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超偏極NMRによる細胞内代謝のリアルタイム解析
No full textQ-LEAP にて進行中の超偏極NMRによる細胞内代謝のリアルタイム解析について、最新の成果をポスターにて発表する。光・量子飛躍フラッグシッププログラム（Q-LEAP）第8回シンポジウムconference poste
放射線結腸線維症における血管内皮傷害の寄与
No full text腸管は骨盤部放射線治療におけるリスク臓器であり、腸線維症は特に重篤な晩期障害とされる。晩期腸管障害の発生には血管内皮の機能障害が関連しているとされるが、腸線維症の発症に及ぼす影響はよくわかっていない。そこで本研究では、骨盤部放射線治療を模倣したマウス尾側半身照射法によって腸血管内皮損傷モデルマウスを作製し、腸線維症の病態形成との関連について検討した。雄性C3Hマウスの尾側半身へ6 GyのX線照射を1回/日、4日間行った。照射マウスは、照射後約30日目から死亡し始め、重度の結腸線維化を伴っていたことがアザン染色により確認された。照射後20～30日目にかけてMilesアッセイにより結腸の血管透過性が亢進していることが確認できた。その一方で、FITC-dextranを用いた腸管バリア機能評価では粘膜透過性の破綻が認められなかったことから、晩期における主要な傷害は腸上皮ではなく血管内皮にあると考えられた。さらに、照射マウス結腸の血管内皮細胞では血管細胞接着分子であるVcam-1の発現が増加し、マクロファージや少量の好酸球が粘膜下層へ浸潤していることが組織免疫染色により確認された。以上のことから、晩期腸管障害における炎症・線維化において、活性化した血管内皮細胞上で発現するVcam-1を介した炎症性白血球の遊走が重要な役割を果たしていると考えられた。また、Vcam-1発現の下方制御が、放射線治療後の腸管炎症および線維症の予防に繋がると考えらえた。第26回菅原・大西記念癌治療増感シンポジウムconference presentatio
Numerical Method for Adjusting Dimple-Wall of Quasi-Optical Gyrotron Mode Converter to Boring Bar Size
No full textA numerical method is proposed for adjusting a dimple-wall (inner surface) of quasi-optical gyrotron mode converter to a finite boring bar size by removing too-small dimples from the original design. Such adjustment is essential for fabrication because there is a limit to reducing the boring bar radius because of worsening machining errors. The numerical method was demonstrated using a dimple-wall geometry designed by using Surf3d. The dimple-wall was successfully adjusted to the boring bar size by using the method so that the too-small dimples were removed. By simulating for different boring bar radii, quality degradations of mode converter by removing the too-small dimples were also evaluated. In this manner, a maximum boring bar radius can be obtained that doesn’t degrade the mode converter quality exceeding a design target. It is one of the most important information for fabricating the mode converter by machining.conference pape
磁区細分化方向性電磁鋼板における内部磁区構造
No full textThe internal magnetic domain structures near the laser irradiation area in a grain-oriented electrical steel sheet were observed by a magnetic microscope utilizing the magnetooptical effect called x-ray magnetic circularly polarized emission, in order to understand the magnetostriction characteristics of grain-oriented electrical steel.In the dc magnetized state, the domain structures consisted of main domains that were separated by 180°domain walls and closure domains. The width of main domains having magnetization antiparallel to the external field were narrow near the laser irradiation area, and the subsurface magnetic domains formed triangular structure. In addition, the magnetization component perpendicular to the sheet plane were observed in the regions adjacent to the main domains. The observed closure domains directly below the laser irradiation area showed magnetization component perpendicular to the sheet plane and elongated along the normal direction. The width of closure domains in the internal layer was wider than that in the surface layer of the steel sheet.journal articl
Highly sensitive positron imaging reveals short-term food distribution patterns in ant groups
No full textStudying food distribution in ant groups is essential for investigating social behavior, offering valuable insights into resource allocation, group dynamics, and environmental adaptation, thereby advancing ecological research. In this work, a highly sensitive and quantitative experimental tool was developed to visualize changes over time in food distribution within ant groups using positron-emitting radionuclides and a radiation imaging system. Food distribution observations within a 100-ant group allowed changes in an index of dispersion for food allocation to be quantified for 3 h. The method’s accuracy was confirmed by cross-checking with the results of a conventional quantification method using a gamma counter. Additionally, we successfully visualized food distribution in a 12-ant group and quantified the amount of food exchanged over a 30-min period. This method can be used to elucidate the mechanisms that control food distribution.journal articl
