146 research outputs found

    Lokiarchaeota archaeon schizorhodopsin-2 (LaSzR2) is an inward proton pump displaying a characteristic feature of acid-induced spectral blue-shift

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    The photoreactive protein rhodopsin is widespread in microorganisms and has a variety of photobiological functions. Recently, a novel phylogenetically distinctive group named 'schizorhodopsin (SzR)' has been identified as an inward proton pump. We performed functional and spectroscopic studies on an uncharacterised schizorhodopsin from the phylum Lokiarchaeota archaeon. The protein, LaSzR2, having an all-trans-retinal chromophore, showed inward proton pump activity with an absorption maximum at 549 nm. The pH titration experiments revealed that the protonated Schiff base of the retinal chromophore (Lys188, pK(a)=12.3) is stabilised by the deprotonated counterion (presumably Asp184, pK(a)=3.7). The flash-photolysis experiments revealed the presence of two photointermediates, K and M. A proton was released and uptaken from bulk solution upon the formation and decay of the M intermediate. During the M-decay, the Schiff base was reprotonated by the proton from a proton donating residue (presumably Asp172). These properties were compared with other inward (SzRs and xenorhodopsins, XeRs) and outward proton pumps. Notably, LaSzR2 showed acid-induced spectral 'blue-shift' due to the protonation of the counterion, whereas outward proton pumps showed opposite shifts (red-shifts). Thus, we can distinguish between inward and outward proton pumps by the direction of the acid-induced spectral shift

    Characteristics of Clinical and Imaging Findings of Epidermoid Cysts under the Skin of the Mental Region

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    Epidermoid cyst often arises in the fl oor of oral cavity; however, it is relatively rare to arise subcutaneously in the mental region. We reported characteristics of clinical and imaging fi ndings of epidermoid cysts under the skin of the mental region. The patient was a 53-year-old male. He complained of a subcutaneous mass without pain in the left mental region. A palpable soft and movable thumb-sized mass without pain was observed at the fi rst examination. Ultrasound examination revealed a well-demarcated mass with heterogenous hyper-echoic internal echo and posterior echo enhancement. On power Doppler sonography, a small amount of blood supply was found around the periphery of the mass. Plain CT scan revealeda globular soft-tissue mass with peripheral high and central low CT values area. The mass was removed under local anesthesia using intraoral approach. A histopathologic diagnosis was epidermoid cyst. Recurrence is not observed 2 years after surgery. There were only 3 reports of epidermoid cysts in the mental region, including our case in Japan, clinically characteristics of age ranging 20 to 66 years of age and the mean age of 46 years, with 2 males and 1 female. The size wasfrom 20 mm to 12 mm in diameter and from the tip of a thumb up to the tip of a small fi nger. Ultrasound images of the inside of epidermoid cysts that we experienced this time showed enhancement of relatively uniform hyperechoic image and posterior echo, which was characteristically slightly diff erent from fi ndings of epidermoid cysts generally reported

    Toward Identification of Order Parameters in Skutterudites - a Wonderland of Strong Correlation Physics -

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    Current status is described toward identifying unconventional order parameters in filled skutterudites with unique ordering phenomena. The order parameters in PrFe4_4P12_{12} and PrRu4_4P12_{12} are discussed in relation to associated crystalline electric field (CEF) states and angular form factors. By phenomenological Landau analysis, it is shown that a scalar order model explains most properties in both PrFe4_4P12_{12} and PrRu4_4P12_{12} with very different magnetic properties. In particular, the highly anisotropic susceptibility induced by uniaxial pressure in PrFe4_4P12_{12} is explained in terms of two types of couplings. In the case of SmRu4_4P12_{12}, the main order parameter at low field is identified as magnetic octupoles. A microscopic mechanism is proposed how the dipole and octupole degrees of freedom mix under the point group ThT_h of skutterudites.Comment: To be published in Proc. International Conference on New Quantum Phenomena in Skutterudite and Related Systems (Suppl. J. Phys. Soc. Jpn 78, 2008

    Lateral–Medial Dissociation in Orbitofrontal Cortex–Hypothalamus Connectivity

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    The orbitofrontal cortex (OFC) is involved in cognitive functions, and is also closely related to autonomic functions. The OFC is densely connected with the hypothalamus, a heterogeneous structure controlling autonomic functions that can be divided into two major parts: the lateral and the medial. Resting-state functional connectivity has allowed us to parcellate the cerebral cortex into putative functional areas based on the changes in the spatial pattern of connectivity in the cerebral cortex when a seed point is moved from one voxel to another. In the present high spatial-resolution fMRI study, we investigate the connectivity-based organization of the OFC with reference to the hypothalamus. The OFC was parcellated using resting-state functional connectivity in an individual subject approach, and then the functional connectivity was examined between the parcellated areas in the OFC and the lateral/medial hypothalamus. We found a functional double dissociation in the OFC: the lateral OFC (the lateral orbital gyrus) was more likely connected with the lateral hypothalamus, whereas the medial OFC (the medial orbital and rectal gyri) was more likely connected with the medial hypothalamus. These results demonstrate the fundamental heterogeneity of the OFC, and suggest a potential neural basis of the OFC-hypothalamic functional interaction

