Oxygen Reduction Electrode Properties of Manganese Oxide Nanosheet-Based Materials

Two types of oxide nanosheet-based materials, H₃O⁺-form regularly stacked manganese oxide nanosheets (H₃O⁺-RG(Mn)) and H₃O⁺-form randomly restacked manganese oxide nanosheets (H₃O⁺-RE(Mn)) were synthesized by soft chemical methods, and their oxygen reduction reaction (ORR) activities were examined by cyclic voltammetry (CV) and semi-steady-state voltammetry (SSV) with a rotating ring-disc electrode at 70 °C in 0.1 M KOH. Both samples showed high onset potentials (E _on) of the ORR current and high efficiencies (Eff ₄) of the 4-electron reduction of oxygen, and E _on and Eff ₄ values were improved by electrochemical oxidation up to 1.2 V (vs. reversible hydrogen electrode) in the CV measurement prior to the SSV measurement. As a result, the nanosheet-based samples exhibited higher ORR activities than the starting materials, K⁺-form layered manganese oxide K_0.5MnO₂ (K⁺-RG(Mn)) and Mn₂O₃, and a well-known ORR catalyst, MnO₂. The H₃O⁺-RE(Mn) sample electrochemically oxidized up to 1.2 V showed the highest ORR activity, E _on = 0.97 V and Eff ₄ = 99%, which were comparable to those of a conventional 20 mass% Pt/C catalyst. The comparison of their ORR activities, BET surface areas and X-ray photoelectron spectra suggests that the enhancement of the ORR activity is attributed to an increase in the numbers of the ORR active sites and a large amount of H₂O in the interlayers and on the surface of the nanosheets because of rapid of H₂O-supply enough for ORR in alkaline solution.     

Analysis of glycosyl bond cleavage and related isotope effects in collision-induced dissociation quadrupole-time-of-flight mass spectrometry of isomeric trehaloses

The configuration isomers alpha,alpha-, alpha,beta-, and beta,beta-trehalose are distinguishable by a relative ion abundance analysis using collision-induced dissociation MS/MS measurements in electrospray ionization quadrupole-time-of-flight mass spectrometry. The relative abundance of the Y-type fragment ion of alpha,alpha-trehalose is the highest and that of beta,beta-trehalose is the lowest, indicating that alpha-glycosyl bonds cleave more easily than beta-glycosyl bonds. The relative ion abundance depends on both the alpha- and beta-glycosyl linkage type and the number of alpha-glycosyl bonds. The reaction path of glycosyl bond cleavage is calculated computationally using the molecular orbital method in the form of Hartree-Fock theory in conjunction with the 6-31G(d) basis set. The results are consistent with the experimental data. Isotope effects on the fragmentation of the glycosyl bonds are detected in the experiments of the H2O/D2O solvent systems. Furthermore, the isotope effect regarding beta,beta-trehalose is larger than those of alpha,alpha- and alpha,beta-trehalose, indicating that the isotope effect on the beta-glycosyl bond cleavage is larger than that on the alpha-glycosyl bond cleavage. The thermal energy increase in trehalose-d8 molecules over the corresponding trehalose molecules is calculated from the vibrational modes.     

The Potential Role of Hepatocyte Growth Factor in Degenerative Disorders of the Synovial Joint and Spine

This paper aims to provide a comprehensive review of the changing role of hepatocyte growth factor (HGF) signaling in the healthy and diseased synovial joint and spine. HGF is a multifunctional growth factor that, like its specific receptor c-Met, is widely expressed in several bone and joint tissues. HGF has profound effects on cell survival and proliferation, matrix metabolism, inflammatory response, and neurotrophic action. HGF plays an important role in normal bone and cartilage turnover. Changes in HGF/c-Met have also been linked to pathophysiological changes in degenerative joint diseases, such as osteoarthritis (OA) and intervertebral disc degeneration (IDD). A therapeutic role of HGF has been proposed in the regeneration of osteoarticular tissues. HGF also influences bone remodeling and peripheral nerve activity. Studies aimed at elucidating the changing role of HGF/c-Met signaling in OA and IDD at different pathophysiological stages, and their specific molecular mechanisms are needed. Such studies will contribute to safe and effective HGF/c-Met signaling-based treatments for OA and IDD.     

