488 research outputs found

    Pauli-blocking Effect in a Quark Model

    Full text link
    Pauli-Blocking effect on the kinetic term is investigated by employing the quark cluster model. The effect can be understood by the change of the degrees of the mixing between the incoming wave and the 0\ell state of the inter-cluster wave function, which can be expressed by a potential which is highly nonlocal. We look into the properties of this effect by comparing equivalent local potentials. In the channel where the Pauli-blocking effect is small, the on-shell equivalent local potential simulates the nonlocal potential well even for the off-shell behavior. On the other hand, the off-shell behavior is very different from the original one where the effect is large. This off-shell behavior, however, can well be simulated by considering the nonlocal matrix elements only between the 0s0s state and the other states. The energy dependent potentials are also constructed and found to be helpful to understand the energy dependence of the effect.Comment: 14 pages, 12 figure

    In Vitro Phosphorylation of Proteins in IAA-Treated Primary Roots and Coleoptiles in Zea mays

    Get PDF
    Five-mm sections of elongation zones which were cut from primary roots or coleoptiles of Zea mays were incubated for designated periods with various concentrations of IAA. In vitro protein phosphorylation in the soluble fractionsprepared from these sections was analyzed by SDS-PAGE. The phosphorylation of proteins in sections of primary roots incubated for 20 or 40 min in the presenceof 10^-7 M IAA was greater than that in the sections incubated in the absence ofIAA. The phosphorylation of proteins in sections of primary roots incubated for 20 min or 2h in the presence of 10^-8,10^-7 or 10^-6 M IAA was higher than that in the sections incubated in the absence of IAA. An incuba-tion for 20 min or 2h with 10^-4 M IAA inhibited the phosphorylation of proteins in sections of primary roots. The growth of the sections of primary roots incubated for 2h in the presence of 10^-7 M IAA or higher concentrations was lower than that of the sections incubated in the absence of IAA. These results suggest that the phosphorylation of proteins which was increased by IAA treatment is independent of an inhibition of the growth induced by IAA in maize primary roots. The phosphorylation of proteins in sections of coleoptiles incubated for 10, 20 or 40 min in the presence of 10^-7 or 10^-5 M IAA was equal to that in the sectionsincubated in the absence of IAA. These results show that IAA regulates growth ofmaize coleoptiles in no relation with phosphorylation of the proteins and that IAA regulates growth of maize mesocotyls via phosphorylation of the proteins, comparing with earlier results [Kato et al. (1996) Plant Cell Phsiol. 37:667]. Coleoptile―IAA treatment―Primary root―Protein phosphorylation―Zea mays

    Model for the Architecture of Claudin-Based Paracellular Ion Channels through Tight Junctions

    Get PDF
    AbstractClaudins are main cell–cell adhesion molecules of tight junctions (TJs) between cells in epithelial sheets that form tight barriers that separate the apical from the basolateral space but also contain paracellular channels that regulate the flow of ions and solutes in between these intercellular spaces. Recently, the first crystal structure of a claudin was determined, that of claudin-15, which indicated the parts of the large extracellular domains that likely form the pore-lining surfaces of the paracellular channels. However, the crystal structure did not show how claudin molecules are arranged in the cell membrane to form the backbone of TJ strands and to mediate interactions between adjacent cells, information that is essential to understand how the paracellular channels in TJs function. Here, we propose that TJ strands consist of claudin protomers that assemble into antiparallel double rows. This model is based on cysteine crosslinking experiments that show claudin-15 to dimerize face to face through interactions between the edges of the extracellular β-sheets. Strands observed by freeze-fracture electron microscopy of TJs also show that their width is consistent with the dimensions of a claudin dimer. Furthermore, we propose that extracellular variable regions are responsible for head-to-head interactions of TJ strands in adjoining cells, thus resulting in the formation of paracellular channels. Our model of the TJ architecture provides a basis to discuss structural mechanisms underlying the selective ion permeability and barrier properties of TJs

    幼児の自然認識の醸成に関する一考察 ―小学校教科への接続を意識した「落ち葉集め」と「たき火」の保育を事例に

    Get PDF
    This study examines what “memory elements” are connected, and how and when preschoolers use those elements to understand nature. Nature and how preschoolers understand it are relevant to elementary school subjects, such as Living Environment Science and Natural Science. Relying on White’s theory of memory elements (1988), this paper analyzes two case studies in which preschoolers brought various concepts of nature into their cognition and extracted relevant memory elements. The analysis clarifies how preschoolers cognize nature in and through their experiences. Findings from the study suggest that preschoolers’ original cognition settles into proto-experience when the obtained memory elements, such as images, motor skills, and episodes are enhanced by preschoolers’ relations with others, narratives of the situation, and their own emotional preference. The results also suggest the possibility that preschoolers’ improved cognition of nature helps them become capable of dealing with elementary school subjects as the structuring of their memory elements, and parts of their memory elements are verbalized and words are muttered, perhaps in the form of self-talk, and the memory elements are transformed into strings, propositions, and intellectual skills

    Application of a Heat- and Steam-Generating Sheet Increases Peripheral Blood Flow and Induces Parasympathetic Predominance

    Get PDF
    To promote the practical application of a Japanese traditional medical treatment, such as hot compresses, we developed a plaster-type warming device consisting of a heat- and steam-generating sheet (HSG sheet). First, we tested its effects when applied to the anterior abdominal wall or lumbar region of women complaining of a tendency towards constipation. Application of the sheet to either region produced a feeling of comfort in the abdomen, as assessed by a survey of the subjects. The significant increases in the total hemoglobin observed in these regions suggested an increase in peripheral blood flow, and significant increases in the HF component on ECG and in the amplitude of gastric motility suggested parasympathetic predominance. We concluded that application of the HSG sheet improves the peripheral hemodynamics and autonomic regulation, induces a feeling of comfort in the abdomen, and provides a beneficial environment for the improvement of gastrointestinal movements

    Novel method to rescue a lethal phenotype through integration of target gene onto the X-chromosome.

    Get PDF
    The loss-of-function mutations of serine protease inhibitor, Kazal type 1 (SPINK1) gene are associated with human chronic pancreatitis, but the underlying mechanisms remain unknown. We previously reported that mice lacking Spink3, the murine homologue of human SPINK1, die perinatally due to massive pancreatic acinar cell death, precluding investigation of the effects of SPINK1 deficiency. To circumvent perinatal lethality, we have developed a novel method to integrate human SPINK1 gene on the X chromosome using Cre-loxP technology and thus generated transgenic mice termed "X-SPINK1". Consistent with the fact that one of the two X chromosomes is randomly inactivated, X-SPINK1 mice exhibit mosaic pattern of SPINK1 expression. Crossing of X-SPINK1 mice with Spink3+/- mice rescued perinatal lethality, but the resulting Spink3-/-;XXSPINK1 mice developed spontaneous pancreatitis characterized by chronic inflammation and fibrosis. The results show that mice lacking a gene essential for cell survival can be rescued by expressing this gene on the X chromosome. The Spink3-/-;XXSPINK1 mice, in which this method has been applied to partially restore SPINK1 function, present a novel genetic model of chronic pancreatitis
    corecore