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R E Marc

Publications and source records attributed to R E Marc.

At least 19 recordsLinked to original sources
PubMed2001

A molecular phenotype atlas of the zebrafish retina.

The rasborine cyprinid Danio rerio (the zebrafish) has become a popular model of retinal function and development. Its value depends, in part, on validation of homologies with retinal cell populations of cyprinine cyprinids. This atlas provides raw and interpreted molecular phenotype data derived from computationally classified sets of small molecule signals from different cell types in the zebrafish retina: L-alanine, L-aspartate, L-glutamine, L-glutamate, glutathione, glycine, taurine and gamma-aminobutyrate. This basis set yields an 8-dimensional signature for every retinal cell and formally establishes molecular signature homologies with retinal neurons, glia, epithelia and endothelia of other cyprinids. Zebrafish photoreceptor classes have been characterized previously: we now show their metabolic profiles to be identical to those of the corresponding photoreceptors in goldfish. The inner nuclear layer is partitioned into precise horizontal, bipolar and amacrine cell layers. The horizontal cell layer contains at least three and perhaps all four known classes of cyprinine horizontal cells. Homologues of cyprinid glutamatergic ON-center and OFF-center mixed rod-cone bipolar cells are present and it appears likely that all five classes are present in zebrafish. The cone bipolar cells defy simple analysis but comprise the largest fraction of bipolar cells, as in all cyprinids. Signature analysis reveals six molecular phenotypes in the bipolar cell cohort: most are superclasses. The amacrine cell layer is composed of approximately equal 64% GABA+ and 35% glycine+ amacrine cells, with the remainder being sparse dopaminergic interplexiform cells and other rare unidentified neurons. These different amacrine cell types are completely distinct in the dark adapted retina, but light adapted retinas display weak leakage of GABA signals into many glycinergic amacrine cells, suggesting widespread heterocellular coupling. The composition of the zebrafish ganglion cell layer is metabolically indistinguishable from that in other cyprinids, and the signatures of glial and non-neuronal cells display strong homologies with those in mammals. As in most vertebrates, zebrafish Müller cells possess a high glutamine, low glutamate signature and contain the dominant pool of glutathione in the neural retina. The retinal pigmented epithelium shows a general mammalian signature but also has exceptional glutathione content (5-10 mM), perhaps required by the unusually high oxygen tensions of teleost retinas. The optic nerve and the marginal zone of the retina reveal characteristic metabolic specializations. The marginal zone is strongly laminated and its nascent neurons display their characteristic signatures before taking their place in the retina proper.

Amacrine Cells↗
PubMed2000

Fundamental GABAergic amacrine cell circuitries in the retina: nested feedback, concatenated inhibition, and axosomatic synapses.

Presynaptic gamma-aminobutyrate-immunoreactive (GABA+) profiles were mapped in the cyprinid retina with overlay microscopy: a fusion of electron and optical imaging affording high-contrast ultrastructural and immunocytochemical visualization. GABA+ synapses, deriving primarily from amacrine cells (ACs), compose 92% of conventional synapses and 98% of the input to bipolar cells (BCs) in the inner plexiform layer. GABA+ AC synapses, the sign-inverting elements of signal processing, are deployed in micronetworks and distinctive synaptic source/target topologies. Nested feedback micronetworks are formed by three types of links (BC --> AC, reciprocal BC <-- AC, and AC --> AC synapses) arranged as nested BC<--> [AC --> AC] loops. Circuits using nested feedback can possess better temporal performance than those using simple reciprocal feedback loops. Concatenated GABA+ micronetworks of AC --> AC and AC --> AC --> AC chains are common and must be key elements for lateral spatial, temporal, and spectral signal processing. Concatenated inhibitions may represent exceptionally stable, low-gain, sign-conserving devices for receptive field construction. Some chain elements are GABA immunonegative (GABA-) and are, thus, likely glycinergic synapses. GABA+ synaptic baskets target the somas of certain GABA+ and GABA- cells, resembling cortical axosomatic synapses. Finally, all myelinated intraretinal profiles are GABA+, suggesting that some efferent systems are sources of GABAergic inhibition in the cyprinid retina and may comprise all axosomatic synapses. These micronetworks are likely the fundamental elements for receptive field shaping in the inner plexiform layer, although few receptive field models incorporate them as functional components. Conversely, simple feedback and feedforward synapses may often be chimeras: the result of an incomplete view of synaptic topology.

