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PURPOSE: Dominant-active RAC1 rescues photoreceptor structure in Drosophila rhodopsin-null mutants, indicating an important role in morphogenesis. This report assesses the morphogenetic effect of activated RAC1 during mammalian rod photoreceptor development using transgenic mice that express constitutively active (CA) RAC1.METHODS: Transgenic mice were generated by expressing CA RAC1 under control
The mechanisms that specify photoreceptor cell-fate determination, especially as regards to short-wave-sensitive (S) versus medium-wave-sensitive (M) cone identity, and maintain their nature and function, are not fully understood. Here we report the importance of general transcription factor II-I repeat domain-containing protein 1 (GTF2IRD1) in maintaining M cone cell identity and function as well
In nonphagocytic cells, Rac1 is a component of NADPH oxidase that produces reactive oxygen species [Ushio-Fukai M (2006) Sci STKE 2006:re8]. Rac1 is expressed abundantly in mammalian retinal photoreceptors, where it is activated in response to light stimuli [Balasubramanian N, Slepak VZ (2003) Curr Biol 13:1306-1310]. We used Cre-LoxP conditional gene targeting to knock down Rac1 expression in mou
X-linked juvenile retinoschisis (XLRS) is a neurodevelopmental abnormality caused by retinoschisin gene mutations. XLRS is characterized by splitting through the retinal layers and impaired synaptic transmission of visual signals resulting in impaired acuity and a propensity to retinal detachment. Several groups have treated murine retinoschisis models successfully using adeno-associated virus (AA
PURPOSE: At an early age, the retinoschisin knockout (Rs1-KO) mouse retina has progressive photoreceptor degeneration with severe disruption of the outer plexiform layer (OPL) that decreases at older ages. The electroretinogram (ERG) undergoes parallel changes. The b-wave amplitude from bipolar cells is reduced disproportionately to the photoreceptor a-wave at young but not at older ages. The prot
PURPOSE: To determine whether cadherin 23 and protocadherin 15 can substitute for one another in the maintenance of the retina and other tissues in the mouse. Does homozygosity for both v and av mutant alleles (i.e., a double homozygous mouse) cause retinal degeneration or an obvious retinal histopathology?METHODS: We generated mice homozygous for both Cdh23(v-6J) and Pcdh15(av-Jfb) alleles. The r
PURPOSE: To characterize the ocular phenotype resulting from mutation of Rab38, a candidate gene for Hermansky-Pudlak syndrome.METHODS: Chocolate mice (cht, Rab38(cht/cht)) and control heterozygous (Rab38(cht/)(+)) and wild-type mice were examined clinically, histologically, ultrastructurally, and electrophysiologically. Mice homozygous for both the Rab38(cht) and the Tyrp1(b) alleles were similar
PURPOSE: The authors characterized the natural history of a retinoschisin gene knockout (Rs1h-KO) mouse model and evaluated the long-term effects of retinal rescue after AAV(2/2)-CMV-Rs1h gene delivery.METHODS: Full-field scotopic electroretinograms (ERGs) were recorded from 44 male hemizygous Rs1h-KO and 44 male wild-type (WT) C57BL/6J mice at six ages between 1 and 16 months. Retinal morphometry
Ciliary neurotrophic factor (CNTF) promotes photoreceptor survival but also suppresses electroretinogram (ERG) responses. This has caused concerns about whether CNTF is detrimental to the function of photoreceptors because it is considered to be a potential treatment for retinal degenerative disorders. Here we report that the suppression of ERG responses is attributable to negative regulation of t
PURPOSE: Mutations of PCDH15, the gene encoding protocadherin 15, cause either nonsyndromic deafness DFNB23 or Usher syndrome type 1F (USH1F) in humans and deafness with balance problems in Ames waltzer (av) mice. Persons with USH1 usually begin to exhibit signs of retinitis pigmentosa (RP) in early adolescence, but av mice are reported to have functional retinas. In this study, the auditory, visu
PURPOSE: To create and evaluate a mouse model of human X-linked juvenile retinoschisis (XLRS) and then investigate whether supplementing with the retinoschisin protein by gene delivery can reverse the abnormal "electronegative" electroretinogram (ERG) retinal response.METHODS: An X-linked retinoschisis mouse (Rs1h-KO) model was created by substituting a neomycin resistance cassette for exon 1 and
At a time when rapidly evolving technologies, political turmoil, and the tensions inherent in multiculturalism and globalization are reshaping historical consciousness, what is the proper role for historians and their work? By way of an answer, the contributors to this volume offer up an illuminating collective meditation on the idea of ethos and its relevance for historical practice. These intell
We show two results related to finding trees and paths in graphs. First, we show that in $O^*(1.657^k2^{l/2})$ time one can either find a $k$-vertex tree with $l$ leaves in an $n$-vertex undirected graph or conclude that such a tree does not exist. Our solution can be applied as a subroutine to solve the $k$-Internal Spanning Tree problem in $O^*(min(3.455^k, 1.946^n))$ time using polynomial space
BACKGROUND: The study investigated whether 3D vision and haptic feedback in combination in a virtual reality environment leads to more efficient learning of laparoscopic skills in novices.MATERIAL AND METHODS: Twenty novices were allocated to two groups. All completed a training course in the LapSim(®) virtual reality trainer consisting of four tasks: 'instrument navigation', 'grasping', 'fine dis
