コムギゾク ショクブツ ニ オケル ベンゾキサジノン セイゴウセイ イデンシ ニ カンスル ケンキュウ

京都大学0048新制・課程博士博士(農学)甲第10906号農博第1412号新制||農||891(附属図書館)学位論文||H16||N3917(農学部図書室)UT51-2004-G753京都大学大学院農学研究科応用生命科学専攻(主査)教授 西岡 孝明, 教授 遠藤 隆, 教授 佐藤 文彦学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDA

Functional characterization of Capsicum chinense vanillin aminotransferase: Detection of vanillylamine-forming activity from vanillin

In capsaicin biosynthesis, vanillin aminotransferase (VAMT; EC 2.6.1.119) catalyzes the conversion of vanillin (V) to vanillylamine (VA). In vitro analysis of the recombinant VAMT enzyme has been reported; however, this enzyme catalyzed only the V-forming reaction and not the VA-forming reaction, which is inconsistent with the postulated pathway for capsaicin biosynthesis. In this study, we expressed, purified, and characterized functional recombinant VAMT of Capsicum chinense cv. Habanero from an Escherichia coli strain. The enzyme catalyzed reversible transamination between V and VA, and its VA-forming activity was high when γ-aminobutyric acid (GABA) was used as an amino donor. The enzyme exhibited maximum activity at pH 8.0 and 55 °C, and was stable up to 60 °C over a pH range from 4.5 to 8.0. The enzyme was stable in the presence of various chemicals and metal ions. The enzyme accepted several 4–8-carbon long primary amines and ω-amino acids with carbon chains longer than 4 as amino donors despite the narrow specificity of the amino acceptor. Based on its kinetic attributes and localization, VAMT appears to have evolved from GABA-aminotransferase to catalyze reversible transamination between V and VA, and is responsible for VA biosynthesis using GABA as an amino donor in the cytosol of capsicum fruit cells

Relationship between swimming performance and maximal oxygen debt, maximal oxygen uptake, and oxygen requirement

エネルギー代謝能力と水泳記録との関係に及ぼす水泳効率(e)の影響, 浮力の影響, および無酸素的代謝と有酸素的代謝の関与の影響について検討することを目的とした. 無酸素的および有酸素的代謝能力の指標として, 最大酸素負債量(O2debtmax)と最大酸素摂取量(V̇O2max)をそれぞれ回流水槽泳で測定した. 毎分酸素需要量(Ė)とeはO2debtmax, V̇O2maxおよび水泳記録から算出した. 被検者は性・年齢・水泳記録の異なるクロール泳者44名であった. 100mの水泳速度とO2debtmaxとの相関は全被検者群でr=0.551(p<0.01)であったものが, e1(100m水泳のe)≦3.33の群(n=14)ではr=0.739(p<0.01), 3.33<e1≦4.19の群(n=17)ではr=0.912(p<0.01), 4.19<e1の群(n=13)ではr=0.645(p<0.05)となった. 400mの水泳速度とV̇O2maxとの相関は全被検者群でr=0.554(p<0.01)であったものが, e4(400m水泳のe)≦5.24の群(n=14)ではr=0.730(p<0.01), 5.24<e4≦6.56の群(n=17)ではr=0.927(p<0.01), 6.56<e4の群(n=13)ではr=0.486となった. 以上のように, 水泳記録と代謝能力との相関はeの不均一な全被検者群よりeのほぼ均一な集団において高くなったことから, 両者の関係はeの要因によって顕著に影響されると結論した. 代謝能力は体重当りの値で示すよりも絶対値で示した場合に水泳記録との相関が高かった. これは, 水泳では浮力の作用により体重が支えられるために生じたと考えられた. 100mと400mの水泳記録は, O2debtmaxあるいはV̇O2maxに対するよりĖに対して, より高い相関を示した. したがって, 短距離泳における有酸素的代謝量の貢献を, また中・長距離泳における無酸素的代謝量の貢献を無視できないと考えられる.The purpose of this study was to discuss the effect of swimming efficiency (e), buoyancy, and participation of aerobic and anaerobic metabolism on the relationship between swimming performance and energy metabolic capacity. The maximal oxygen debt (O_2 debt_max) and maximal oxygen uptake (V̇o_2max) were measured after and during swimming in a swimming flume, as a parameter of anaerobic and aerobic capacity, respectively. Oxygen requirement (Ė) and swimming efficiency (e) were calculated from O_2 debt_max, V̇o_2max, and swimming record. The subjects consisted of 44 freestyle swimmers with different sex, age and swimming record. The correlation between O_2 debt_max and 100m swimming speed was r=0.551 (p<0.01) for the group) of whole subjects, while the coefficients for the three groups classified in terms of e_1 (e in 100m swimming) were r=0.739 (p<0.01) for the low e_1 group (N=14, e_1=3.33), r=0.912 (p<0.01) for the intermediate e_1 group (N=17, 3.33<e_1=4.19), and r=0.645 (p<0.05) for the high e_1 group (N=13,4.19<e_1). The correlation coefficient between V̇o_2max and 400m swimming speed was r=0.554 (p<0.01) for the whole group including all the subjects, while these coefficients for the sub-groups formed for e_4 (e in 400m swimming) were r=0.730 (p<0.01) for the low e_4 group (N=14, e_4≦5.24), r=0.927 (p<0.01) for the intermediate e_4 group (N=17, 5.24<e_4≦6.56) and r=0.486 for the high e_4 group (N=13, 6.56<e_4). Thus, correlations between swimming performance and metabolic capacity became higher for the group of subjects with homogeneous e than for the group of whole subjects with greater variability in their e. This result suggests that the relationship between swimming performance and metabolic capacity is markedly effected by the factor of e. Correlations between swimming performance and metabolic capacity were higher in absolute value than in relative value (/kg). This is probably because body weight is supported by buoyancy in swimming. Swimming performances in 100m and 400m races correlated higher with E than with O_2 debt_max or V̇o2_max. This suggests that contributions of aerobic metabolism in sprint race, and of anaerobic metabolism in middle and long distance races should not be underestimated