Animals↗
PubMed1999

Mapping glutamatergic drive in the vertebrate retina with a channel-permeant organic cation.

Patterns of neuronal excitation in complex populations can be mapped anatomically by activating ionotropic glutamate receptors in the presence of 1-amino-4-guanidobutane (AGB), a channel-permeant guanidinium analogue. Intracellular AGB signals were trapped with conventional glutaraldehyde fixation and were detected by probing registered serial thin sections with anti-AGB and anti-amino acid immunoglobulins, revealing both the accumulated AGB and the characteristic neurochemical signatures of individual cells. In isolated rabbit retina, both glutamate and the ionotropic glutamate receptor agonists alpha-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA), kainic acid (KA), and N-methyl-D-aspartic acid (NMDA) activated permeation of AGB into retinal neurons in dose-dependent and pharmacologically specific modes. Horizontal cells and bipolar cells were dominated by AMPA/KA receptor activation with little or no evidence of NMDA receptor involvement. Strong NMDA activation of AGB permeation was restricted to subsets of the amacrine and ganglion cell populations. Threshold agonist doses for the most responsive cell groups (AMPA, 300 nm; KA, 2 microM; NMDA, 63 microm; glutamate, 1 mM) were similar to values obtained from electrophysiological and neurotransmitter release measures. The threshold for activation of AGB permeation by exogenous glutamate was shifted to <200 microM in the presence of the glutamate transporter antagonist dihydrokainate, indicating substantial spatial buffering of extracellular glutamate levels in vitro. Agonist-activated permeation of AGB into neurons persisted under blockades of Na+ -dependent transporters, voltage-activated Ca2+ and Na+ channels, and ionotropic gamma-aminobutyric acid and glycine receptors. Cholinergic agonists evoked no permeation.

Agmatine↗
PubMed1999

Kainate activation of horizontal, bipolar, amacrine, and ganglion cells in the rabbit retina.

Patterns of excitation in populations of retinal bipolar, amacrine, and ganglion cells were mapped by activating alpha-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA) and kainate (KA) receptors with KA in the presence of the channel-permeant guanidinium analogue 1-amino-4-guanidobutane (AGB). Registered serial thin sections were probed with immunoglobulins targeting AGB, glutamate, glycine, and gamma-aminobutyric acid (GABA) to visualize KA-evoked responses and the neurochemical signatures of distinct cell types. OFF-center cone bipolar cells and both type A and type B horizontal cells were strongly activated by KA. ON-center cone bipolar cells displayed weak AGB signals that arose at least partially, if not entirely, from coupling with KA-responsive glycinergic amacrine cells, whereas rod bipolar cells exhibited no detectable AGB permeation after KA activation. GABA-positive amacrine cells displayed a range of KA responses, some possessing little AGB signal even after strong KA activation, whereas all identifiable glycine-positive amacrine cells were driven by KA. Quantitative agonist responsivities of cells in the ganglion cell layer revealed that starburst amacrine cells are the most KA-responsive cell type in that layer. Ganglion cells varied in KA responsivity across morphologic subtypes, with a large alpha-like ganglion cell group the being the most KA responsive. Some ganglion cells displayed weak KA responses, even with saturating doses, that may have been be due to an absence of AMPA/KA receptors or to the existence of AGB-impermeant AMPA/KA receptor complexes.

Agmatine↗
PubMed1998

Amino acid signatures in the normal cat retina.

