scholarly journals Asymmetric Distributions of Achromatic Bipolar Cells in the Mouse Retina

2022 ◽  
Vol 15 ◽  
Author(s):  
Zachary J. Sharpe ◽  
Angela Shehu ◽  
Tomomi Ichinose
Keyword(s):  
Visual Processing ◽  
Fluorescent Protein ◽  
Bipolar Cells ◽  
Mouse Retina ◽  
Temporal Region ◽  
Retinal Tissue ◽  
Evolutionary Changes ◽  
Asymmetric Distributions ◽  
Nasal Region ◽  
Green Fluorescent

In the retina, evolutionary changes can be traced in the topography of photoreceptors. The shape of the visual streak depends on the height of the animal and its habitat, namely, woods, prairies, or mountains. Also, the distribution of distinct wavelength-sensitive cones is unique to each animal. For example, UV and green cones reside in the ventral and dorsal regions in the mouse retina, respectively, whereas in the rat retina these cones are homogeneously distributed. In contrast with the abundant investigation on the distribution of photoreceptors and the third-order neurons, the distribution of bipolar cells has not been well understood. We utilized two enhanced green fluorescent protein (EGFP) mouse lines, Lhx4-EGFP (Lhx4) and 6030405A18Rik-EGFP (Rik), to examine the topographic distributions of bipolar cells in the retina. First, we characterized their GFP-expressing cells using type-specific markers. We found that GFP was expressed by type 2, type 3a, and type 6 bipolar cells in the Rik mice and by type 3b, type 4, and type 5 bipolar cells in the Lhx4 mice. All these types are achromatic. Then, we examined the distributions of bipolar cells in the four cardinal directions and three different eccentricities of the retinal tissue. In the Rik mice, GFP-expressing bipolar cells were more highly observed in the nasal region than those in the temporal retina. The number of GFP cells was not different along with the ventral-dorsal axis. In contrast, in the Lhx4 mice, GFP-expressing cells occurred at a higher density in the ventral region than in the dorsal retina. However, no difference was observed along the nasal-temporal axis. Furthermore, we examined which type of bipolar cells contributed to the asymmetric distributions in the Rik mice. We found that type 3a bipolar cells occurred at a higher density in the temporal region, whereas type 6 bipolar cells were denser in the nasal region. The asymmetricity of these bipolar cells shaped the uneven distribution of the GFP cells in the Rik mice. In conclusion, we found that a subset of achromatic bipolar cells is asymmetrically distributed in the mouse retina, suggesting their unique roles in achromatic visual processing.

scholarly journals Inhibitory inputs tune the light response properties of dopaminergic amacrine cells in mouse retina

2013 ◽  
Vol 110 (2) ◽  
pp. 536-552 ◽  
Author(s):  
G. S. Newkirk ◽  
M. Hoon ◽  
R. O. Wong ◽  
P. B. Detwiler
Keyword(s):  
Visual Processing ◽  
Fluorescent Protein ◽  
Bright Light ◽  
Light Response ◽  
Amacrine Cells ◽  
Membrane Properties ◽  
Mouse Retina ◽  
Light Onset ◽  
Threshold Response ◽  
Green Fluorescent

Dopamine (DA) is a neuromodulator that in the retina adjusts the circuitry for visual processing in dim and bright light conditions. It is synthesized and released from retinal interneurons called dopaminergic amacrine cells (DACs), whose basic physiology is not yet been fully characterized. To investigate their cellular and input properties as well as light responses, DACs were targeted for whole cell recording in isolated retina using two-photon fluorescence microscopy in a mouse line where the dopamine receptor 2 promoter drives green fluorescent protein (GFP) expression. Differences in membrane properties gave rise to cell-to-cell variation in the pattern of resting spontaneous spike activity ranging from silent to rhythmic to periodic burst discharge. All recorded DACs were light sensitive and generated responses that varied with intensity. The threshold response to light onset was a hyperpolarizing potential change initiated by rod photoreceptors that was blocked by strychnine, indicating a glycinergic amacrine input onto DACs at light onset. With increasing light intensity, the ON response acquired an excitatory component that grew to dominate the response to the strongest stimuli. Responses to bright light (photopic) stimuli also included an inhibitory OFF response mediated by GABAergic amacrine cells driven by the cone OFF pathway. DACs expressed GABA (GABAAα1 and GABAAα3) and glycine (α2) receptor clusters on soma, axon, and dendrites consistent with the light response being shaped by dual inhibitory inputs that may serve to tune spike discharge for optimal DA release.

