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Kim, K . M .,Nakajima, S .,Nakajima, Y . 전남대학교 약품개발연구소 1997 약품개발연구지 Vol.6 No.1
Primary neuron cultures were made separately from the substantia nigra pars compacta and the substantia nigra pats reticulate of neonatal rats. Using the whole-cell patch-clamp, we tested for the presence of dopamine and GABA receptor subtypes by applying dopamine receptor agonists [the D₂ receptor agonist quinpirole and the D₁ receptor agonist R(+)-SKF-38393) and GABA receptor agonists (GABA and baclofen). The D₂ agonists and the GABA_B agonist increased an inward rectifier K^+ conductance, while the D₁ agonist decreased this K^+ conductance. Application of GABA increased membrane conductance, probably by increasing Cl^- permeability through GABA_A, receptors. Following the physiological tests, the same neuron was examined by double immunocytochemical labeling for antibody to tyrosine hydroxylase and antibody to GABA. Neurons which responded to the D₂ agonist were dopaminergic neurons, while neurons which did not respond to D₂ agonist were mostly GABAergic or non-dopaminergic/non-GABAergic. Neurons which responded to the D₁ agonist were non-dopaminergic/non-GABAergic. GABA_A receptors were present in all types of neurons, while GABA_B receptors were located on some dopaminergic neurons and some GABAergic neurons. These results largely agree with the published data on in vita or brain slice preparations, indicating that these neurons of neonatal rat brains, after being dissociated, produce the same transmitters and the same receptors in culture as those in vivo.
Nakajima, K.,Yin, X.,Takei, Y.,Seog, D.H.,Homma, N.,Hirokawa, N. Cell Press 2012 Neuron Vol.76 No.5
KIF5 (also known as kinesin-1) family members, consisting of KIF5A, KIF5B, and KIF5C, are microtubule-dependent molecular motors that are important for neuronal function. Among the KIF5s, KIF5A is neuron specific and highly expressed in the central nervous system. However, the specific roles of KIF5A remain unknown. Here, we established conditional Kif5a-knockout mice in which KIF5A protein expression was postnatally suppressed in neurons. Epileptic phenotypes were observed by electroencephalogram abnormalities in knockout mice because of impaired GABA<SUB>A</SUB> receptor (GABA<SUB>A</SUB>R)-mediated synaptic transmission. We also identified reduced cell surface expression of GABA<SUB>A</SUB>R in knockout neurons. Importantly, we identified that KIF5A specifically interacted with GABA<SUB>A</SUB>R-associated protein (GABARAP) that is known to be involved in GABA<SUB>A</SUB>R trafficking. KIF5A regulated neuronal surface expression of GABA<SUB>A</SUB>Rs via an interaction with GABARAP. These results provide an insight into the molecular mechanisms of KIF5A, which regulate inhibitory neural transmission.
Solar neutrino measurements in Super-Kamiokande-IV
Abe, K.,Haga, Y.,Hayato, Y.,Ikeda, M.,Iyogi, K.,Kameda, J.,Kishimoto, Y.,Marti, Ll.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakajima, T.,Nakayama, S.,Orii, A.,Sekiya, H.,Shiozawa, M.,Sonoda, Y.,Takeda, A. American Physical Society 2016 Physical Review D Vol.94 No.5
<P>Upgraded electronics, improved water system dynamics, better calibration and analysis techniques allowed Super-Kamiokande-IV to clearly observe very low-energy B-8 solar neutrino interactions, with recoil electron kinetic energies as low as similar to 3.5 MeV. Super-Kamiokande-IV data-taking began in September of 2008; this paper includes data until February 2014, a total livetime of 1664 days. The measured solar neutrino flux is (2.308 +/- 0.020)(stat)(-0.040)(+0.039) (syst)) x 10(6)/(cm(2) sec) assuming no oscillations. The observed recoil electron energy spectrum is consistent with no distortions due to neutrino oscillations. An extended maximum likelihood fit to the amplitude of the expected solar zenith angle variation of the neutrino-electron elastic scattering rate in SK-IV results in a day/night asymmetry of (-3.6 +/- 1.6(stat) +/- 0.6(syst)%. The SK-IV solar neutrino data determine the solar mixing angle as sin(2)theta(12) = 0.327(-0.031)(+0.026), all SK solar data (SK-I, SK-II, SK III and SK-IV) measures this angle to be sin(2)theta(12) = 0.334(-0.023)(+0.027), the determined mass-squared splitting is Delta m(21)(2) = 4.8(-0.8)(+1.5) x 10(-5) eV(2).</P>
Abe, K.,Haga, Y.,Hayato, Y.,Ikeda, M.,Iyogi, K.,Kameda, J.,Kishimoto, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakajima, T.,Nakano, Y.,Nakayama, S.,Orii, A.,Sekiya, H.,Shiozawa, M.,Takeda, A.,Tanaka, H. American Physical Society 2017 Physical Review D Vol.95 No.1
<P>We have searched for proton decay via p -> e(+) pi(0) and p -> mu(+) pi(0) using Super-Kamiokande data from April 1996 to March 2015, 0.306 megaton center dot years exposure in total. The atmospheric neutrino background rate in Super-Kamiokande IV is reduced to almost half that of phase I-III by tagging neutrons associated with neutrino interactions. The reach of the proton lifetime is further enhanced by introducing new signal criteria that select the decay of a proton in a hydrogen atom. No candidates were seen in the p -> e(+) pi(0) search. Two candidates that passed all of the selection criteria for p -> mu(+) pi(0) have been observed, but these are consistent with the expected number of background events of 0.87. Lower limits on the proton lifetime are set at tau/B(p -> mu(+) pi(0)) > 1.6 x 10(34) years and tau/B(p -> mu(+) pi(0) ) > 7.7 x 10(33) years at 90% confidence level.</P>
