Weathering of the Granite Soils and Its Influence on the Stability of Slope

The cutting slopes in granite soil regions are exposed in air and subjected to temperature change and water infiltration immediately after cutting. Then the strength of the soil mass is lowered successively up to failure point. In order to clarify the cause of the phenomena, the authors tried to examine a slope selected in a granite soil region by means of physical, chemical and mineralogical analysis. According to the results obtained from the above experiments, it is concluded that the original ground before cutting can be classified into three zones with characteristic clay minerals and the more the ground is weathered initially, the more rapidly their strength decreases excepting for the severely weathered part. These results are considered to depend largely on the fact that the soil grains weathered originally in the long period of time are relatively sensitive or unstable to chemical and mechanical actions

Physical Relation of Source I to IRc2 in the Orion KL Region

We present mid-infrared narrow-band images of the Orion BN/KL region, and N-band low-resolution spectra of IRc2 and the nearby radio source "I." The distributions of the silicate absorption strength and the color temperature have been revealed with a sub-arcsecond resolution. The detailed structure of the 7.8 micron/12.4 micron color temperature distribution was resolved in the vicinity of IRc2. A mid-infrared counterpart to source I has been detected as a large color temperature peak. The color temperature distribution shows an increasing gradient from IRc2 toward source I, and no dominant temperature peak is seen at IRc2. The spectral energy distribution of IRc2 could be fitted by a two-temperature component model, and the "warmer component" of the infrared emission from IRc2 could be reproduced by scattering of radiation from source I. IRc2 itself is not self-luminous, but is illuminated and heated by an embedded luminous young stellar object located at source I.Comment: 20 pages, 11 figures. Minor corrections had been done in the ver.2. Accepted for publication in PAS

Damage of Membrane Functions in the Yeast Saccharomyces cerevisiae by Near-UV Irradiation

酵母Saccharomyces cerevisiaeに長波長紫外光を照射すると,酵母の生存率は光量に依存して急激に低下した.この現象の発現機構についての知見を得るために,細胞膜機能として非常に重要な透過障壁能と能動輸送能の長波長紫外照射による損傷について,光量一効果曲線を作成して調べた. 酵母に10J/mlの長波長紫外光を照射すると生存率は50%に低下する.この照射光量は,細胞膜の透過障壁能の破壊を引き起こし,細胞内のカリウムイオンおよびナトリウムイオンの非選択的漏出と細胞膜非透過性物質の細胞内への浸入をもたらした .5J/ml以下の光量は酵母の生存率にほとんど影響を与えないが,アミノ酸の取り込み速度の著しい低下とポンプあるいはチャンネル機構の損傷を予想させるカリウムイオンの選択的漏出をもたらした.また,動力学的解析結果から,アミノ酸の取り込み速度低下の要因は､細胞膜表面に存在するレセプターの損傷によるものではなく､受容以降の輸送系の損傷によることが示唆された

Calcium and strontium stable isotopes reveal similar behaviors of essential Ca and nonessential Sr in stream food webs

