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Featured researches published by Daisuke Yamauchi.


Journal of Bacteriology | 2013

Formation of Highly Twisted Ribbons in a Carboxymethylcellulase Gene-Disrupted Strain of a Cellulose-Producing Bacterium

Tomonori Nakai; Yasushi Sugano; Makoto Shoda; Hitoshi Sakakibara; Kazuhiro Oiwa; Satoru Tuzi; Tomoya Imai; Junji Sugiyama; Miyuki Takeuchi; Daisuke Yamauchi; Yoshinobu Mineyuki

Cellulases are enzymes that normally digest cellulose; however, some are known to play essential roles in cellulose biosynthesis. Although some endogenous cellulases of plants and cellulose-producing bacteria are reportedly involved in cellulose production, their functions in cellulose production are unknown. In this study, we demonstrated that disruption of the cellulase (carboxymethylcellulase) gene causes irregular packing of de novo-synthesized fibrils in Gluconacetobacter xylinus, a cellulose-producing bacterium. Cellulose production was remarkably reduced and small amounts of particulate material were accumulated in the culture of a cmcax-disrupted G. xylinus strain (F2-2). The particulate material was shown to contain cellulose by both solid-state (13)C nuclear magnetic resonance analysis and Fourier transform infrared spectroscopy analysis. Electron microscopy revealed that the cellulose fibrils produced by the F2-2 cells were highly twisted compared with those produced by control cells. This hypertwisting of the fibrils may reduce cellulose synthesis in the F2-2 strains.


Journal of Electron Microscopy | 2013

Micro-CT observations of the 3D distribution of calcium oxalate crystals in cotyledons during maturation and germination in Lotus miyakojimae seeds

Daisuke Yamauchi; Daisuke Tamaoki; Masato Hayami; Miyuki Takeuchi; Ichirou Karahara; Mayuko Sato; Kiminori Toyooka; Hiroshi Nishioka; Yasuko Terada; Kentaro Uesugi; Hidekazu Takano; Yasushi Kagoshima; Yoshinobu Mineyuki

The cotyledon of legume seeds is a storage organ that provides nutrients for seed germination and seedling growth. The spatial and temporal control of the degradation processes within cotyledons has not been elucidated. Calcium oxalate (CaOx) crystals, a common calcium deposit in plants, have often been reported to be present in legume seeds. In this study, micro-computed tomography (micro-CT) was employed at the SPring-8 facility to examine the three-dimensional distribution of crystals inside cotyledons during seed maturation and germination of Lotus miyakojimae (previously Lotus japonicus accession Miyakojima MG-20). Using this technique, we could detect the outline of the embryo, void spaces in seeds and the cotyledon venation pattern. We found several sites that strongly inhibited X-ray transmission within the cotyledons. Light and polarizing microscopy confirmed that these areas corresponded to CaOx crystals. Three-dimensional observations of dry seeds indicated that the CaOx crystals in the L. miyakojimae cotyledons were distributed along lateral veins; however, their distribution was limited to the abaxial side of the procambium. The CaOx crystals appeared at stage II (seed-filling stage) of seed development, and their number increased in dry seeds. The number of crystals in cotyledons was high during germination, suggesting that CaOx crystals are not degraded for their calcium supply. Evidence for the conservation of CaOx crystals in cotyledons during the L. miyakojimae germination process was also supported by the biochemical measurement of oxalic acid levels.


INTERNATIONAL WORKSHOP ON X-RAY AND NEUTRON PHASE IMAGING WITH GRATINGS | 2012

Extracting tissue and cell outlines of Arabidopsis seeds using refraction contrast X-ray CT at the SPring-8 facility

Daisuke Yamauchi; Daisuke Tamaoki; Masato Hayami; Kentaro Uesugi; Akihisa Takeuchi; Yoshio Suzuki; Ichirou Karahara; Yoshinobu Mineyuki

How biological form is determined is one of the important questions in developmental biology. Physical forces are thought to be the primary determinants of the biological forms, and several theories for this were proposed nearly a century ago. To evaluate how physical forces can influence biological forms, precise determination of cell and tissue shapes and their geometries is necessary. Computed tomography (CT) is useful for visualizing three-dimensional structures without destroying a sample. Because recent progress in micro-CT has enabled visualizing cells and tissues at the sub-micron level, we investigated if we could extract cell and tissue outlines of seeds using refraction contrast X-ray CT available at the SPring-8 synchrotron radiation facility. We used Arabidopsis seeds because Arabidopsis is a well-known model plant and its seed size is small enough to obtain whole images using the X-ray CT experimental system. We could trace the outlines of tissues in dry seeds using beamline BL20B2 (10 keV, ...


Bioscience, Biotechnology, and Biochemistry | 2005

Enhancement of linear gramicidin expression from Bacillus brevis ATCC 8185 by casein peptide.

