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Search Results: 1 - 10 of 820 matches for " SS Koide "
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GC-1 mRHBDD1 knockdown spermatogonia cells lose their spermatogenic capacity in mouse seminiferous tubules
Yong Wang, Wei Song, Shuchun Li, Xin Guan, Shiying Miao, Shudong Zong, SS Koide, Linfang Wang
BMC Cell Biology , 2009, DOI: 10.1186/1471-2121-10-25
Abstract: Stable mRHBDD1 knockdown GC-1 cells were sensitive to apoptotic stimuli, PS341 and UV irradiation. In vitro, they survived and proliferated normally. However, they lost the ability to survive and differentiate in mouse seminiferous tubules.Our findings suggest that mRHBDD1 may be associated with mammalian spermatogenesis.Spermatogenesis generates functional sperm cells from initially undifferentiated germ cells. This involves the proliferation of spermatogonia, meiosis of spermatocytes and the differentiation of spermatids into spermatozoa. It is a complex developmental program in which myriad events take place to ensure that the germ cells reach their proper stages of development at the appropriate times. Normal spermatogenesis requires a well-regulated balance of several processes, including cell proliferation, differentiation and apoptosis.Apoptosis is a key phenomenon during spermatogenesis. For instance, an early, massive wave of germ cell apoptosis occurs at puberty. This event takes place during postnatal weeks 2 to 4 in mice, with a peak after 3 weeks [1-3]. It is estimated that 75% of spermatogenic cells undergo apoptosis during development [4,5], ensuring the maintenance of a critical ratio between maturing germ cells and Sertoli cells [2,6]. Sporadic apoptosis also occurs, primarily in spermatogonia and spermatocytes [2], eliminating defective germ cells with mutated DNA [7].The Rhomboid family comprises polytopic membrane proteins, which may be the most widely-conserved membrane proteins identified to date [8]. They share conserved biochemical properties in all biological kingdoms. Rhomboid proteases, which have been well studied in Drosophila, appear to regulate EGF receptor signalling pathways, thereby controlling growth and development [9,10]. In addition, some yeast Rhomboid proteases have been found to play important roles in mitochondrial membrane remodelling [11], while some parasite proteases containing a Rhomboid domain are important for invasiv
S_4 Flavor Symmetry Embedded into SU(3) and Lepton Masses and Mixing
Koide, Yoshio
High Energy Physics - Phenomenology , 2007, DOI: 10.1088/1126-6708/2007/08/086
Abstract: Based on an assumption that an S_4 flavor symmetry is embedded into SU(3), a lepton mass matrix model is investigated. A Frogatt-Nielsen type model is assumed, and the flavor structures of the masses and mixing are caused by VEVs of SU(2)_L-singlet scalars \phi_u and \phi_d which are nonets (8+1) of the SU(3) flavor symmetry, and which are broken into 2+3+3' and 1 of S_4. If we require the invariance under the transformation (\phi^{(8)},\phi^{(1)}) \to (-\phi^{(8)},+\phi^{(1)}) for the superpotential of the nonet field \phi^{(8+1)}, the model leads to a beautiful relation for the charged lepton masses. The observed tribimaximal neutrino mixing is understood by assuming two SU(3) singlet right-handed neutrinos \nu_R^{(\pm)} and an SU(3) triplet scalar \chi.
Broken SU(3) Flavor Symmetry and Tribimaximal Neutrino Mixing
Koide, Yoshio
High Energy Physics - Phenomenology , 2007,
Abstract: Recent work on a lepton mass matrix model based on an SU(3) flavor symmetry which is broken into S_4 is reviewed. The flavor structures of the masses and mixing are caused by VEVs of SU(2)_L-singlet scalars \phi which are nonets ({\bf 8}+{\bf 1}) of the SU(3) flavor symmetry, and which are broken into {\bf 2}+{\bf 3}+{\bf 3}' and {\bf 1} of S_4. If we require the invariance under the transformation (\phi^{(8)},\phi^{(1)}) \to (-\phi^{(8)},+\phi^{(1)}) for the superpotential of the nonet field \phi^{(8+1)}, the model leads to a beautiful relation for the charged lepton masses. The observed tribimaximal neutrino mixing is understood by assuming two SU(3) singlet right-handed neutrinos \nu_R^{(\pm)} and an SU(3) triplet scalar \chi.
