19 research outputs found
Theoretical Investigation of the H2O2‑Induced Degradation Mechanism of Hydrated Nafion Membrane via Ether-Linkage Dissociation
Structural characteristics of cell walls of kenaf ( Hibiscus cannabinus L.) and fixation of carbon dioxide
Decomposition of (1–3,1–4)-β-Glucan and Expression of the (1–3,1–4) -β-Glucanase Gene in Rice Stems during Ripening
To elucidate the possible participation of hemicellulose decomposition in lodging resistance, we studied the change of hemicellulose and cellulose content in the stems of rice during the ripening stage by methylation analysis and the expression of related genes by Northern blotting. In the rice stem in ripening stage, content of (1-3,1-4)-β-glucan, a component of hemicellulose, decreased markedly although the content of arabinoxylan, a major component of hemicellulose, and cellulose showed little change during the same growth period. On the other hand, expression of the Gns 1 gene, which may encode (1-3,1-4) -β-glucanase that catalyzes the degradation of (1-3,14) -β-glucan, increased sharply in the stem. The mechanism of decomposition of (1-3,1-4) -β-glucan in rice stem and the possible association with lodging resistance is discussed
Leaf litter decomposition of selected urban tree species during mulching
Leaf litter decomposition and changes in the chemical components of four urban tree species (Cinnamomum camphora Sieb., Zelkova serrata Makino, Firmiana simplex W. F. Wight, Ginkgo biloba Linn) during one-year mulching were analyzed. The mass loss of the leaf litters ranged from 30.5% (Z. serrata) to 52.7% (G. biloba) after one year. Annual decomposition rates were 0.63, 0.36, 0.48 and 0.75 for the leaf litters of C. camphora, Z. serrata, F. simplex and G. biloba, respectively. Both water and 80% aqueous ethanol extracts decreased significantly during the one year of mulching. The amount of total neutral sugars decreased and their total losses were 50.7, 37.9, 66.1 and 71.6% based on their initial amount. Glucose accounted for about half the mass of the total neutral sugar. The relative content of Klason residue increased during mulching, suggesting that Klason residue resists decomposition. Even though the main part of Klason residue of leaves is not lignin, it should be emphasized that the residue obtained by the Klason procedure is a critical factor in leaf litter decomposition. The nitrogen content increased during the one year of mulching and the high content of nitrogen content would also contribute to the high content of Klason residue in leaf litter.都市の代表的な都市緑化樹木であるクスノキ(Cinnamomum camphora Sieb.),ケヤキ(Zelkova serrata Makino),アオギリ(Firmiana simplex W. F. Wight),イチョウ(Ginkgo biloba Linn)を対象として,それらの落葉のマルチングにおける分解過程を明らかにするため,落葉をリターバッグに封入し,圃場に敷きならした。2ヶ月ごとに回収し,重量,細胞壁化学成分の測定を行った。全体の重量の減少は1 年の試験期間中に最低のケヤキで30.5%,最高のイチョウで52.7%であった。分解速度の指標となるオルソン指数関係式よる分解係数Kはクスノキ,ケヤキ,アオギリ,イチョウ(以下,この記載順による)でそれぞれ0.63,0.36,0.48,0.75 であった。落葉およびそのマルチング処理試料の成分分析は,主に抽出区分(80%含水エタノールおよび水による逐次抽出)を除いたあとの抽出残渣について行った。マルチングによって抽出区分の割合は速やかに減少したが,抽出残渣の重量減少は緩慢であった。細胞壁多糖類の主体である中性糖の含有率はすべての樹種で当初20% 前後であったのが,1 年のマルチング後に各樹種でそれぞれ,50.7%,37.9%,66.1%,71.6%減少した。一般的にリグニン量の指標とされているKlason 残渣の,未抽出の試料中の含有率は当初22.6%(イチョウ)から38.3%(ケヤキ)の範囲であったが,マルチングとともにその相対含有率は継続的に増加した。このように,マルチングによる落葉の重量減少に寄与する成分は,抽出区分と細胞壁構成多糖が主体であって,Klason 残渣を構成する成分は落葉中の難分解物であることが確認された。窒素の含有量は木材に比べ高く,マルチング過程で増加した。高い窒素含有量は落葉のKlason 残渣含有量が高くなる一つの要因と考えられる
