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Search Results: 1 - 10 of 1530 matches for " Masaki Fujisawa "
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Identification of potential target genes for the tomato fruit-ripening regulator RIN by chromatin immunoprecipitation
Masaki Fujisawa, Toshitsugu Nakano, Yasuhiro Ito
BMC Plant Biology , 2011, DOI: 10.1186/1471-2229-11-26
Abstract: Using immunoprecipitated (IPed) DNA fragments recovered by chromatin immunoprecipitation (ChIP) with anti-RIN antibody from ripening tomato fruit, we analyzed potential binding sites for RIN (CArG-box sites) in the promoters of representative ripening-induced genes by quantitative PCR. Results revealed nearly a 5- to 20-fold enrichment of CArG boxes in the promoters of LeACS2, LeACS4, PG, TBG4, LeEXP1, and LeMAN4 and of RIN itself, indicating direct interaction of RIN with their promoters in vivo. Moreover, sequence analysis and genome mapping of 51 cloned IPed DNAs revealed potential RIN binding sites. Quantitative PCR revealed that four of the potential binding sites were enriched 4- to 17-fold in the IPed DNA pools compared with the controls, indicating direct interaction of RIN with these sites in vivo. Near one of the four CArG boxes we found a gene encoding a protein similar to thioredoxin y1. An increase in the transcript level of this gene was observed with ripening in normal fruit but not in the rin mutant, suggesting that RIN possibly induces its expression.The presented results suggest that RIN controls fruit softening and ethylene production by the direct transcriptional regulation of cell-wall-modifying genes and ethylene biosynthesis genes during ripening. Moreover, the binding of RIN to its own promoter suggests the presence of autoregulation for RIN expression. ChIP-based analyses identified a novel RIN-binding CArG-box site that harbors a gene associated with RIN expression in its flanking region. These findings clarify the crucial role of RIN in the transcriptional regulation of ripening initiation and progression.Ripening processes of many kinds of fruit involve various biochemical and physiological changes, such as softening, enrichment of pigments, organic acids and nutrients (e.g., vitamins and sugars), and development of aroma and flavor. These changes make fruits attractive for the human diet. For climacteric fruits, autocatalytic ethylene pr
Numerical Study on Nonlinear Sound Propagation for Parametric Array  [PDF]
Kei Fujisawa
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2014, DOI: 10.4236/jfcmv.2014.23014
Abstract: This paper presents the numerical study on the nonlinear sound propagation for the parametric array using the compressible form of Navier-Stokes equations combined with the mass and energy conservation equations and the state equation. These governing equations are solved by finite difference time domain (FDTD) based method. The numerical result is shown for the parametric sound propagation in the near field of the sound source in cylindrical coordinate. The result indicates the generation of low-frequency unsteady beat by the interaction of two frequency sound waves in the near field, which grows to a difference frequency sound in the far field.
Prenatal Exposure to a Polychlorinated Biphenyl (PCB) Congener Influences Fixation Duration on Biological Motion at 4-Months-Old: A Preliminary Study
Hirokazu Doi, Shota Nishitani, Takashi X. Fujisawa, Tomoko Nagai, Masaki Kakeyama, Takahiro Maeda, Kazuyuki Shinohara
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059196
Abstract: Adverse effects of prenatal exposure to polychlorinated biphenyl (PCB) congeners on postnatal brain development have been reported in a number of previous studies. However, few studies have examined the effects of prenatal PCB exposure on early social development. The present study sought to increase understanding of the neurotoxicity of PCBs by examining the relationship between PCB congener concentrations in umbilical cord blood and fixation patterns when observing upright and inverted biological motion (BM) at four-months after birth. The development of the ability to recognize BM stimuli is considered a hallmark of socio-cognitive development. The results revealed a link between dioxin-like PCB #118 concentration and fixation pattern. Specifically, four-month-olds with a low-level of prenatal exposure to PCB #118 exhibited a preference for the upright BM over inverted BM, whereas those with a relatively high-level of exposure did not. This finding supports the proposal that prenatal PCB exposure impairs the development of social functioning, and indicates the importance of congener-specific analysis in the risk analysis of the adverse effects of PCB exposure on the brain development.
