Vibrational Energy Flow in Photoactive Yellow Protein Revealed by Infrared Pump–Visible Probe Spectroscopy

Vibrational energy flow in the electronic ground state of photoactive yellow protein (PYP) is studied by ultrafast infrared (IR) pump–visible probe spectroscopy. Vibrational modes of the chromophore and the surrounding protein are excited with a femtosecond IR pump pulse, and the subsequent vibrational dynamics in the chromophore are selectively probed with a visible probe pulse through changes in the absorption spectrum of the chromophore. We thus obtain the vibrational energy flow with four characteristic time constants. The vibrational excitation with an IR pulse at 1340, 1420, 1500, or 1670 cm^–1 results in ultrafast intramolecular vibrational redistribution (IVR) with a time constant of 0.2 ps. The vibrational modes excited through the IVR process relax to the initial ground state with a time constant of 6–8 ps in parallel with vibrational cooling with a time constant of 14 ps. In addition, upon excitation with an IR pulse at 1670 cm^–1, we observe the energy flow from the protein backbone to the chromophore that occurs with a time constant of 4.2 ps

Electron Injection Dynamics at the SILAR Deposited CdS Quantum Dot/TiO₂ Interface

Semiconductor quantum dots with their tunable band gap energies offer new opportunities for controlling photoresponse and photoconversion efficiency of solar cells. Exciton dissociation, charge injection, and charge recombination are key steps for efficient interfacial electron transfer. Here, electron injection and carrier relaxation dynamics at the CdS quantum dot/TiO₂ interface were investigated by using ultrafast transient absorption spectroscopy and global fitting analyses. The CdS/TiO₂ composites were prepared by depositing CdS in the TiO₂ nanocrystalline films by the successive ionic layer adsorption and reaction (SILAR) technique. Comparing the transient absorption spectra of CdS/TiO₂ composites formed by different numbers of CdS coating cycles and CdS/Al₂O₃ revealed size-dependent electron injection from excited CdS into TiO₂ nanoparticles, which occurred on a time scale of 1–9 ps. We also demonstrated that holes are trapped in a localized state with a time constant of 0.3 ps, which was faster than the electron trapping with a time constant of about 30 ps

Differential Analysis of Protein Expression in RNA-Binding-Protein Transgenic and Parental Rice Seeds Cultivated under Salt Stress

Transgenic plants tolerant to various environmental stresses are being developed to ensure a consistent food supply. We used a transgenic rice cultivar with high saline tolerance by introducing an RNA-binding protein (RBP) from the ice plant (<i>Mesembryanthemum crystallinum</i>); differences in salt-soluble protein expression between nontransgenic (NT) and RBP rice seeds were analyzed by 2D difference gel electrophoresis (2D-DIGE), a gel-based proteomic method. To identify RBP-related changes in protein expression under salt stress, NT and RBP rice were cultured with or without 200 mM sodium chloride. Only two protein spots differed between NT and RBP rice seeds cultured under normal conditions, one of which was identified as a putative abscisic acid-induced protein. In NT rice seeds, 91 spots significantly differed between normal and salt-stress conditions. Two allergenic proteins of NT rice seeds, RAG1 and RAG2, were induced by high salt. In contrast, RBP rice seeds yielded seven spots and no allergen spots with significant differences in protein expression between normal and salt-stress conditions. Therefore, expression of fewer proteins was altered in RBP rice seeds by high salt than those in NT rice seeds

Reciprocal expression of Slug and Snail in human oral cancer cells

<div><p>Snail, also called Snai1, is a key regulator of EMT. Snail plays crucial roles in cancer progression, including resistance to anti-tumor drugs and invasion by various cancer cells. Slug, also known as Snai2, is also involved in the aggravation of certain tumors. In this study, we examined the roles of Slug in human oral squamous cell carcinoma (OSCC) cells. Slug is highly expressed in these cells, and Slug siRNA effectively represses anti-tumor drug resistance and invasive properties. In addition, transforming growth factor (TGF)-β upregulates the expression of Snail and Slug and promotes resistance to anti-tumor drugs in OSCC cells. Surprisingly, Slug siRNA appears to upregulate Snail expression considerably in OSCC cells. Snail siRNA also appears to upregulate Slug expression. Thus, either Slug or Snail siRNA alone partially mitigates malignant phenotypes in the presence of TGF-β, whereas both Slug and Snail siRNAs together dramatically suppress them. Therefore, Slug and Snail in tandem, but not alone, are potential therapeutic targets for nucleic acid medicines to treat oral cancer.</p></div

Slug and Snail siRNAs regulate mRNA expression of IL-6 and IL-8.

