In vitro HIV-1 selective integration into the target sequence and decoy-effect of the modified sequence.

Although there have been a few reports that the HIV-1 genome can be selectively integrated into the genomic DNA of cultured host cell, the biochemistry of integration selectivity has not been fully understood. We modified the in vitro integration reaction protocol and developed a reaction system with higher efficiency. We used a substrate repeat, 5'-(GTCCCTTCCCAGT)(n)(ACTGGGAAGGGAC)(n)-3', and a modified sequence DNA ligated into a circular plasmid. CAGT and ACTG (shown in italics in the above sequence) in the repeat units originated from the HIV-1 proviral genome ends. Following the incubation of the HIV-1 genome end cDNA and recombinant integrase for the formation of the pre-integration (PI) complex, substrate DNA was reacted with this complex. It was confirmed that the integration selectively occurred in the middle segment of the repeat sequence. In addition, integration frequency and selectivity were positively correlated with repeat number n. On the other hand, both frequency and selectivity decreased markedly when using sequences with deletion of CAGT in the middle position of the original target sequence. Moreover, on incubation with the deleted DNAs and original sequence, the integration efficiency and selectivity for the original target sequence were significantly reduced, which indicated interference effects by the deleted sequence DNAs. Efficiency and selectivity were also found to vary discontinuously with changes in manganese dichloride concentration in the reaction buffer, probably due to its influence on the secondary structure of substrate DNA. Finally, integrase was found to form oligomers on the binding site and substrate DNA formed a loop-like structure. In conclusion, there is a considerable selectivity in HIV-integration into the specified sequence; however, similar DNA sequences can interfere with the integration process, and it is therefore difficult for in vivo integration to occur selectively in the actual host genome DNA

Tremendous Enhancement of Torque Density in HTS Induction/Synchronous Machine for Transportation Equipments

We succeeded in tremendous enhancement of torque density as well as power density in High Temperature Superconducting Induction/Synchronous Machine (HTS-ISM) for next generation transportation equipments. First, we fabricated and tested the 20 kW-class prototype as the validation of our design concept (1st generation). And then, the 70% reduction of the motor's volume is challenged with the same power (2nd generation). We successfully realized the tremendous enhancement of the torque density, and further the overload tolerance was also realized at the steady state

Hyaluronic acid and its derivative as a multi-functional gene expression enhancer: Protection from non-specific interactions, adhesion to targeted cells, and transcriptional activation

Hyaluronic acid (HA), a natural anionic mucopolysaccharide, can be deposited onto the cationic surface of DNA/polyethyleneimine (PEI) complexes to recharge the surface potential and reduce nonspecific interactions with proteins. HA can also be used as a ligand to target specific cell receptors. Furthermore, HA-coating enhanced the transcriptional activity of the plasmid/PEI complexes, probably by loosening the tight binding between DNA and PEI, which facilitated the approach of transcription factors. Amphoteric HA derivative having spermine side chains (Spn-HA) with a structure similar to HMG protein showed higher transcription-enhancing activity than HA. Plasmid/PEI/Spn-HA ternary complex exhibited 29-fold higher transgene expression efficiency than naked plasmid/PEI complexes in CHO cells

Efficient Stabilization of Na Storage Reversibility by Ti Integration into O′3-Type NaMnO2

The development of an energy storage system with abundant elements is a key challenge for a sustainable society, and the interest of Na intercalation chemistry is extending throughout the research community. Herein, the impact of Ti integration into NaMnO2 in a binary system of x NaMnO2–(1–x) TiO2 (0.5≤x≤1) is systematically examined for rechargeable Na battery applications. Stoichiometric NaMnO2, which is classified as an in-plane distorted O′3-type layered structure, delivers a large initial discharge capacity of approximately 200 mAh g-1, but insufficient capacity retention is observed, most probably associated with dissolution of Mn ions on electrochemical cycles. Ti-substituted samples show highly improved electrode performance as electrode materials. However, the appearance of a sodium-deficient phase, Na4Mn4Ti5O18 with a tunnel-type structure, is observed for Ti-rich phases. Among the samples in this binary system, Na0.8Mn0.8Ti0.2O2 (x=0.8), which is a mixture of a partially Ti-substituted O′3-type layered oxide (Na0.88Mn0.88Ti0.12O2) and tunnel-type Na4Mn4Ti5O18 as a minor phase elucidated by Rietveld analysis on both neutron and X-ray diffraction patterns, shows good electrode performance on the basis of energy density and cyclability. Both phases are electrochemically active as evidenced by in situ X-ray diffraction study, and the improvement of reversibility originates from the suppression of Mn dissolution on electrochemical cycles. From these results, the feasibility of Mn-based electrode materials for high-energy rechargeable Na batteries made from only abundant elements is discussed in detail