Characterization of Ribeye Subunits in Zebrafish Hair Cells Reveals That Exogenous Ribeye B-Domain and CtBP1 Localize to the Basal Ends of Synaptic Ribbons

Synaptic ribbons are presynaptic structures formed by the self-association of RIBEYE–the main structural component of ribbon synapses. RIBEYE consists of two domains: a unique N-terminal A-domain and a C-terminal B-domain that is identical to the transcription co-repressor C-terminal binding protein 2 (CtBP2). Previous studies in cell lines have shown that RIBEYE A-domain alone is sufficient to form ribbon-like aggregates and that both A- and B- domains form homo-and heterotypic interactions. As these interactions are likely the basis for synaptic-ribbon assembly and structural plasticity, we wanted to examine how zebrafish Ribeye A- and B- domains interact with synaptic ribbons in vivo. To that end, we characterized the localization of exogenously expressed Ribeye A- and B- domains and the closely related protein, CtBP1, in the hair cells of transgenic zebrafish larvae. Unexpectedly, exogenously expressed Ribeye A-domain showed variable patterns of localization in hair cells; one zebrafish paralog of A-domain failed to self-associate or localize to synaptic ribbons, while the other self-assembled but sometimes failed to localize to synaptic ribbons. By contrast, Ribeye B-domain/CtBP2 was robustly localized to synaptic ribbons. Moreover, both exogenously expressed B-domain/CtBP2 and CtBP1 were preferentially localized to the basal end of ribbons adjacent to the postsynaptic density. Overexpression of B-domain/CtBP2 also appeared to affect synaptic-ribbon composition; endogenous levels of ribbon-localized Ribeye were significantly reduced as hair cells matured in B-domain/CtBP2 transgenic larvae compared to wild-type. These results reveal how exogenously expressed Ribeye domains interact with synaptic ribbons, and suggest a potential organization of elements within the ribbon body

Commercial Off-The-Shelf GPU Qualification for Space Applications

With increased sensor data rates, and limited downlink capability, NASA missions have increased demands for onboard processing for applications ranging from synthetic aperture radar (SAR) data reduction to hyperspectral image processing and recognition, and even artificial intelligence (AI). Graphics Processor Units (GPUs) offer an attractive processing architecture for many of the applications due to their massive parallelism. As no radiation hardened GPU devices currently exist, any near term GPU-based onboard processors must use commercially available devices. To address this need NASA GSFC is collaborating with Cubic Aerospace Incorporated to, (a) characterize the capability of GPUs to meet the demands of a candidate onboard processing application, thereby demonstrating their ability to improve mission performance, reduce spacecraft SWaP, and potentially enable new missions, and (b) evaluate the radiation tolerance of capable COTS GPU devices to determine their suitability for spaceflight applications and understand any mitigations that are needed. A candidate onboard processing image has been prototyped and evaluated on a commercial GPU board and has demonstrated significantly increased processing throughput. Radiation tests for commercial GPU devices are planned for early fiscal year 2019

The Segmented Aperture Interferometric Nulling Testbed (SAINT) III: Control Systems Analysis and Preliminary Results

This work presents a detailed current performance analysis for the telescope, pointing, and coronagraph com- ponent subsystems of the Segmented Aperture Interferometric Nulling Testbed (SAINT). The project pairs an active segmented mirror with the Visible Nulling Coronagraph (VNC) towards demonstrating capabilities for the future space observatories needed to directly detect and characterize Earth-sized worlds around nearby stars. We describe approaches to optimize subsystem wavefront sensing and control parameters, summarizing relevant scal- ing relations between these parameters, residual errors, and observed contrast measurements. Preliminary results from diagnostic testing under various control states are presented along with intermediate contrast measurements towards demonstrating the full system

Presencia de Pb, Cr y Ni en peces de la especie Xiphophorus birmanni del rio Calnali, Hidalgo

Los peces de la especie Xiphophorus birchmanni, habitan en arroyos rocosos poco profundos, son nativos de la cuenca del río Panuco, ésta especie está presentando afectaciones como la hibridación y disminución de la población, estos efectos pueden ser consecuencia del aumento de las actividades antropogénicas, dentro de los cuerpos de agua o por escorrentías que transportan contaminantes, incrementando las concentraciones de sustancias tóxicas, entre ellas los metales pesados como el Pb, Cr y Ni, siendo estos elementos tóxicos para el desarrollo y supervivencia de los organismos acuáticos. El objetivo de este trabajo fue determinar concentraciones de Pb, Cr y Ni en músculo y vísceras de peces de la especie Xiphophorus birchmanni. Los peces fueron recolectados en marzo del 2012, ubicando tres sitios de muestreo en el municipio de Calnali, Edo. de Hidalgo, que forma parte de la subcuenca del río Panuco. Se extrajeron músculo y vísceras de los peces, se secaron en una estufa y posteriormente se digestaron en microondas con ácido nítrico. El análisis de los metales pesados fue determinado en el equipo de Espectrofotometría de absorción atómica, modelo SpectrAA 880, marca Varian. Encontrando las concentraciones promedio de Pb>Ni>Cr, tanto en musculo como en vísceras en los tres sitios de muestreo

Segmented Aperture Interferometric Nulling Testbed (SAINT) II: Component Systems Update

"This work presents updates to the coronagraph and telescope components of the Segmented Aperture Interfer-ometric Nulling Testbed (SAINT). The project pairs an actively-controlled macro-scale segmented mirror withthe Visible Nulling Coronagraph (VNC) towards demonstrating capabilities for the future space observatoriesneeded to directly detect and characterize a significant sample of Earth-sized worlds around nearby stars inthe quest for identifying those which may be habitable and possibly harbor life. Efforts to improve the VNCwavefront control optics and mechanisms towards repeating narrowband results are described. A narrative isprovided for the design of new optical components aimed at enabling broadband performance. Initial work withthe hardware and software interface for controlling the segmented telescope mirror is also presented.