<p><b>(A and B)</b> Phosphorylation of STAT3 at Y705 residue were determined by immunoblotting following transfection with either Slug or Snail siRNA in SAS cells treated with TGF-β. α-tubulin was used as a loading control. <b>(C–H)</b> After the knockdown of either Slug or Snail in HSC4 (C, D, and E) and SAS (F, G, and H) cells, the cells were treated with 1 ng/ml TGF-β for 24 h. mRNA levels of IL-6 (C, D, F, and G) and IL-8 (E and H) were analyzed by qRT-PCR. mRNA levels were normalized to the amount of <i>GAPDH</i> mRNA. Slug siRNA (#1 and #2) and Snail siRNA (#1 and #2) were used. Each value represents the mean ± s.d. of triplicate determinations from a representative experiment. Similar results were obtained in at least three independent experiments. NC, non-specific negative control siRNA.</p

Slug and Snail induction in HSC4 cells in response to TGF-β.

<p><b>(A, B, and C)</b> Slug and Snail mRNA and protein levels in HSC4 cells that had either been treated with 1 ng/ml TGF-β for 24 h or left untreated were determined by qRT-PCR (A and B) and immunoblot analyses (C), respectively. Values were normalized to the amount of <i>GAPDH</i> mRNA (A and B) while α-tubulin was used as a loading control for immunoblotting (C). <b>(D)</b> Invasion assays were performed in HSC4 cells treated with or without 1 ng/ml TGF-β, followed by quantification analyses. The value of the control cells is indicated as “1”. <b>(E)</b> HSC4 cells were treated with 1 ng/ml TGF-β for 24 h, the cells were exposed to docetaxel (DTX; 10 μM). The viable cells were trypsinized and counted using a hemocytometer. The value of the control cells is indicated as “1”. <b>(F and G)</b> Following the siRNA-mediated knockdown of either Slug, Snail, or both in HSC4 cells, the cells were treated with 1 ng/ml TGF-β for 24 h. The levels of Slug and Snail mRNA and protein were determined by qRT-PCR (F) and immunoblotting (G), respectively. mRNA levels were normalized to the amount of <i>GAPDH</i> mRNA (F) while α-tubulin was used as a loading control for immunoblotting (G). <b>(H)</b> After the siRNA-mediated knockdown of either Slug, Snail, or both in HSC4 cells treated with 1 ng/ml TGF-β, the cells were subjected to invasion assays, followed by taking photos and quantification. The value of the control cells is indicated as “1”. <b>(I)</b> After siRNA-mediated knockdown of either Slug, Snail, or both in HSC4 cells treated with 1 ng/ml TGF-β for 24 h, the cells were exposed to docetaxel (DTX) for 24 h. The viable cells were trypsinized and counted using a hemocytometer. The value of the control cells is indicated as “1”. Slug siRNA (#1) and Snail siRNA (#1) were used. Each value represents the mean ± s.d. of triplicate determinations from a representative experiment. Similar results were obtained in at least three independent experiments. NC, non-specific negative control siRNA. <i>p</i> values were determined by Student’s <i>t-test</i>. *<i>p</i> < 0.05, **<i>p</i> < 0.01; n.s., not significant.</p

Slug and Snail expression in various OSCC cell lines.

<p><b>(A)</b> Slug and Snail protein levels in OSCC cell lines were determined by immunoblotting with α-tubulin as a loading control. <b>(B and C)</b> Following the knockdown of either Slug alone, or of Slug and Snail in tandem, in HSC4 cells, mRNA and protein levels of Slug and Snail were examined by qRT-PCR (B) and immunoblot analysis (C), respectively. mRNA levels measured were normalized to the amount of <i>GAPDH</i> mRNA (B) while α-tubulin was used as a loading control for immunoblotting (C). long exp., long exposure. <b>(D)</b> Invasion assays were performed on HSC4 cells transfected with either Slug siRNA alone or both Slug and Snail siRNAs. After photos were taken (bottom panels), cell invasion was quantified (top panel). The value of the cells transfected with control siRNA is indicated as “1”. <b>(E)</b> After the knockdown of either Slug alone, or of Slug and Snail in tandem, in HSC4 cells, the cells were exposed to docetaxel (DTX; 3 μM) for 24 h. Cell viability was evaluated by cell count assay. The value of the control cells is indicated as “1”. NC, non-specific negative control siRNA. Slug siRNA (#1) and Snail siRNA (#1) were used. Each value represents the mean ± s.d. of triplicate determinations from a representative experiment. Similar results were obtained in at least three independent experiments <i>p</i> values were determined by Student’s <i>t-test</i>. *<i>p</i> < 0.05; n.s., not significant.</p

Overexpression of Slug and Snail in SAS cells.