PURPOSE: To establish a nomogram of amino acid signatures in normal neurons, glia, and retinal pigment epithelium (RPE) of the cat retina, guided by the premise that micromolecular signatures reflect cellular identity and metabolic integrity. The long-range objective was to provide techniques to detect subtle aberrations in cellular metabolism engendered by model interventions such as focal retinal detachment. METHODS: High-performance immunochemical mapping, image registration, and quantitative pattern recognition were combined to analyze the amino acid contents of virtually all cell types in serial 200-nm sections of normal cat retina. RESULTS: The cellular cohorts of the cat retina formed 14 separable biochemical theme classes. The photoreceptor --> bipolar cell --> ganglion cell pathway was composed of six classes, each possessing a characteristic glutamate signature. Amacrine cells could be grouped into two glycine- and three gamma-aminobutyric acid (GABA)-dominated populations. Horizontal cells possessed a distinctive GABA-rich signature completely separate from that of amacrine cells. A stable taurine-glutamine signature defined Müller cells, and a broad-spectrum aspartate-glutamate-taurine-glutamine signature was present in the normal RPE. CONCLUSIONS: In this study, basic micromolecular signatures were established for cat retina, and multiple metabolic subtypes were identified for each neurochemical class. It was shown that virtually all neuronal space can be accounted for by cells bearing characteristic glutamate, GABA, or glycine signatures. The resultant signature matrix constitutes a nomogram for assessing cellular responses to experimental challenges in disease models.

Alanine↗
PubMed1998

Amino acid signatures in the detached cat retina.

PURPOSE: Expressions of certain macromolecules are altered by experimental retinal detachment in the cat. Related alterations in micromolecular signatures of neurons, Müller cells, and the retinal pigment epithelium (RPE) were investigated. METHODS: High-performance immunochemical mapping, image registration, and quantitative pattern recognition were combined to analyze the amino acid contents of virtually all retinal cell types after 3 to 84 days of detachment. RESULTS: Retinal micromolecular signatures showed a spectrum of alterations. The glutamate contents of Müller cells increased and remained elevated for weeks after detachment. Multispectral signatures of Müller cells showed massive metabolic instability in early detachment stages that ultimately resolved as a homogeneous profile significantly depleted in glutamine. Retinal pigment epithelial cell signals also changed dramatically, displaying an initial glutamate spike and then a prolonged decline, even as taurine levels followed an opposite pattern of initial loss and slow restoration. Neurotransmitter signatures of surviving neurons showed extensive precursor-level variation, and, in one case, GABAergic horizontal cells displayed anomalous sprouting. CONCLUSIONS: Dramatic changes in Müller cell amino acid signatures triggered by retinal detachment are partially consistent with losses in glutamine synthetase activity. Taurine signal variations suggest that orthotopic RPE cells attempt to regulate abnormal taurine concentrations in the enlarged subretinal space. Surviving neurons possess characteristic neurotransmitter signals, but their metabolite regulation seems abnormal. On balance, microchemical and structural anomalies develop in the detached cat retina that represent serious barriers to recovery of normal visual function.

Amino Acids↗
PubMed1996

Amino acid signatures in the primate retina.

Pattern recognition of amino acid signals partitions virtually all of the macaque retina into 16 separable biochemical theme classes, some further divisible by additional criteria. The photoreceptor-->bipolar cell-->ganglion cell pathway is composed of six separable theme classes, each possessing a characteristic glutamate signature. Neuronal aspartate and glutamine levels are always positively correlated with glutamate signals, implying that they largely represent glutamate precursor pools. Amacrine cells may be parsed into four glycine-dominated (including one glycine/GABA immunoreactive population) and four GABA-dominated populations. Horizontal cells in central retina possess a distinctive GABA signature, although their GABA content is constitutively lower than that of amacrine cells and shows both regional and sample variability. Finally, a taurine-glutamine signature defines Müller's cells. We thus have established the fundamental biochemical signatures of the primate retina along with multiple metabolic subtypes for each neurochemical class and demonstrated that virtually all neuronal space can be accounted for by cells bearing characteristic glutamate, GABA, or glycine signatures.

Amino Acids↗
PubMed1995

Pattern recognition of amino acid signatures in retinal neurons.

