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1.
Takuo Yamakura Akio Hagihara Sukristijono Sukardjo Husato Ogawa 《Ecological Research》1987,2(3):215-227
The form of tropical trees was studied with reference to the production structure of the component individuals of a tropical
rain forest stand in Sebulu, East Kalimantan in Indonesian Borneo, since the production structure as a physical or bio-economical
basis of tree form still remains obscure in tropical rain forests. The pipe model theory successfully explained the crown
shapes of different trees, and its parameter, designated as specific pipe length, suggested an increase in the cost of leaf
mass growth with an increase in crown size. A mathematical model consisting of exponential functions of aboveground height
was applied for describing stem form, and its properties were examined through changes in its coefficients and by adopting
an assumption of the geometrical similarity of individual stem form as a criterion for comparing differences in stem form
among individual trees. Furthermore, the cost of buttersses was discussed using the relation between bole- and buttress weight
calculated from the mathematical model. 相似文献
2.
Min-Hua Zong Toshiaku Fukui Takuo Kawamoto Atsuo Tanaka 《Applied microbiology and biotechnology》1991,36(1):40-43
Summary Bioconversion of three organosilicon compounds of different chain length between the silicon atom and the hydroxyl group (Me3Si(CH2)nOH, n = 1–3) by horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1.) was studied. Furthermore, the effect of the silicon atom on the HLADH-catalysed reaction was examined in comparison with the corresponding carbon compounds. HLADH could catalyse the dehydrogenation of trimethylsilyeethanol (n = 2) and trimethylsilylpropanol (n = 3). Trimethylsilylethanol was a better substrate than both its carbon analogue, 3,3-dimethylbutanol, and ethanol. The improved activity of HLADH on trimethylsilylethanol could be accounted for by a higher affinity toward HLADH and a lower activation energy of the reaction by HLADH than those of the carbon counterpart. These are derived from physical properties of the silicon atom, that is, the lower electronegativity and the bigger radius than those of the carbon atom. In contrast, HLADH showed no activity on trimethylsilylmethanol (n = 1), whereas it catalysed the dehydrogenation of the carbon analogue, 2,2-dimethylpropanol, fairly well. The reason for the inactivity of HLADH in the case of trimethylsilylmethanol based on the electric effect of the silicon atom is also discussed.
Offsprint requests to: A. Tanaka 相似文献
3.
利用脂肪酶在有机溶剂中催化对映选择性酯化反应对外消旋薄荷醇进行了有效的光学拆分。对分别使用酸酐和相应的游离羧酸作酰基给体时的反应性能进行了比较。发现酸酐的反应性远高于对应的游离羧酸,但在酶的催化作用下酸酐易水解成为游离羧酸;在微水系统中使用过高浓度的酸酐会导致酶缺水而失活,同时会促进手性醇的非选择性酯化,从而降低产物的光学纯度。然而,在连续流加丙酸酐的半批式反应系统中,所有这些缺点均可有效地克服。与使用游离丙酸的批式反应系统相比,dl-薄荷醇的反应时间缩短了一半,酶的稳定性大幅度提高,而产物l薄荷醇酯的光学纯度不相上下(>98%e)。 相似文献
4.
Albert T. Ichiki I. Reid Collmann Takuo Sonoda John A. MacGuire Kathy L. Wenzel Stephen Krauss 《Cancer immunology, immunotherapy : CII》1977,3(2):119-124
Summary The peripheral blood leukocytes from 29 patients with adenocarcinoma of the colon were studied sequentially for the T-cell level, the rosette-inhibition titer of antithymocyte globulin and the blastogenic response to PHA and Con A to evaluate the T-cell immunocompetence. The level of E-rosette-forming cells and the blastogenic response did not reflect the immunocompetence of the T-cell population. Fluctuations in the rosette-inhibition titer of antithymocyte globulin (ATG) were observed; an increased ATG titer indicated an unfavorable clinical course, while a decreased ATG titer was observed with patients who had a favorable clinical course. The rosette-inhibition titer with antithymocyte globulin was observed to be an important indicator of competent T cells in patients with colorectal cancer.Supported by the Physicians' Medical Education and Research Foundation and General Research Supports FundsAbbreviations used that are not spelled out in the text are: AET 2-aminoethylisothiouronium bromide; ATG Antithymocyte globulin; ALG Antilymphocyte globulin; E-RFC Erythrocyte rosette-forming cells; PHA Phytohemagglutinin; Con A Concanavalin A; E Sheep erythrocyte 相似文献
5.
A new method for the production of pectin from citrus peel was developed. For this purpose, a microorganism which produces a protopectin-solubilizing enzyme was isolated and identified as a variety of Trichosporon penicillatum. The most suitable conditions for the pectin production were determined as follows. Citrus (Citrus unshiu) peel was suspended in water (1:2, wt/vol), the organism was added, and fermentation proceeded over 15 to 20 h at 30°C. During the fermentation, the pectin in the peel was extracted almost completely without macerating the peel. By this method, 20 to 25 g of pectin was obtained per kg of peel. The pectin obtained was special in that it contained neutral sugar at high levels, which was determined to have a molecular weight suitable for practical applications. 相似文献
6.
