LUBACが生成する直鎖状ユビキチン鎖の腸管上皮細胞およびマクロファージにおける細胞特異的な腸炎への寄与機構

京都大学新制・課程博士博士(医学)甲第24796号医博第4988号新制||医||1066(附属図書館)京都大学大学院医学研究科医学専攻(主査)教授 竹内 理, 教授 上野 英樹, 教授 椛島 健治学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Butterfly fauna in the Higashi-Hiroshima Campus, Hiroshima University

東広島キャンパスのチョウ相を把握するために，2015年の4月から11月にかけてルートセンサス法によるチョウの調査を行った。本調査では5科56種のチョウを確認した。さらに調査期間外に10種のチョウを確認した。合計すると東広島キャンパスで5科66種のチョウを確認した。区域によって出現する種が異なるが，自然区と隣接する圃場で最も多くの種を確認した。以前の調査結果と比較すると，キャンパスの環境が変化した可能性が示唆された。We investigated the butterfly fauna in the Higashi-Hiroshima campus of Hiroshima University using route census surveys conducted from April to November 2015. Fifty-six species belonging to five families were recorded in this study. Ten additional species were found outside the survey period, which resulted in the detection of 66 species of butterflies (five families). The species richness was the highest in the farm field adjacent to the natural forest; however, the detected butterfly species differed from one area to another. Considering previous surveys made in this campus, the present results suggested slight environmental changes in and around the Higashi-Hiroshima campus

FtsH Protease in the Thylakoid Membrane: Physiological Functions and the Regulation of Protease Activity

Protein homeostasis in the thylakoid membranes is dependent on protein quality control mechanisms, which are necessary to remove photodamaged and misfolded proteins. An ATP-dependent zinc metalloprotease, FtsH, is the major thylakoid membrane protease. FtsH proteases in the thylakoid membranes of Arabidopsis thaliana form a hetero-hexameric complex consisting of four FtsH subunits, which are divided into two types: type A (FtsH1 and FtsH5) and type B (FtsH2 and FtsH8). An increasing number of studies have identified the critical roles of FtsH in the biogenesis of thylakoid membranes and quality control in the photosystem II repair cycle. Furthermore, the involvement of FtsH proteolysis in a singlet oxygen- and EXECUTER1-dependent retrograde signaling mechanism has been suggested recently. FtsH is also involved in the degradation and assembly of several protein complexes in the photosynthetic electron-transport pathways. In this minireview, we provide an update on the functions of FtsH in thylakoid biogenesis and describe our current understanding of the D1 degradation processes in the photosystem II repair cycle. We also discuss the regulation mechanisms of FtsH protease activity, which suggest the flexible oligomerization capability of FtsH in the chloroplasts of seed plants

Layout Optimization of the Beam Spot Locations Scanned by Electromagnets in Particle Beam Therapy

This paper presents a layout optimization method of the spot locations of pencil beam scanning for particle beam cancer therapy. With the pencil beam scanning technique, the particle beam is scanned from spot to spot in the tumor by using scanning magnets. To provide clinically ideal dose distributions and less-invasive treatment to the patients, both the spot locations and the number of particles given to each spot should be optimized. However, the spot layout is fixed with a lattice pattern in many prior studies. We propose the optimization method to derive the non-lattice spot layout to realize an acceptable dose distribution with a reduced number of spots. With the proposed method, a large enough number of spots were located densely at the initial state, and then the spots with the smallest contribution were removed one by one through iterations. The number of particles given to each spot was determined by solving a quadratic problem. Furthermore, we also propose the idea to accelerate the optimization process by simultaneously removing multiple spots. The algorithm was confirmed by numerical examples of both two-dimensional and three-dimensional cases. The dose quality with the optimized spot layout was better than that with the conventional lattice spot patterns, with all tested cases. In the optimized spot layout, the spots were located on the closed lines which were concentric to the target contour. We also confirmed the proposed method of multiple-remotion can accelerate the optimization process without violating the dose quality

Geometric trade-off between contractile force and viscous drag determines the actomyosin-based motility of a cell-sized droplet

動きまわる人工細胞、その鍵は摩擦にあり --細胞が狭い空間を利用して運動する仕組みを解明--. 京都大学プレスリリース. 2022-07-21.Cell migration in confined environments is fundamental for diverse biological processes from cancer invasion to leukocyte trafficking. The cell body is propelled by the contractile force of actomyosin networks transmitted from the cell membrane to the external substrates. However, physical determinants of actomyosin-based migration capacity in confined environments are not fully understood. Here, we develop an in vitro migratory cell model, where cytoplasmic actomyosin networks are encapsulated into droplets surrounded by a lipid monolayer membrane. We find that the droplet can move when the actomyosin networks are bound to the membrane, in which the physical interaction between the contracting actomyosin networks and the membrane generates a propulsive force. The droplet moves faster when it has a larger contact area with the substrates, while narrower confinement reduces the migration speed. By combining experimental observations and active gel theory, we propose a mechanism where the balance between sliding friction force, which is a reaction force of the contractile force, and viscous drag determines the migration speed, providing a physical basis of actomyosin-based motility in confined environments

Phos-tag-based approach to study protein phosphorylation in the thylakoid membrane

Protein phosphorylation is a fundamental post-translational modification in all organisms. In photoautotrophic organisms, protein phosphorylation is essential for the fine-tuning of photosynthesis. The reversible phosphorylation of the photosystem II (PSII) core and the light-harvesting complex of PSII (LHCII) contribute to the regulation of photosynthetic activities. Besides the phosphorylation of these major proteins, recent phosphoproteomic analyses have revealed that several proteins are phosphorylated in the thylakoid membrane. In this study, we utilized the Phos-tag technology for a comprehensive assessment of protein phosphorylation in the thylakoid membrane of Arabidopsis. Phos-tag SDS-PAGE enables the mobility shift of phosphorylated proteins compared with their non-phosphorylated isoform, thus differentiating phosphorylated proteins from their non-phosphorylated isoforms. We extrapolated this technique to two-dimensional (2D) SDS-PAGE for detecting protein phosphorylation in the thylakoid membrane. Thylakoid proteins were separated in the first dimension by conventional SDS-PAGE and in the second dimension by Phos-tag SDS-PAGE. In addition to the isolation of major phosphorylated photosynthesis-related proteins, 2D Phos-tag SDS-PAGE enabled the detection of several minor phosphorylated proteins in the thylakoid membrane. The analysis of the thylakoid kinase mutants demonstrated that light-dependent protein phosphorylation was mainly restricted to the phosphorylation of the PSII core and LHCII proteins. Furthermore, we assessed the phosphorylation states of the structural domains of the thylakoid membrane, grana core, grana margin, and stroma lamella. Overall, these results demonstrated that Phos-tag SDS-PAGE is a useful biochemical tool for studying in vivo protein phosphorylation in the thylakoid membrane protein