Pattern recognition of amino acid signals partitions the cells of the goldfish retina into nine statistically unique biochemical theme classes and permits a first-order chemical mapping of virtually all cellular space. Photoreceptors, bipolar cells, and ganglion cells display a set of unique, nominally glutamatergic type E1, E1+E2, and E4 signatures, respectively. All horizontal cells are assignable to a GABAergic gamma 2 class or a non-GABAergic class with a glutamate-rich E3 signature. The amacrine cell layer is largely a mixture of (1) a taurine-dominated T1 Müller's cell signature and (2) GABAergic gamma 1, glycinergic G1, and dual glycinergic/GABAergic G gamma 1 amacrine cell signatures. Several major conclusions emerge from this work. (1) Glutamatergic, GABAergic, and glycinergic neural signatures and glial signatures account for over 99% of the cellular space in the retina. (2) All known neurons in the goldfish retina are associated with a set of conventional nonpeptide neurotransmitters. (3) Multiple forms of metabolic profiles are associated with a single nominal neurotransmitter category. (4) Glutamate and aspartate contents exhibit overlapping distributions and are not adequate univariate probes for identifying cell classes. (5) Signatures can serve as quantitative measures of cell state.

Amino Acids↗
PubMed1993

New aspects of dopaminergic interplexiform cell organization in the goldfish retina.

Dopaminergic interplexiform cells (DA-IPCs) in the goldfish retina have been reexamined by light and electron microscopic immunocytochemistry with antisera against dopamine (DA) or tyrosine hydroxylase (TH). Successful immunostaining with a specific anti-DA antiserum offers further direct support for DA-IPCs. Anti-DA immunocytochemistry in combination with [3H]-DA autoradiography shows 92% colocalization of the two markers, indicating that [3H]-DA autoradiography is a reliable technique for identification of DA-IPCs. Incubations with anti-TH antiserum show that immunoreactive DA-IPCs have a homogeneous distribution, with an average frequency of 71 +/- 8 cells/mm2 in retinas of 14-15 cm long goldfish. Their arrangement is distinctly nonrandom. Electron microscopy of TH-immunoreactive cell processes confirms that horizontal cell axons synapse onto DA-IPCs and adds the following junctional arrangements to the circuit diagram of the DA-IPC: 1) adjacent serial synapses between DA-IPCs, external horizontal cells, and putative glycinergic interplexiform cells, 2) junctional appositions between DA-IPCs and photoreceptor cells, 3) junctional appositions between neighbouring DA-IPCs, and 4) the "gap junctional complex," typically consisting of a DA-IPC process juxtaposed with a gap junction between horizontal cell axons. The gap junction is flanked by clusters of small, round vesicles and groups of electron-dense structures resembling intermediate filaments. These morphological results support the functional involvement of DA-IPCs in adaptive retinomotor movements and in horizontal cell gap junction modulation and/or dynamics. They also suggest particular interaction between the dopaminergic and the glycinergic IPC system in the outer plexiform layer of goldfish retina.

Animals↗
PubMed1992

All indoleamine-accumulating cells in the rabbit retina contain GABA.

The indoleamine-accumulating amacrine cells of the rabbit retina are wide-field and numerous. They form a dense plexus in sublamina 5 of the inner plexiform layer where they make reciprocal synapses with rod bipolar cells. To provide a quantitative test for the colocalization of serotonin (5-HT) and gamma-aminobutyric acid (GABA) in the rabbit retina, we designed two parallel double-label experiments. In the first series, the indoleamine-accumulating cells were labeled with 5,7-dihydroxytryptamine (5,7-DHT), which was subsequently visualized by photooxidation in the presence of diaminobenzidine. This was combined with autoradiography for 3H-muscimol. In the second and complementary series, 3H-5-HT uptake was combined with postembedding GABA immunocytochemistry. These two experiments provided essentially identical results: over 98% of the indoleamine-accumulating amacrine cells were double-labeled. This means that, within the limit of experimental error, all the indoleamine-accumulating amacrine cells are GABAergic. The indoleamine-accumulating amacrine cells account for 15-20% of a large diverse group of GABA amacrine cells. In addition, the rare type 3 indoleamine-accumulating cells and fine processes running in the optic fiber layer were double-labeled. If there is insufficient 5-HT to support a transmitter role in the rabbit retina, our results suggest that the indoleamine-accumulating cells may use GABA as a neurotransmitter. Thus, rod bipolar cells, in common with other bipolar cell types, receive extensive negative feedback at GABA-mediated reciprocal synapses.

