内蒙古红花尔基鸟类群落与植被类型相互关系研究

调查了内蒙北部红花尔基夏季鸟类群落,一共记录了28种鸟类。在每个实验地取5个10m×10m的样方进行植被调查。利用线性回归方程来确定植被郁闭度和鸟类数量和鸟类密度的关系。分析结果显示鸟类数量和鸟类密度的变化及鸟类群落的形成是随着森林类型和总植物量而变化。鸟类数量和密度都随总植物量的降低而减少。鸟类群落的相似性在繁殖时期非常低,在同一分类簇中,最大相似性不超过0.65。这表明鸟类群落间种类的构成存在着显著差异。鸟类的繁殖密度与森林的生长阶段具有密切的关系,一般情况下,从稀疏的草原生态系统到顶级生态系统鸟类的密度呈现逐渐增加的趋势。图3表4参21。     

Maxillofacial rhabdomyosarcoma in the canine maxillofacial area

Three dogs had a diagnosis of maxillofacial rhabdomyosarcoma. These dogs were treated with surgery and/or radiotherapy, and had poor clinical responses. The tumor tissues in all three cases were observed around the upper premolar teeth with ulcerative lesions and CT examinations in each case revealed extensive bony involvement into the maxilla. Two cases were subjected to surgical excision of the tissues, followed by an external radiation therapy. The other case was only treated with palliative radiation. Outcomes of the treatment of all the cases were quite poor because of the invasive and refractory nature of the tumor cells, leading to the local recurrence and lung metastasis early in the clinical course. All dogs died within two months of the first admission.     

Effect of winter wheat cover cropping with no-till cultivation on the community structure of arbuscular mycorrhizal fungi colonizing the subsequent soybean

Winter cover crops increase the amount of indigenous arbuscular mycorrhizal fungi (AMF) in the soil, providing beneficial effects such as enhancement of phosphorus uptake by the subsequent crop. However, its impact on the AMF community structure is not well understood. In the present study, we aimed to reveal the effect of winter wheat cover cropping with no-till cultivation on the AMF community structures in soil and roots of the subsequent soybean. For this purpose, we conducted a field experiment consisting of two treatments, no-till soybean cultivation after winter wheat cover cropping (NTWC) and conventional soybean cultivation after winter fallow management as a control (CONT). At the flowering stage of soybean, higher AMF colonization of soybean roots was observed in the NTWC plots compared with the CONT plots. Additionally, aboveground biomass and phosphorus uptake of soybean in the NTWC plots were significantly higher than those in the CONT plots. Molecular community analyses based on PCR-denaturing gradient gel electrophoresis (DGGE) of AMF 18S rRNA genes indicated that the AMF community structures in the soil and soybean root of the NTWC plots were clearly different from those of the CONT plots. The DGGE profiles showed that the wheat cover cropping preferentially increased some phylotypes belonging to Glomeraceae and Claroideoglomeraceae. In addition, most of the phylotypes were characteristically observed in the subsequent soybean root of the NTWC plots, strongly suggesting that these phylotypes colonizing the cover crop wheat were taken over by the subsequent soybean. Our study revealed the significant effect of winter cover cropping with no-till cultivation on the structure of AMF community colonizing the subsequent soybean.     

RAPD Polymorphism of the White-Flowered Gourd (Lagenaria siceraria (Molina) Standl. Landraces and its Wild Relatives in Kenya