Charged Lepton Mass Relations in a Supersymmetric Yukawaon Model
Koide, Yoshio
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.79.033009
Abstract: According to an idea that effective Yukawa coupling constants Y_f^{eff} are given vacuum expectation values < Y_f> of fields ("Yukawaons") Y_f as Y_f^{eff}=y_f < Y_f>/\Lambda, a possible superpotential form in the charged lepton sector under a U(3) [or O(3)] flavor symmetry is investigated. It is found that a specific form of the superpotential can lead to an empirical charged lepton mass relation without any adjustable parameters.
Phenomenological Meaning of a Neutrino Mass Matrix Related to Up-Quark Masses
Koide, Yoshio
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.78.093006
Abstract: Recently, a curious neutrino mass matrix has been proposed: it is related to up-quark masses, and it can excellently give a nearly tribimaxial mixing. It is pointed out that, in order to obtain such successful results, three phenomenological relations among masses and CKM parameters must be simultaneously satisfied. This suggests that there must be a specific flavor-basis in which down-quark and charged lepton mass matrices are simultaneously diagonalized.
Charged Lepton Mass Formula -- Development and Prospect --
Koide, Yoshio
High Energy Physics - Phenomenology , 2007, DOI: 10.1142/S0218301307006770
Abstract: The recent devolopment on the charged lepton mass forumula m_e+m_{\mu}+m_{\tau}={2/3}(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_{\tau}})^2 is reviewed. An S_3 or A_4 model will be promising for the mass relation.
Microscopic formula for transport coefficients of causal hydrodynamics
Koide, T.
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevE.75.060103
Abstract: The Green-Kubo-Nakano formula should be modified in relativistic hydrodynamics because of the problem of acausality and the breaking of sum rules. In this work, we propose a formula to calculate the transport coefficients of causal hydrodynamics based on the projection operator method. As concrete examples, we derive the expressions for the diffusion coefficient, the shear viscosity coefficient, and corresponding relaxation times.
Neutrino Mass Hierarchies in a Mass Matrix Form Versus its Inverse Form
Koide, Yoshio
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.78.037302
Abstract: A neutrino mass matrix model M_\nu with M_\nu^T =M_\nu and a model with its inverse matrix form \widetilde{M}_\nu = m_0^2 (M_\nu^*)^{-1} can be diagonalized by the same mixing matrix U_\nu. It is investigated whether a scenario which provides a matrix model M_\nu with normal mass hierarchy can also give a model with an inverted mass hierarchy by considering a model with an inverse form of M_\nu.
Neutrino Mass Matrix Related to Up-Quark Masses and Nearly Tribimaximal Mixing -- Based on a Yukawaon model --
Koide, Yoshio
High Energy Physics - Phenomenology , 2008, DOI: 10.1142/S0217751X09047077
Abstract: Based on a new approach (the so-called Yukawaon model) to the mass spectra and mixings, a neutrino mass matrix which is described in terms of the up-quark masses and CKM matrix parameters is proposed. The mass matrix successfully leads to a nearly tribimaximal mixing without assuming any discrete symmetry.
A_4 Symmetry and Lepton Masses and Mixing
Koide, Yoshio
High Energy Physics - Phenomenology , 2007, DOI: 10.1140/epjc/s10052-007-0433-1
Abstract: Stimulated by Ma's idea which explains the tribimaximal neutrino mixing by assuming an A_4 flavor symmetry, a lepton mass matrix model is investigated. A Frogatt-Nielsen type model is assumed, and the flavor structures of the masses and mixing are caused by the VEVs of SU(2)_L-singlet scalars \phi_i^u and \phi_i^d (i=1,2,3), which are assigned to {\bf 3} and ({\bf 1}, {\bf 1}',{\bf 1}'') of A_4, respectively.
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