NMR Structure of Retinal Guanylate Cyclase Activating Protein 5 (GCAP5) with R22A Mutation That Abolishes Dimerization and Enhances Cyclase Activation.

Guanylate cyclase activating protein-5 (GCAP5) in zebrafish photoreceptors promotes the activation of membrane receptor retinal guanylate cyclase (GC-E). Previously, we showed the R22A mutation in GCAP5 (GCAP5) abolishes dimerization of GCAP5 and activates GC-E by more than 3-fold compared to that of wild-type GCAP5 (GCAP5). Here, we present ITC, NMR, and functional analysis of GCAP5 to understand how R22A causes a decreased dimerization affinity and increased cyclase activation.

Mechanically-Durable Antireflective Subwavelength Nanoholes on Glass Surfaces Using Lithography-Free Fabrication.

Traditional multilayer antireflection (AR) surfaces are of significant importance for numerous applications, such as laser optics, camera lenses, and eyeglasses. Recently, technological advances in the fabrication of biomimetic AR surfaces capable of delivering broadband omnidirectional high transparency combined with self-cleaning properties have opened an alternative route toward realization of multifunctional surfaces which would be beneficial for touchscreen displays or solar harvesting devices. However, achieving the desired surface properties often requires sophisticated lithography fabrication methods consisting of multiple steps.

NMR and EPR-DEER Structure of a Dimeric Guanylate Cyclase Activator Protein-5 from Zebrafish Photoreceptors.

Retinal guanylate cyclases (RetGCs) are regulated by a family of guanylate cyclase-activating proteins (called GCAP1-7). GCAPs form dimers that bind to Ca and confer Ca sensitive activation of RetGC during visual phototransduction. The GCAP5 homologue from zebrafish contains two nonconserved cysteine residues (Cys15 and Cys17) that bind to ferrous ion, which stabilizes GCAP5 dimerization and diminishes its ability to activate RetGC.

Industrial-grade anti-reflection coatings with extreme scratch resistance.

Anti-reflection coatings are widely used throughout the field of optical technology such as in corrective eyeglasses, camera lenses, and microscope optics, to improve the transmittance and reduce the reflectance of glass and other transparent materials. To date, these coatings have suffered from relatively poor scratch resistance and high scratch visibility compared to standard glasses. This has limited their use in applications requiring high mechanical durability such as on the chemically strengthened glasses widely used in modern touch screen devices.

Photoreceptor calcium sensor proteins in detergent-resistant membrane rafts are regulated via binding to caveolin-1.

Rod cell membranes contain cholesterol-rich detergent-resistant membrane (DRM) rafts, which accumulate visual cascade proteins as well as proteins involved in regulation of phototransduction such as rhodopsin kinase and guanylate cyclases. Caveolin-1 is the major integral component of DRMs, possessing scaffolding and regulatory activities towards various signaling proteins. In this study, photoreceptor Ca-binding proteins recoverin, NCS1, GCAP1, and GCAP2, belonging to neuronal calcium sensor (NCS) family, were recognized as novel caveolin-1 interacting partners.

Structural Characterization of Ferrous Ion Binding to Retinal Guanylate Cyclase Activator Protein 5 from Zebrafish Photoreceptors.

Sensory guanylate cyclases (zGCs) in zebrafish photoreceptors are regulated by a family of guanylate cyclase activator proteins (called GCAP1-7). GCAP5 contains two nonconserved cysteine residues (Cys15 and Cys17) that could in principle bind to biologically active transition state metal ions (Zn and Fe). Here, we present nuclear magnetic resonance (NMR) and isothermal titration calorimetry (ITC) binding analyses that demonstrate the binding of one Fe ion to two GCAP5 molecules (in a 1:2 complex) with a dissociation constant in the nanomolar range.

Regulatory function of the C-terminal segment of guanylate cyclase-activating protein 2.

