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Search Results: 1 - 10 of 1250 matches for " Tomoaki Sakamoto "
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Characterization of a Tos17 Insertion Mutant of Rice Auxin Signal Transcription Factor Gene, OsARF24  [PDF]
Tomoaki Sakamoto, Yoshiaki Inukai
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.41013
Abstract: Auxin signaling plays a key role in the regulation of various growth and developmental processes in higher plants. Auxin response factors (ARFs) are transcription factors that regulate the expression of auxin-response genes. The osarf24-1 mutant contains a truncation of domain IV in the C-terminal dimerization domain of a rice ARF protein, OsARF24. This mutant showed auxin-deficient phenotypes and reduced sensitivity to auxin. However, OsARF24 protein contains an SPL-rich repression domain in its middle region and acts as a transcriptional repressor. These results imply that the C-terminal dimerization domain, especially the C-terminal half of domain IV, is essential for the proper regulation of OsARF24 function as a transcriptional repressor in rice.
Genetic Background Influences Brassinosteroid-Related Mutant Phenotypes in Rice  [PDF]
Tomoaki Sakamoto, Hidemi Kitano, Shozo Fujioka
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.42028
Abstract: In two cases, mutations in the same brassinosteroid-related genes caused different phenotypes in japonica varieties Nipponbare and Taichung 65. The mutant phenotypes were less severe in the Taichung 65 background than in the Nipponbare background. Three newly isolated brassinosteroid-insensitive mutants (d61-1N, d61-11, and d61-12) derived from a Nipponbare mutant library were found to be alleles of d61, which represent defects in the OsBRI1 gene. Although the Nipponbare-derived mutant d61-1N had the same nucleotide substitution as the previously characterized Taichung 65-derived mutant d61-1T, these two mutants showed different phenotypes for plant stature, internode elongation pattern, and seed shape; in each case, d61-1N (in the Nipponbare genetic background) had the more severe mutant phenotype. Similar trends were seen for phenotypes caused by mutants of d2, a brassinosteroid biosynthesis gene. Consistent with these phenotypes, the expression of brassinosteroid-responsive genes was lower in the Nipponbare-derived mutants. These results can be explained by our findings that feed-forward up-regulation of OsBRI1 did not occur in the Nipponbare-derived mutants and that an mPing transposon is inserted into the promoter region of Nipponbare OsBRI1. Based on these results, we conclude that the expression of OsBRI1, especially its feed-forward up-regula
New Alleles of Rice ebisu dwarf (d2) Mutant Show both Brassinosteroid-Deficient and -Insensitive Phenotypes  [PDF]
Tomoaki Sakamoto, Yoichi Morinaka, Hidemi Kitano, Shozo Fujioka
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.312208
Abstract: ebisu dwarf (d2) is a mutant caused by mutation in a rice brassinosteroid biosynthetic enzyme gene, CYP90D2/D2, thereby conferring a brassinosteroid-deficient dwarf phenotype. Three newly isolated d2 alleles derived from a Nippon- bare mutant library (d2-3, d2-4, and d2-6) produced more severe dwarf phenotypes than the previously characterized null allele from a Taichung 65 mutant library, d2-1. Linkage analysis and a complementation test clearly indicated that the mutant phenotypes in d2-6 were caused by defects in CYP90D2/D2, and exogenous treatment with brassinolide, a bioactive brassinosteroid, rescued the dwarf phenotype of three Nipponbare-derived d2 mutants. However, the content of endogenous bioactive brassinosteroid, castasterone, and the expression of brassinosteroid-response genes indicated that partial suppression of the brassinosteroid response in addition to a brassinosteroid deficiency has occurred in the Nipponbare-derived d2 mutants. Based on these results, we discuss the possibility that wild-type Nipponbare has some defects in an unknown factor or factors related to the brassinosteroid response in rice.
Remifentanil Has Sufficient Hypnotic and Amnesic Effect for Induction of Anesthesia by Itself  [PDF]
Takeshi Yokoyama, Eiji Sakamoto, Fumiyasu Yamasaki, Koichi Yamashita, Tomoaki Yatabe, Kunio Suwa
Open Journal of Anesthesiology (OJAnes) , 2014, DOI: 10.4236/ojanes.2014.41002
Abstract:

With a small-dose remifentanil, some patients showed no reaction and did not remember it postoperatively. We, therefore, hypothesized that remifentanil may decrease the level of consciousness and/or exhibit amnesic effect when stimulations are avoided. Thirty-patients were divided into two groups: non-stimulation group and stimulation group. Anesthesia was induced with 1 micro-g·kg?1·min?1 of remifentanil using no additional hypnotic agent. In the non-stimulation group, patients were left free from any stimulation except non-invasive blood pressure monitoring. In the stimulation group, patients were asked to follow verbal commands. The level of consciousness was evaluated with electroencephalogram and BIS-value derived from it. In the non-stimulation group, all patients reached the decreased level of consciousness in 5 minutes. In the stimulation group, however, 14 patients were judged to be still conscious. 10 patients could open their mouth at the 5th minute, but 9 of these 10 patients did not remember it postoperatively. In conclusion, remifentanil, with no additional anesthetics, exhibited hypnotic and amnesic effects when stimulations were kept minimal.

