三种杓兰根相关真菌多样性和生态功能

【背景】除了菌根真菌(Orchid mycorrhizal fungi,OrMF)外,兰科植物根中还有其它内生真菌,称为根相关真菌(Root-associated fungi,RAF)。【目的】采用分离培养的方法获得同一栖息地针叶林和灌木林两种不同生境西藏杓兰、黄花杓兰和无苞杓兰的RAF菌株,研究其真菌谱系、多样性和生态功能结构。【方法】从杓兰根碎屑中分离RAF,通过总DNA提取、PCR扩增及测序得到ITS(Internaltranscribedspacer)序列;进行系统发育和多样性分析,并通过NCBI数据库比对得到相似性最高序列的注释信息来分析RAF生态学特性。【结果】共分离得到278株RAF,25种OTU类型,包括23个子囊菌门OTU,2个毛霉菌门OTU。RAF物种丰富度分析发现西藏杓兰的较黄花杓兰高,不同生境没有显著差异;不同杓兰物种较不同生境的RAF群落分化程度高。生态功能分析显示25个OTU包括共生型、腐生型和致病型3种营养型,以及外生菌根菌群、植物病原菌群、内生真菌群、动物病原菌群、真菌寄生菌群、杜鹃花类菌根群、未定义的腐生菌群和不确定型8种共位群。【结论】阐明不同生境采集的不同杓兰中RAF的分布特点和生态功能,为未来研究RAF与杓兰属植物的共生关系奠定基础。     

Zoonotic filariasis caused by Onchocerca dewittei japonica in a resident of Hiroshima Prefecture,Honshu, Japan

A female of Onchocerca sp. was found to be the probable causative agent of a subcutaneous nodule in the left knee of a 70-year-old man in a rural area of Hiroshima Prefecture, Honshu, the main island of Japan. We compared the characteristics of the agent with the features of the four previously suspected species found in cattle and horses in various parts of the world, as well as O. lupi and O. jakutensis that were suspected or proved, respectively, in zoonotic cases in Europe. In addition, the morphologic characteristics of this parasite were compared with those of the four Onchocerca species found in wild animals in Japan. Based on such characteristics as the large triangle ridges, the considerable distance between any two adjacent ridges, and the absence of inner cuticular striae in the longitudinal sections, we found the causative agent in the present case to be identical to the female of Onchocerca dewittei japonica. All five previous cases of zoonotic onchocerciasis in Japan had been found in Oita, Kyushu, the main southern island. This human case caused by O. dewittei japonica suggests that zoonotic onchocerciasis is liable to occur in rural areas in Japan where wild boar, Simulium vectors, and humans overlap.     

Effect of streaked shearwaterCalonectris leucomelas on species composition ofPersea thunbergii forest on Kanmurijima Island,Kyoto Prefecture,Japan

The effects of trampling and burrowing by streaked shearwaters were studied on thePersea thunbergii forest in Kanmurijima Is. The vegetation data were analysed using both the phytosociological tabulation method and principal component analysis (PCA). The vegetation ordination on the first axis reflected the environmental gradient from light to heavy disturbance by the streaked shearwater, and the vegetation ordination on the second axis represented the gradient from the latter phase of forest succession to retrogressive succession. The position of the three vegetation groups in the ordination diagram successfully explained the relation between the habitat and the species composition. The disturbance caused by activities of the streaked shearwater such as burrowing and trampling causes a decrease of species, especially character species of Camellietea japonicae, and also causes retrogressive succession: patches ofMallotus japonicus develop and many heliophytes occur.     

A supplementary contribution of ants in the pollination of an orchid, Epipactis thunbergii, usually pollinated by hover flies

It has been controversial how extensively ants contribute to pollination, and we evaluated the contribution of the Japanese carpenter ant, Camponotus japonicus, to the pollination of an orchid, Epipactis thunbergii. Two-year field studies revealed that (1) the ant workers foraged even in cool/cloudy conditions and accordingly visited orchid flowers more frequently (about 40% of all the visitors) than hover flies, the principle pollinators (10–20%), and that (2) the flower-visiting ants occasionally removed pollinia from the anther and then delivered pollen onto the stigmatic surface of other flowers, although self-pollination might frequently occur in the consecutive visits of flowers within an inflorescence. An artificial pollination experiment with pollinia which had been transferred to the ant integument showed that (3) the treated flowers produced as many fruits and seeds as control flowers. We concluded that C. japonicus workers could actually pollinate E. thunbergii flowers and their relative importance as pollinators appeared to be largely dependent on the abundance of flower-visiting workers or weather conditions during the flowering period, which mainly determined the availability of hover flies.     