Alternative splicing of MSH4 causes ms5 male sterility in soybean
No full textBecause soybean is a self-pollinating crop and artificial crossing is labor-intensive, we have been developing a recurrent selection method based on insect-mediated pollination using the male sterility gene ms5 and honeybees (Apis mellifera). The male sterility ms5 gene is advantageous for recurrent selection because of the d2 locus, which controls cotyledon color in mature seeds and can be used as a phenotypic selection marker for the ms5 male sterility. However, occasional self-fertilization occurs because of instability of male sterility. Identification of the gene responsible for ms5 male sterility may resolve the problem. We narrowed down the candidate ms5 locus to a 54-kbp region using fine mapping with simple sequence repeat (SSR) markers. Bulked-DNA analysis using next-generation sequencing revealed a deletion and a nucleotide substitution as a candidate variation in the region. The variations were identified in intron of MutS homolog (GmMSH4), which modulates chromosomal recombination in meiosis. The ms5 transcript contained a novel exon with a premature termination codon. This exon originated from an alternative splice acceptor site caused by the deletion and nucleotide substitution, disrupting gene function. Co-segregation of male sterility with five independent mutations in GmMSH4 was confirmed using progeny of mutant lines. Mutations in GmMSH4 led to biased DNA partitioning during meiosis, resulting in collapsed or enlarged pollen and suggesting that ms5 male sterility is caused by the failure of pollen formation during meiosis due to loss of function of GmMSH4. In some genetic backgrounds, normal transcripts were detected in addition to the aberrant transcript, and the ratio between them varied among materials. Although the mechanism underlying the increased production of the normal transcript has not yet been identified, we speculate that an increase in its abundance restores normal pollen formation, thereby enabling self-fertilization. Future studies will aim to identify the conditions that influence transcript composition and to demonstrate the effectiveness of recurrent selection breeding in soybean using the ms5 male sterility system.Advancing Soybean Breeding: Genetics, Genomics, Biotechnology and Agronomyconference poste
Unraveling emotion regulation: optical and mathematical dissection of complex neural population dynamics
No full textEmotion regulation enables adaptive responses to environmental changes, and thus is critical for survival. The brain plays a central role in this process, with the prefrontal cortex serving as a key hub that coordinates emotional regulation by integrating external sensory information, interoceptive signals, and past experiences (i.e., memories). Although it has been proposed that neurons in the prefrontal cortex work together as a group for such complex processes, the mechanisms by which these neuronal populations store and process information for emotion regulation remain poorly understood. To address this point, we have been developing in vivo deep-brain two-photon imaging methods in mice, which enable imaging of brain regions implicated in emotion regulation (including the medial prefrontal cortex and the brainstem) at cellular resolution. We also integrated the imaging system with behavioral paradigms to monitor neural representations during emotion regulation, and combined them with machine learning-based analyses to dissect the underlying neural computation. In this talk, I will present our recent findings on neural population dynamics underlying fear memory. Specifically, I will discuss how our approach seeks to uncover the computations by which neural populations, organized into networks, give rise to fear memory encoding.The 7th International Symposium for Bioimagingconference presentatio
