High-frequency dielectric relaxation of liquid crystals: THz time-domain spectroscopy of liquid crystal colloids

Copyright © 2006 Optical Society of America. This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-23-11433 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Terahertz time-domain spectroscopy has been used to study the dielectric relaxation of pure 4’–n-pentyl–4–cyanobiphenyl (5CB) liquid crystal (LC) and its mixtures with 10 µm SiO2 particles in the frequency range 0.2–2 THz. For the pure sample, we find that spatial inhomogeneities consisting of oriented domains, comparable in size to our probe area (~1 mm2), cause a large scatter in the measured dielectric function, due to varying contributions from the ordinary and extraordinary components. In the LC/particle mixtures, ordering of the LC at the surface of the SiO2 particles results in a break-up of these domains, giving rise to a spatially much more homogeneous dielectric response. The inferred dielectric function can be interpreted using effective medium theory and the Debye relaxation model. We observe this stabilizing effect for interparticle distances < ~30 µm, setting a lower limit for the size of oriented domains in the bulk LC

Characterization of an epimastigote-stage-specific hemoglobin receptor of Trypanosoma congolense

Background: Since Trypanosorna spp. lack a complete heme synthesis pathway, the parasites are totally dependent on their host for heme throughout all of the stages of their life -cycle. We herein report the identification and characterization of a T. congolense epimastigote form (EMF)-specific hemoglobin (Hb) receptor. The gene was initially reported to encode a T. congolense haptoglobin (Hp)-Hb complex receptor (TcHpHbR) based on its similarity to a gene encoding a T brucei Hp-Hb complex receptor (TbHpHbR). Methods: Trypanosorna congolense IL3000 was used in this study. A TcHpHbR gene was PCR amplified from the parasite genome. The recombinant protein was used as an immunogen to raise antibodies for immunofluorescence assay and immunoblotting. Hemoglobin uptake by the parasite was examined by using Alexa 488 labelled Hb and visualized by confocal laser scanning microscopy. The qualitative and quantitative interaction between TcHpHbR and its ligand were measured using a surface plasmon resonance assay. Results: We found that, unlike TbHpHbR, TcHpHbR was exclusively expressed in the EMF stage at RNA and protein levels. The recombinant TcHpHbR (rTcHpHbR) was co-precipitated with free-Hb in a GST-pull down assay. Surface plasmon resonance revealed that rTcHpHbR binds free-Hb with high affinity (dissociation constant (K,A) =2.1x10(-8) M) but free-Hp with low affinity (Kd = 2.2x10(-7) M). Furthermore, Alexa 488-labelled-Hb was only taken up by the EMF and co-localized with tomato lectin, which is a marker of endocytic compartments (flagellar pocket and lysosome). Conclusion: We conclude that the T. congolense EMF takes up free-Hb via TcHpHbR, a receptor which is specific to this developmental stage. We therefore propose renaming TcHpHbR as T congolense EMF-specific Hb receptor (TcEpHbR)

Structural insights into tetraspanin CD9 function

Umeda, R., Satouh, Y., Takemoto, M. et al. Structural insights into tetraspanin CD9 function. Nat Commun 11, 1606 (2020). https://doi.org/10.1038/s41467-020-15459-

Autoantibody-induced internalization of nicotinic acetylcholine receptor α3 subunit exogenously expressed in human embryonic kidney cells

Autoantibody against nicotinic acetylcholine receptor (nAChR) α3 subunit has been implicated in the pathogenesis of paraneoplastic neurological syndrome. To examine the effect of anti-α3 subunit autoantibody on cell-surface nAChRs, we established human embryonic kidney 293 cells stably co-expressing α3 and β4 subunits. Upon incubation with seropositive patient\u27s serum, this cell line showed co-accumulation of patient\u27s IgG and α3 subunits in the cytoplasm. These data support the hypothesis that anti-α3 subunit autoantibody induces internalization of cell-surface nAChRs and thereby impairs synaptic transmission. © 2012 Elsevier B.V. All rights reserved