Neuronal responses to Ca2+-signals are provided by EF-hand-type neuronal Ca2+-sensor (NCS) proteins, which have similar core domains containing Ca2+-binding and target-recognizing sites. NCS proteins vary in functional specificity, probably depending on the structure and conformation of their non-conserved C-terminal segments. Here, we investigated the role of the C-terminal segment in guanylate cyclase activating protein-2, GCAP2, an NCS protein controlling the Ca2+-dependent regulation of photoreceptor guanylate cyclases.

Zinc Is Involved in Depression by Modulating G Protein-Coupled Receptor Heterodimerization.

5-Hydroxytryptamine 1A receptor and galanin receptor 1 belong to the G protein-coupled receptors superfamily, and they have been described to heterodimerize triggering an anomalous physiological state that would underlie depression. Zinc supplementation has been widely reported to improve treatment against major depressive disorder. Our work has focused on the study and characterization of these receptors and its relationships with zinc both under purified conditions and in cell culture.

Transverse Anderson Localization in Disordered Glass Optical Fibers: A Review.

Disordered optical fibers show novel waveguiding properties that can be used for various device applications, such as beam-multiplexed optical communications and endoscopic image transport. The strong transverse scattering from the transversely disordered optical fibers results in transversely confined beams that can freely propagate in the longitudinal direction, similar to conventional optical fibers, with the advantage that any point in the cross section of the fiber can be used for beam transport. For beam multiplexing and imaging applications, it is highly desirable to make the localized beam radius as small as possible.

Monolithically integrated micro- and nanostructured glass surface with antiglare, antireflection, and superhydrophobic properties.

Hierarchical micro- and nanostructured surfaces have previously been made using a variety of materials and methods, including particle deposition, polymer molding, and the like. These surfaces have attracted a wide variety of interest for applications including reduced specular reflection and superhydrophobic surfaces. To the best of our knowledge, this paper reports the first monolithic, hierarchically structured glass surface that combines micro- and nanoscale surface features to simultaneously generate antiglare (AG), antireflection (AR), and superhydrophobic properties.

Image transport through a disordered optical fibre mediated by transverse Anderson localization.

Transverse Anderson localization of light allows localized optical-beam-transport through a transversely disordered and longitudinally invariant medium. Its successful implementation in disordered optical fibres recently resulted in the propagation of localized beams of radii comparable to that of conventional optical fibres. Here we demonstrate optical image transport using transverse Anderson localization of light.

Fabrication and characterization of disordered polymer optical fibers for transverse Anderson localization of light.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 μm. Initially, each strand is 200 μm in diameter and 8-inches long.

Multiple-beam propagation in an Anderson localized optical fiber.

We investigate the simultaneous propagation of multiple beams in a disordered Anderson localized optical fiber. The profiles of each beam fall off exponentially, enabling multiple channels at high-density. We examine the influence of fiber bends on the movement of the beam positions, which we refer to as drift.

Detailed investigation of the impact of the fiber design parameters on the transverse Anderson localization of light in disordered optical fibers.

We recently reported the observation of transverse Anderson localization as the waveguiding mechanism in optical fibers with random transverse refractive index profiles [Opt. Lett. 37, 2304 (2012)].

Observation of transverse Anderson localization in an optical fiber.

We utilize transverse Anderson localization as the waveguiding mechanism in optical fibers with random transverse refractive index profiles. Using experiments and numerical simulations, we show that the transverse localization results in an effective propagating beam diameter that is comparable to that of a typical index-guiding optical fiber.

Antithetical modes of and the Ca(2+) sensors targeting in ANF-RGC and ROS-GC1 membrane guanylate cyclases.

THE MEMBRANE GUANYLATE CYCLASE FAMILY HAS BEEN BRANCHED INTO THREE SUBFAMILIES: natriuretic peptide hormone surface receptors, Ca(2+)-modulated neuronal ROS-GC, and Ca(2+)-modulated odorant surface receptor ONE-GC. The first subfamily is solely modulated by the extracellularly generated hormonal signals; the second, by the intracellularly generated sensory and sensory-linked signals; and the third, by combination of these two. The present study defines a new paradigm and a new mechanism of Ca(2+) signaling.

