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The electronic structure of the organic semiconductor titanyl phthalocyanine (TiO-Pc) has been investigated using synchrotron radiation-excited X-ray emission and absorption spectroscopies. The C and N K-edge spectra display similarities with those recorded from other metal-Pcs, while the O K-edge and Ti L-edge spectra support the premise that the titanyl species are spatially isolated. Good agreement is found between a calculation of the partial density of states and the measured spectra, although the Ti L-edge spectra differ from a previous study. Two energy loss features are reported from resonant X-ray inelastic scattering at the Ti L-edge associated with O 2p–Ti 3d* and N 2p–Ti 3d* charge transfer transitions. [ABSTRACT FROM AUTHOR]

The electronic structure of thin films of the organic semiconductor vanadyl phthalocyanine has been studied using synchrotron radiation-excited resonant soft X-ray emission spectroscopy, resonant inelastic soft X-ray scattering, X-ray absorption spectroscopy, and X-ray photoemission spectroscopy. The C, N, V, and O partial densities of states for both the valence and conduction bands have been determined, as well as the core level electronic structure. Good agreement was found between the experimental measurements of the valence and conduction bands, and the results of a density functional calculation. [ABSTRACT FROM AUTHOR]

The yeast nucleoporin Nup2p is associated primarily with the nuclear basket of nuclear pore complexes and is required for efficient importin-α:β-mediated nuclear protein import as well as efficient nuclear export of Kap60p/importin-α. Residues 1-51 of Nup2p bind tightly to Kap60p and are required for Nup2p function in vivo. We have determined the 2.6 Å resolution crystal structure of a complex between this region of Nup2p and the armadillo repeat domain of Kap60p. Nup2p binds along the inner concave groove of Kap60p, but its interaction interface is different from that employed for nuclear localization signal (NLS) recognition although there is some overlap between them. Nup2p binds Kap60p more strongly than NLSs and accelerates release of NLSs from Kap60p. Nup2p itself is released from Kap60p by Cse1p:RanGTP only in the presence of the importin-β binding (IBB) domain of Kap60p. These data indicate that Nup2p increases the overall rate of nuclear trafficking by coordinating nuclear import termination and importin recycling as a concerted process. [ABSTRACT FROM AUTHOR]

Sumoylation is involved in mediating protein-protein interactions, subcellular compartmentalization and protein stability. Our analysis of various Wnt signaling molecules revealed that one of them, Tcf-4, is sumoylated at the endogenous level. At least one sumoylation site, Lys297, of Tcf-4 was identified. The sumoylation of Tcf-4 was enhanced by PIASy, a SUMO E3 enzyme, and inhibited by Axam, a desumoylation enzyme. Although PIASy did not affect the interaction of Tcf-4 with β-catenin or DNA, Tcf-4, SUMO-1 and PIASy were co-localized in the nucleus and present in a complex in the PML body. PIASy enhanced β-catenin-dependent transcriptional activity of Tcf-4, whereas Axam inhibited it. Reduction of the protein level of Axam by RNA interference led to an increase in sumoylation of Tcf-4 and activation of Tcf-4. Furthermore, β-catenin and PIASy activated Tcf-4K297R, in which Lys297 was changed to arginine, less than wild-type Tcf-4. These results suggest that sumoylation of Tcf-4 is involved in β-catenin-dependent and Tcf-4-mediated gene expression in the Wnt signaling pathway. [ABSTRACT FROM AUTHOR]

A photoacoustic imaging system composed of a flexible bundle of thin hollow-optical fibers is proposed for endoscopic diagnosis. In this system, a bundle of 127 hollow-optical fibers with an inner diameter of 100 μm was fabricated. The total diameter of the bundle was 2.1 mm, and the minimum bending radius was around 10 mm. Owing to the small numerical aperture of hollow optical fibers, a high resolution image was obtained without using a lens array at the distal end. In the imaging system, the hollow fibers in the bundle were aligned at the input end, so the hollow fibers were sequentially excited by linearly scanning the laser beam at the input end. Photoacoustic imaging systems consisting of the bundled fibers for excitation of acoustic wave and piezoelectric probes for detection of photoacoustic signals were built. By using the systems, photoacoustic images of blood vessels in the ovarian membrane of fish were taken to test the feasibility of the system. As a result, photoacoustic images of the vessel were successfully obtained with a laser fluence of around 6.6 mJ cm−2. [ABSTRACT FROM AUTHOR]