Synthesis and characterization of oligonucleotides containing 2′-fluorinated thymidine glycol as inhibitors of the endonuclease III reaction

Endonuclease III (Endo III) is a base excision repair enzyme that recognizes oxidized pyrimidine bases including thymine glycol. This enzyme is a glycosylase/lyase and forms a Schiff base-type intermediate with the substrate after the damaged base is removed. To investigate the mechanism of its substrate recognition by X-ray crystallography, we have synthesized oligonucleotides containing 2′-fluorothymidine glycol, expecting that the electron-withdrawing fluorine atom at the 2′ position would stabilize the covalent intermediate, as observed for T4 endonuclease V (Endo V) in our previous study. Oxidation of 5′- and 3′-protected 2′-fluorothymidine with OsO(4) produced two isomers of thymine glycol. Their configurations were determined by NMR spectroscopy after protection of the hydroxyl functions. The ratio of (5R,6S) and (5S,6R) isomers was 3:1, whereas this ratio was 6:1 in the case of the unmodified sugar. Both of the thymidine glycol isomers were converted to the corresponding phosphoramidite building blocks and were incorporated into oligonucleotides. When the duplexes containing 2′-fluorinated 5R- or 5S-thymidine glycol were treated with Escherichia coli endo III, no stabilized covalent intermediate was observed regardless of the stereochemistry at C5. The 5S isomer was found to form an enzyme–DNA complex, but the incision was inhibited probably by the fluorine-induced stabilization of the glycosidic bond

Characterization of a Y-Family DNA Polymerase eta from the Eukaryotic Thermophile Alvinella pompejana

Human DNA polymerase η (HsPolη) plays an important role in translesion synthesis (TLS), which allows for replication past DNA damage such as UV-induced cis-syn cyclobutane pyrimidine dimers (CPDs). Here, we characterized ApPolη from the thermophilic worm Alvinella pompejana, which inhabits deep-sea hydrothermal vent chimneys. ApPolη shares sequence homology with HsPolη and contains domains for binding ubiquitin and proliferating cell nuclear antigen. Sun-induced UV does not penetrate Alvinella's environment; however, this novel DNA polymerase catalyzed efficient and accurate TLS past CPD, as well as 7,8-dihydro-8-oxoguanine and isomers of thymine glycol induced by reactive oxygen species. In addition, we found that ApPolη is more thermostable than HsPolη, as expected from its habitat temperature. Moreover, the activity of this enzyme was retained in the presence of a higher concentration of organic solvents. Therefore, ApPolη provides a robust, human-like Polη that is more active after exposure to high temperatures and organic solvents

高校生における異文化体験と国際的資質の関連 : 海外研修旅行の効果

本研究の目的は， 日本の高校生を対象に，国際的資質が海外研修旅行における異文化体験へ与える影響を検討することであった。3か国のうち1か国を選択して海外研修旅行を経験した高校生158人に対し，国際的資質および異文化体験を測定する賀問紙調査を実施した。その結呆，旅行後の国際的資質が有意に高まったが，その効果量は低かった。また異文化に対する認識の肯定的変化は，旅行の結果高まったほか，旅行前の国際的資質に強く影響受けることが明らかとなった。教育効果の検証における個人要因導入の必要性について考察された。The purpose of this study was lo examine the impact of international disposition on cross-cultural experiences in an oversea school trip among Japanese high school students. 158 high school students who participated in one in three foreign countries\u27 trip answered the questionnaire regarding international disposition and cross-cultural experiences. The results showed that scores of international disposition significantly increased but the effect sizes were moderate. Positively changes of the realization toward other countries also increased and were positively influenced by international disposition before the trip. Application of individual factors to the examination of the teaching effectiveness was discussed

Vector meson dominance and the rho meson

We discuss the properties of vector mesons, in particular the rho^0, in the context of the Hidden Local Symmetry (HLS) model. This provides a unified framework to study several aspects of the low energy QCD sector. Firstly, we show that in the HLS model the physical photon is massless, without requiring off field diagonalization. We then demonstrate the equivalence of HLS and the two existing representations of vector meson dominance, VMD1 and VMD2, at both tree level and one loop order. Finally the S matrix pole position is shown to provide a model and process independent means of specifying the rho mass and width, in contrast to the real axis prescription currently used in the Particle Data Group tables.Comment: 18 pages, REVTE

Toward single-mode random lasing within a submicrometre-sized spherical ZnO particle film

We had recently reported unique random laser action such as quasi-single-mode and low-threshold lasing from a submicrometre-sized spherical ZnO nanoparticle film with polymer particles as defects. The present study demonstrates a novel approach to realize single-mode random lasing by adjusting the sizes of the defect particles. From the dependence of random lasing properties on defect size, we find that the average number of lasing peaks can be modified by the defect size, while other lasing properties such as lasing wavelengths and thresholds remain unchanged. These results suggest that lasing wavelengths and thresholds are determined by the resonant properties of the surrounding scatterers, while the defect size stochastically determines the number of lasing peaks. Therefore, if we optimize the sizes of the defects and scatterers, we can intentionally induce single-mode lasing even in a random structure (Fujiwara et al 2013 Appl. Phys. Lett. 102 061110)

Double threshold behavior in a resonance-controlled ZnO random laser

We observed unusual lasing characteristics, such as double thresholds and blue-shift of lasing peak, in a resonance-controlled ZnO random laser. From the analysis of lasing threshold carrier density, we found that the lasing at 1st and 2nd thresholds possibly arises from different mechanisms; the lasing at 1st threshold involves exciton recombination, whereas the lasing at 2nd threshold is caused by electron-hole plasma recombination, which is the typical origin of conventional random lasers. These phenomena are very similar to the transition from polariton lasing to photon lasing observed in a well-defined cavity laser

Low-threshold and quasi-single-mode random laser within a submicrometer-sized ZnO spherical particle film

An unique random laser exhibiting quasi-single-mode and low lasing threshold is developed by a homogenized submicrometer-sized zinc oxide particle film dispersed with intentionally introduced polymer particles as point defects. Such unique random lasing is dominantly initiated at the defect sites, although multi-mode peaks with a collapsed broad emission spectrum are observed at the defect-free sites as in the conventional random lasers. Thus our proposed simple structure can possibly provide the controllability of lasing properties even in random structures