Inhibition of E coli ATPase activity by a troponin component, TN-I, and by mitochondrial ATPase inhibitor.

The enzymic activity of Mg2+- or Ca2+-stimulated ATPase from Escherichia coli was inhibited by one of the troponin components, TN-I, and by mitochondrial ATPase inhibitor (F1-inhibitor). The inhibitory ability of component TN-I against Mg2+-stimulated AtPase activity was lost after digestion of component TN-I with trypsin. The Mg2+-stimulated ATPase activity inhibited by component TN-I was completely restored by the addition of another troponin component TN-C.     

Anin vivo bioassay for TSH-releasing factor (TRF)

Résumé Une méthode de bioétalonnagein vivo pour la mise en évidence de l'activité TRF (TSH-releasing factor) est décrite. Cette méthode est basée sur la mesure de la radíoactivité totale du sang chez le rat normal (non-hypophysectomisé) prétraité avec I¹³¹ et une dose liminaire del-thyroxine. La spécificité de ce test est discutée; Vasopressine, ocytocine,-MSH,-MSH sont inactifs dans ce test.     

Reduction of Pt Usage in Fuel Cell Electrocatalysts Using Carbon Nanotubes and Non-Pt Metals

The high-priced and limited Pt constitutes a high barrier to commercialization of fuel cells. Pt is essential for the electrode catalyst of polymer electrolyte fuel cells （PEFCs）. A reduction in Pt usage is one of the key requirements for the commercialization of fuel cells for use in everyday life, because of its high price and limited availability, and the difficulty of finding suitable substitutes. Non-Pt fuel cell catalysts will decrease the demand for Pt by PEFCs, enabling more Pt to be available for use in other essential products, and make fuel cells more popular. The cheaper Mo2C is known to possess similar catalytic activities and electronic structures to Pt. Carbon black （CB） is widely used as the support for Pt nanoparticles. However,     

Functional characterization of a heteromeric NMDA receptor channel expressed from cloned cDNAs.

The glutamate receptor (GluR) channel plays a key part in brain function. Among GluR channel subtypes, the NMDA (N-methyl-D-aspartate) receptor channel which is highly permeable to Ca2+ is essential for the synaptic plasticity underlying memory, learning and development. Furthermore, abnormal activation of the NMDA receptor channel may trigger the neuronal cell death observed in various brain disorders. A complementary DNA encoding a subunit of the rodent NMDA receptor channel (NMDAR1 or zeta 1) has been cloned and its functional properties investigated. Here we report the identification and primary structure of a novel mouse NMDA receptor channel subunit, designated as epsilon 1, after cloning and sequencing the cDNA. The epsilon 1 subunit shows 11-18% amino-acid sequence identity with rodent GluR channel subunits that have been characterized so far and has structural features common to neurotransmitter-gated ion channels. Expression from cloned cDNAs of the epsilon 1 subunit together with the zeta 1 subunit in Xenopus oocytes yields functional GluR channels with high activity and characteristics of the NMDA receptor channel. Furthermore, the heteromeric NMDA receptor channel can be activated by glycine alone.     

Aplysianin-A,an antibacterial and antineoplastic glycoprotein in the albumen gland of a sea hare,Aplysia kurodai

Summary Aplysianin-A, an antibacterial and antineoplastic factor in the albumen gland of the sea hareAplysia kurodai, was isolated. It had a molecular weight of approximately 320 kD and consisted of subunits with a molecular weight of 85 kD. It contained 9.8% neutral sugar. Aplysianin A showed 50% inhibition ofBacillus subtilis growth at a concentration of 4 g protein/ml and 50% lysis of murine MM46 tumor cells at 14 ng protein/ml. A partial identity of antigenic specificity of the purified specimen with an antineoplastic factor fromAplysia eggs was observed in immunodiffusion tests.Acknowledgment. We are indebted to the staff of Fisheries Research Laboratory, Faculty of Agriculture, University of Tokyo, Maisaka, for the collection of sea hares.     

Cloning of adiponectin receptors that mediate antidiabetic metabolic effects

Adiponectin (also known as 30-kDa adipocyte complement-related protein; Acrp30) is a hormone secreted by adipocytes that acts as an antidiabetic and anti-atherogenic adipokine. Levels of adiponectin in the blood are decreased under conditions of obesity, insulin resistance and type 2 diabetes. Administration of adiponectin causes glucose-lowering effects and ameliorates insulin resistance in mice. Conversely, adiponectin-deficient mice exhibit insulin resistance and diabetes. This insulin-sensitizing effect of adiponectin seems to be mediated by an increase in fatty-acid oxidation through activation of AMP kinase and PPAR-alpha. Here we report the cloning of complementary DNAs encoding adiponectin receptors 1 and 2 (AdipoR1 and AdipoR2) by expression cloning. AdipoR1 is abundantly expressed in skeletal muscle, whereas AdipoR2 is predominantly expressed in the liver. These two adiponectin receptors are predicted to contain seven transmembrane domains, but to be structurally and functionally distinct from G-protein-coupled receptors. Expression of AdipoR1/R2 or suppression of AdipoR1/R2 expression by small-interfering RNA supports our conclusion that they serve as receptors for globular and full-length adiponectin, and that they mediate increased AMP kinase and PPAR-alpha ligand activities, as well as fatty-acid oxidation and glucose uptake by adiponectin.     

Molecular cloning and expression of cDNA for human granulocyte colony-stimulating factor

Granulocyte colony-stimulating factor (G-CSF) is a member of the CSF family of hormone-like glycoproteins that regulate haematopoietic cell proliferation and differentiation, and G-CSF almost exclusively stimulates the colony formation of granulocytes from committed precursor cells in semi-solid agar culture. Recently, Nomura et al. have established a human squamous carcinoma cell line (designated CHU-2) from a human oral cavity tumour which produces large quantities of CSF constitutively, and the CSF produced by CHU-2 cells has been purified to homogeneity from the conditioned medium. We have now determined the partial amino-acid sequence of the purified G-CSF protein, and by using oligonucleotides as probes, have isolated several clones containing G-CSF complementary DNA from the cDNA library prepared with messenger RNA from CHU-2 cells. The complete nucleotide sequences of two of these cDNAs were determined and the expression of the cDNA in monkey COS cells gave rise to a protein showing authentic G-CSF activity. Furthermore, Southern hybridization analysis of DNA from normal leukocytes and CHU-2 cells suggests that the human genome contains only one gene for G-CSF and that some rearrangement has occurred within one of the alleles of the G-CSF gene in CHU-2 cells.     

Altered thymic T-cell selection due to a mutation of the ZAP-70 gene causes autoimmune arthritis in mice

Rheumatoid arthritis (RA), which afflicts about 1% of the world population, is a chronic systemic inflammatory disease of unknown aetiology that primarily affects the synovial membranes of multiple joints. Although CD4(+) T cells seem to be the prime mediators of RA, it remains unclear how arthritogenic CD4(+) T cells are generated and activated. Given that highly self-reactive T-cell clones are deleted during normal T-cell development in the thymus, abnormality in T-cell selection has been suspected as one cause of autoimmune disease. Here we show that a spontaneous point mutation of the gene encoding an SH2 domain of ZAP-70, a key signal transduction molecule in T cells, causes chronic autoimmune arthritis in mice that resembles human RA in many aspects. Altered signal transduction from T-cell antigen receptor through the aberrant ZAP-70 changes the thresholds of T cells to thymic selection, leading to the positive selection of otherwise negatively selected autoimmune T cells. Thymic production of arthritogenic T cells due to a genetically determined selection shift of the T-cell repertoire towards high self-reactivity might also be crucial to the development of disease in a subset of patients with RA.     

A novel protein family mediates Casparian strip formation in the endodermis

Polarized epithelia are fundamental to multicellular life. In animal epithelia, conserved junctional complexes establish membrane diffusion barriers, cellular adherence and sealing of the extracellular space. Plant cellular barriers are of independent evolutionary origin. The root endodermis strongly resembles a polarized epithelium and functions in nutrient uptake and stress resistance. Its defining features are the Casparian strips, belts of specialized cell wall material that generate an extracellular diffusion barrier. The mechanisms localizing Casparian strips are unknown. Here we identify and characterize a family of transmembrane proteins of previously unknown function. These 'CASPs' (Casparian strip membrane domain proteins) specifically mark a membrane domain that predicts the formation of Casparian strips. CASP1 displays numerous features required for a constituent of a plant junctional complex: it forms complexes with other CASPs; it becomes immobile upon localization; and it sediments like a large polymer. CASP double mutants display disorganized Casparian strips, demonstrating a role for CASPs in structuring and localizing this cell wall modification. To our knowledge, CASPs are the first molecular factors that are shown to establish a plasma membrane and extracellular diffusion barrier in plants, and represent a novel way of epithelial barrier formation in eukaryotes.