Tomonori Nakai; Daisuke Yamauchi; Kou Kubota

Bacillus brevis (Brevibacillus parabrevis) ATCC 8185 synthesizes two kinds of antibiotic peptides, cyclopeptide tyrocidine and linear gramicidin. The production of linear gramicidin can be induced by the standard method (using a skim milk medium for pre-culture and beef broth for the main culture) employed for the induction of tyrocidine. In this study, we tried to determine the optimal growth medium for B. brevis ATCC 8185 for synthesizing linear gramicidin. The yield of linear gramicidin produced by the standard method was 3.11 μg/ml. When beef broth was used both as the pre-medium and the main medium, the yield of the antibiotic was only 0.59 μg/ml. To confirm the influence of skim milk, the strain was grown in a 1% skim milk medium. As a result, the amount of linear gramicidin produced reached 20.3 μg/ml. These findings show the importance of skim milk in the production of linear gramicidin. In the skim milk medium, the cells produced an extracellular protease 2 h before the linear gramicidin was expressed. The 1% skim milk medium pretreated by this protease did not allow the induction of linear gramicidin into the cells, and protease activity was not detected in the supernatant of the culture. When the cells were cultivated in a 1% egg albumin medium, protease activity from the supernatant of the culture was detected, but production of linear gramicidin was not observed. Therefore, a 1% casein medium was used for production of linear gramicidin. As a result, the yield of linear gramicidin produced in the medium reached 6.69 μg/ml. We concluded that a digested product of the extracellular protease from casein enhances linear gramicidin production.


Plant Signaling & Behavior | 2015

Preprophase band formation and cortical division zone establishment: RanGAP behaves differently from microtubules during their band formation.

Takatoshi Yabuuchi; Tomonori Nakai; Seiji Sonobe; Daisuke Yamauchi; Yoshinobu Mineyuki

Correct positioning of the division plane is a prerequisite for plant morphogenesis. The preprophase band (PPB) is a key intracellular structure of division site determination. PPB forms in G2 phase as a broad band of microtubules (MTs) that narrows in prophase and specializes few-micrometer-wide cortical belt region, named the cortical division zone (CDZ), in late prophase. The PPB comprises several molecules, some of which act as MT band organization and others remain in the CDZ marking the correct insertion of the cell plate in telophase. Ran GTPase-activating protein (RanGAP) is accumulated in the CDZ and forms a RanGAP band in prophase. However, little is known about when and how RanGAPs gather in the CDZ, and especially with regard to their relationships to MT band formation. Here, we examined the spatial and temporal distribution of RanGAPs and MTs in the preprophase of onion root tip cells using confocal laser scanning microscopy and showed that the RanGAP band appeared in mid-prophase as the width of MT band was reduced to nearly 7 µm. Treatments with cytoskeletal inhibitors for 15 min caused thinning or broadening of the MT band but had little effects on RanGAP band in mid-prophase and most of late prophase cells. Detailed image analyses of the spatial distribution of RanGAP band and MT band showed that the RanGAP band positioned slightly beneath the MT band in mid-prophase. These results raise a possibility that RanGAP behaves differently from MTs during their band formation.


Bioscience, Biotechnology, and Biochemistry | 2015

An N-terminal region of a Myb-like protein is involved in its intracellular localization and activation of a gibberellin-inducible proteinase gene in germinated rice seeds

Keita Sutoh; Kenji Washio; Ryozo Imai; Masamitsu Wada; Tomonori Nakai; Daisuke Yamauchi

The expression of the gene for a proteinase (Rep1) is upregulated by gibberellins. The CAACTC regulatory element (CARE) of the Rep1 promoter is involved in the gibberellin response. We isolated a cDNA for a CARE-binding protein containing a Myb domain in its carboxyl-terminal region and designated the gene Carboxyl-terminal Myb1 (CTMyb1). This gene encodes two polypeptides of two distinctive lengths, CTMyb1L and CTMyb1S, which include or exclude 213 N-terminal amino acid residues, respectively. CTMyb1S transactivated the Rep1 promoter in the presence of OsGAMyb, but not CTMyb1L. We observed an interaction between CTMyb1S and the rice prolamin box-binding factor (RPBF). A bimolecular fluorescence complex analysis detected the CTMyb1S and RPBF complex in the nucleus, but not the CTMyb1L and RPBF complex. The results suggest that the arrangement of the transfactors is involved in gibberellin-inducible expression of Rep1. Schematic representation of the function of CTMyb1. CTMyb1S interacts with OsGAMyb in the mediation of RPBF and activate the Rep1 promoter, although CTMyb1L complexed with RPBF is exported from nucleus to cytoplasm.


Annals of Botany | 2012

Demonstration of osmotically dependent promotion of aerenchyma formation at different levels in the primary roots of rice using a ‘sandwich’ method and X-ray computed tomography

Ichirou Karahara; Konomi Umemura; Yuumi Soga; Yuki Akai; Tadafumi Bando; Yuko Ito; Daisuke Tamaoki; Kentaro Uesugi; Jun Abe; Daisuke Yamauchi; Yoshinobu Mineyuki


Plant Biotechnology | 2007

Hormonal regulation of the expression of cysteine proteinase genes in germinated cotyledons of common bean seeds

Daisuke Yamauchi


Plant Morphology | 2015

Three-dimensional imaging of plant tissues using X-ray micro-computed tomography

Ichirou Karahara; Daisuke Yamauchi; Kentaro Uesugi; Yoshinobu Mineyuki


Journal of Electron Microscopy | 2018

PB-06Three-dimensional Morphological Analysis of Supporting Tissues in the Dried Peduncle of Arabidopsis by X-ray Micro-CT

Kimitaka Sasaki; Masaki Muramoto; Daisuke Tamaoki; Sachiko Yano; Fumiaki Tanigaki; Toru Shimazu; Haruo Kasahara; Hirokazu Kasahara; Daisuke Yamauchi; Kentaro Uesugi; Masato Hoshino; Akihisa Takeuchi; Yoshio Suzuki; Yoshinobu Mineyuki; Seiichiro Kamisaka; Ichirou Karahara

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Kentaro Uesugi

Tokyo Institute of Technology

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