GATE Monte Carlo simulation of an ultrahigh resolution mouse brain PET scanner
No full textSpatial resolution is the most important factor for preclinical positron emission tomography (PET) especially for rodent brain imaging. Previously, we developed a mouse brain PET scanner with staggered 3-layer DOI detectors using 0.8 mm crystal pitch thereby achieving 0.45 mm resolution. However, there is still room for spatial resolution improvement with finer crystal pitch. Here we propose a new mouse brain PET design to further enhance in spatial resolution. The proposed PET scanner consists of staggered 3-layer DOI detectors using 0.6 mm crystal pitch. The crystal thicknesses of the 1st, 2nd, and 3rd layers are 3, 3 and 5 mm thereby resulting in a total thickness of 11 mm. The PET has a 48 mm ring diameter and 22.6 mm axial FOV with 2-ring structure. Each ring has 16 DOI detectors. We conducted GATE Monte Carlo simulations to investigate the achievable spatial resolution with the proposed PET. To evaluate the spatial resolution, four NEMA 22Na sources (D=0.25 mm) with spacing of 5 mm in the radial direction were scanned with an energy window of 400-600 keV and reconstructed using FBP algorithm. To evaluate imaging performance, a resolution phantom having six different rod diameters (0.45, 0.50, 0.55, 0.6, 0.7, and 0.8 mm) was scanned and reconstructed by using OSEM algorithm with 8 subsets and 50 iterations. The average spatial resolution with FBP algorithm was 0.55±0.07 mm, which was 22% better than that of the previous work in JSAP2024. The 0.45 mm rods of the resolution phantom could be resolved with a valley-to-peak ratio of 0.440±0.104, which is under the Rayleigh criterion (0.735). In the near future, we plan to develop a prototype mouse brain PET scanner to validate the GATE simulation results.2026年第７３回応用物理学会春季学術講演会conference presentatio
211Atを利用した放射能・化学形同時分析技術の開発
No full textタンデム加速器実験課題「211Rn/211Atジェネレータ開発と関連研究」での成果として、加速器で製造する医療用RIであるAt-211の放射能・化学形同時分析技術開発において製品化した分析装置を販売開始したこと、並びに更なる性能向上のための研究開発について報告した。東海・重イオン科学シンポジウムータンデム加速器成果報告会ーconference presentatio
Low- and high-dose-rate radiation exposure alters the cellular composition and dynamics of the rat mammary epithelium for weeks preceding carcinogenesis
No full textIn animals, low-dose-rate radiation induces cancer at a reduced rate compared with a high-dose-rate at an identical cumulative dose, although the underlying mechanism is not well understood. The immediate responses of cells to irradiation are well established, including DNA double-strand break repair, cell-cycle arrest and cell death; conversely, the changes in tissues weeks after irradiation are not well understood. We therefore analyzed cellular dynamics in rat mammary tissue weeks after high- or low-dose irradiation. We irradiated 5-week-old rats with 2 Gy (30 Gy/h) or 3- to 5-week-old rats with continuous 2 Gy (6 mGy/h). For histological analysis, luminal cells were identified with anti-cytokeratin (CK) 8+18; CK8+18Low cells are luminal progenitor cells, and CK8+18High cells are luminal mature cells. To evaluate cell composition by flow cytometry, epithelial cells were isolated from mammary tissue. The proliferative potential of luminal progenitor cells—as measured by Ki-67 on paraffin sections—decreased 2 weeks after irradiation at either the high- or low-dose rate but recovered to the control level by 4 weeks. No significant difference was observed in the S phase and total cell-cycle length identified by 5-ethynyl-2’-deoxyuridine and 5-bromo-2’-deoxyuridine or cell death marked by cleaved caspase-3 among the dose-rates. Furthermore, the composition of luminal mature cells changed 2–6 weeks after completing the high- and, to a lesser extent, low-dose-rate radiation exposure, indicating potential proliferative stimulation of luminal progenitor cells related to susceptibility to carcinogenesis. These findings suggest that the altered cell composition and dynamics of luminal cells for several weeks contribute to carcinogenesis.journal articl