Nonlinear Acoustic Shadow Method to Reduce Reverberation Artifact  [PDF]
Kei Fujisawa, Akira Asada
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2016, DOI: 10.4236/jfcmv.2016.42005
Abstract: A novel technique for reducing reverberation artifact in acoustic shadow imaging using nonlinear ultrasound interaction, called nonlinear acoustic shadow method, has been developed and experimentally studied. In this technique, the conventional acoustic shadow method is modified by using the secondary wave generated by nonlinear interaction of two primary sound waves emitted from parametric array. Either conventional or nonlinear acoustic shadow imaging is carried out for aluminum square cylinder and the size of the shadow is compared. The result shows that the nonlinear acoustic shadow method reduces reverberation artifact inside the square cylinder and has better accuracy in the size measurement than conventional acoustic shadow method.
Sound Source Measurement of a Semi-Circular Cylinder in a Uniform Flow by Particle Image Velocimetry  [PDF]
Yasuyuki Oguma, Nobuyuki Fujisawa
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2016, DOI: 10.4236/jfcmv.2016.44014
Abstract: In this paper, the measurement of an aerodynamic sound source for a semi-circular cylinder in a uniform flow is described using Particle Image Velocimetry (PIV). This experimental technique is based on vortex sound theory, where the time derivative of vorticity is evaluated with the aid of two sets of standard PIV systems. The experimental results indicate that the sound source for the semi-circular cylinder is located around the shear layer near the edge of the semi-circular cylinder. The sound source intensity and the area are reduced in the semi-circular cylinder compared with those of a circular cylinder. This result indicates that the aerodynamic sound of the semi- circular cylinder is smaller than that of the circular cylinder, which supports the microphone measurement result.
Effect of Rotation and Revolution on Performance of Blade-Free Planetary Mixer  [PDF]
Takayuki Yamagata, Nobuyuki Fujisawa
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2019, DOI: 10.4236/jfcmv.2019.71001
Abstract: In this study, flow structures and mixing performance in a blade-free planetary mixer, which combines rotation and revolution motions inside a cylindrical vessel, are numerically investigated. Flow fields in the mixer vessel are simulated in a single rotating reference frame with various revolution speeds and a fixed rotation speed. The mixing process is investigated by a Lagrangian particle tracking method and the mixing performance is evaluated based on particle concentration. The results of the numerical simulations show that a vortical flow with an axis inclined with respect to the rotation axis of the vessel is generated by the combined influence of the rotation and revolution motions. The flow structure and vortical flow intensity vary as a function of the precession rate, which is the ratio of the revolution speed to rotation speed. The mixing performance of the blade-free planetary mixer is found to be maximum at aspecific precession rate.
Seismicity in the Antarctic Continent and Surrounding Ocean  [PDF]
Masaki Kanao
Open Journal of Earthquake Research (OJER) , 2014, DOI: 10.4236/ojer.2014.31002
Abstract:

Seismicity in the Antarctic and surrounding ocean is evaluated based on the compiling data by the International Seismological Centre (ISC). The Antarctic continent and surrounding ocean have been believed to be one of the aseismic regions of the Earth for many decades. However, according to the development of Global Seismic Networks and local seismic arrays, the number of tectonic earthquakes detected in and around the Antarctic continent has been increased. A total of 13 seismicity areas are classified into the Antarctic continent (3 areas) and oceanic regions within the Antarctic Plate (10 areas). In general, seismic activity in the continental areas is very low in Antarctica. However, a few small earthquakes are identified. Wilkes Land in East Antarctica is the most tectonically active area in the continent, with several small earthquake events having been detected during the last four decades. In the oceanic region, in contrast, seismic activity in the area of 120?-60? W sector is three times higher than that in the other oceanic areas. This may be considered to be involved in a tectonic stress concentration toward the Easter Island Triple Junction between the Antarctic Plate, the Pacific Plate and the Nazu- ca micro-Plate. Three volcanic areas, moreover, the Deception Island, the Mts. Erebus and Melbourn, are also found to be high seismic activities in contrast with surrounding vicinity areas.

