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Tsuyoshi K.,Kyushu University | Shigejiro Y.,Kyushu University | Keiko N.,Kyoto Prefectural University | Takuhiko M.,Niigata University | And 9 more authors.
Nihon Ringakkai Shi/Journal of the Japanese Forestry Society | Year: 2011

Since 1990's, In Kyushu region, the abandonment of sites after clear-cutting plantations is increasing rapidly in Japan. Abandoned clear-cut sites may result in reduced soil and water conservation. In this study, we investigated erosions, osions, landslides and factors limiting vegetation recovery (e.g. Damage caused by browsing by sika deer and invasion by bamboo and luxuriant vine species) in 199 abandoned clear-cut sites in the Kyushu region. Among 199 sites, 8 sites (4.2%) showed severe erosions and landslides. However, 125 sites (62.8%) showed some factors limiting vegetation recovery. Thus, the abandoned clear-cut sites are problematic, and browsing by sika deer and invasion by bamboo or vine may add limiting vegetation recovery to this problem, although a few of severe erosions and landslides currently.

Guo J.,Kyushu University | Hirasaki N.,Kyushu University | Miyata Y.,Nagasaki Agriculture and Forestry Technical Development Center | Tanaka K.,Nagasaki University | And 5 more authors.
PLoS ONE | Year: 2016

The current study demonstrated that theasinensin A (TSA) had a potential to form the complex with hydrophobic Trp-containing dipeptides, and to reduce their membrane potential by artificial-lipid membrane taste sensor. At a 1:3 molar ratio of the 6 Trp-containing dipeptides together with TSA, we observed a significant chemical shift of the protons of the dipeptides (Ää) to a high magnetic field, when analyzed using 1H-nuclear-magnetic resonance (NMR) spectroscopy. The Ää values were correlated with the hydrophobicity (log P) of the dipeptides and significant correlations were obtained (P = 0.022, R2 = 0.77); e.g., Trp-Leu with the highest log P value of 1.623 among the tested dipeptides showed the highest Ää value of 0.105 ppm for the H7 proton of Trp-Leu, while less chemical shifts were observed in theasinensin B and epigallocatechin-3-O-gallate. Diffusion-ordered NMR spectroscopy revealed that the diffusion coefficient of 3 mM of Trp-Leu (7.6 ? 10-11 m2 /s) at a pulse field gradient in the range 0.05-0.3 T/m decreased in the presence of 3 mM TSA (6.6 ? 10-11 m2 /s), suggesting that Trp-Leu forms a complex with TSA. Quantum mechanical calculations and rotating frame nuclear Overhauser effect-NMR spectroscopy provided configuration information on the geometry of the complex that Trp-Leu formed with TSA (1:1 complex) with a ÄG energy of -8.7 kJ/mol. A sensor analysis using artificial-lipid membranes demonstrated that the changes in membrane potential of 1 mM Trp-Leu (21.8 ± 1.3 mV) and Leu-Trp (5.3 ± 0.9 mV) were significantly (P < 0.001) reduced by 1 mM TSA (Trp-Leu, 13.1 ± 2.4 mV; Leu-Trp, 3.5 ± 0.5 mV; TSA alone, 0.2 ± 0.01 mV), indicating the effective suppression of hydrophobicity of dipeptides by TSA-formed complex. © 2016 Guo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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