A novel xylogenic suspension culture model for exploring lignification in <it>Phyllostachys</it> bamboo

<p>Abstract</p> <p>Background</p> <p>Some prominent cultured plant cell lines, such as the BY-2 cell line of tobacco (<it>Nicotiana tabacum</it> cv. ‘Bright Yellow 2’) and the T87 cell line of Arabidopsis (<it>Arabidopsis thaliana</it> L. Heynh., ecotype Columbia) are used as model plant cells. These suspension cell culture systems are highly applicable for investigating various aspects of plant cell biology. However, no such prominent cultured cell lines exist in bamboo species.</p> <p>Results</p> <p>We standardized a novel xylogenic suspension culture model in order to unveil the process of lignification in living bamboo cells. Initial signs of lignin deposition were able to be observed by a positive phloroglucinol-HCl reaction at day 3 to 5 under lignification conditions (LG), i.e., modified half-strength Murashige and Skoog medium (m1/2MS) containing 10 μM 6-benzyladenine (BA) and 3% sucrose. Two types of xylogenic differentiation, both fiber-like elements (FLEs) with cell wall thickening and tracheary elements (TEs) with formation of perforations in the cell wall, were observed under these conditions. The suspension cells rapidly formed secondary cell wall components that were highly lignified, making up approximately 25% of the cells on a dry weight basis within 2 weeks. Detailed features involved in cell growth, differentiation and death during lignification were characterized by laser scanning microscopic imaging. Changes in transcript levels of xylogenesis-related genes were assessed by RT-PCR, which showed that the transcription of key genes like <it>PAL1</it>, <it>C4H</it>, <it>CCoAOMT</it>, and <it>CCR</it> was induced at day 4 under LG conditions. Furthermore, interunit linkage of lignins was compared between mature bamboo culms and xylogenic suspension cells by heteronuclear single quantum coherence (HSQC) NMR spectroscopy. The presence of the most common interunit linkages, including β-aryl ether (β-<it>O</it>-4), phenylcoumaran (β-5) and resinol (β-β) structures was identified in the bamboo cultured cell lignin (BCCL) by HSQC NMR. In addition to these common features of lignin, several differences in lignin substructures were also found between the BCCL and the bamboo milled wood lignin (BMWL).</p> <p>Conclusions</p> <p>Our xylogenic suspension culture model could be used for detailed characterization of physiological and molecular biological events in living bamboo cells.</p