The present study was performed to investigate genetic diversity of Kenyan landraces of the white-flowered gourd (Lagenaria siceraria), which exhibits tremendous morphological variation. RAPD analyses were performed on 53 landraces of the cultivated species L. siceraria and 42 accessions of three wild species (40 L. sphaerica, 1 L. abyssinica, and 1 L. breviflora). A total of 432 polymorphic bands were detected using 54 primers. The four species were clearly differentiated from one another. Intra-specific variations were investigated with L. siceraria and its wild relative L. sphaerica. Landraces of the cultivated species collected from different ethnic communities or regions were differentiated. Morphological variations were not associated with RAPD variations. Bitter landraces collected in Maasai communities showed two specific RAPD bands. In the wild species, accessions collected from the eastern and western sides of the Great Rift Valley were genetically differentiated from each other. In both species, genetic and geographical distance matrices computed among all pairs of accessions were significantly correlated, implying that the observed geographical variation can be explained by the 'Isolation by distance model'. Progeny plants derived from a common mother in L. siceraria showed a low level of segregation in RAPD pattern, suggesting that collected landraces are cultivated, maintaining their inherent traits although they are monoecious and insect-pollinated, whereas the wild relative L. sphaerica showed a higher level of segregation. The morphological diversity observed among landraces of L. siceraria is the result of human selection and their genetic identities are maintained by inbreeding probably resulting from frequent self-pollination.     

Very long baseline interferometric observations made with an orbiting radio telescope

An orbiting spacecraft and ground observatories have been used to obtain interferometric observations of cosmic radio sources. The Tracking and Data Relay Satellite System (TDRSS) was used as the orbiting observatory in conjunction with two 64- meter radio telescopes at ground observatories, one in Australia and one in Japan. The quasars 1730-130 (NRAO 530), 1510-089, and 1741-038 were observed at a frequency of 2.3 gigahertz, and a maximum projected baseline of 1.4 earth diameters was achieved. All quasar observations for which valid data were acquired resulted in detected fringes. Many of the techniques proposed for a dedicated very long baseline interferometry observatory in space were used successfully in this experiment.     

Insect antifeedant activity of flavones and chromones against Spodoptera litura

The antifeedant polymethylated flavones 5-hydroxy-3,6,7,8,4'-heptamethoxyflavone, 5-hydroxy-3,6,7,8-tetramethoxyflavone, and 5,6-dihydroxy-3,7-dimethoxyflavone have been isolated from the cudweed, Gnaphalium affine D. Don (Compositae). These flavonoids and authentic analogues showed insect antifeedant activity against the common cutworm (Spodoptera litura F.). In a previous paper, it was suggested that there was no substituent on the B-ring of the flavonoid for the beneficial antifeedant activity against the common cutworm. These flavonoids having a phenyl group as the B-ring and the chromone as elimination of the B-ring from the flavonoids were used to test the hypothesis of the previously described B-ring effect. The known fact is that Sculletaria baicarensis (Rutaceae) produced the 2-phenyl flavone. Test compounds and their methylated derivatives were prepared from this material for the structure-activity relationship (SAR) study of insect antifeedant activity. In spite of the 2-phenyl flavonoids, some tested compounds did not show any insect antifeedant activity against the common cutworm, although these inactive flavonoids were deficient in the 6-substituent group on the A-ring of the flavonoid. This 6-position-substituted derivative almost showed strong insect antifeedant activity against common cutworm. Moreover, the tested flavonoids having a hydroxyl group as a substituent on any of the positions tended to increase the activity. These results suggested the importance of the 6-position substitution on the flavonoid; however, hydrophilic substituents decreased the activity. Baicalein (5,6,7-trihydroxyflavone) derivatives did not show any activity despite having the 6-substituent derivative. Although the activity of some chromones increased the activity of the flavone, the bulky B-ring was a disadvantage for the antifeedant activity. It was suggested that the charge on C(3) and C(5) of the flavonoid was important for the biological activity. Additionally, an adequate hydrogen bonding property, which is different from lipophilicity, was an advantage for the activity on the basis of a QSAR analysis.     

