for efficient nutrient uptake of several widespread arctic plant species. Knowledge of temporal variation of ECM fungi, and the relationship of these patterns to environmental variables, is essential to understand energy and nutrient cycling in Arctic ecosystems. We sampled roots of Bistorta vivipara ten times over two years; three times during the growing‐season (June, July and September) and twice during winter (November and April) of both years. We found 668 ECM OTUs belonging to 25 different ECM lineages, whereof 157 OTUs persisted throughout all sampling time‐points. Overall, ECM fungal richness peaked in winter and species belonging to Cortinarius, Serendipita and Sebacina were more frequent in winter than during summer. Structure of ECM fungal communities was primarily affected by spatial factors. However, after accounting for spatial effects, significant seasonal variation was evident revealing correspondence with seasonal changes in environmental conditions. We demonstrate that arctic ECM richness and community structure differ between summer (growing‐season) and winter, possibly due to reduced activity of the core community, and addition of fungi adapted for winter conditions forming a winter‐active fungal community. Significant month × year interactions were observed both for fungal richness and community composition, indicating unpredictable between‐year variation. Our study indicates that addressing seasonal changes requires replication over several years.     

一株侵染豌豆蚜的昆虫病原真菌的分离及鉴定

【目的】从采集到的自然染菌的豌豆蚜Acyrthosiphon pisum虫尸分离纯化得到一株病原真菌,定名为TF-2。本研究旨在确定该菌株的分类地位,为豌豆蚜生物防治提供真菌资源。【方法】对自然染菌的豌豆蚜虫尸上寄生真菌TF-2进行回接试验,分离纯化出致病菌株TF-2;在显微镜下配制TF-2菌株不同浓度孢子悬浮液,采用浸渍法和离体叶片饲养法测定其对豌豆蚜成虫的毒力;利用光学显微镜观察菌株形态学特征。PCR扩增TF-2的rDNA-ITS序列并测序,构建系统发育树对TF-2菌株进行分子鉴定。【结果】毒力测定结果表明,TF-2菌株对豌豆蚜成虫表现出很强的致病力,1×10⁷孢子/mL处理6 d后豌豆蚜成虫校正死亡率达到100%。TF-2在PDA培养基上菌落呈圆形,白色或淡黄色毡状,菌落背面呈奶油色;菌株孢梗呈瓶状,在菌丝上单生或侧生2～3个,大小为(19-42)μm×(1.1-2.5)μm,基部较粗至尖端逐渐变细,分生孢子长椭圆形,大小为(4.2-11.8)μm×(1.6-2.6)μm。菌丝体产生晶体呈八面体。该菌株的rDNA-ITS序列与长孢蜡蚧菌Lecanicilli...