<p><b>(A, B, and C)</b> SAS cells transfected with plasmids encoding either HA-tagged Slug or Snail were subjected to immunoblot (A) and qRT-PCR analyses (B and C). α-tubulin was used as a loading control (A). mRNA levels were normalized to the amount of <i>GAPDH</i> mRNA (B and C). <b>(D and E)</b> SAS cells transfected with plasmids encoding either HA-tagged Slug or Snail were exposed to docetaxel (DTX; 10 μM) (D) or Erlotinib (5 μM) (E) for 24 h. The viable cells were trypsinized and counted using a hemocytometer. The value of the control cells is indicated as “1”. <b>(F)</b> Invasion assays were performed on SAS cells transfected with either HA-tagged Slug or Snail. The value of the control cells is indicated as “1”. Each value represents the mean ± s.d. of triplicate determinations from a representative experiment. Similar results were obtained in at least three independent experiments. Cont., negative control plasmid. <i>p</i> values were determined by Student’s <i>t-test</i>. **<i>p</i> < 0.01.</p

Self-Assembly of Maltoheptaose-<i>block</i>-polycaprolactone Copolymers: Carbohydrate-Decorated Nanoparticles with Tunable Morphology and Size in Aqueous Media

This paper describes the systematic investigation into the aqueous self-assembly of a series of block copolymers (BCPs) consisting of maltoheptaose (MH; as the A block) and poly­(ε-caprolactone) (PCL; as the B block), i.e., linear AB-type diblock copolymers with varied PCL molecular weights (MH-<i>b</i>-PCL_{(2.5k,3.3k,5k,10k)}), AB_<i>y</i>-type (<i>y</i> = 2, MH-<i>b</i>-(PCL_5k)₂; <i>y</i> = 3, MH-<i>b</i>-(PCL_3.3k)₃), A₂B₂-type ((MH)₂-<i>b</i>-(PCL_5k)₂), and A_<i>x</i>B-type miktoarm star polymers (<i>x</i> = 2, (MH)₂-<i>b</i>-PCL_10k; <i>x</i> = 3, (MH)₃-<i>b</i>-PCL_10k), which had been precisely synthesized via the combination of the living ring-opening polymerization and click reaction. Under similar conditions, the nanoprecipitation method was employed to self-assemble them in an aqueous medium. Imaging and dynamic light scattering techniques indicated the successful formation of the carbohydrate-decorated nanoparticles via self-assembly. The MH-<i>b</i>-PCLs formed regular core–shell micellar nanoparticles with the hydrodynamic radius (<i>R</i>_h) of 17–43 nm. MH-<i>b</i>-(PCL_5k)₂ and MH-<i>b</i>-(PCL_3.3k)₃, which have an <i>N</i>_PCL comparable to MH-<i>b</i>-PCL_10k, were found to form large compound micelles with relatively large radii (<i>R</i>_h of 49 and 56 nm, respectively). On the other hand, (MH)₂-<i>b</i>-(PCL_5k)₂, (MH)₂-<i>b</i>-PCL_10k, and (MH)₃-<i>b</i>-PCL_10k predominantly formed the regular core–shell micellar nanoparticles (<i>R</i>_h = 29–39 nm) with a size smaller than that of MH-<i>b</i>-PCL_10k (<i>R</i>_h = 43 nm)

Protective effect of 2M Glucose on the ability of IgE to bind to the high affinity receptor after heating at 56°C for 30 min.

<p>RS ATL8 cells seeded at a density of 50.000 cells per well were sensitised with a 50-fold dilution of Par j 2 serum pool, which had been left unheated or heated either in the presence or in the absence of 2M Glucose. After overnight incubation with the sera, cells were stimulated with optimal concentrations of anti-IgE (1 µg/mL) or Par j 2 recombinant allergen (100 pg/mL) and luciferase production measured after 4 hours. ; *: p<0.05; **: <i>p</i><0.01; ***: p<0.001; n.s.: not significant (Student t-test).</p