Molecular characterization of imipenem-resistant Pseudomonas aeruginosa in Hiroshima, Japan

Pseudomonas aeruginosa showing resistance to imipenem were found in 100 of 1,058 strains (9.5%) from six hospitals (a-f) in Hiroshima City, Japan. Of the 100 strains, 14 (14%) were double disk synergy test positive using sodium mercaptoacetic acid disks, and 18 (18%) were bla(IMP-1) or bla(VIM-2) allele positive by polymerase chain reaction (PCR). Among 100 imipenem-resistant strains, 32 were categorized into multi-drug resistant strains, in which 13 were positive for the metallo-beta-lactamase gene. Fifty-one strains (51%) among the 100 imipenem-resistant strains had elevated RND efflux pump activity against levofloxacin. But only 6 of 51 strains were classified as multi-drug resistant strains. The pulsed field gel electrophoresis analysis of the Spe I-digested DNA from the 100 isolates suggested not only clonal spread but spread of heterogeneous clones started to contribute to the prevalence of metallo-beta-lactamase producing P. aeruginosa strains in Japanese hospitals.     

Antigenic Characterization of Chlamydia pneumoniae Isolated in Hiroshima,Japan

The morphology and antigenic property of elementary bodies (EBs) of new Chlamydia pneumoniae YK-41 strain isolated in Hiroshima, Japan, were compared with those of C. pneumoniae strains TW-183 and AR-39, C. trachomatis L2/434/Bu strain and C. psittaci Cal 10 and Budgerigar-1 strains by SDS-PAGE and immunoblotting techniques. In spite of a clear difference in EB morphology between the YK-41 and the other C. pneumoniae strains used, protein profile of the YK-41 strain in SDS-PAGE was similar to that of the other strains. However, some quantitative difference in 200 and 98 kDa peptides and a faint difference in SDS-PAGE pattern was also observed in the molecular masses from 42 to 50 kDa. Immunoblot analysis with the patient serum at the convalescent stage revealed the presence of genus-specific and species-specific antigens in YK-41 EBs: i. e., the major outer membrane protein and 73 kDa peptides were genus-specific and the peptides of 43, 46, 53, 60 and 98 kDa appeared to be C. pneumoniae-specific.     

Increased incidence of rare cancers and varied age distributions by cancer group: A population-based cancer registry study in Hiroshima Prefecture,Japan

BackgroundEpidemiological characteristics of many types of rare cancers are limited especially in Asia. Therefore, this study aimed to describe the burden and changing time trends of rare cancers in Hiroshima, Japan.MethodsThe internationally agreed RARECAREnet list of rare cancers was used to identify patients diagnosed with cancers from 2005 to 2015 who were registered in the Hiroshima Prefecture Cancer Registry. Quality indicators specific to rare cancers were assessed by cancer grouping. Crude incidence rates (IRs) and age-standardized rates (ASRs) were calculated for 216 single cancers (rare and common) included in the list. A joinpoint regression was used to analyze age distribution and time trends in the ASRs for 12 internationally agreed rare cancer families. Quality indicators, ASRs, and IRs in Japan were identified to examine IR differences and the effects on data accuracy.ResultsThe 231,328 cases were used to calculate the IRs of each cancer. Epithelial tumors in rare families increased with age, but nonepithelial tumors occurred at any age. The proportion of rare cancer families to total cancers was stable. The time trend for families of head and neck cancers (annual percent change and 95 % confidence interval: 2.4 %; 1.2–3.7 %), neuroendocrine tumors (6.6 %; 5.1–8.1 %), and hematological cancers (4.3 %; 3.2–5.5 %) markedly increased.ConclusionThe ASRs of several rare cancers increased because of increased knowledge of these diseases, improved diagnostic techniques, and aggressive diagnoses.     

