Recognition and characterization of four Thai xylariaceous fungi inhabiting various tropical foliages as endophytes by DNA sequences and host plant preference

A total of 202 strains of xylariaceous fungi (183 endophytic strains isolated from 25 plant species of 24 genera in 21 families and 19 saprobic strains), segregated into four clades, were examined by nuclear rDNA internal transcribed spacer (ITS) sequence and beta-tubulin coding region analyses to clarify their taxonomic status and species boundaries. Three of the four species clades were assigned to Xylaria cubensis (100 strains), Xylaria grammica (33 strains), and Nemania diffusa (48 strains). Another fungus was tentatively assigned to Nemania cf. bipapillata (21 strains). Comparison of the host plants revealed that X. cubensis inhabited healthy leaves of at least 24 plant species (23 genera of 21 families) as endophytes; N. diffusa was found on 19 plant species (18 genera of 15 families), Nemania cf. bipapillata on 11 species (10 genera of 9 families), and X. grammica on 8 species (8 genera of 7 families). The present results suggest that the major xylariaceous endophytes in tropical plants are likely to be non-host specific, or have a wide range of host plant preferences.     

The role of the motile tubular vacuole system in mycorrhizal fungi

Mycorrhizal fungi, to be effective for the plant, must be able to transfer mineral nutrient elements from sites of uptake at hyphal tips across various distances to the exchange region in the mycorrhiza. Vacuoles are likely to be important in this transport, since they contain elements of nutritional significance in abundance. In tip cells of hyphae of most fungi –- known to include three ectomycorrhizal basidiomycetes, an ericoid mycobiont, and two arbuscular mycorrhizal fungi –- the vacuoles form a motile tubular reticulum. The vacuoles are most active in hyphal tips, but non-motile vacuoles at a distance from the tip can be induced to become motile by environmental changes. Neither the tubular vacuolar reticulum nor its contents are properly preserved by conventional fixation and embedding. Vacuolar tubules are readily shown in vivo with fluorescent tracers, throughout the extramatrical mycelium and in outer hyphae of the sheath in eucalypt mycorrhizas synthesised with Pisolithus sp., but they have proved harder to label in field-collected ectomycorrhizas and ericoid mycorrhizas. Freeze-substitution does preserve the structure of vacuoles and vacuolar tubules, and careful anhydrous techniques allow them to be microanalysed, indicating high content of K and P in vacuoles of hyphal tips, and also in sheath and Hartig net of ectomycorrhizas. Vacuoles contain polyphosphate in diffuse, non-granular form. Polyphosphate is present right up to the tip region of hyphae as well as in sheath and Hartig net: thus important mineral nutrient elements are present at both ends of the long hyphal transport pathway. Exactly what happens in between, however, remains to be elucidated.     

Unusual nuclear inclusions in four nerve biopsies. An ultrastructural study

The authors have reported four cases where the study of peripheral nerve biopsy revealed the presence of abnormal cells in the endoneurial space. Their bulky nuclei contain in fact numerous deposits more or less tubular reminiscent of the intranuclear structures observed in the multiple sclerosis brains, and other very rare diseases. Exceptionally it seems have these images been described in peripheral nerves. It must be stressed that only one patient had an inflammatory type disease. The meaning of these images is discussed, though no definite conclusion could be reached.     

Sorption of heavy metals by four basidiomycetous fungi

Biosorptions of Pb²⁺, Cr⁶⁺, Cd²⁺ and Ni²⁺ were investigated, with special emphasis on the first one, using live and dead fungal mycelia. Of the four fungi, namely Polyporus ostreiformis, Volvariella volvacea, Pleurotus sajor-caju and Phanerochaete chrysosporium, the last one was found to be most effective in Pb²⁺ removal. Total biosorption was effected in 6 days up to the Pb²⁺ concentration of 6 mg/l, with a specific uptake of 1.33 mg Pb²⁺/g dry cell mass. The removal of other three metals varied between 28.8–73.3% from a medium containing 4 mg/l of each of the metals.Laboratory facilities created under M.Tech programme in Biotechnology and Engineering (sponsored by Department of Biotechnology, Govt. of India) were partly utilized for this study.     

