de Haas-van Alphen γ oscillation for the symmetry direction [011] in lead—Origin of the long beat and the shape of the third zone electron arm

Systematic dHvA studies on the γ oscillation in lead have been performed deliberately choosing the specimen crystal consisting of two subgrains with slight misorientation; our intention here is to clarify the origin of the anomalous beat which has been frequently observed in addition to the well-known 42.5 cycle beat. It has been found that the anomalous beat appears periodically and that its angular dependence can be described by H ∝ θ where H is the magnetic field at which the anomalous beat is observed and θ (?1) is the angle which specifies the magnetic field direction measured from the suitably chosen specimen axis sufficiently close to [011]. These results are successfully interpreted on the basis of Van Dyke's model of the third zone electron arm coupled with the microstructure of the specimen crystal. This conclusion is in agreement with the suggestion by Anderson et al. (1975) concerning the third zone electron arm in lead.     

Vacuum UV laser-induced fluorescence study of the collisional removal of Br(P1/2) atoms by small molecules

This Letter reports on the application of the vacuum ultraviolet laser-induced fluorescence detection of Br(²P_1/2) atoms at 157.48 nm to the kinetic study of collisional removal of Br(²P_1/2) by small molecules at 295 K. Gas mixtures of a small amount of CH₃Br and an excess amount of collision partners are exposed to pulsed laser irradiation at 193 nm. Temporal decay profile of the Br* LIF intensity has been monitored to determine the collisional removal rate coefficients. The collision partners are H₂, CO₂, CF₄, CF₂H₂, H₂O, CH₃OH, and SF₅CF₃, and the results are compared to literature data.     

Red light in chemiluminescence and yellow-green light in bioluminescence: color-tuning mechanism of firefly, Photinus pyralis, studied by the symmetry-adapted cluster-configuration interaction method

The yellow-green luminescence from firefly luciferase has long been understood to be the emission from enol-oxyluciferin. However, a recent experiment showed that an oxyluciferin constrained to the keto form produced a yellow-green emission in luciferase (Branchini, B. R.; Murtiashaw, M. H.; Magyar, R. A.; Portier, N. C.; Ruggiero, M. C.; Stroh, J. G. J. Am. Chem. Soc. 2002, 124, 2112-2113). The present quantum mechanical/molecular mechanical and symmetry-adapted cluster-configuration interaction (SAC-CI) theoretical study supports the keto-form to be the yellow-green bioluminescence state in luciferase. We give the theoretically optimized structure of the excited state of oxyluciferin within luciferase, which gives luminescence calculated by the SAC-CI method that is close to the experimental value. Coulombic interactions with neighboring residues, in particular Arg218 and the phosphate group of AMP, play important roles in the color-tuning mechanism. Transformation to the enol form is energetically unfavorable in the luciferase environment. The twisted intramolecular charge-transfer (TICT) state is meta stable and would be easily relaxed to the co-planer structure. Further analyses were performed to verify the spectral-tuning mechanism based on the protonation state and the resonance structure of oxyluciferin.     

Cantharimide dimers from the Chinese blister beetle, Mylabris phalerate PALLAS

Five cantharidin-related compounds were isolated from the Chinese blister beetle, Mylabris phalerate PALLAS (Meloidae). Their structures were determined based on spectroscopic and chemical evidence. Three of them were identified as cantharimide dimers, which consist of two units of cantharimide combined with a tri-, tetra-, or penta-methylene group.     

Role of solution structure in the electrochemical intercalation of Ca2+ into graphite layers

In this study, we investigated the electrochemical intercalation of Ca²⁺ into graphite as an anode material for calcium-ion batteries (CIBs). The electrochemical intercalation of Ca²⁺ into a graphite electrode is possible when γ-butyrolactone (GBL) is utilized as a solvent, resulting in a reversible charge/discharge capacity. The GBL-based electrolyte allows a reversible redox reaction, thereby resulting in the intercalation and deintercalation of Ca²⁺ within the graphite electrode. Conversely, Ca²⁺ cannot be intercalated between the graphite layers in the ethylene carbonate–diethyl carbonate (EC–DEC)–based electrolyte. Analyses of the solution structures of both cases indicated that the interaction between the GBL solvent and Ca²⁺ was weak whereas that between the EC–DEC solvent and Ca²⁺ was strong. As a result of analyzing the surface of the negative electrode after charging and discharging from XPS, it was confirmed that a component that seems to be a solid electrolyte interphase (SEI) was confirmed in the graphite electrode using the GBL-based electrolyte.

     

Atomic force microscopy dissects the hierarchy of genome architectures in eukaryote, prokaryote, and chloroplast.

Because of its applicability to biological specimens (nonconductors), a single-molecule-imaging technique, atomic force microscopy (AFM), has been particularly powerful for visualizing and analyzing complex biological processes. Comparative analyses based on AFM observation revealed that the bacterial nucleoids and human chromatin were constituted by a detergent/salt-resistant 30-40-nm fiber that turned into thicker fibers with beads of 70-80 nm diameter. AFM observations of the 14-kbp plasmid and 110-kbp F plasmid purified from Escherichia coli demonstrated that the 70-80-nm fiber did not contain a eukaryotic nucleosome-like "beads-on-a-string" structure. Chloroplast nucleoid (that lacks bacterial-type nucleoid proteins and eukaryotic histones) also exhibited the 70-80-nm structural units. Interestingly, naked DNA appeared when the nucleoids from E. coli and chloroplast were treated with RNase, whereas only 30-nm chromatin fiber was released from the human nucleus with the same treatment. These observations suggest that the 30-40-nm nucleoid fiber is formed with a help of nucleoid proteins and RNA in E. coli and chroloplast, and that the eukaryotic 30-nm chromatin fiber is formed without RNA. On the other hand, the 70-80-nm beaded structures in both E. coli and human are dependent on RNA.     

The Dimeric Form of 1,3-Diaminoisoquinoline Derivative Rescued the Mis-splicing of Atp2a1 and Clcn1 Genes in Myotonic Dystrophy Type 1 Mouse Model

Expanded CUG repeat RNA in the dystrophia myotonia protein kinase (DMPK) gene causes myotonic dystrophy type 1 (DM1) and sequesters RNA processing proteins, such as the splicing factor muscleblind-like 1 protein (MBNL1). Sequestration of splicing factors results in the mis-splicing of some pre-mRNAs. Small molecules that rescue the mis-splicing in the DM1 cells have drawn attention as potential drugs to treat DM1. Herein we report a new molecule JM642 consisted of two 1,3-diaminoisoquinoline chromophores having an auxiliary aromatic unit at the C5 position. JM642 alternates the splicing pattern of the pre-mRNA of the Ldb3 gene in the DM1 cell model and Clcn1 and Atp2a1 genes in the DM1 mouse model. In vitro binding analysis by surface plasmon resonance (SPR) assay to the r(CUG) repeat and disruption of ribonuclear foci in the DM1 cell model suggested the binding of JM642 to the expanded r(CUG) repeat in vivo, eventually rescue the mis-splicing.