D-manno-3-Heptulose (5) was synthesized by dimethyl sulfoxide-phosphorus pentaoxide oxidation of 1,2:3,4:6,7-tri-O-isopropylidene-D-glycero-D-manno-heptitol (3, prepared from volemitol), followed by hydrolysis. D-ido-3-Heptulose (8) was synthesized similarly by oxidation of 1,2:4,5:6,7-tri-O-isopropylidene-D-glycero-l-galacto-heptitol (7, prepared from D-glycero-l-galacto-heptitol, 6). Another tri-O-isopropylidene derivative (11), having a free primary hydroxyl group, was produced in larger amount than 7, and 11 yielded D-glycero-l-galacto-heptose (14). Compound 8 was also synthesized by way of 1,2:4,5.6,7-tri-O-isopropylidene-D-glycero-l-gulo-heptitol (15). The production of 15 from D-glycero-l-gulo-heptitol (13) was accompanied by a larger amount of 2,3:4,5:6,7-tri-O-isopropylidene-D-glycero-D-ido-heptitol (17) which, upon oxidation followed by hydrolysis, yielded D-glycero-D-ido-heptose (18). One of the two tri-O-isopropylidene derivatives obtained by acetonation of perseitol, 2,3:4,5:6,7-tri-O-isopropylidene-D-glycero-D-galacto-heptitol (19), yielded D-glycero-D-galacto-heptose (20). 相似文献
7.
[目的]探讨ompH基因在禽多杀性巴氏杆菌致病过程中的作用.[方法]利用同源重组原理构建中间为四环素抗性基因,两侧为ompH基因上下游同源序列同源的敲除载体pWSK29△ompH,将敲除载体电击转入C48-3株感受态细胞中,通过四环素抗性和菌落PCR筛选ompH基因的敲除突变株,并通过组合PCR、逆转录PCR和DNA测序对突变株进行验证.用生物学功能实验比较野生株、互补株和突变株在生长速率、荚膜结构、粘着能力和致病性等方面的差异.[结果]组合PCR、逆转录PCR和DNA测序结果证实ompH基因的敲除突变株C48-3△ompH构建成功,电镜观察结果证实ompH基因的缺陷影响细菌的荚膜合成能力,粘附实验结果显示与野生株C48-3和互补株C48-3C相比突变株C48-3△ompH对CEF细胞的粘附能力显著降低(P<0.01),而小鼠毒力实验结果表明突变株C48-3△ompH的致病性相对减弱.[结论]本实验构建的突变株C48-3△ompH,为进一步研究多杀性巴氏杆菌的致病机理奠定基础. 相似文献
8.
Kinetic resolution of organosilicon compounds by stereoselective dehydrogenation with horse liver alcohol dehydrogenase 总被引:3,自引:0,他引:3
Toshiaki Fukui Min-Hua Zong Takuo Kawamoto Atsuo Tanaka 《Applied microbiology and biotechnology》1992,38(2):209-213
Streoselective dehydrogenation of three isomers of trimethylsilypropanol was carried out with horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1.) and optically active organosilicon compounds were obtained in a water-organic solvent two-layer system with coenzyme regeneration. Furthermore, we examined the effects of the silicon atom on stereoselectivity of HLADH compared to the corresponding carbon compounds. Substitution of the silicon atom for the carbon atom was found to improve the stereoselectivity of HLADH. For example, the optical purity of the remaining 1-trimethylsilyl-2-propanol was higher than 99% enantiomeric excess (ee) at 50% conversion, whereas that of the carbon analogue was 84% ee. This phenomenon was probably ascribable to the bulkiness of the organosilicon compounds derived from their longer Si-C bond. Kinetic analysis in an aqueous monolayer system demonstrated that the specific properties of the silicon atom greatly affected the reactivity of these substrate compounds.Correspondence to: A. Tanaka 相似文献
9.
Miura T Fukami TA Hasegawa K Ono N Suda A Shindo H Yoon DO Kim SJ Na YJ Aoki Y Shimma N Tsukuda T Shiratori Y 《Bioorganic & medicinal chemistry letters》2011,21(19):5778-5783
Heat shock protein 90 (Hsp90) is a molecular chaperone which regulates maturation and stabilization of its substrate proteins, known as client proteins. Many client proteins of Hsp90 are involved in tumor progression and survival and therefore Hsp90 can be a good target for developing anticancer drugs. With the aim of efficiently identifying a new class of orally available inhibitors of the ATP binding site of this protein, we conducted fragment screening and virtual screening in parallel against Hsp90. This approach quickly identified 2-aminotriazine and 2-aminopyrimidine derivatives as specific ligands to Hsp90 with high ligand efficiency. In silico evaluation of the 3D X-ray Hsp90 complex structures of the identified hits allowed us to promptly design CH5015765, which showed high affinity for Hsp90 and antitumor activity in human cancer xenograft mouse models. 相似文献
10.
We examined the Mn(II) oxidation performance of a bacterium, BY86, collected at Yunotaki Falls Hokkaido, Japan. The bacterium showed rapid oxidation of Mn(II), and brown precipitates containing Mn formed within a few days of incubation. The presence of higher oxidation states of Mn than Mn(II) was ascertained by the UV-vis and XANES sutdy. This bacterium did not oxidize As(III) to As(V) in the absence of Mn. In the presence of Mn, however, As(III) was rapidly oxidized to As(V) on the cell surfaces. These findings indicate that BY86 does not have the ability to directly oxidize As(III) to As(V) within a short period of contact, but indirectly oxidizes it by the Mn oxides generated on the cell surfaces. A phylogenetical study disclosed that BY86 was most closely related to Bacillus cereus with an identity of 99.90%. It is expected that our findings in this study will contribute to the study of Mn(II)-oxidizing bacteria, which play an important role in the biogeochemical cycling of Mn as well as other trace elements including As. 相似文献