Distribution of arbuscular mycorrhizal fungi in four semi-mangrove plant communities

To better understand the diversity and species composition of arbuscular mycorrhizal fungi (AMF) in mangrove ecosystems, the AMF colonization and distribution in four semi-mangrove plant communities were investigated. Typical AMF hyphal, vesicle and arbuscular structures were commonly observed in all the root samples, indicating that AMF are important components on the landward fringe of mangrove habitats. AMF spores were extracted from the rhizospheric soils, and an SSU rDNA fragment from each spore morph-type was amplified and sequenced for species identification. AMF species composition and diversity in the roots of each semi-mangrove species were also analyzed based on an SSU-ITS-LSU fragment, which was amplified, cloned and sequenced from root samples. In total, 11 unique AMF sequences were obtained from spores and 172 from roots. Phylogenetic analyses indicated that the sequences from the soil and roots were grouped into 5 and 14 phylotypes, respectively. AMF from six genera including Acaulospora, Claroideoglomus, Diversispora, Funneliformis, Paraglomus, and Rhizophagus were identified, with a further six phylotypes from the Glomeraceae family that could not be identified to the genus level. The AMF genus composition in the investigated semi-mangrove communities was very similar to that in the intertidal zone of this mangrove ecosystem and other investigated mangrove ecosystems, implying possible fungal adaptation to mangrove conditions.     

Tulasnein and podospirone from the coprophilous xylariaceous fungus Podosordaria tulasnei

Tulasnein (1), a new metabolite with strong antimicrobial and weaker cytotoxic and phytotoxic activity, was isolated from culture filtrates of three strains of the xylariaceous coprophilous fungus Podosordaria tulasnei. The producing strains were identified by their rhizomorphs and by ITS rDNA sequence analysis. A second new metabolite, podospirone (2), was also produced by all three strains whereas the weakly cytotoxic (+)-3,4-anhydroshikimic acid methyl ester (3) was detected in only one strain.     

Rhizosphere and phyllosphere fungi of four fern plants growing in Saudi Arabia

Seventy-eight species in addition to 1 variety of A. flavus belonging to 31 genera were collected from the rhizosphere (55 species + 1 variety and 24 genera) and phyllosphere (59 species and 22 genera) of Adiantum capillus-veneris, Ceterach officinarum, Asplenium filare and Cheilanthes catanensis.In the rhizosphere, the most common genera were Aspergillus, Penicillium, Fusarium, Mucor and yeasts. In the phyllosphere, the most prevalent fungi were Cladosporium herbarum, C. sphaerospermum, Alternaria alternata, Drechslera spicifera, Aspergillus spp., Penicillium spp., Cephalosporium roseo-griseum, Myrothecium verrucaria, Mucor racemosus and yeasts.     

Ultrastructure of the haustoria or intracellular hyphae in four different fungi

Summary An examination was made of the ultrastructure of haustoria or intracellular hyphae in four fungi: an obligate parasite (Puccinia hordei), a facultative parasite (Exobasidium japonicum) and two facultative saprophytes (Phytophthora palmivora and Sclerotinia fructigena). P. hordei haustoria showed the typical ultrastructure and host-parasite interface of most of the obligate parasites already studied. Connections between the host endoplasmic reticulum and host plasmalemma were observed at the encapsulation site. Tubules connecting the haustorial cytoplasm with the encapsulation, through the haustorial wall were occasionally seen. The host cell remained alive in the presence of the parasite. E. japonicum haustoria lacked a neck and encapsulation and were irregularly shaped, with branches which appeared to be partly surrounded by a sheath. Some of these branches showed cytoplasmic connections between the parasite and the host through the sheath. All the observed haustoria of E. japonicum were anucleate and contained only a few mitochondria and sparse membranes. The host cell was dead and its organelles disorganized. P. palmivora haustoria were simple with nucleus, endoplasmic reticulum, mitochondria and Golgi bodies. Neither sheath nor encapsulation was observed, and the host cell was also dead and disorganized. S. fructigena did not produce haustoria of any kind, the intercellular hyphae became intracellular by the degradation of the host cell walls, and the host cells were killed in advance of the growing hyphae.It is suggested that a new definition of haustorium is required to include all these intermediate haustorial bodies which cannot be included within the present concept of haustorium.     

