Conserved transcriptional regulation of a cone phototransduction gene in vertebrates

AbstractcGMP-phosphodiesterase (PDE) is a key component in visual phototransduction. Rod and cone photoreceptors each produce their unique cGMP-PDE subunits. The α′ catalytic subunits are believed to be cone-specific. In this study, we report that transfection of the −132 to +139 sequence in the upstream region of the human α′-PDE gene fused to luciferase cDNA gives the highest level of reporter gene transcription in cultured retinoblastoma Y79 cells. Transgenic Xenopus laevis carrying this sequence fused to green fluorescent protein (GFP) expressed GFP in cones, suggesting a conserved regulatory mechanism for α′-PDE transcription in both human and frog

Structure Of Interfaces In A-si

We present experimental results on the atomic structure of the interfaces between a-Si:H and a-SiNx:H layers obtained by analyzing the intensity of the Raman lines from zone-folded acoustic phonons and of the peaks of x-ray diffraction at grazing angles. We determine the width of these interfaces and their stability under thermal annealing in temperatures below the crystallization temperature.69277878

STRUCTURE OF INTERFACES IN A-SI-H/A-SINX-H SUPERLATTICES

We present experimental results on the atomic structure of the interfaces between a-Si: H and a-SiN(x):H layers obtained by analyzing the intensity of the Raman lines from zone-folded acoustic phonons and of the peaks of x-ray diffraction at grazing angles. We determine the width of these interfaces and their stability under thermal annealing in temperatures below the crystallization temperature.69277878

Progressive alterations in ultraviolet-B induced phototropism during Arabidopsis development

Low fluence rate ultraviolet-B radiation (280-315 nm) substantially affects plant morphology. Numerous UV-B induced morphological adaptations in Arabidopsis are ascribed to the UV-B specific photoreceptor UV RESISTANCE LOCUS 8 (UVR8). Well documented examples are shorter petioles and shorter stems. Alterations are also observed at the cellular level such as changes in cell elongation, division and differentiation. Notwithstanding this extensive knowledge of UV-B responses, the mechanisms by which UV-B radiation controls plant architecture are poorly understood. Our recent research in Arabidopsis revealed that unilateral narrow-band UV-B radiation can induce reorientation of etiolated hypocotyls through UVR8 mediated signaling. This response is triggered by unilateral radiation of wavelengths shorter than 340 nm and is temporally distinct from phototropin-mediated phototropic bending. Analysis of the kinetics of plant reorientation allowed us to quantify the relative contribution of UVR8 and phototropins in steering this UV-B induced phototropic movement of etiolated hypocotyls. These data indicate that in etiolated seedlings, phototropins are more sensitive to UV-B for regulating phototropism than UVR8 and therefore mask the effect of UVR8. Phototropin signaling under UV-B is mechanistically similar to that in blue light, involving phototropin autophosphorylation and NPH3 dephosphorylation. Furthermore, the negative feedback controlled by REPRESSOR OF UV-B PHOTOMORPHOGENESIS prevents UVR8-mediated fast phototropin-dependent bending. The UVR8-phototropin relationship described for etiolated seedlings is not universally applicable. We found that the main photoreceptor for UV-B-induced phototropism in inflorescence stems is UVR8, with a less significant role for phototropins. The contribution of UVR8 expressed in different cell layers to this response is currently being examined. Based on pharmacological assays, mutant analysis and reporter lines, this shifting role of UVR8 and phototropins during plant development will be presented and discussed

℮-conome: an automated tissue counting platform of cone photoreceptors for rodent models of retinitis pigmentosa

