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Carmona P.,CSIC - Institute for the Structure of Matter | Molina M.,Escuela Universitaria de Optica
Biochemistry | Year: 2010

The secondary structure of the loop IIId domain in the RNA of hepatitis C virus (HCV) is well-conserved among different genotypes of HCV, which suggests that the nucleocapsid proteins may interact with the genome RNA through this loop structure. Using infrared spectroscopy, we monitored structural changes occurring in HCV core protein and loop IIId upon formation of nucleocapsid-like particles (NLPs). The protein secondary structure of these particles involves β-sheet enrichment in relation to its protein monomer. The phosphodiester backbone vibrations of loop IIId reflect the predominant C3′-endo conformation of the riboses involved in the RNA A-form and reveal the packaging-imposed transition of the said RNA segments toward single-stranded structure within the NLPs. Intermolecular protein-nucleic acid contacts in these particles involve RNA phosphate groups and positively charged amino acid residues such as arginine and lysine. Two-dimensional correlation spectroscopic analysis of the spectra measured in the course of deuteration shows synchronous cross-peaks correlating two bands assigned to guanine and arginine side chain, which is consistent with the presence of guanine-arginine interactions in these NLPs. This is also supported by the kinetically favored formation of NLPs having HCV core protein and guanine-enriched synthetic oligonucleotides. We also found that these NPLs are fully permeable to water molecules. © 2010 American Chemical Society.

Silva-Lopez M.,Escuela Universitaria de Optica | Rico-Garcia J.M.,Escuela University Of Optica | Alda J.,Escuela Universitaria de Optica
Optica Pura y Aplicada | Year: 2012

The amplitude and phase spatial maps around the focal plane of a laser beam are recovered. Irradiance maps are obtained using a tomographic method based on the knife-edge technique, and the beam phase is obtained by means of an algorithm based on the Irradiance Transport Equation (ITE). Information on the amplitude and phase distribution of an incoming beam is useful for characterization of nanophotonic devices (such as antenna-couple detectors) that are sensitive to these parameters. This method avoids the use of image-forming devices which are not suitable under low spatial resolution conditions. © Sociedad Española de Óptica.

Chamorro E.,Complutense University of Madrid | Bonnin-Arias C.,Complutense University of Madrid | Perez-Carrasco M.J.,Escuela Universitaria de Optica | De Luna J.M.,Escuela Universitaria de Optica | And 2 more authors.
Photochemistry and Photobiology | Year: 2013

Human visual system is exposed to high levels of natural and artificial lights of different spectra and intensities along lifetime. Light-emitting diodes (LEDs) are the basic lighting components in screens of PCs, phones and TV sets; hence it is so important to know the implications of LED radiations on the human visual system. The aim of this study was to investigate the effect of LEDs radiations on human retinal pigment epithelial cells (HRPEpiC). They were exposed to three light-darkness (12 h/12 h) cycles, using blue-468 nm, green-525 nm, red-616 nm and white light. Cellular viability of HRPEpiC was evaluated by labeling all nuclei with DAPI; Production of reactive oxygen species (ROS) was determined by H2DCFDA staining; mitochondrial membrane potential was quantified by TMRM staining; DNA damage was determined by H2AX histone activation, and apoptosis was evaluated by caspases-3,-7 activation. It is shown that LED radiations decrease 75-99% cellular viability, and increase 66-89% cellular apoptosis. They also increase ROS production and DNA damage. Fluorescence intensity of apoptosis was 3.7% in nonirradiated cells and 88.8%, 86.1%, 83.9% and 65.5% in cells exposed to white, blue, green or red light, respectively. This study indicates three light-darkness (12 h/12 h) cycles of exposure to LED lighting affect in vitro HRPEpiC. Effects of monochromatic and white LED lighting on human retinal pigment epithelial cells in vitro. HRPEpiC cells were exposed to LED lighting (irradiated cells) or maintained in darkness (control) for three light-darkness cycles (12 h/12 h). Apoptosis determined by the activation of caspases-3, -7 is observed as a pink coloration around DAPI-stained cells: (1) Representative images of effects of LED lighting on HRPEpiC cells and (2) Graphs displays mean fluorescence intensity radios of irradiated cells versus non irradiated controls. Bars represent mean ± SD from n = 3-5 experiments. The asterisk (*) indicates significant differences as compared to controls (P < 0.05, Student's t-test). © 2012 The American Society of Photobiology.

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