Heating experiments of carbon grains: Implication for the origin of interstellar dust

Amorphous carbonaceous grains produced in a methane gas atmosphere were analyzed by high resolution transmission electron microscope (HRTEM). Structural alteration of the amorphous carbonaceous grains was directly observed by in situ HRTEM observation. The specimen was heated to a maximum of 550℃. The HRTEM image of a prepared specimen showed the structure of the onion-like carbon. The onion-like structure distorted at 100℃, which suggested the evaporation of -OH groups included in the grains. Upon heating to 260℃, the centers of the onion-like grains formed holes of the order of 3 nm in size. On further heating to 550℃, the structure of the chained grains with a size of 10 nm changed to graphite sheets with a length of 50 nm by the surface melting coalescence among chained grains. The structural changes at the above temperatures have been observed only in amorphous carbonaceous grains produced in a methane gas atmosphere and have been attributed to the existence of hydrogen in the grains

Fabrication of Apatite Films on Ti Substrates of Simple and Complicated Shapes by Using Stable Solutions of Ca Complex

Titanium (Ti) is known as the most popular implant materials. In addition, the coating technology of hydroxyapatite (HA) or carbonate-containing apatite (CA) on Ti substrates having various shapes has been interested from the viewpoint for improvement of implant’s osteoconductivity. The fabrication of apatite coatings on metallic substrates has been investigated by several techniques. We developed novel wet processes using some stable solutions in which Ca complexes and phosphate ion dissolve simultaneously. The CA film can be deposited homogeneously on substrates, Ti plate and Ti fiber mesh, using a stable precursor solution involving a Ca2+ complex of ethylenediaminetetraacetic acid (EDTA). Another stable aqueous solution was prepared by the addition of phosphoric acid to a calcium hydrogen carbonate solution. The solution is adequate to be sprayed facilely onto a Ti plate by using an airbrush. It is important that the fabricated apatite films by the spray process have the characteristic network structures. The materials with these CA films are nontoxic and have the excellent bonding ability to bone tissues

Diversification processes of teleost intron-less opsin genes

Opsins are universal photosensitive proteins in animals. Vertebrates have a variety of opsin genes for visual and non-visual photoreceptions. Analysis of the gene structures shows that most opsin genes have introns in their coding regions. However, teleosts exceptionally have several intron-less opsin genes which are presumed to have been duplicated by an RNA-based gene duplication mechanism, retroduplication. Among these retrogenes, we focused on the Opn4 (melanopsin) gene responsible for non-image-forming photoreception. Many teleosts have five Opn4 genes including one intron-less gene, which is speculated to have been formed from a parental intron-containing gene in the Actinopterygii. In this study, to reveal the evolutionary history of Opn4 genes, we analyzed them in teleost (zebrafish and medaka) and non-teleost (bichir, sturgeon and gar) fishes. Our synteny analysis suggests that the intron-less Opn4 gene emerged by retroduplication after branching of the bichir lineage. In addition, our biochemical and histochemical analyses showed that, in the teleost lineage, the newly acquired intron-less Opn4 gene became abundantly used without substantial changes of the molecular properties of the Opn4 protein. This stepwise evolutionary model of Opn4 genes is quite similar to that of rhodopsin genes in the Actinopterygii. The unique acquisition of rhodopsin and Opn4 retrogenes would have contributed to the diversification of the opsin gene repertoires in the Actinopterygii and the adaptation of teleosts to various aquatic environments

Neutron scattering study on spin correlations and fluctuations in the transition-metal-based magnetic quasicrystal Zn-Fe-Sc

Spin correlations and fluctuations in the 3d-transition-metal-based icosahedral quasicrystal Zn-Fe-Sc have been investigated by neutron scattering using polycrystalline samples. Magnetic diffuse scattering has been observed in the elastic experiment at low temperatures, indicating development of static short-range-spin correlations. In addition, the inelastic scattering experiment detects a $Q$-independent quasielastic signal ascribed to single-site relaxational spin fluctuations. Above the macroscopic freezing temperature $T_{\rm f} \simeq 7$ K, the spin relaxation rate shows Arrhenius-type behavior, indicating thermally activated relaxation process. In contrast, the relaxation rate remains finite even at the lowest temperature, suggesting a certain quantum origin for the spin fluctuations below $T_{\rm f}$.Comment: To be published in Phys. Rev.

Evaluation of Bone Toxicity in Various Bones of Aged Rats

The aim of the present study was to provide a method for evaluating bone toxicity induced by drugs in various bones in aged rats. Male Crl:CD (SD) rats at 46 weeks of age were administered 15 mg/m2 body surface area of doxorubicin, which effects the growth plate in weanling rats, weekly for 9 weeks by intravenous injection, and the femur, sternum, humerus and tibia were examined histopathologically. In the doxorubicin-treated group, thinning of the growth plate was remarkably observed in the proximal tibia and humerus; however, these changes were not observed in other regions. In addition, the osteoclast number per bone perimeter in the proximal tibia was significantly higher than others in control aged rat. Thus, recognizing the various histological reactions related to the time of epiphyseal closure is important for evaluating bone toxicity in aged rats

Identification of the basic amino acid residues on the PsbP protein involved in the electrostatic interaction with photosystem II

AbstractThe PsbP protein is an extrinsic subunit of photosystem II (PSII) that is essential for photoautotrophic growth in higher plants. Several crystal structures of PsbP have been reported, but the binding topology of PsbP in PSII has not yet been clarified. In this study, we report that the basic pocket of PsbP, which consists of conserved Arg48, Lys143, and Lys160, is important for the electrostatic interaction with the PSII complex. Our release-reconstitution experiment showed that the binding affinities of PsbP-R48A, -K143A, and -K160A mutated proteins to PSII were lower than that of PsbP-WT, and triple mutations of these residues greatly diminished the binding affinity to PSII. Even when maximum possible binding had occurred, the R48A, K143A, and K160A proteins showed a reduced ability to restore the rate of oxygen evolution at low chloride concentrations. Fourier transform infrared resonance (FTIR) difference spectroscopy results were consistent with the above finding, and suggested that these mutated proteins were not able to induce the normal conformational change around the Mn cluster during S1 to S2 transition. Finally, chemical cross-linking experiments suggested that the interaction between the N-terminus of PsbP with PsbE was inhibited by these mutations. These data suggest that the basic pocket of PsbP is important for proper association and interaction with PSII. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy