Kyoto University

About: Kyoto University is a education organization based out in Kyoto, Japan. It is known for research contribution in the topics: Population & Catalysis. The organization has 85837 authors who have published 217215 publications receiving 6526826 citations. The organization is also known as: Kyōto University & Kyōto daigaku.

Evidence for shock acceleration of high-energy electrons in the supernova remnant SN1006

Abstract: HIGH-ENERGY cosmic rays (relativistic heavy nuclei) play an important role in heating interstellar matter in the Milky Way1,2, and they affect chemical abundances through collisions with atoms in the interstellar gas2. Although it has long been thought that these cosmic rays arise from supernovae3,4, direct evidence for such an association has been lacking. Here we report X-ray observations of the remnant of supernova 1006, made by the ASCA satellite, which indicate that emission from the edges of the remnant shell is dominated by radiation from electrons accelerated to energies of ~ 100 TeV within the shock front. Ions in the shell are likely to have been accelerated to similar energies, thus giving rise to very-high-energy cosmic rays.

Ghrelin, an Endogenous Growth Hormone Secretagogue, Is a Novel Orexigenic Peptide That Antagonizes Leptin Action Through the Activation of Hypothalamic Neuropeptide Y/Y1 Receptor Pathway

Abstract: Ghrelin, an endogenous ligand for growth hormone secretagogue (GHS) receptor originally isolated from the stomach, occurs in the hypothalamic arcuate nucleus and may play a role in energy homeostasis. Synthetic GHSs have activated the hypothalamic arcuate neurons containing neuropeptide Y (NPY), suggesting the involvement of NPY in some of ghrelin actions. This study was designed to elucidate the role of ghrelin in the regulation of food intake. A single intracerebroventricular (ICV) injection of ghrelin (5-5,000 ng/rat) caused a significant and dose-related increase in cumulative food intake in rats. Ghrelin (500 ng/rat) was also effective in growth hormone-deficient spontaneous dwarf rats. Hypothalamic NPY mRNA expression was increased in rats that received a single ICV injection of ghrelin (500 ng/rat) (approximately 160% of that in vehicle-treated groups, P < 0.05). The ghrelin's orexigenic effect was abolished dose-dependently by ICV co-injection of NPY Y1 receptor antagonist (10-30 microg/rat). The leptin-induced inhibition of food intake was reversed by ICV co-injection of ghrelin in a dose-dependent manner (5-500 ng/rat). Leptin reduced hypothalamic NPY mRNA expression by 35% (P < 0.05), which was abolished by ICV co-injection of ghrelin (500 ng/rat). This study provides evidence that ghrelin is an orexigenic peptide that antagonizes leptin action through the activation of hypothalamic NPY/Y1 receptor pathway.

Cloning, sequencing and expression of complementary DNA encoding the muscarinic acetylcholine receptor

Abstract: Cloning and sequence analysis of DNA complementary to porcine cerebral messenger RNA encoding the muscarinic acetylcholine receptor predict the complete amino-acid sequence of this protein. Expression of the complementary DNA produced functional muscarinic receptor in Xenopus oocytes. The muscarinic receptor is homologous with the beta-adrenergic receptor and rhodopsin in both amino-acid sequence and suggested transmembrane topography.

Nanomaterials derived from metal–organic frameworks

Abstract: The thermal transformation of metal–organic frameworks (MOFs) generates a variety of nanostructured materials, including carbon-based materials, metal oxides, metal chalcogenides, metal phosphides and metal carbides. These derivatives of MOFs have characteristics such as high surface areas, permanent porosities and controllable functionalities that enable their good performance in sensing, gas storage, catalysis and energy-related applications. Although progress has been made to tune the morphologies of MOF-derived structures at the nanometre scale, it remains crucial to further our knowledge of the relationship between morphology and performance. In this Review, we summarize the synthetic strategies and optimized methods that enable control over the size, morphology, composition and structure of the derived nanomaterials. In addition, we compare the performance of materials prepared by the MOF-templated strategy and other synthetic methods. Our aim is to reveal the relationship between the morphology and the physico-chemical properties of MOF-derived nanostructures to optimize their performance for applications such as sensing, catalysis, and energy storage and conversion. Nanomaterials derived from metal–organic frameworks (MOFs) show good performance in sensing, gas storage, catalysis and energy-related applications. In this Review, the influence of the morphology of MOF-derived nanostructures on their performance is elucidated, and the opportunities in this field are discussed.

Development of peripheral lymphoid organs and natural killer cells depends on the helix–loop–helix inhibitor Id2

Abstract: Transcription factors with a basic helix-loop-helix (HLH) motif have been shown to be crucial for various cell differentiation processes during development of multicellular organisms. Id proteins inhibit the functions of these transcription factors in a dominant-negative manner by suppressing their heterodimerization partners through the HLH domains. Members of the Id family also promote cell proliferation, implying a role in the control of cell differentiation. Here we show that Id2 is indispensable for normal development of mice. Id2-/- mice lack lymph nodes and Peyer's patches. However, their splenic architecture is normal, exhibiting T-cell and B-cell compartments and distinct germinal centres. The cell population that produces lymphotoxins, essential factors for the development of secondary lymphoid organs, is barely detectable in the Id2-/- intestine. Furthermore, the null mutants show a greatly reduced population of natural killer (NK) cells, which is due to an intrinsic defect in NK-cell precursors. Our results indicate that Id2 has an essential role in the generation of peripheral lymphoid organs and NK cells.