Physiological characteristics of Japanese red pine, Pinus densiflora Sieb. et Zucc., in declined forests at Mt. Gokurakuji in Hiroshima Prefecture, Japan

The decline of Japanese red pine trees (Pinus densiflora Sieb. et Zucc.) at Mt. Gokurakuji (693 m a.s.l.), 30 km west of Hiroshima city, west Japan, was studied. The effects of air pollution and acid deposition on the physiological characteristics of the trees, especially those of the needles, were investigated. Ozone concentration was not correlated with the physiological status of the needles and SO₂ concentration was not high in the declined area. NO₂ concentration correlated negatively with needle longevity while it correlated positively with ethylene emission from 1-year-old needles. Average needle longevity was about 2.8 years in non-declined areas; however the longevity was 1.3 years in the most polluted area. The minimal fluorescence at night (F ₀)of 1-year-old needles decreased with increasing NO₂ concentration. The maximum stomatal conductance (gl), net photosynthesis (P _n)and intercellular CO₂ concentration (C _i) in the declined areas were lower than in the non- declined areas (about 50%, 30% and 20% lower, respectively). The lower C _isuggested that the major part of the decrease in P _ncan be explained by stomatal restriction. The soil pH, N content and C/N ratio showed no significant difference between the declined and non-declined areas. The physiological disorders of needles were due to the damage by air pollutants, and important roles of NO₂ are suggested. Lowering of P _n and the shortening of needle longevity appear to be the main causes of the decline in pines in the forest decline area. Received: 16 December 1998 / Accepted: 7 January 2000     

Spatial patterns and determinants of common root-associated fungi in a subtropical forest of China

AimsSpatial patterns of fungal populations are affected by plant distribution, abiotic factors, fungal dispersal ability and inter-species interactions. While several studies have addressed spatial patterns of some mycorrhizal, saprotrophic and pathogenic fungi, the method based on fruit-body surveys is not efficient and unreliable to study the spatial pattern of root-associated fungal species because most fungi in plant roots do not have sporocarps and cannot be identified based only on morphological traits. Our aims are (i) to determine the spatial pattern of common root-associated fungi; (ii) to evaluate whether the abundance and spatial pattern of root-associated fungi and categories of fungi, reflect their biotic and abiotic niche constraints.     

Distribution of ericoid mycorrhizal endophytes and root-associated fungi in neighbouring Ericaceae plants in the field

Three hundred and twenty-seven fungal endophyte isolates were obtained from hair roots of neighbouring Woollsia pungens Cav. (Muell.) and Leucopogon parviflorus (Andr.) Lindl. (both Ericaceae) plants at an Australian dry sclerophyll forest site and mapped according to the root segments from which they were obtained. Restriction fragment length polymorphism (RFLP) analysis of the rDNA internal transcribed spacer (ITS) region indicated that the isolate assemblage comprised 21 RFLP-types (= putative taxa), five of which were shown in gnotobiotic culture experiments to be ericoid mycorrhizal endophytes. While two mycorrhizal RFLP-types were exclusive to either W. pungens or L. parviflorus, RFLP-type VI was isolated from both hosts. This putative taxon had strong ITS sequence identity with Helotiales ericoid mycorrhizal ascomycetes, comprised ca. 75% of all isolates from each plant and was spatially widespread in both root systems. Inter-simple sequence repeat PCR analysis indicated that two and four genotypes of RFLP-type VI were present in the W. pungens and L. parviflorus root systems respectively, however single genotypes appeared to dominate each root system. One genotype was present in both root systems. The data suggest that assemblages of ericoid mycorrhizal fungi from hair roots of individual Ericaceae plants in dry sclerophyll forest habitats are characterised by relatively low genetic diversity.     