    Scalar order: possible candidate for order parameters in skutterudites

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    Phenomenological Landau analysis shows that the properties of ordered phases in some skutterudites are consistently accounted for by a scalar order parameter which preserves the cubic symmetry, even in the ordered phase. A universal value is found for the anisotropy ratio of the transition temperature in a magnetic field, homogeneous magnetization, and induced staggered magnetization. The difference in magnetic behavior between PrFe4_4P12_{12} and PrRu4_4P12_{12} near their phase transitions is explained within a single framework. For the low-field phase of PrFe4_4P12_{12}, the scalar order with the Γ1g\Gamma_{1g} symmetry can explain (i) the absence of field induced dipoles perpendicular to the magnetic field, (ii) isotropic magnetic susceptibility in the ordered phase, (iii) the field angle dependence of the transition temperature, and (iv) the splitting pattern of the 31^{31}P nuclear magnetic resonance (NMR) spectra. It is proposed how the order parameter in SmRu4_4P12_{12} is identified by NMR analysis of a single crystal.Comment: 4 pages, 4 figure

    Multipole State of Heavy Lanthanide Filled Skutterudites

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    We discuss multipole properties of filled skutterudites containing heavy lanthanide Ln from a microscopic viewpoint on the basis of a seven-orbital Anderson model. For Ln=Gd, in contrast to naive expectation, quadrupole moments remain in addition to main dipole ones. For Ln=Ho, we find an exotic state governed by octupole moment. For Ln=Tb and Tm, no significant multipole moments appear at low temperatures, while for Ln=Dy, Er, and Yb, dipole and higher-order multipoles are dominant. We briefly discuss possible relevance of these multipole states with actual materials.Comment: 5 pages, 3 figure

    A novel GTPase, CRAG, mediates promyelocytic leukemia protein–associated nuclear body formation and degradation of expanded polyglutamine protein

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    Polyglutamine diseases are inherited neurodegenerative diseases caused by the expanded polyglutamine proteins (polyQs). We have identified a novel guanosine triphosphatase (GTPase) named CRAG that contains a nuclear localization signal (NLS) sequence and forms nuclear inclusions in response to stress. After ultraviolet irradiation, CRAG interacted with and induced an enlarged ring-like structure of promyelocytic leukemia protein (PML) body in a GTPase-dependent manner. Reactive oxygen species (ROS) generated by polyQ accumulation triggered the association of CRAG with polyQ and the nuclear translocation of the CRAG–polyQ complex. Furthermore, CRAG promoted the degradation of polyQ at PML/CRAG bodies through the ubiquitin–proteasome pathway. CRAG knockdown by small interfering RNA in neuronal cells consistently blocked the nuclear translocation of polyQ and enhanced polyQ-mediated cell death. We propose that CRAG is a modulator of PML function and dynamics in ROS signaling and is protectively involved in the pathogenesis of polyglutamine diseases

    Microscopic Aspects of Multipole Properties of Filled Skutterudites

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    We discuss low-temperature multipole states of Nd-based filled skutterudites by analyzing a multiorbital Anderson model with the use of a numerical renormalization group method. In order to determine the multipole state, we take a procedure to maximize the multipole susceptibility matrix. Then, it is found that the dominant multipole state is characterized by the mixture of 4u magnetic and 5u octupole moments. The secondary state is specified by 2u octupole. When we further take into account the coupling between ff electrons in degenerate Γ67−\Gamma_{67}^{-} (eue_{\rm u}) orbitals and dynamical Jahn-Teller phonons with EgE_{\rm g} symmetry, quadrupole fluctuations become significant at low temperatures in the mixed multipole state with 4u magnetic and 5u octupole moments. Finally, we briefly discuss possible relevance of the present results to actual Nd-based filled skutterudite compounds.Comment: 6 pages, 3 figures. To appear in the Proceedings of the 17th International Conference on Magnetism (ICM2006

    Fabrication of Fe-based ribbon with controlled permeability by Joule heating under tensile stress

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    We prepared an Fe-based ribbon with controlled permeability and low magnetic loss by Continuous Stress-Annealing by Joule Heating (CSA-JH) method. The shortest annealing time necessary for the obtaining of the ribbons with completely developed anisotropy was 1 sec, but in order to obtain the sufficiently crystallized ribbons with small saturation magnetostriction it is required to perform annealing longer than 2 sec. A toroidal core was prepared from a long ribbon with controlled permeability and small saturation magnetostriction, and the magnetic loss and relative permeability of the core were evaluated in the frequency range of 0.1 - 3 MHz. The permeability was kept constant up to 2 MHz, and the magnetic loss is lower than that for other types of core with a similar permeability value. These results suggest that the CSA-JH method is a promising method for realizing an Fe-based core with excellent magnetic properties.Proceedings of the 18th International Symposium on Soft Magnetic Material
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