Statistics of Seismic Tremors with Harmonic Overtones Recorded at Syowa Station, Antarctica: October 2014-March 2015  [PDF]
Masaki Kanao
International Journal of Geosciences (IJG) , 2017, DOI: 10.4236/ijg.2017.86046
Abstract: During the period from October 2014 to March 2015, a total number of 82 seismic tremors and 66 ice-quakes were identified in both three-component short-period seismographs (HES) and broadband seismographs (STS-1) at Syowa Station (SYO), Antarctica. Statistics of the number of these tremors indicated that many tremors were likely to occur when large increases in temperature and/or wind speed during the period. This implied that the rapid increase in temperature enhanced a melting speed of cryosphere environment with generating seismic energy; the tremors were also excited by stormy conditions, associated with interactive resonance between sea-ices and oceanic swells. The characteristic tremors of harmonic overtones with strong amplitudes were explained by repetitive sources, suggesting inter-glacial asperities such as the collision of icebergs and fast sea-ice, calving of glaciers/ice-streams at the coastal environment of Antarctica. These high amplitude tremors occurred independently from other majority types of events, characterized by non-linear, small amplitude and weak signals at the stormy condition and rapid increase in temperature.
Oxidative Stress-Induced Glomerular Mineralocorticoid Receptor Activation Limits the Benefit of Salt Reduction in Dahl Salt-Sensitive Rats
Kento Kitada, Daisuke Nakano, Ya Liu, Yoshihide Fujisawa, Hirofumi Hitomi, Yuki Shibayama, Hirotaka Shibata, Yukiko Nagai, Hirohito Mori, Tsutomu Masaki, Hiroyuki Kobori, Akira Nishiyama
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041896
Abstract: Background Mineralocorticoid receptor (MR) antagonists attenuate renal injury in salt-sensitive hypertensive rats with low plasma aldosterone levels. We hypothesized that oxidative stress causes MR activation in high-salt-fed Dahl salt-sensitive rats. Furthermore, we determined if MR activation persisted and induced renal injury, even after switching from a high- to a normal-salt diet. Methods and Findings High-salt feeding for 4 weeks increased dihydroethidium fluorescence (DHE, an oxidant production marker), p22phox (a NADPH oxidase subunit) and serum and glucocorticoid-regulated kinase-1 (SGK1, an MR transcript) in glomeruli, compared with normal-salt feeding, and these changes persisted 4 weeks after salt withdrawal. Tempol treatment (0.5 mmol/L) during high-salt feeding abolished the changes in DHE fluorescence, p22phox and SGK1. Dietary salt reduction after a 4-week high-salt diet decreased both blood pressure and proteinuria, but was associated with significantly higher proteinuria than in normal control rats at 4 weeks after salt reduction. Administration of tempol during high-salt feeding, or eplerenone, an MR antagonist (100 mg/kg/day), started after salt reduction, recovered proteinuria to normal levels at 4 weeks after salt reduction. Paraquat, a reactive oxygen species generator, enhanced MR transcriptional activity in cultured rat mesangial cells and mouse podocytes. Conclusions These results suggest that oxidative stress plays an important role in glomerular MR activation in Dahl salt-sensitive rats. Persistent MR activation even after reducing salt intake could limit the beneficial effects of salt restriction.
Magnetized stars with differential rotation and a differential toroidal field
Kotaro Fujisawa
Physics , 2015, DOI: 10.1093/mnras/stv905
Abstract: We have succeeded in obtaining magnetized equilibrium states with differential rotation and differential toroidal magnetic fields. If an internal toroidal field of a proto-neutron star is wound up from the initial poloidal magnetic field by differential rotation, the distribution of the toroidal magnetic field is determined by the profile of this differential rotation. However, the distributions of the toroidal fields in all previous magnetized equilibrium studies do not represent the magnetic winding by the differential rotation of the star. In this paper, we investigate a formulation of a differential toroidal magnetic field that represents the magnetic field wound up by differential rotation. We have developed two functional forms of differential toroidal fields which correspond to a v-constant and a j-constant field in analogy to differential rotations. As the degree of the differential becomes very high, the toroidal magnetic field becomes highly localized and concentrated near the rotational axis. Such a differential toroidal magnetic field would suppress the low-T/|W| instability more efficiently even if the total magnetic field energy is much smaller than that of a non-differential toroidal magnetic field.
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