History of Katayama disease: schistosomiasis japonica in Katayama district, Hiroshima, Japan

Historical account of Katayama disease is presented as a centenary record since the discovery of Schistosoma japonicum in Japan in 1904. The ever unknown endemic disease was called Katayama disease. Katayama district, Hiroshima Prefecture is one of endemic areas of schistosomiasis japonica in Japan. The causative parasite was first discovered in a human case in Katayama district. After the discovery of the parasite, life history, diagnosis, treatment, control measures and even eradication have been worked out, attempted and succeeded in Katayama district together with other endemic areas in Japan. Hiroshima Prefecture declared safety from the disease in 1980.     

Diversity and metabolic potential of culturable root-associated bacteria from Origanum vulgare in sub-Himalayan region

Study of rhizospheric bacteria from important plants is very essential, as they are known to influence plant growth and productivity, and also produce industrially important metabolites. Origanum vulgare is a perennial medicinal aromatic plant rich in phenolic antioxidants. Present study investigates the diversity of culturable root-associated bacteria from this plant in Palampur, India, which constitutes a unique ecosystem due to high rain fall, wide temperature fluctuations and acidic soil. Both root endophytes and rhizospheric soil bacteria were isolated, which resulted in a total of 120 morphologically different isolates. They were found to group into 21 phylotypes based on restriction fragment length polymorphism analysis. Growth medium composition had significant effect on the diversity of the isolated bacterial populations. The isolates were characterized for various metabolic, plant growth promoting (PGP) and other biotechnologically useful activities, based on which they were clustered into groups by principal component analysis. Majority of the isolates belonged to ??-Proteobacteria and Firmicutes. Pseudomonas and Stenotrophomonas were the most dominant species and together constituted 27.5?% of the total isolates. Many isolates, especially ??-Proteobacteria, showed very high PGP activities. Few isolates exhibited very high antioxidant activity, which may find potential applications in food and health industries. Firmicutes were catabolically the most versatile group and produced several hydrolytic enzymes. To the best of our knowledge, it is the first study describing rhizospheric microbial community of O. vulgare.     

Seroepidemiological study of norovirus infection in Aichi Prefecture, Japan

The serological prevalence of IgG antibody to seven NoV strains (GI.1, GI.4, GII.3, GII.4, GII.10, GII.12 and GII.15) among inhabitants aged 1–62 years of Aichi Prefecture, Japan was studied. Age-related seroprevalence was measured by ELISA using baculovirus-expressed recombinant VLP antigens. Seropositive rates for all seven VLP antigens gradually increased with age. Among the tested antigens, the highest seropositive rate was for the GII.4 strain. This result is consistent with the recent epidemic of NoV infection due to GII.4 strain in Japan.     

Comparison of the diversity of root-associated bacteria in Phragmites australis and Typha angustifolia L. in artificial wetlands

Common reed (Phragmites australis) and narrow-leaved cattail (Typha angustifolia L.) are two plant species used widely in artificial wetlands constructed to treat wastewater. In this study, the community structure and diversity of root-associated bacteria of common reed and narrow-leaved cattail growing in the Beijing Cuihu Wetland, China, were investigated using 16S rDNA library and PCR–denaturing gradient gel electrophoresis methods. Root-associated bacterial diversity was higher in common reed than in narrow-leaved cattail. In both plant species, the dominant root-associated bacterial species were Alpha, Beta and Gamma Proteobacteria, including the genera Aeromonas, Hydrogenophaga, Ideonella, Uliginosibacterium and Vogesella. Acidobacteria, Actinobacteria, Nitrospirae and Spirochaetes were only found in the roots of common reed. Comparing the root-associated bacterial communities of reed and cattail in our system, many more species of bacteria related involved in the total nitrogen cycle were observed in reed versus cattail, while species involved in total phosphorus and organic matter removal were mainly found in cattail. Although we cannot determine their nutrient removal capacity separately, differences in the root-associated bacterial communities may be an important factor contributing to the differing water purification effects mediated by T. angustifolia and P. australis wetlands. Thus, further work describing the ecosystem functions of these bacterial species is needed, in order to fully understand how effective common reed- and narrow-leaved cattail-dominated wetlands are for phytoremediation.     