Lead, Cadmium and Cobalt (Pb, Cd, and Co) Leaching of Glass-Clay Containers by pH Effect of Food

Recent studies have shown that handcrafted glass-clay containers are a health risk because they can be contaminated by heavy metals, which can be transferred to food, thus reaching the human body to potentially cause illness. Therefore, in the present work, we evaluate the leaching of lead, cadmium, and cobalt from glass-clay containers into two types of food: tomato sauce (salsa), and chickpea puree. The containers were obtained from four regions in the Mexican state of Hidalgo. Repetitive extractions from the containers were carried out to quantify the leaching of the heavy metals into the salsa, the chickpea puree, and acetic acid using the technique proposed by the USFDA. The results show that greater use of the containers leads to more leaching of heavy metals into both types of food and into the acetic acid, with the greatest metal extraction recorded for the Ixmiquilpan vessels. These results indicate that the metals present in the glass-clay containers leach into the food and that increased reuse increases the risk to the people who use them in food preparation

Ribeye B-domain/CtBP2s disrupts endogenous Ribeye retention at synaptic ribbons in 5 dpf hair cells.

<p>(A–B) Representative images of immunolabel or fluorescent tag in posterior lateral line NM3 hair cells of 5 dpf larvae. Scale bars: 3 µm (main panels), 1 µm (insets). (A, A’) Ribeye a (blue) and Ribeye b (red) antibody labeling of synaptic ribbons, and anti-myc antibody labeling of B domain-myc (cyan) in a WT (A) and a transgenic (A’) larva. Dashed circles indicate weak nuclear localization of B-domain. (B, B’) Ribeye (B-domain)-myc (cyan), Ribeye b (magenta), and MAGUK (yellow) immunolabel in a WT (B) and a transgenic (B’) larva. Red asterisks indicate strong nuclear localization of B-domain. Red arrows indicate cells with moderate levels of B-domain in the cytosol. (C) Box plots of cumulative immunolabel intensities of presynaptic Ribeye immunolabeled spheres and postsynaptic MAGUK immunolabeled patches in 5 dpf transgenic B domain-myc larvae and WT siblings. These plots show the median value (horizontal bar), the upper and lower quartiles (box), and the range (whiskers). Whiskers indicate the 10^th and 90^th percentiles. ****P<0.0001, defined by a Mann-Whitney U Test. Each plot represents a population of intensity measurements collected from NM3 hair cells of 7–8 individual larvae. (D) Relative expression level of <i>ribeye b</i> transcripts in the posterior lateral line of 5 dpf transgenic B domain-myc larvae and WT siblings. Expression data was normalized to <i>b-actin</i> expression. The level of gene expression in WT siblings was normalized to one. Error bars are s.e.m.</p

Ribeye B-domain/CtBP2s and CtBP1 localizes to the basal end of synaptic ribbons facing the postsynaptic density.

<p>Isosurface renderings of ribbon synapses extrapolated from z-stack confocal images of Ribeye b (magenta), GFP or myc (cyan), and MAGUK (yellow). Dashed arrows indicate the ribbon synapses used from the images to generate the 3D renderings. (A–A’) Ribeye (B-domain)-GFP (cyan) with Ribeye b (magenta), and MAGUK (yellow) in 3 dpf larvae. Note that B-domain-GFP within synaptic ribbons appears adjacent to patches of MAGUK. (B–B’) Ribeye (B-domain)/CtBP2s-myc (cyan) with Ribeye b (magenta), and MAGUK (yellow) in 5 dpf larvae. Note that B-domain-myc within synaptic ribbons also appears adjacent to patches of MAGUK. (C–C’) CtBP1-myc (cyan) with Ribeye b (magenta), and MAGUK (yellow) in 5 dpf larvae. Synaptic ribbon localization of CtBP1 appears comparable to Ribeye (B-domain)/CtBP2s.</p

CtBP1 localizes to synaptic ribbons, but does not disrupt endogenous Ribeye.

<p>Representative images of immunolabel in posterior lateral line NM3 hair cells of 5 dpf larvae. Scale bars: 3 µm (main panels), 1 µm (insets). (A) Ribeye b antibody labeling of synaptic ribbons (magenta) and MAGUK antibody labeling of postsynaptic densities (yellow) in a WT sibling larva. Anti-myc (cyan) immunolabel was performed as a negative control. (B–C) CtBP1-myc (cyan), Ribeye b (magenta), and MAGUK (yellow) immunolabel in two representative transgenic larvae. (B) CtBP1-myc (cyan) is strongly localized to the nucleus with weak synaptic localization. The red arrow indicates a synaptic ribbon containing CtBP1-myc. Note that Ribeye immunolabel intensity in all four synaptic ribbons appears comparable. (C) CtBP1-myc (cyan) is weakly localized to the nucleus with strong synaptic localization. Presynaptic Ribeye immunolabel intensity is not reduced compared to WT (A).</p