Recent studies showed the potential of stable isotopes of the macronutrient calcium (δ⁴⁴/⁴⁰Ca) and nonessential strontium (δ⁸⁸/⁸⁶Sr) as new trophic level indicators in terrestrial vertebrates and marine teleost fishes. In this study, we tested whether similar Ca and Sr isotopic fractionation trends existed in macroinvertebrate-dominated stream food webs compared to vertebrates despite their physiological differences. We have determined the δ⁴⁴/⁴⁰Ca and δ⁸⁸/⁸⁶Sr values as well as the ⁸⁷Sr/⁸⁶Sr ratios of stream macroinvertebrates and small gobies and their potential metal sources (stream water, periphyton, and terrestrial plant litter) in upper and lower reaches of two streams in the Lake Biwa catchment, central Japan. The ⁸⁷Sr/⁸⁶Sr ratios revealed that stonefly nymphs, crustacea, and gobies mostly relied on aquatic Sr sources. Higher ⁸⁷Sr/⁸⁶Sr ratios of some crane fly and caddisfly larvae, mayfly, dobsonfly, and dragonfly nymphs indicated greater terrestrial contributions via plant litter. Positive correlations between the δ⁴⁴/⁴⁰Ca and δ⁸⁸/⁸⁶Sr values implied that similar Ca and Sr sources existed, and that Ca and Sr stable isotopes underwent similar fractionation trends although Sr was not essential. The δ⁴⁴/⁴⁰Ca and partly the δ⁸⁸/⁸⁶Sr values were positively correlated with Sr/Ca ratios and negatively with δ¹⁵N values indicating trophic effects on Ca and Sr stable isotopes. The enrichment of ⁴⁴Ca and ⁸⁸Sr in large filter-feeding caddisfly larvae was a notable exception from these trophic trends. Our data confirm that the trophic ⁴⁴Ca and ⁸⁸Sr depletion observed for marine teleost fishes and terrestrial vertebrates also applied to macroinvertebrate-dominated stream food webs despite their different physiologies indicating that shared mechanisms of Ca and Sr isotopic fractionation may exist at the cellular or molecular level between these taxa

Accelerated tumor growth in mice deficient in DNAM-1 receptor

Since the identification of ligands for human and mouse DNAM-1, emerging evidence has suggested that DNAM-1 plays an important role in the T cell– and natural killer (NK) cell–mediated recognition and lysis of tumor cells. However, it remains undetermined whether DNAM-1 is involved in tumor immune surveillance in vivo. We addressed this question by using DNAM-1–deficient mice. DNAM-1–deficient cytotoxic T lymphocyte (CTL) and NK cells showed significantly less cytotoxic activity against DNAM-1 ligand-expressing tumors in vitro than wild-type (WT) cells. The methylcholanthrene (MCA)-induced fibrosarcoma cell line Meth A expressed the DNAM-1 ligand CD155, and DNAM-1–deficient mice showed increased tumor development and mortality after transplantation of Meth A cells. Moreover, the DNAM-1–deficient mice developed significantly more DNAM-1 ligand-expressing fibrosarcoma and papilloma cells in response to the chemical carcinogens MCA and 7,12-dimethylbenz[a]anthracene (DMBA), respectively, than did WT mice. These results indicate that DNAM-1 plays an important role in immune surveillance of tumor development

Parkinson’s disease-associated iPLA2-VIA/PLA2G6 regulates neuronal functions and α-synuclein stability through membrane remodeling

Mutations in the iPLA2-VIA/PLA2G6 gene are responsible for PARK14-linked Parkinson’s disease (PD) with α-synucleinopathy. However, it is unclear how iPLA2-VIA mutations lead to α-synuclein (α-Syn) aggregation and dopaminergic (DA) neurodegeneration. Here, we report that iPLA2-VIA–deficient Drosophila exhibits defects in neurotransmission during early developmental stages and progressive cell loss throughout the brain, including degeneration of the DA neurons. Lipid analysis of brain tissues reveals that the acyl-chain length of phospholipids is shortened by iPLA2-VIA loss, which causes endoplasmic reticulum (ER) stress through membrane lipid disequilibrium. The introduction of wild-type human iPLA2-VIA or the mitochondria–ER contact site-resident protein C19orf12 in iPLA2-VIA–deficient flies rescues the phenotypes associated with altered lipid composition, ER stress, and DA neurodegeneration, whereas the introduction of a disease-associated missense mutant, iPLA2-VIA A80T, fails to suppress these phenotypes. The acceleration of α-Syn aggregation by iPLA2-VIA loss is suppressed by the administration of linoleic acid, correcting the brain lipid composition. Our findings suggest that membrane remodeling by iPLA2-VIA is required for the survival of DA neurons and α-Syn stability