Suppression of debris movement by forests and damage to forests by debris deposition

 Forest buffer zones have recently been introduced in an attempt to suppress debris movement caused by mass wasting. There are, however, many questions left unsolved regarding the role of forests in suppressing debris movement and damage to forests by debris deposition. A number of debris avalanches occurred in southern Fukushima Prefecture and Hiroshima Prefecture in August 1998 and June 1999, respectively. Suppression of debris movement by forests and damage to forests by debris deposition were investigated in this study using aerial photographic interpretation and topographic analysis. Of the debris avalanches delineated in the Fukushima and Hiroshima areas, 282 and 84 sites, respectively, were forested, and 43 and seven sites, respectively, were nonforested. Topographic parameters, land use, and forest type at each site were surveyed by aerial photographic interpretation and topographic analysis. Suppression of debris movement by forest vegetation was confirmed by higher equivalent coefficients of friction and shorter average deposition zone length (about 28% and 55% shorter in the Fukushima and Hiroshima areas, respectively) in forested sites compared with nonforested sites. While previous studies suggested that the width of the forest zone required to prevent sediment outflow by surface erosion increases with increasing slope gradient, no clear relationship was found in this study. While the length of deposition zone of debris material (this study) is strongly affected by the dynamic solid friction coefficient and fluid friction of debris material, the length of deposition zone of the outflow of surface wash (past studies) is mainly affected by the tractive force of water flow. Among the 65 trees that remained at the terminus of deposition zones at five sites, 36 were alive and 29 were dead. Damage to the forest increases with increasing thickness of deposits and decreases with increasing tree diameter. Such results are useful for designing forest buffer zones. Received: June 18, 2001 / Accepted: August 21, 2002 Correspondence to:Y. Ishikawa     

Design and biological activity of a novel fungicide,quinofumelin

Developed by Mitsui Chemicals Agro, Inc. (Tokyo, Japan), quinofumelin is a novel fungicide with a distinct chemical structure including 3-(isoquinolin-1-yl) quinoline, demonstrating fungicidal activity against a variety of fungi, including rice blast and gray mold. We screened our compound library to identify curative compounds for rice blast and evaluated the effect of fungicide-resistant strains of gray mold. Our research demonstrated that quinofumelin has curative effects against rice blast and is not cross-resistant to existing fungicides. Accordingly, the use of quinofumelin can be considered a novel approach for disease control in agricultural production. In this report, the discovery of quinofumelin from the initial compound is described in detail.     

Experimental infection of Japanese encephalitis virus in dogs

A previous serosurvey of Japanese encephalitis virus (JEV) among dogs suggested that dogs are well suited for use as sentinels for assessing the risk of JEV transmission to humans. To examine the clinical symptoms and duration of anti-JEV antibodies in dogs, three dogs were experimentally challenged with JEV. All JEV-infected dogs did not show any clinical signs or abnormal blood tests, except for C-reactive protein. Virus-neutralization titers rapidly increased and were maintained until 70 days postinfection, and neither the virus nor the viral genome was detected in blood. Thus, since dogs live in close proximity to humans as companion animals, they are well suited for use as sentinels for surveying the human risk of JEV infection.     

Relationships between ammonia oxidizers and N2O and CH4 fluxes in agricultural fields with different soil types

Nitrous oxide (N₂O) is a greenhouse gas that contributes to the destruction of stratospheric ozone, and agricultural soil is an important source of N₂O. Aerobic soils are sinks for atmospheric methane (CH₄), a greenhouse gas. Ammonia monooxygenase (AMO) can oxidize CH₄, but CH₄ is mostly oxidized by methane monooxygenase (MMO), and CH₄ oxidation by AMO is generally negligible in the soil. We monitored the N₂O and CH₄ fluxes after urea application in fields containing different soils using an automated sampling system to determine the effects of environmental and microbial factors on the N₂O and CH₄ fluxes. The soil types were Low-humic Andosol (Gleyic Haplic Andosol), yellow soil (Gleyic Haplic Alisol) and gray lowland soil (Entric Fluvisol). Cumulative N₂O emissions from the yellow soil were higher than those from other soil types, although the difference was not significant. The CH₄ uptake level by Andosol was one order of magnitude higher than that by other soils. There were significant relationships between the ammonia oxidation potential, AOB and AOA amoA copy numbers, and the CH₄ uptake. In contrast, the gene copy numbers of methane-oxidizing bacteria (MOB) pmoA were below the detection limit. Our results suggested that the AMOs of AOB and AOA may have more important roles than those previously considered during CH₄ oxidation in agricultural soils treated with N fertilizers.