Emergence of a Helical Flux Rope Under an Active Region Prominence

Continuous observations were obtained of active region 10953 with the Solar Optical Telescope (SOT) on board the \emph{Hinode} satellite during 2007 April 28 to May 9. A prominence was located over the polarity inversion line (PIL) in the south-east of the main sunspot. These observations provided us with a time series of vector magnetic fields on the photosphere under the prominence. We found four features: (1) The abutting opposite-polarity regions on the two sides along the PIL first grew laterally in size and then narrowed. (2) These abutting regions contained vertically-weak, but horizontally-strong magnetic fields. (3) The orientations of the horizontal magnetic fields along the PIL on the photosphere gradually changed with time from a normal-polarity configuration to a inverse-polarity one. (4) The horizontal-magnetic field region was blueshifted. These indicate that helical flux rope was emerging from below the photosphere into the corona along the PIL under the pre-existing prominence. We suggest that this supply of a helical magnetic flux into the corona is associated with evolution and maintenance of active-region prominences.Comment: 10 pages, 2 figures, accepted for publication in ApJ Letter

Multi-Wavelength Observation of Electron Acceleration in the 2006 December 13 Flare

We present a multi-wavelength observation of a solar flare occurring on 2006 December 13 with Hinode, RHESSI, and the Nobeyama Radio Observatory, to study the electron acceleration site and mechanism. The Solar Optical Telescope (SOT) on board Hinode observed elongated flare ribbons, and RHESSI observed double-footpoint hard X-ray (HXR) sources appearing in part of the ribbons. A photospheric vector magnetogram obtained from SOT reveals that the HXR sources are located at the region where horizontal magnetic fields change the direction. The region is interpreted as the footpoint of magnetic separatrix. Microwave images taken with the Nobeyama Radioheliograph show a loop structure connecting the HXR sources. The brighter parts of the microwave intensity are located between the top and footpoints of the loop. We consider these observations as an evidence of the electron acceleration near the magnetic separatrix and injection parallel to the field line.Comment: 20 pages, 7 figures, accepted by Ap

Gliding Motility of Babesia bovis Merozoites Visualized by Time-Lapse Video Microscopy

BACKGROUND: Babesia bovis is an apicomplexan intraerythrocytic protozoan parasite that induces babesiosis in cattle after transmission by ticks. During specific stages of the apicomplexan parasite lifecycle, such as the sporozoites of Plasmodium falciparum and tachyzoites of Toxoplasma gondii, host cells are targeted for invasion using a unique, active process termed "gliding motility". However, it is not thoroughly understood how the merozoites of B. bovis target and invade host red blood cells (RBCs), and gliding motility has so far not been observed in the parasite. METHODOLOGY/PRINCIPAL FINDINGS: Gliding motility of B. bovis merozoites was revealed by time-lapse video microscopy. The recorded images revealed that the process included egress of the merozoites from the infected RBC, gliding motility, and subsequent invasion into new RBCs. The gliding motility of B. bovis merozoites was similar to the helical gliding of Toxoplasma tachyzoites. The trails left by the merozoites were detected by indirect immunofluorescence assay using antiserum against B. bovis merozoite surface antigen 1. Inhibition of gliding motility by actin filament polymerization or depolymerization indicated that the gliding motility was driven by actomyosin dependent process. In addition, we revealed the timing of breakdown of the parasitophorous vacuole. Time-lapse image analysis of membrane-stained bovine RBCs showed formation and breakdown of the parasitophorous vacuole within ten minutes of invasion. CONCLUSIONS/SIGNIFICANCE: This is the first report of the gliding motility of B. bovis. Since merozoites of Plasmodium parasites do not glide on a substrate, the gliding motility of B. bovis merozoites is a notable finding

看護基礎教育におけるActive Learning の手法を用いた公衆衛生学教育の試み（第１報）

本研究は、A 大学看護学部の看護基礎教育で実施されたActive Leaning の手法を用いた公衆衛生学の\演習プログラムにおける学生の学びを明らかにすることを目的とした。対象は、A 大学看護学部の学士課\程に在籍する2 年次の学生であり、演習は、大学に対する「大学内禁煙対策における政策提言」を目指し、\3 年間を一纏まりとして計画され、1 年目の演習では、調査計画を立案した。その結果、対象者は【看護\職の役割意識の深化】、【ヘルスプロモーション概念の体験的理解】、【予防活動の有用性と重要性】、【ハイ\リスクアプローチの必要性と困難さ】、【喫煙に至る機序への関心】、【公衆衛生の対象の多様性】について\の学びを得ており、公衆衛生学の授業にActive Leaning の手法を用いることで抽象的になりがちな公衆\衛生学の概念を具体的な実像をもって理解できたことが示唆された。今後の課題として、演習目的に応じ\た評価方法の検討があげられた。\利益相反なし