Supersymmetry in quantum mechanics with point interactions
Tomoaki Nagasawa,Makoto Sakamoto,Kazunori Takenaga
Physics , 2002, DOI: 10.1016/S0370-2693(03)00575-6
Abstract: We investigate supersymmetry in one-dimensional quantum mechanics with point interactions. We clarify a class of point interactions compatible with supersymmetry and present N=2 supersymmetric models on a circle with two point interactions as well as a superpotential. A hidden su(2) structure inherent in the system plays a crucial role to construct the N=2 supercharges. Spontaneous breaking of supersymmetry due to point interactions and an extension to higher N-extended supersymmetry are also discussed.
Extended supersymmetry and its reduction on a circle with point singularities
Tomoaki Nagasawa,Makoto Sakamoto,Kazunori Takenaga
Physics , 2005, DOI: 10.1088/0305-4470/38/37/009
Abstract: We investigate $N$-extended supersymmetry in one-dimensional quantum mechanics on a circle with point singularities. For any integer $n$, $N=2n+1$ supercharges are explicitly constructed in terms of discrete transformations, and a class of singularities compatible with supersymmetry is clarified. In our formulation, the supersymmetry can be reduced to $M$-extended supersymmetry for any integer $M
Supersymmetry and discrete transformations on S^1 with point singularities
Tomoaki Nagasawa,Makoto Sakamoto,Kazunori Takenaga
Physics , 2003, DOI: 10.1016/j.physletb.2003.12.065
Abstract: We investigate N-extended supersymmetry in one-dimensional quantum mechanics on a circle with point singularities. For any integer n, N=2n supercharges are explicitly constructed and a class of point singularities compatible with supersymmetry is clarified. Key ingredients in our construction are n sets of discrete transformations, each of which forms an su(2) algebra of spin 1/2. The degeneracy of the spectrum and spontaneous supersymmetry breaking are briefly discussed.
Effects of Abscisic Acid Treatment on Berry Coloration and Expression of Flavonoid Biosynthesis Genes in Grape  [PDF]
Ayako Katayama-Ikegami, Tomoaki Sakamoto, Kana Shibuya, Takane Katayama, Mei Gao-Takai
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.79127
Abstract: In order to enhance berry coloration of bright-red grape cultivars, the effects of abscisic acid (ABA) treatment on the quantity and composition of anthocyanins as well as the expression of genes related to flavonoid biosynthesis in the berry were examined. Exogenous ABA treatment increased anthocyanin content, especially petunidin- and malvidin-type anthocyanins. Quantitative real-time PCR analysis revealed that ABA treatment around véraison resulted in the upregulation of genes encoding enzymes responsible for both general flavonoid and anthocyanin biosynthesis. On the other hand, the gene expressions of enzymes involved in proanthocyanidin synthesis were drastically decreased at véraison and remained extremely low even with ABA treatment. Thus, increases in the total amount and composition ratios of petunidin- and malvidin-type anthocyanins were mainly caused by ABA-induced upregulation of uridine diphosphate glucose flavonoid glucosyl transferase, glutathione S-transferase 4, O-methyl transferase and flavonoid 3’, 5’ hydroxylase expression, resulting in the deep coloration of berry of skin.
Emergent Supersymmetry in Warped Backgrounds
Tomoaki Nagasawa,Satoshi Ohya,Kazuki Sakamoto,Makoto Sakamoto
Symmetry, Integrability and Geometry : Methods and Applications , 2011,
Abstract: We show that quantum mechanical supersymmetries are emerged in Kaluza-Klein spectrum of linearized gravity in several warped backgrounds as a consequence of higher-dimensional general coordinate invariance. These emergent supersymmetries play an essential role for the spectral structure of braneworld gravity. We show that for the case of braneworld models with two codimension-1 branes the spectral pattern is completely determined only through the supersymmetries.
Hierarchy of QM SUSYs on a Bounded Domain
Tomoaki Nagasawa,Satoshi Ohya,Kazuki Sakamoto,Makoto Sakamoto,Kosuke Sekiya
Physics , 2008, DOI: 10.1088/1751-8113/42/26/265203
Abstract: We systematically formulate a hierarchy of isospectral Hamiltonians in one-dimensional supersymmetric quantum mechanics on an interval and on a circle, in which two successive Hamiltonians form N=2 supersymmetry. We find that boundary conditions compatible with supersymmetry are severely restricted. In the case of an interval, a hierarchy of, at most, three isospectral Hamiltonians is possible with unique boundary conditions, while in the case of a circle an infinite tower of isospectral Hamiltonians can be constructed with two-parameter family of boundary conditions.
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