Morphological and Genetic Diversities of Habenaria radiata (Orchidaceae) in the Kinki Area,Japan

Floral organs have evolved from leaves for reproduction, and the morphological analyses help to understand the plant diversity and evolution. Habenaria radiata (syn. Pecteilis radiata) is a terrestrial orchid living in wetlands in Japan, Russia, South Korea, and China. The habitats of this plant in Japan have been reduced because of environmental destruction and overexploitation, and thus it is on the Red List of Japan as a Near Threatened species. One of the three petals of the H. radiata flower is called a lip or labellum, which resembles a flying white bird, egret, or white heron, with its proposed function being to attract pollinators. To understand the diversity of H. radiata plants in different areas, we examined the lip morphology and phylogeny of populations from eight habitats in the Kinki area, Japan. The complex shapes of the lips were quantified and presented as a radar chart, enabling characterization of the morphological difference among populations. Phylogenetic analysis with microsatellite markers that we generated showed the variation of genetic diversity among populations, suggesting the different degrees of inbreeding, outbreeding, and vegetative propagation. Our approach offers a basic method to characterize the morphological and genetic diversity in natural populations.     

Difference in environmental degradability between poly(ethylene succinate) and poly(3-hydroxybutyrate)

A chemosynthetic aliphatic polyester, poly(ethylene succinate) (PESu), was degraded by a poly(3-hydroxybutyrate) (P(3HB)) depolymerase in vitro. While P(3HB) exhibited good biodegradability in all environments, PESu hardly underwent biodegradation in a marine environment. To understand the difference in environmental degradability between PESu and P(3HB), we investigated the distribution of P(3HB)- and PESu-degrading microbes in various environments. PESu-degrading microbes were never detected in marine environments. PESu-degrading bacteria isolated from various environments in this study belonged to the phyla Firmicutes and Proteobacteria. Most PESu-degrading bacterial isolates could not degrade P(3HB), suggesting that PESu was not degraded by P(3HB) depolymerase in actual environments. In addition, all bacterial isolates that were screened for P(3HB) degrading activity from various environments in this study did not degrade PESu, suggesting that PESu does not induce P(3HB) depolymerase in their bacteria and P(3HB)-degrading bacteria are not involved in biodegradation of PESu in actual environments. Taken together, these results could be related with the low biodegradability of PESu in marine environments.     

Site-specific functionalization of proteins by organopalladium reactions

A new carbon-carbon bond has been regioselectively introduced into a target position (position 32 or 174) of the Ras protein by two types of organopalladium reactions (Mizoroki-Heck and Sonogashira reactions). Reaction conditions were screened by using a model peptide, and the stability of the Ras protein under the reaction conditions was examined by using the wild-type Ras protein. Finally, the iF-Ras proteins containing a 4-iodo-L-phenylalanine residue were subjected to organopalladium reactions with vinylated or propargylated biotin. Site-specific biotinylations of the Ras protein were confirmed by Western blot and LC-MS/MS.     

Myofibril-Bound Serine Proteinase (MBP) and its Degradation of Myofibrillar Proteins

Proteolysis of a myofibril-bound serine proteinase (MBP) from carp Cyprinus carpio on myofibrillar proteins and their gel formation ability were investigated. MBP readily decomposed myosin heavy chain as indicated by SDS-PAGE. In the preparation of kamaboko, the gel formation ability was diminished by addition of MBP. The optimum degradation temperatures of MBP to myosin heavy chain in myofibril and kamaboko gel were 55°C and 60°C, respectively. The degradation effects of MBP on actin, α-actinin and tropomyosin were studied by the immunoblotting method. Because of its myofibril-bound and myofibrillar protein degradation characteristics, MBP was regarded as the proteinase most probably involved in the modori effect.