Structural difference between leaf blade and petiole of original and mulched leaf litter of Ginkgo biloba
Lignin structural differences in leaf blade and petiole tissue from original and mulched leaf litter of G. biloba were analyzed. The total yield of neutral sugar in petiole was higher compared to that of leaf blade in both original and mulched samples. Lignin content obtained by an acetyl bromide procedure in petiole gave similar values to Klason lignin content corrected by subtracting the protein content. Total yields of alkaline nitrobenzene oxidation and ozonation products based on Klason residue and acetyl bromide lignin were lower compared to wood samples, while the yield based on assumed lignin content coincided with the value from wood samples. These results revealed that the Klason method and acetyl bromide procedure overestimated the value for the lignin content of leaves. The accurate content of lignin can be estimated from the methoxyl content of the Klason residue落葉のマルチング過程における化学成分の動態を詳しく見るためには,葉の組織ごとの化学成分の違いを考慮する必要がある。そこで,イチョウ落葉とそのマルチング処理物を,葉片と葉柄に分けて成分分析を行い,マルチングによる変化を調べた。細胞壁多糖の中性糖総量は葉片に比べ葉柄のほうが多かった。リグニンについて,Klason 法に加えてアセチルブロミド法によって直接測定するとともに,メトキシル基量をもとに推定値を求めた。葉柄ではKlason 残渣量をタンパク質について補正するとアセチルブロミド法の値とほぼ一致し,高いKlason 残渣量はタンパク質の混入によることが明らかとなった。しかし,葉片についてはKlason 残渣にタンパク質以外の成分が大量に混入していた。Klason 残渣およびアセチルブロミドリグニンをベースとした葉片のニトロベンゼン酸化生成物量およびオゾン酸化によるリグニン由来の生成物も極めて少なかった。メトキシル基量をもとに計算したリグニン量推定値をベースとしたそれらの収率は葉片および葉柄ともに木粉のそれと一致する値が得られた。Klason 法およびアセチルブロミド法は葉,特に木質化してない葉片のリグニン含有量を過大評価することが明らかになった
Decomposition of (1–3,1–4)-β-Glucan and Expression of the (1–3,1–4) -β-Glucanase Gene in Rice Stems during Ripening
Detection behavior of phenolic compounds in a dual-electrode system assembled from track-etched membrane electrodes
Electrochemical detection behavior of phenolic compounds in a series dual-electrode detector constructed from track-etched membrane electrodes (TEMEs) was investigated using microbore high-performance liquid chromatography. This detector featured complete electrolysis provided by the electrode structure, which consisted of cylindrical pores with a uniform diameter. The collection efficiency, which was defined as the ratio of peak areas observed at the first and second working electrodes, ranged from negative values up to 1.0. Because it reflected the electrochemical reaction's reversibility and the reaction products' stability, the substance-inherent collection efficiency varied over a much broader range of values than that obtained with conventional electrochemical detectors. The collection efficiencies of catechol and hydroquinone were up to 1.0. Resorcinol produced an anodic peak at both the first and second working electrodes despite a lower potential for polarization of the second electrode than the first electrode. In this case, the collection efficiency was negative. The results showed that the resulting product was oxidized in a low potential region. Catechin compounds, which have both catechol and resorcinol moieties, displayed the characteristics of both catechol and resorcinol simultaneously. Gallic acid, which produced an irreversible cyclic voltammogram, showed a quasi-reversible property produced by a relatively short transition time in the dual-electrode detector. The reported data will be valuable for peak identification and estimation of peak purities in complex chromatograms