scholarly journals Analysis of orientation bias in cat retina

1982 ◽  
Vol 329 (1) ◽  
pp. 243-261 ◽  
Author(s):  
W. R. Levick ◽  
L. N. Thibos
Keyword(s):  
Cat Retina ◽  
Orientation Bias

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

scholarly journals Influences of Histone Stoichiometry on the Target Site Preference of Retrotransposons Ty1 and Ty2 in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 761-776 ◽  
Author(s):  
Lori A Rinckel ◽  
David J Garfinkel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Promoter Region ◽  
Target Site ◽  
Site Preference ◽  
Wild Type ◽  
Histone Proteins ◽  
Protein Levels ◽  
In The Wild ◽  
Type Strains ◽  
Orientation Bias

Abstract In Saccharomyces cerevisiae, the target site specificity of the retrotransposon Ty1 appears to involve the Ty integration complex recognizing chromatin structures. To determine whether changes in chromatin structure affect Ty1 and Ty2 target site preference, we analyzed Ty transposition at the CAN1 locus in mutants containing altered levels of histone proteins. A Δhta1-htb1 mutant with decreased levels of H2A and H2B histone proteins showed a pattern of Ty1 and Ty2 insertions at CAN1 that was significantly different from that of both the wild-type and a Δhta2-htb2 mutant, which does not have altered histone protein levels. Altered levels of H2A and H2B proteins disrupted a dramatic orientation bias in the CAN1 promoter region. In the wild-type strains, few Ty1 and Ty2 insertions in the promoter region were oriented opposite to the direction of CAN1 transcription. In the Δhta1-htb1 background, however, numerous Ty1 and Ty2 insertions were in the opposite orientation clustered within the TATA region. This altered insertion pattern does not appear to be due to a bias caused by selecting canavanine resistant isolates in the different HTA1-HTB1 backgrounds. Our results suggest that reduced levels of histone proteins alter Ty target site preference and disrupt an asymmetric Ty insertion pattern.

Action and localization of acetylcholine in the cat retina

1987 ◽  
Vol 58 (5) ◽  
pp. 997-1015 ◽  
Author(s):  
M. Schmidt ◽  
M. F. Humphrey ◽  
H. Wassle
Keyword(s):  
Ganglion Cell ◽  
Amacrine Cells ◽  
Cell Types ◽  
Functional Independence ◽  
Dendritic Morphology ◽  
Immunocytochemical Staining ◽  
Simultaneous Application ◽  
Cat Retina ◽  
Topographical Distribution ◽  
Cholinergic Amacrine Cells

1. Retinal ganglion cells were recorded extracellularly in the intact eye of anesthetized adult cats. The effects of acetylcholine (ACh), the muscarinic antagonist scopolamine (Sco), the nicotinic antagonist dihydro-beta-erythroidine (DBE), and the acetylcholinesterase inhibitor physostigmine (Phy) on maintained and light-evoked ganglion cell discharge was examined using iontophoresis techniques. 2. A monoclonal antibody directed against the ACh synthesizing enzyme choline acetyltransferase (ChAT) was used to label cholinergic cells in retinal wholemounts. The topographical distribution of these cells was studied. 3. Intracellular filling with the fluorescent dye lucifer yellow (LY) was performed to identify the dendritic morphology of putative cholinergic neurons. 4. ACh increased and Sco decreased neuronal activity of all brisk ganglion cell types under all stimulus conditions tested in this study. The action of ACh was abolished during simultaneous application of Sco. 5. DBE raised the firing rate of ON-center brisk cells and decreased activity of OFF-center brisk cells. Again there was no difference under different stimulus conditions. During DBE application the ACh action on OFF-center cells was completely blocked. The ACh action on ON-center cells was diminished. 6. Phy prolonged and enhanced ACh action on all ganglion cell types. During simultaneous stimulation of the receptive-field center and the surround, Phy caused an activity shift in favor of the center response. 7. Immunocytochemical staining revealed two populations of amacrine cells, one in the inner nuclear layer, and the other in the ganglion cell layer. Their total density increased from 250 cells/mm2 in the periphery to 2,700 cells/mm2 in the central area. Analysis of the distribution pattern indicated a functional independence of the two subpopulations. 8. The dendritic morphology of putative cholinergic amacrine cells in the cat retina resembled that of rabbit and rat "starburst" amacrines, which are known to be cholinergic. 9. The possible function of cholinergic amacrine cells in the cat retina is discussed in view of the present findings and compared with results from other mammalian species.

The orientation bias of Chi sequences is a general tendency of G-rich oligomers

Gene ◽  
2000 ◽  
Vol 259 (1-2) ◽  
pp. 207-215 ◽  
Author(s):  
Reina Uno ◽  
Yoichi Nakayama ◽  
Kazuharu Arakawa ◽  
Masaru Tomita
Keyword(s):  
General Tendency ◽  
Orientation Bias

Light-dependent hydration of the space surrounding photoreceptors in the cat retina

1994 ◽  
Vol 11 (4) ◽  
pp. 743-752 ◽  
Author(s):  
Jian-Dong Li ◽  
Victor I. Govardovskii ◽  
Roy H. Steinberg
Keyword(s):  
Mathematical Model ◽  
Time Course ◽  
Distal Portion ◽  
Subretinal Space ◽  
Volume Increase ◽  
Physiological Event ◽  
Cat Retina ◽  
Interphotoreceptor Matrix ◽  
Space Marker

AbstractWe have studied the effect of retinal illumination on the concentration of the extracellular space marker tetramethylammonium (TMA+) in the dark-adapted cat retina using double-barreled ion-selective microelectrodes. The retina was loaded with TMA+ by a single intravitreal injection. Retinal illumination produced a slow decrease in , which was maximal in amplitude in the most distal portion of the space surrounding photoreceptors, the subretinal space. The light-evoked decrease in was considerably slower and of a different overall time course than the light-evoked decrease in , also recorded in the subretinal space. decreased to a peak at 38 s after the onset of illumination, then slowly recovered towards the baseline, and transiently increased following the offset of illumination. It resembled the light-evoked decreases previously recorded in the in vitro preparations of frog (Huang & Karwoski, 1990, 1992) and chick (Li et al., 1992, 1994) but was considerably larger in amplitude, 22% compared with 7%. As in frog, where it was first recorded, the light-evoked decrease is considered to originate from a light-evoked increase in the volume of the subretinal space (or subretinal hydration). A mathematical model accounting for diffusion predicted that the volume increase underlying the response was 63% on average and could be as large as 95% and last for minutes. The estimated volume increase was then used to examine its effect on K+ concentration in the subretinal space. We conclude that a light-dependent hydration of the subretinal space represents a significant physiological event in the intact cat eye, which should affect the organization of the interphotoreceptor matrix, and the concentrations of all ions and metabolites located in the subretinal space.

Localization of glycine uptake and receptors in the cat retina

1987 ◽  
Vol 75 (2) ◽  
pp. 147-151 ◽  
Author(s):  
Jutta Jäger ◽  
Heinz Wässle
Keyword(s):  
Glycine Uptake ◽  
Cat Retina
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