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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.
T Isobe Y I Fang D Muno T Okuyama D Ohmori F Yamakura 《Biochemistry international》1988,16(3):495-501
Alignment of the amino acid sequences of the Pseudomonas ovalis and Photobacterium leiognathi iron-superoxide dismutases (Fe-SODs) with the known sequences of the manganese-superoxide dismutases (Mn-SODs) shows that both types of SOD are highly homologous (33-53% identity) and share residues for the metal coordination. The amino acid residues that form the environment of the metal ions appear to be also conserved between the Fe- and Mn-SODs, except that the Phe-84 and Gln-154 in the Mn-SODs are replaced by Tyr and Ala, respectively, in the Fe-enzymes. Since this latter residue contributes to formation of the hydrophobic metal-ligand environment through hydrogen bonding with Trp-133 and Tyr-34 in the Mn-SODs, its substitution by Ala should cause different micro environments between the metal centers of the Fe- and Mn-SODs. This difference may account for the metal specificity of both types of SODs demonstrated by previous reconstitution experiments. 相似文献
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Importance of topography and soil texture in the spatial distribution of two sympatric dipterocarp trees in a Bornean rainforest 总被引:1,自引:0,他引:1
Akira?ItohEmail author Takuo?Yamakura Tatsuhiro?Ohkubo Mamoru?Kanzaki Peter A.?Palmiotto James V.?LaFrankie Peter S.?Ashton Hua Seng?Lee 《Ecological Research》2003,18(3):307-320
Relationships between spatial distributions and site conditions, namely topography and soil texture, were analyzed for two congeneric emergent trees, Dryobalanops aromatica and Dryobalanops lanceolata (Dipterocarpaceae), in a tropical rainforest in Sarawak, East Malaysia. A 52-ha permanent plot was divided into 1300 quadrats measuring 20m×20m; for each Dryobalanops species, the number and total basal area of trees 1cm in d.b.h. were compared among groups of quadrats with different site conditions. Because spatial distributions of both Dryobalanops and site-condition variables were aggregated, Monte-Carlo permutation tests were applied to analyze the relationships. Both single and multifactor statistical tests showed that the density and basal area distributions of the two species were significantly non-random in relation to soil texture and topographic variables. D.aromatica was significantly more abundant at higher elevations, in sandy soils, and on convex and steep slopes. In contrast, D.lanceolata preferred lower elevations and less sandy soils. In the study plot, there were very few sites (3 of 1150 quadrats tested) where the models of Hayashis method predicted the co-occurrence of the two species. These results suggest that between-species differences in habitat preferences are so large that they alone explain the spatially segregated distributions of these two species within the 52-ha study plot. 相似文献
6.
Munehiro Uda Hiroaki Kawasaki Ayako Shigenaga Takeshi Baba Fumiyuki Yamakura 《Bioscience reports》2012,32(6):521-530
Nitration of tryptophan residues is a novel post-translational modification. In the present
study, we examined whether NO2Trp (nitrotryptophan)-containing proteins are produced in
the hippocampus and cerebellum of the adult rat under physiological conditions in
vivo. Using Western blot analysis with anti-6-NO2Trp-specific antibody, we found
many similar immunoreactive spots in the protein extracts from both regions. These spots were
subsequently subjected to trypsin digestion and LC-ESI-MS/MS (LC-electrospray ionization-tandem MS)
analysis. We identified several cytoskeletal proteins and glycolytic enzymes as
NO2Trp-containing proteins and determined the position of nitrated tryptophan residues
with significant ion score levels (P<0.05) in several proteins in both
regions. We also observed that the total amount of NO2Trp-containing proteins in the
cerebellum was significantly greater than that in the hippocampus (P<0.05).