5,7-Dihydroxytryptamine↗
PubMed1990

Interplexiform cells of the goldfish retina.

Dopaminergic and glycinergic interplexiform cells (IPCs) in the goldfish retina were impregnated by using two new Golgi protocols. The two cell types have markedly different morphological characteristics: Dopaminergic IPCs have primary dendrites that descend into and stratify in the inner plexiform layer, where they give rise to processes that project to the outer plexiform layer. Conversely, glycinergic IPCs have primary dendrites that ascend to the outer plexiform layer and from this dendritic arbor, many processes then project into the inner plexiform layer. The apparent coverage of dopaminergic IPCs is almost four times that of glycinergic IPCs. Even so, the coverage of each glycinergic IPC in the outer plexiform layer allows it to provide an accurate copy of the S-space to the inner plexiform layer. Considering the known GABAergic and glycinergic synaptologies in the inner plexiform layer, the glycinergic IPC must form a major element in the retinal circuitry of the goldfish.

Animals↗
PubMed1990

GABA-ergic and glycinergic pathways in the inner plexiform layer of the goldfish retina.

GABA-ergic and glycinergic circuitry in the inner plexiform layer of the goldfish retina was evaluated by electron microscopic autoradiography of 3H-GABA and 3H-glycine uptake, combined with retrograde horseradish peroxidase (HRP) labeling of ganglion cells. GABA-ergic and glycinergic synapses were found on labeled ganglion cells throughout the inner plexiform layer. This reinforces the idea that physiological evidence of GABA-ergic and glycinergic influence on a variety of ganglion cells in goldfish and carp often reflects direct inputs. Double-labeled synapses are presented as evidence of direct type Ab amacrine cell input to on-center ganglion cells. At least one population of type Aa sustained-off GABA-ergic amacrine cell is proposed, on the basis of profuse GABA-ergic inputs onto bipolar cells in sublamina a. Similar GABA-labeled profiles are shown to synapse onto HRP-labeled probable off-center ganglion cells. Thus GABA-ergic amacrine cells not only provide the predominant feedback to depolarizing (on-center) and hyperpolarizing (off-center) bipolar cells but also provide feed-forward inputs to on- and off-center ganglion cells. Large-caliber GABA-ergic dendrites present in both sublaminae a and b resemble those expected of a previously described bistratified, transient amacrine cell. These processes synapse onto HRP-labeled ganglion cell profiles in both sublaminae. Two morphologies of glycinergic amacrine cell are proposed on the basis of light microscopic autoradiography, 1) the previously described small pyriform cell and 2) a multipolar cell. The differential connectivity of the glycinergic neurons described, however, remains indistinguishable. Whereas abundant glycinergic inputs to ganglion cells occur throughout the inner plexiform layer, contacts between glycinergic profiles and bipolar cells are extremely rare. Therefore, interpreting the meaning of glycinergic input to ganglion cells will require further study of amacrine cell circuitry.

Animals↗
PubMed1990

Patterns of glutamate immunoreactivity in the goldfish retina.

Postembedding silver-intensified immunogold procedures reveal high levels of glutamate immunoreactivity in "vertical" elements of the goldfish retina: (1) Red-sensitive and green-sensitive cones display strong glutamate immunoreactivity, especially in their synaptic terminals, but blue-sensitive cones are poorly immunoreactive. (2) All type Mb (on-center) and Ma (off-center) mixed rod-cone bipolar cells and all identifiable cone bipolar cells are highly glutamate immunoreactive. We find no evidence for bipolar cells that lack glutamate immunoreactivity. (3) The majority of the somas in the ganglion cell layer and certain large cells of the amacrine cell layer resembling displaced ganglion cells are strongly glutamate immunoreactive. (4) Despite their high affinity symport of acidic amino acids, the endogenous levels of glutamate in Müller's cells are among the lowest in the retina. (5) GABAergic neurons possess intermediate levels of glutamate immunoreactivity. Quantitative immunocytochemistry coupled with digital image analysis allows estimates of intracellular glutamate levels. Photoreceptors and bipolar and ganglion cells contain from 1 to 10 mM glutamate. The bipolar and ganglion cell populations maintain high intracellular glutamate concentrations, averaging about 5 mM, whereas red-sensitive and green-sensitive cones apparently maintain lower levels. Importantly, photoreceptor glutamate levels are extremely volatile, and in vitro maintenance is required to preserve cone glutamate immunoreactivity in the goldfish. GABAergic horizontal and amacrine cells contain about 0.3-0.7 mM glutamate, which matches the values predicted from the Km of glutamic acid decarboxylase. Müller's cells and non-GABAergic amacrine cells contain less than 0.1 mM glutamate. Though Müller's cells are known to possess potent glutamate symport, they clearly possess equally potent mechanisms for maintaining low intracellular glutamate concentrations.