东北4种林木干基腐朽病原真菌潜在分布范围预测及其生态位分析

东北地区木生真菌物种资源丰富, 包括了数十种林木干基腐朽病原真菌。过去对该类真菌曾进行多次调查, 获取了大量物种分布数据, 但对于非重点调查区域是否存在某种真菌物种却不明确。本文选取东北地区具有代表性的4种林木干基腐朽病原真菌, 即红缘拟层孔菌(Fomitopsis pinicola)、落叶松锈迷孔菌(Porodaedalea laricis)、桦剥管孔菌(Piptoporus betulinus)和香栓孔菌(Trametes suaveolens), 根据其地理分布数据和分布地的环境因子数据, 以最大熵模型(MaxEnt)对这些种类在东北地区可能的分布范围进行了模拟预测, 以曲线下面积(area under the receiver operating characteristic curve, AUC)对模型有效性进行评价, 并对各物种的生态位进行了分析。结果显示, 以MaxEnt方法获得的各物种预测模型均获得了较高的AUC值, 分别为0.990, 0.990, 0.989和0.967, 表明4种林木干基腐朽病原真菌预测模型的有效性较高。物种分布模型涉及的环境变量对模型的贡献率显示, 最暖季降水量(Bio18)、温度的年较差(Bio7)、最干季均温(Bio9)等变量对各物种模型贡献率较高。该研究结果为预测4种病原真菌在东北地区的分布范围和科学防治该类病原真菌提供了依据。     

Longevity and fecundity ofAcarus siro on four field and eight storage fungi

Egg production and longevity of isolated pairs ofAcarus siro L., when fed on mycelial pellets of selected fungi from shake cultures, were compared with those on a control diet of wheatgerm and brewer's yeast. The mites were always less productive on the fungal diet. They did best on the yeastHansenula anomola and worst on the field fungusAlternaria alternata. There was very little difference between egg production on wheatgerm alone and that on the control diet of wheatgerm and yeast. On the control diet, males lived longer than females. Fungal diets usually shortened male lives, while in two-thirds of the cases female lifespans were unaffected.     

四种野生食用菌粗多糖的抗氧化活性

利用DPPH自由基清除法、羟基自由基(OH.)清除法、铁离子鳌合能力及测定还原能力等方法对鸡油菌Cantharellus cibarius、变绿红菇Russula virescens、蜜环菌Armillaria mellea和棕灰口蘑Tricholoma myomyces等4种食用菌的粗多糖进行了抗氧化活性评价。结果显示,4种真菌粗多糖均不同程度地具有抗氧化活性。在DPPH自由基清除试验中,棕灰口蘑和蜜环菌表现出很强的活性,其EC50值分别为1.35 g/L、1.53 g/L;棕灰口蘑和蜜环菌对羟基自由基的清除能力也要优于其他2种食用菌,其EC50值分别为0.65 g/L、0.78 g/L;棕灰口蘑的铁离子螯合能力明显优于其他3种测试菌,其EC50值为1.69 g/L;在还原力方面同样是棕灰口蘑活性最强,蜜环菌次之,其EC50值为1.05 g/L、1.37 g/L。     

Airborne fungi in four stations of the St. Petersburg Underground railway system

The fungal and bacterial aerobiota of four St. Petersburg Underground stations has been examined over a 4-month period. In the indoor air of St. Petersburg Underground 50 fungal species were found, among which were likely deteriogenic fungi. The most prevailing genera were Acremonium, Aspergillus, Cladosporium and Penicillium. Fungal spore density in the underground air was within the sanitary level accepted for public buildings. The spore densities and specificities correlated with the station type. A more specific (independent of outdoor) air mycobiota was found in deeper stations. All fungal isolates were tested in laboratory conditions for their ability to produce extracellular proteinase, phospholipase, and hemolytic activities which can be associated to virulence. Only 2 of the 75 isolates expressed a high level of all three activities. Assuming this figure can serve as a rough assessment of pathogenicity potential, the risk of invasive mycoses was not considered significant. But taking into account the situation with peak-hours overcrowding, it may be concluded that the risk of “mould” allergic diseases for some categories of the underground passengers in St. Petersburg does exist.