Moreover, IP (immunoprecipitation) assays using anti-aldolase C antibody showed that the relative
intensity of immunostaining for NO2Trp over aldolase C was much higher in cerebellum than
in hippocampus. The amounts of nNOS (neuronal nitric oxide synthase) and eNOS (endothelial nitric
oxide synthase) were much greater in cerebellum than in hippocampus. This is the first evidence of
several specific sites of nitrated tryptophan in proteins under physiological conditions in
vivo. 相似文献
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Amino acid volume and hydropathy of a transmembrane site determine glycine and anesthetic sensitivity of glycine receptors. 总被引:6,自引:0,他引:6
Two specific amino acid residues in transmembrane segments (TM) 2 and 3 are critical for the enhancement of glycine receptor (GlyR) function by volatile anesthetics. To determine which physicochemical characteristics of these sites determine their roles in anesthetic actions, an extensive series of single amino acid mutations at amino acid residue 288 (Ala-288) in TM3 of the alpha1 GlyR subunit was tested for modulation by volatile anesthetics. The mutations changed the apparent affinities of receptors for glycine; replacements with larger volumes and less hydropathy exhibited higher affinities for glycine. Potentiation by anesthetics was reduced by specific mutations at Ala-288. The molecular volume of the substituents was negatively correlated with the extent of potentiation by isoflurane, enflurane, and 1-chloro-1,2,2-trifluorocyclobutane, whereas there was no correlation between anesthetic enhancement and polarity, hydropathy, or hydrophilicity of substituents. In contrast to anesthetics, no correlation was found between the effects of the nonanesthetics 1,2-dichlorohexafluorocyclobutane or 2, 3-dichlorooctafluorobutane and any physicochemical property of the substituent. These results suggest that the molecular volume and hydropathy of the amino acid at position 288 in TM3 regulate glycine and anesthetic sensitivity of the GlyR and that this residue might represent one determinant of an anesthetic binding site. 相似文献
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Novel oligosaccharide has suppressive activity against human leukemia cell proliferation 总被引:1,自引:0,他引:1
Hosomi O Misawa Y Takeya A Matahira Y Sugahara K Kubohara Y Yamakura F Kudo S 《Glycoconjugate journal》2009,26(2):189-198
Various oligosaccharides containing galactose(s) and one glucosamine (or N-acetylglucosamine) residues with β1–4, α1–6 and β1–6 glycosidic bond were synthesized; Galβ1–4GlcNH2, Galα1–6GlcNH2, Galα1–6GlcNAc, Galβ1–6GlcNH2, Galβ1–4Galβ1–4GlcNH2 and Galβ1–4Galβ1–4GlcNAc. Galα1–6GlcNH2 (MelNH2) and glucosamine (GlcNH2) had a suppressive effect on the proliferation of K562 cells, but none of the other saccharides tested containing GlcNAc
showed this effect. On the other hand, the proliferation of the human normal umbilical cord fibroblast was suppressed by none
of the saccharides other than GlcNH2. Adding Galα1–6GlcNH2 or glucosamine to the culture of K562 cell, the cell number decreased strikingly after 72 h. Staining the remaining cells
with Cellstain Hoechst 33258, chromatin aggregation was found in many cells, indicating the occurrence of cell death. Furthermore,
all of the cells were stained with Galα1–6GlcNH-FITC (MelNH-FITC). Neither the control cells nor the cells incubated with
glucosamine were stained. On the other hand, when GlcNH-FITC was also added to cell cultures, some of them incubated with
Galα1–6GlcNH2 were stained. The difference in the stainability of the K562 cells by Galα1–6GlcNH-FITC and GlcNH-FITC suggests that the
intake of Galα1–6GlcNH2 and the cell death induced by this saccharide is not same as those of glucosamine. The isolation of the Galα1–6GlcNH2 binding protein was performed by affinity chromatography (melibiose-agarose) and LC-MS/MS, and we identified the human heterogeneous
ribonucleoprotein (hnRNP) A1 (34.3 kDa) isoform protein (30.8 kDa). The hnRNP A1 protein was also detected from the eluate(s)
of the MelNH-agarose column by the immunological method (anti-hnRNP-A1 and HRP-labeled anti-mouse IgG (γ) antibodies). 相似文献
10.
Takuo Yamakura 《Journal of plant research》1987,100(2):109-128
Natural forest communities are made up of different overlapping elementary subpopulations consisting of individuals of different
species and ages. To stratify the individuals of a forest stand into elementary subpopulations by using tree height records,
a graphical method was empirically proposed employing a derivative of Pearson's type VII distribution as a basis. Arranging
all of the individual trees in a stand in the descending order of their height (x), and introducing the rank (N) of any individual in the ordered ranking ofx, finite difference (n) ofN and three values ofx, i.e.,x(N), x(N−n), andx(N+n) labelled byN, N−n, andN+n, respectively, the proposed method used the linear relation betweenx(N) and [x(N−n)+x(N+n)]. On thex(N) vs.[x(N−n)+x(N+n)] diagram, the relation between both the variables could be approximated by a few segmental linear relations and used for stratifying
the individuals of a forest stand into subpopulations. The method was applied for analyzing the vertical stratification in
forest stands of different forest formations in Japan, Southeast Asia, Africa, and South America. The conclusions on stratification
which resulted from the proposed method corresponded well to the conclusions on stratification from profile diagrams. 相似文献