Temporal-imaging system with simple external-clock triggering.

We demonstrate a temporal imaging system based on parametric mixing that allows simple triggering from an external clock by using a time-lens-based pump laser. We integrate our temporal imaging system into a time-to-frequency measurement scheme and demonstrate the ability to perform characterization of temporal waveforms with 1.4-ps resolution and a 530-ps record length.

Highly-efficient coupling of linearly- and radially-polarized femtosecond pulses in hollow-core photonic band-gap fibers.

We demonstrate extremely efficient excitation of linearly-, radially-, and azimuthally-polarized modes in a hollow-core photonic band-gap fiber with femtosecond laser pulses. We achieve coupling efficiencies as high as 98% with linearly polarized input Gaussian beams and with high-power pulses we obtain peak intensities greater than 10(14) W/cm(2) inside and transmitted through the fiber. With radially polarized pulses, we achieve 91% total transmission through the fiber while maintaining the polarization state.

Ca(2+)-modulated vision-linked ROS-GC guanylate cyclase transduction machinery.

Vertebrate phototransduction depends on the reciprocal relationship between two-second messengers, cyclic GMP and Ca(2+). The concentration of both is reciprocally regulated including the dynamic synthesis of cyclic GMP by a membrane bound guanylate cyclase. Different from hormone receptor guanylate cyclases, the cyclases operating in phototransduction are regulated by the intracellular Ca(2+)-concentration via small Ca(2+)-binding proteins.

Silica-glass contribution to the effective nonlinearity of hollow-core photonic band-gap fibers.

We measure the effective nonlinearity of various hollow-core photonic band-gap fibers. Our findings indicate that differences of tens of nanometers in the fiber structure result in significant changes to the power propagating in the silica glass and thus in the effective nonlinearity of the fiber. These results show that it is possible to engineer the nonlinear response of these fibers via small changes to the glass structure.

Generation of megawatt optical solitons in hollow-core photonic band-gap fibers.

The measured dispersion of a low-loss, hollow-core photonic band-gap fiber is anomalous throughout most of the transmission band, and its variation with wavelength is large compared with that of a conventional step-index fiber. For an air-filled fiber, femtosecond self-frequency--shifted fundamental solitons with peak powers greater than 2megawatts can be supported. For Xe-filled fibers, nonfrequency-shifted temporal solitons with peak powers greater than 5.

Low-loss hollow-core silica/air photonic bandgap fibre.

Photonic bandgap structures use the principle of interference to reflect radiation. Reflection from photonic bandgap structures has been demonstrated in one, two and three dimensions and various applications have been proposed. Early work in hollow-core photonic bandgap fibre technology used a hexagonal structure surrounding the air core; this fibre was the first demonstration of light guided inside an air core of a photonic bandgap fibre.

Functional restoration of the Ca2+-myristoyl switch in a recoverin mutant.

Recoverin is a neuronal calcium sensor protein that plays a crucial role in vertebrate phototransduction. It undergoes a Ca(2+)-myristoyl switch when Ca(2+) binds to its two functional EF-hand motifs (EF-hands 2 and 3), each present in one of recoverin's two domains. Impairment of Ca(2+)-binding in recoverin leads to a disturbance of the Ca(2+)-myristoyl switch and loss of its regulatory properties, i.

The myristoylation of the neuronal Ca2+ -sensors guanylate cyclase-activating protein 1 and 2.

Guanylate cyclase-activating proteins (GCAPs) are Ca(2+)-binding proteins with a fatty acid (mainly myristic acid) that is covalently attached at the N terminus. Myristoylated forms of GCAP were produced in E. coli by coexpression of yeast N-myristoyl-transferase.