Diversity of nematode destroying fungi in Taita Taveta,Kenya

The diversity of nematode destroying fungi in Taita Taveta, Wundanyi division, Coast Province, Kenya, was investigated between May 2006 and December 2007 aiming at harnessing their potential in the biological control of plant parasitic nematodes in the area. Given that the intensity of land cultivation is continually increasing in the study area, it is prudent to document the status of the nematode destroying fungi before the remaining forest habitats are ultimately disrupted. Soil samples were collected from forest, maize/bean, napier grass, shrub and vegetable fields, which represented the main land use types in the study area. The soil sprinkle technique method was used to isolate the nematode destroying fungi from the soil. The fungi were identified to species level. Eighty-five isolates, distributed in eight genera and 14 taxa were identified as nematode destroying fungi. The species identified were Arthrobotrys dactyloides, Arthrobotrys oligospora, Arthrobotrys superba, Acrostalagamus obovatus, Dactyllela lobata, Harposporium aungulilae, Harposporium liltiputanum, Harposporium spp, Haptoglosa heterospora, Monacrosporium asterospernum, Monacrosporium cianopagum, Myzocytium, spp, Nematoctonus georgenious and Nematoctonus leptosporus. Vegetable land use had the highest diversity of nematode destroying fungi. The results show that the study area is rich in nematode destroying fungi with A. oligospora being widespread and a possible candidate for biological control of plant parasitic nematodes.     

纳帕海高原湿地真菌群落多样性和组成的分布

【背景】位于滇西北的纳帕海高原湿地,是我国唯一的低纬度、高海拔、季节性半封闭型高原湿地。真菌在湿地生态系统的维持和稳定中发挥着特殊作用,然而关于纳帕海高原湿地真菌群落多样性和组成的研究目前仍无报道。【目的】对纳帕海高原湿地不同季节和土壤类型真菌群落多样性和组成及与环境因子的关系开展系统研究分析,促进对高原湿地微生物多样性的深入认识。【方法】采用荧光定量PCR和高通量测序技术,分析了纳帕海高原湿地不同季节和土壤类型中真菌的数量、群落多样性和组成及其与环境因子的关系。【结果】真菌数量级的变化对于人为干扰下的湿地土壤退化是敏感的响应指标。在真菌群落组成中,约有60%以上未确定的分类信息,40%有确定分类信息的包括6个门17个纲37个目53个科63个属,大部分分类信息集中在Ascomycota门,相对优势属为Gibberella。通过分类水平、OTU水平和β多样性分析比较,在纳帕海高原湿地整体真菌群落多样性和组成受季节变化影响不显著,但不同土壤类型的变化呈显著差异,推测是由于不同采样区植物根际效应和种类的影响。CCA (Canonical correlation analysis)分析表明,在不同采样区受不同土壤理化因子的影响。【结论】揭示了纳帕海高原湿地土壤真菌群落多样性和组成的区域特征,从微生物学角度进一步提出了对纳帕海高原湿地环境保护和恢复的重要性。     

Abundance of Naked Amoebae in Sediments of Hiroshima Bay, Seto Inland Sea of Japan

ABSTRACT The present paper provides the first data on naked amoebae from sediments of Hiroshima Bay. Three stations in the inner part of the bay were sampled over a three-month period. Abundance of naked amoebae ranged from 1,019 to 45,561 cells/g dry sediment. Results indicate: (i) surface sediment populations in most cases were higher than subsurface populations; (ii) there was some evidence of temporal variation with counts generally increasing from March to May: and (iii) the site located near Hiroshima City had fewer amoebae on several occasions than the other two sites. There was a negative exponential relationship between acid-volatile sulfide concentration and abundance of amoebae. Most amoebae were small with the average size ranging from 6.6–14 μm. Morphotype 1, amoebae that extend lobose pseudopodia or subpseudopodia during normal locomotion, were dominant (40–100% of enumerated amoebae). Morphotypes 2 and 3 (limax amoebae) were found in lower numbers than the other two morphotypes. The proportion of amoebae occupied by Morphotype 4 (fan-shaped or discoidal-flattened amoebae) was higher at a lower total abundance.