A comparison of receptive field and tracer coupling size of horizontal cells in the rabbit retina

Bloomfield, Stewart A.; Xin, Daiyan; Persky, Seth E.

doi:10.1017/s0952523800009524

Cited by 66 publications

(100 citation statements)

References 55 publications

(87 reference statements)

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“…For each horizontal cell type, the spread of dye was qualitatively similar to that previously reported in rabbit retina (Vaney, 1991(Vaney, , 1993(Vaney, , 1994Hampson et al, 1994;Mills & Massey, 1994, Bloomfield et al, 1995. Fig.…”

Section: Horizontal Cell Staining Patternssupporting

confidence: 84%

“…These factors cannot explain the findings in Fig. 4A of Bloomfield et al (1995) that continual iontophoresis up until time of fixation is ineffective after about 8 min. In our model, continual addition of tracer must label progressively further cells equally effectively.…”

Section: Counting Stained Somas To Estimate Relative Couplingmentioning

confidence: 79%

“…This may partially explain why the data of Bloomfield et al (1995) (their Fig. 2B) asymptote after only 15 min of iontophoresis, with no more coupling observable with added diffusion time.…”

Section: Counting Stained Somas To Estimate Relative Couplingmentioning

confidence: 90%

“…Although the literature is rich in examples of estimating coupling parameters from spread of fluorescent dye in various vertebrate and invertebrate tissues (Weidman, 1966;Safranyos & Caveney, 1985;Zimmerman & Rose, 1985;Brink & Dewey, 1978, 1980Imanaga, 1989;Jaslove & Brink, 1989;Rae et al, 1996), quantification of Neurobiotin coupling has thus far relied solely on counting the number of stained somas (e.g. Hampson et al, 1992Hampson et al, , 1994Bloomfield et al, 1995). Beyond this, there have thus far been no quantitative dye studies in neural tissue, nor quantitative studies of permeability to cationic tracers.…”

Section: Introductionmentioning

confidence: 99%

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The kinetics of tracer movement through homologous gap junctions in the rabbit retina

Mills

Massey

1998

Vis Neurosci

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Observation of the spread of biotinylated or fluorescent tracers following injection into a single cell has become one of the most common methods of demonstrating the presence of gap junctions. Nevertheless, many of the fundamental features of tracer movement through gap junctions are still poorly understood. These include the relative roles of diffusion and iontophoretic current, and under what conditions the size of the stained mosaic will increase, asymptote, or decline. Additionally, the effect of variations in amount of tracer introduced, as produced by variation in electrode resistance following cell penetration, is not obvious. To examine these questions, Neurobiotin was microinjected into the two types of horizontal cell of the rabbit retina and visualized with streptavidinCy3. Images were digitally captured using a confocal microscope. The spatial distribution of Neurobiotin across the patches of coupled cells was measured. Adequate fits to the data were obtained by fitting to a model with terms for diffusion and amount of tracer injected. Results indicated that passive diffusion is the major source of tracer movement through gap junctions, whereas iontophoretic current played no role over the range tested. Fluorescent visualization, although slightly less sensitive than peroxidase reactions, produced staining intensities with a more useful dynamic range. The rate constants for movement of Neurobiotin between A-type horizontal cells was about ten times greater than that for B-type horizontal cells. Although direct extrapolation to ion conductances cannot be assumed, tracer movement can be used to give an estimate of relative coupling rates across cell types, retinal location, or modulation conditions in intact tissue.

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Section: Horizontal Cell Staining Patternssupporting

confidence: 84%

Section: Counting Stained Somas To Estimate Relative Couplingmentioning

confidence: 79%

Section: Counting Stained Somas To Estimate Relative Couplingmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The kinetics of tracer movement through homologous gap junctions in the rabbit retina

Mills

Massey

1998

Vis Neurosci

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“…Light adaptation has profound effects on receptive field size and tracer coupling in cone-driven horizontal cells (Baldridge & Ball, 1991;Lankheet et al, 1993;Bloomfield et al, 1995) and AII amacrine cells . Smaller but still significant changes are observed in some photoreceptors.…”