<p>Abstract</p> <p>Background</p> <p>Retinitis pigmentosa is characterized by the sequential loss of rod and cone photoreceptors. The preservation of cones would prevent blindness due to their essential role in human vision. Rod-derived Cone Viability Factor is a thioredoxin-like protein that is secreted by rods and is involved in cone survival. To validate the activity of Rod-derived Cone Viability Factors (RdCVFs) as therapeutic agents for treating retinitis Pigmentosa, we have developed e-conome, an automated cell counting platform for retinal flat mounts of rodent models of cone degeneration. This automated quantification method allows for faster data analysis thereby accelerating translational research.</p> <p>Methods</p> <p>An inverted fluorescent microscope, motorized and coupled to a CCD camera records images of cones labeled with fluorescent peanut agglutinin lectin on flat-mounted retinas. In an average of 300 fields per retina, nine Z-planes at magnification X40 are acquired after two-stage autofocus individually for each field. The projection of the stack of 9 images is subject to a threshold, filtered to exclude aberrant images based on preset variables. The cones are identified by treating the resulting image using 13 variables empirically determined. The cone density is calculated over the 300 fields.</p> <p>Results</p> <p>The method was validated by comparison to the conventional stereological counting. The decrease in cone density in <it>rd1 </it>mouse was found to be equivalent to the decrease determined by stereological counting. We also studied the spatiotemporal pattern of the degeneration of cones in the <it>rd1 </it>mouse and show that while the reduction in cone density starts in the central part of the retina, cone degeneration progresses at the same speed over the whole retinal surface. We finally show that for mice with an inactivation of the Nucleoredoxin-like genes <it>Nxnl1 </it>or <it>Nxnl2 </it>encoding RdCVFs, the loss of cones is more pronounced in the ventral retina.</p> <p>Conclusion</p> <p>The automated platform ℮-conome used here for retinal disease is a tool that can broadly accelerate translational research for neurodegenerative diseases.</p

Non-Coding RNAs in Retinal Development

Retinal development is dependent on an accurately functioning network of transcriptional and translational regulators. Among the diverse classes of molecules involved, non-coding RNAs (ncRNAs) play a significant role. Members of this family are present in the cell as transcripts, but are not translated into proteins. MicroRNAs (miRNAs) are small ncRNAs that act as post-transcriptional regulators. During the last decade, they have been implicated in a variety of biological processes, including the development of the nervous system. On the other hand, long-ncRNAs (lncRNAs) represent a different class of ncRNAs that act mainly through processes involving chromatin remodeling and epigenetic mechanisms. The visual system is a prominent model to investigate the molecular mechanisms underlying neurogenesis or circuit formation and function, including the differentiation of retinal progenitor cells to generate the seven principal cell classes in the retina, pathfinding decisions of retinal ganglion cell axons in order to establish the correct connectivity from the eye to the brain proper, and activity-dependent mechanisms for the functionality of visual circuits. Recent findings have associated ncRNAs in several of these processes and uncovered a new level of complexity for the existing regulatory mechanisms. This review summarizes and highlights the impact of ncRNAs during the development of the vertebrate visual system, with a specific focus on the role of miRNAs and a synopsis regarding recent findings on lncRNAs in the retina

New Approaches in the Differentiation of Human Embryonic Stem Cells and Induced Pluripotent Stem Cells toward Hepatocytes

Orthotropic liver transplantation is the only established treatment for end-stage liver diseases. Utilization of hepatocyte transplantation and bio-artificial liver devices as alternative therapeutic approaches requires an unlimited source of hepatocytes. Stem cells, especially embryonic stem cells, possessing the ability to produce functional hepatocytes for clinical applications and drug development, may provide the answer to this problem. New discoveries in the mechanisms of liver development and the emergence of induced pluripotent stem cells in 2006 have provided novel insights into hepatocyte differentiation and the use of stem cells for therapeutic applications. This review is aimed towards providing scientists and physicians with the latest advancements in this rapidly progressing field

A Second-Generation Device for Automated Training and Quantitative Behavior Analyses of Molecularly-Tractable Model Organisms

A deep understanding of cognitive processes requires functional, quantitative analyses of the steps leading from genetics and the development of nervous system structure to behavior. Molecularly-tractable model systems such as Xenopus laevis and planaria offer an unprecedented opportunity to dissect the mechanisms determining the complex structure of the brain and CNS. A standardized platform that facilitated quantitative analysis of behavior would make a significant impact on evolutionary ethology, neuropharmacology, and cognitive science. While some animal tracking systems exist, the available systems do not allow automated training (feedback to individual subjects in real time, which is necessary for operant conditioning assays). The lack of standardization in the field, and the numerous technical challenges that face the development of a versatile system with the necessary capabilities, comprise a significant barrier keeping molecular developmental biology labs from integrating behavior analysis endpoints into their pharmacological and genetic perturbations. Here we report the development of a second-generation system that is a highly flexible, powerful machine vision and environmental control platform. In order to enable multidisciplinary studies aimed at understanding the roles of genes in brain function and behavior, and aid other laboratories that do not have the facilities to undergo complex engineering development, we describe the device and the problems that it overcomes. We also present sample data using frog tadpoles and flatworms to illustrate its use. Having solved significant engineering challenges in its construction, the resulting design is a relatively inexpensive instrument of wide relevance for several fields, and will accelerate interdisciplinary discovery in pharmacology, neurobiology, regenerative medicine, and cognitive science