Kyushu University

About: Kyushu University is a education organization based out in Fukuoka, Japan. It is known for research contribution in the topics: Population & Catalysis. The organization has 68284 authors who have published 135190 publications receiving 3055928 citations. The organization is also known as: Kyūshū Daigaku.

Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1

Abstract: The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.

Haematopoietic cell-specific CDM family protein DOCK2 is essential for lymphocyte migration

Abstract: Cell migration is a fundamental biological process involving membrane polarization and cytoskeletal dynamics1, both of which are regulated by Rho family GTPases2,3,4,5. Among these molecules, Rac is crucial for generating the actin-rich lamellipodial protrusion, a principal part of the driving force for movement3,6. The CDM family proteins, Caenorhabditis elegans CED-5, human DOCK180 and Drosophila melanogaster Myoblast City (MBC), are implicated to mediate membrane extension by functioning upstream of Rac7,8,9,10,11,12. Although genetic analysis has shown that CED-5 and Myoblast City are crucial for migration of particular types of cells8,9,12, physiological relevance of the CDM family proteins in mammals remains unknown. Here we show that DOCK2, a haematopoietic cell-specific CDM family protein13, is indispensable for lymphocyte chemotaxis. DOCK2-deficient mice (DOCK2-/-) exhibited migration defects of T and B lymphocytes, but not of monocytes, in response to chemokines, resulting in several abnormalities including T lymphocytopenia, atrophy of lymphoid follicles and loss of marginal-zone B cells. In DOCK2-/- lymphocytes, chemokine-induced Rac activation and actin polymerization were almost totally abolished. Thus, in lymphocyte migration DOCK2 functions as a central regulator that mediates cytoskeletal reorganization through Rac activation.

Heat activation of TRPM5 underlies thermal sensitivity of sweet taste

Abstract: One of the most intriguing features of taste perception is its modulation by temperature. It is well known that warming enhances perceived sweetness and bitterness. In addition, around half of the human population experiences taste sensations just by changing the temperature of the tongue, a phenomenon known as ‘thermal taste’. A possible molecular explanation for these thermal effects on taste is now at hand. Activation of the receptors for sweet, bitter and umami taste in specialized cells of the tongue causes opening of the TRPM5 ion channel. This channel has now been found to be activated by heat. Direct heat activation of TRPM5 could lead to activation of taste receptors even in the absence of anything to taste. TRPM5, a cation channel of the TRP superfamily, is highly expressed in taste buds of the tongue, where it has a key role in the perception of sweet, umami and bitter tastes1,2. Activation of TRPM5 occurs downstream of the activation of G-protein-coupled taste receptors and is proposed to generate a depolarizing potential in the taste receptor cells2. Factors that modulate TRPM5 activity are therefore expected to influence taste. Here we show that TRPM5 is a highly temperature-sensitive, heat-activated channel: inward TRPM5 currents increase steeply at temperatures between 15 and 35 °C. TRPM4, a close homologue of TRPM5, shows similar temperature sensitivity. Heat activation is due to a temperature-dependent shift of the activation curve, in analogy to other thermosensitive TRP channels3. Moreover, we show that increasing temperature between 15 and 35 °C markedly enhances the gustatory nerve response to sweet compounds in wild-type but not in Trpm5 knockout mice. The strong temperature sensitivity of TRPM5 may underlie known effects of temperature on perceived taste in humans4,5,6, including enhanced sweetness perception at high temperatures and ‘thermal taste’, the phenomenon whereby heating or cooling of the tongue evoke sensations of taste in the absence of tastants7.

Rho-Kinase Is an Important Therapeutic Target in Cardiovascular Medicine

Abstract: Rho-kinase has been identified as one of the effectors of the small GTP-binding protein Rho. Accumulating evidence has demonstrated that Rho/Rho-kinase pathway plays an important role in various cellular functions, not only in vascular smooth muscle cell (VSMC) contraction but also in actin cytoskeleton organization, cell adhesion and motility, cytokinesis, and gene expressions, all of which may be involved in the pathogenesis of cardiovascular disease. At molecular level, Rho-kinase upregulates various molecules that accelerate inflammation/oxidative stress, thrombus formation, and fibrosis, whereas it downregulates endothelial nitric oxide synthase. The expression of Rho-kinase itself is mediated by protein kinase C/NF-κB pathway with an inhibitory and stimulatory modulation by estrogen and nicotine, respectively. At cellular level, Rho-kinase mediates VSMC hypercontraction, stimulates VSMC proliferation and migration, and enhances inflammatory cell motility. In animal studies, Rho-kinase has been shown to be substantially involved in the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, stroke and heart failure, and to enhance central sympathetic nerve activity. Finally, in clinical studies, fasudil, a Rho-kinase inhibitor, is effective for the treatment of a wide range of cardiovascular disease, including cerebral and coronary vasospasm, angina, hypertension, pulmonary hypertension, and heart failure, with a reasonable safety. Thus, Rho-kinase is an important therapeutic target in cardiovascular medicine.

Rice gibberellin-insensitive dwarf mutant gene Dwarf 1 encodes the α-subunit of GTP-binding protein

Abstract: A rice Dwarf 1 gene was identified by using a map-based cloning strategy. Its recessive mutant allele confers a dwarf phenotype. Linkage analysis revealed that a cDNA encoding the α-subunit of GTP-binding protein cosegregated with d1 in 3,185 d1 segregants. Southern hybridization analysis with this cDNA as a probe showed different band patterns in several d1 mutant lines. In at least four independent d1 mutants, no gene transcript was observed by Northern hybridization analysis. Sequencing analysis revealed that an 833-bp deletion had occurred in one of the mutant alleles, which resulted in an inability to express GTP-binding protein. A transgenic d1 mutant with GTP-binding protein gene restored the normal phenotype. We conclude that the rice Dwarf 1 gene encodes GTP-binding protein and that the protein plays an important role in plant growth and development. Because the d1 mutant is classified as gibberellin-insensitive, we suggest that the GTP-binding protein might be associated with gibberellin signal transduction.