Section: Introductionmentioning

confidence: 99%

Connexin 35/36 is phosphorylated at regulatory sites in the retina

Kothmann

Li²,

Burr

et al. 2007

Vis Neurosci

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Connexin 35/36 is the most widespread neuronal gap junction protein in the retina and central nervous system. Electrical and/or tracer coupling in a number of neuronal circuits that express this connexin are regulated by light adaptation. In many cases the regulation of coupling depends on signaling pathways that activate protein kinases such as PKA, and Cx35 has been shown to be regulated by PKA phosphorylation in cell culture systems. To examine whether phosphorylation might regulate Cx35/36 in the retina we developed phospho-specific polyclonal antibodies against the two regulatory phosphorylation sites of Cx35 and examined the phosphorylation state of this connexin in the retina. Western blot analysis with hybrid bass retinal membrane preparations showed Cx35 to be phosphorylated at both the Ser110 and Ser276 sites, and this labeling was eliminated by alkaline phosphatase digestion. The homologous sites of mouse and rabbit Cx36 were also phosphorylated in retinal membrane preparations. Quantitative confocal immunofluorescence analysis showed gap junctions identified with a monoclonal anti-Cx35 antibody to have variable levels of phosphorylation at both the Ser110 and Ser276 sites. Unusual gap junctions that could be identified by their large size (up to 32 μm 2 ) and location in the IPL showed a prominent shift in phosphorylation state from heavily phosphorylated in nighttime, dark-adapted retina to weakly phosphorylated in daytime, light-adapted retina. Both Ser110 and Ser276 sites showed significant changes in this manner. Under both lighting conditions other gap junctions varied from non-phosphorylated to heavily phosphorylated. We predict that changes in the phosphorylation states of these sites correlate with changes in the degree of coupling through Cx35/36 gap junctions. This leads to the conclusion that connexin phosphorylation mediates changes in coupling in some retinal networks. However, these changes are not global and likely occur in a cell type-specific or possibly a gap junction-specific manner.

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Tracer coupling pattern of amacrine and ganglion cells in the rabbit retina

1997

Self Cite

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We examined the tracer coupling pattern of more than 15 morphological types of amacrine and ganglion cells in the rabbit retina. Individual cells were injected intracellularly with the biotinylated tracer Neurobiotin, which was then allowed to diffuse across gap junctions to label neighboring neurons. We found that homologous and/or heterologous tracer coupling was common for most proximal neurons. In fact, the starburst amacrine cell was the only amacrine cell type that showed no evidence of coupling. The remaining types of amacrine cell were coupled exclusively to other amacrines, either homologously or, more often, through a combination of homologous and heterologous junctions. In only one case did we visualize labeled ganglion cells following injection of Neurobiotin into an amacrine cell. In contrast, injection of Neurobiotin into ganglion cells almost always resulted in the labeling of amacrine cells. Taken together, these results suggest a directionality to the movement of tracer across gap junctions connecting amacrine and ganglion cells. We found that the coupling pattern for a given morphological type of cell was generally stereotypic and consistent across retinas. The notable exceptions to this finding were alpha ganglion cells and cells with morphology corresponding to that of on-off direction selective ganglion cells. In both cases, individual cells showed either extensive coupling to both amacrine and ganglion cells or no coupling at all. A notable finding was that, in every case, the neighboring cells within a tracer-coupled array were always within one gap junction of the injected neuron. Furthermore, in many cases, the array formed by the somata of tracer-coupled cells was almost perfectly coincident with the dendritic arbor of the injected cell. Thus, our results indicate that whereas coupling is extensive within the proximal retina, individual cells partake in coupled networks that are stereotypic and highly circumscribed.

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A comparison of receptive field and tracer coupling size of horizontal cells in the rabbit retina

Cited by 66 publications

References 55 publications

The kinetics of tracer movement through homologous gap junctions in the rabbit retina

The kinetics of tracer movement through homologous gap junctions in the rabbit retina

Connexin 35/36 is phosphorylated at regulatory sites in the retina

Tracer coupling pattern of amacrine and ganglion cells in the rabbit retina

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