Animals↗
PubMed1988

Norepinephrine is a presynaptic input to visual corpus callosum cells.

The neurochemical identity of presynaptic inputs to cell bodies of corpus callosum fibers (callosal cells) located in visual cortex of the cat was investigated using a double labeling technique. Callosal cells were labeled by horseradish peroxidase applied to the severed ends of callosal fibers, and [3H]norepinephrine (NE) was injected into the crown of the lateral gyrus corresponding to the visual cortical area 17/18 border to label synapses. The tissue surrounding the injection sites was processed for electron microscope autoradiography. The results show that NE can be localized to cortical synapses contacting callosal cells in visual cortex of the cat.

Animals↗
PubMed1988

Serotonergic and serotonin-accumulating neurons in the goldfish retina.

Autoradiography of goldfish retinas incubated in micromolar levels of 3H-serotonin displayed 3 kinds of labeled somas in the inner nuclear layer: S1 amacrine cells with heavy labeling, large somas, and a sparse distribution (approximately 93/mm2); S2 amacrine cells with moderate labeling, smaller somas, and a denser distribution (approximately 500/mm2); and a subset of bipolar cells with light labeling, small somas, and a very dense distribution (approximately 4000/mm2). Serotonin-like immunoreactivity was observed only in S1 amacrine cells and their synaptic terminals. Radiolabeled terminals in the inner plexiform layer formed 4 strata that were differentially assigned to the 3 cell types. S1 amacrine cells arborized in sublayers 1 and 5, received inputs from type a1 bipolar cells and amacrine cells, and made synapses on other amacrine cells, type a1 bipolar cells and unidentified processes. Thus, S1 amacrine cells seem to receive significant input from "off-center" pathways. S2 amacrine cells arborized in sublayer 3 and made synapses onto amacrine cells. Labeled bipolar cell terminals were exclusively located in sublayer 2 and were identified as type a2 mixed rod-cone bipolar cells. We conclude that the S1 amacrine cell is truly serotonergic and that radiolabeling of S2 amacrine cells and type a2 bipolar cells is due to cross-specificity for another carrier or processes unrelated to their neurochemical identities. These observations partially reconcile many previous observations on the types, numbers, and synaptologies of teleost retinal neurons identified by different markers for indoleaminergic transmission.

Animals↗
PubMed1988

Gap junctions in the inner plexiform layer of the goldfish retina.

Oblique thin sections of the goldfish inner plexiform layer (IPL) were examined to characterize the processes engaging in gap junctions. Omission of en bloc uranyl acetate staining enhanced the relative visibility of gap junctions, thus facilitating surveys. Three general categories were identified: (1) extensive gap junctions between large caliber amacrine cell dendrites presynaptic to ganglion cells and other amacrine cells in distal and proximal IPL; (2) moderate to small gap junctions between amacrine cell synaptic terminals or small amacrine cell-like processes of similar cytoplasmic appearance; and (3) gap junctions between the telodendria/terminals of bipolar cells. Most instances of gap junctions in the goldfish IPL seem to represent cases of homologous coupling. We have not found unambiguous cases of heterologous coupling as in the mammalian retina, nor have we yet found mixed synapses. Taken together with previous physiological and anatomical findings, homologous coupling occurs between pairs of rods, cones, horizontal cells, bipolar cells and amacrine cells in the goldfish retina, and this in turn implies that direct intercellular communication among like cell types is a common theme in retinal circuitry.

Animals↗