Richard, E.,Okumura, K.,Abe, K.,Haga, Y.,Hayato, Y.,Ikeda, M.,Iyogi, K.,Kameda, J.,Kishimoto, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakajima, T.,Nakano, Y.,Nakayama, S.,Orii, A.,Sekiya, H.,Shiozawa, American Physical Society 2016 Physical Review D Vol.94 No.5
<P>A comprehensive study of the atmospheric neutrino flux in the energy region from sub-GeV up to several TeV using the Super-Kamiokande (SK) water Cherenkov detector is presented in this paper. The energy and azimuthal spectra, and variation over time, of the atmospheric nu(e) + (nu) over bar (e) and nu(mu) + (nu) over bar (mu) fluxes are measured. The energy spectra are obtained using an iterative unfolding method by combining various event topologies with differing energy responses. The azimuthal spectra depending on energy and zenith angle, and their modulation by geomagnetic effects, are also studied. A predicted east-west asymmetry is observed in both the nu(e) and nu(mu) samples at 8.0 sigma and 6.0 sigma significance, respectively, and an indication that the asymmetry dipole angle changes depending on the zenith angle was seen at the 2.2 sigma level. The measured energy and azimuthal spectra are consistent with the current flux models within the estimated systematic uncertainties. A study of the long-term correlation between the atmospheric neutrino flux and the solar magnetic activity cycle is performed, and a weak preference for a correlation was seen at the 1.1 sigma level, using SK-I-SK-IV data spanning a 20-year period. For several particularly strong solar activity periods, corresponding to Forbush decrease events, no theoretical prediction is available but a deviation below the typical neutrino event rate is seen at the 2.4 sigma level. The seasonal modulation of the neutrino flux is also examined, but the change in flux at the SK site is predicted to be negligible, and, as expected, no evidence for a seasonal correlation is seen.</P>
Novel Anisotropic Superconductivity in Silicides
T. Tamegai,G. J. Li,K. Uozato,T. Nakagawa,Y. Nakajima 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The discovery of superconductivity with Tc ∽39 K in MgB2 renewed our interest in intermetalic compounds containing light elements. We have revisited superconductivity in anisotropic silicides, such as CaMSi (M = Al and Ga), R5Ir4Si10 (R: rare-earth elements), and Lu2Fe3Si5. In CaAlSi with the AlB2 structure, an anomalous angular dependence of the upper critical field is found, sugesting the presence of a decoupled superconducting region. An X-ray diffraction study has shown the presence of a pronounced superlatice structure along thec-axis. Magneto-optical observations on the ac-plane of CaAlSi reveal the presence of strong inhomogeneities. Most R5Ir4Si10 (R: Sc, Y, rare-earth elements) compounds show a charge-density wave instability with the ex- ception of Sc5Ir4Si10, which shows the highest Tc among these compounds. We have compared their anisotropic superconductivity in order to get some insight into the exceptional properties of Sc5Ir4Si10. Lu2Fe3Si5 is a superconductor with Tc ∽ 6 K and containing nonmagnetic iron. Previous specific heat measurements show that Lu2Fe3Si5 has a large residual density of state in the superconducting state. We have sucesfuly grown high-quality single crystals of Lu2Fe3Si5 and found a signature of the presence of a second superconducting gap as in MgB2.
Kyung, W. S.,Huh, S. S.,Koh, Y. Y.,Choi, K.-Y.,Nakajima, M.,Eisaki, H.,Denlinger, J. D.,Mo, S.-K.,Kim, C.,Kim, Y. K. Nature Publishing Group 2016 NATURE MATERIALS Vol.15 No.12
<P>The superconducting transition temperature (T-c) in a FeSe monolayer on SrTiO3 is enhanced up to 100 K (refs 1-4). High T-c is also found in bulk iron chalcogenides with similar electronic structure(5-7) to that of monolayer FeSe, which suggests that higher T-c may be achieved through electron doping, pushing the Fermi surface (FS) topology towards leaving only electron pockets. Such an observation, however, has been limited to chalcogenides, and is in contrast to the iron pnictides, for which the maximum T-c is achieved with both hole and electron pockets forming considerable FS nesting instability(8-11). Here, we report angle-resolved photoemission characterization revealing a monotonic increase of T-c from 24 to 41.5 K upon surface doping on optimally doped Ba(Fe1-xCox)(2)As-2. The doping changes the overall FS topology towards that of chalcogenides through a rigid downward band shift. Our findings suggest that higher electron doping and concomitant changes in FS topology are favourable conditions for the superconductivity, not only for iron chalcogenides, but also for iron pnictides.</P>