Glycine receptors of A-type ganglion cells of the mouse retina

2007 ◽  
Vol 24 (4) ◽  
pp. 471-487 ◽  
Author(s):  
SRIPARNA MAJUMDAR ◽  
LIANE HEINZE ◽  
SILKE HAVERKAMP ◽  
ELENA IVANOVA ◽  
HEINZ WÄSSLE
Keyword(s):  
Fluorescent Protein ◽  
Ganglion Cells ◽  
Glycine Receptor ◽  
Mouse Retina ◽  
Inhibitory Input ◽  
Visual Channel ◽  
Fast Kinetics ◽  
Transgenic Mouse Line ◽  
Green Fluorescent ◽  
Α Subunits

A-type ganglion cells of the mouse retina represent the visual channel that transfers temporal changes of the outside world very fast and with high fidelity. In this study we combined anatomical and physiological methods in order to study the glycinergic, inhibitory input of A-type ganglion cells. Immunocytochemical studies were performed in a transgenic mouse line whose ganglion cells express green fluorescent protein (GFP). The cells were double labeled for GFP and the four α subunits of the glycine receptor (GlyR). It was found that most of the glycinergic input of A-type cells is through fast, α1-expressing synapses. Whole-cell currents were recorded from A-type ganglion cells in retinal whole mounts. The response to exogenous application of glycine and spontaneous inhibitory postsynaptic currents (sIPSCs) were measured. By comparing glycinergic currents recorded in wildtype mice and in mice with specific deletions of GlyRα subunits (Glra1spd-ot,Glra2−/−,Glra3−/−), the subunit composition of GlyRs of A-type ganglion cells could be further defined. Glycinergic sIPSCs of A-type ganglion cells have fast kinetics (decay time constant τ = 3.9 ± 2.5 ms, mean ± SD). Glycinergic sIPSCs recorded inGlra2−/−andGlra3−/−mice did not differ from those of wildtype mice. However, the number of glycinergic sIPSCs was significantly reduced inGlra1spd-otmice and the remaining sIPSCs had slower kinetics than in wildtype mice. The results show that A-type ganglion cells receive preferentially kinetically fast glycinergic inputs, mediated by GlyRs composed of α1 and β subunits.

scholarly journals Biomolecular Contrast Agents for Optical Coherence Tomography

2019 ◽  
Author(s):  
George J. Lu ◽  
Li-dek Chou ◽  
Dina Malounda ◽  
Amit K. Patel ◽  
Derek S. Welsbie ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Contrast Agents ◽  
Fluorescent Protein ◽  
Mouse Retina ◽  
Optical Coherence ◽  
Gas Vesicles ◽  
Cellular Functions ◽  
Green Fluorescent

ABSTRACTOptical coherence tomography (OCT) has gained wide adoption in biological and medical imaging due to its exceptional tissue penetration, 3D imaging speed and rich contrast. However, OCT plays a relatively small role in molecular and cellular imaging due to the lack of suitable biomolecular contrast agents. In particular, while the green fluorescent protein has provided revolutionary capabilities to fluorescence microscopy by connecting it to cellular functions such as gene expression, no equivalent reporter gene is currently available for OCT. Here we introduce gas vesicles, a unique class of naturally evolved gas-filled protein nanostructures, as the first genetically encodable OCT contrast agents. The differential refractive index of their gas compartments relative to surrounding aqueous tissue and their nanoscale motion enables gas vesicles to be detected by static and dynamic OCT at picomolar concentrations. Furthermore, the OCT contrast of gas vesicles can be selectively erasedin situwith ultrasound, allowing unambiguous assignment of their location. In addition, gas vesicle clustering modulates their temporal signal, enabling the design of dynamic biosensors. We demonstrate the use of gas vesicles as reporter genes in bacterial colonies and as purified contrast agentsin vivoin the mouse retina. Our results expand the utility of OCT as a unique photonic modality to image a wider variety of cellular and molecular processes.

scholarly journals Connectivity map of bipolar cells and photoreceptors in the mouse retina

2016 ◽  
Author(s):  
Christian Behrens ◽  
Timm Schubert ◽  
Silke Haverkamp ◽  
Thomas Euler ◽  
Philipp Berens
Keyword(s):  
Visual Processing ◽  
Plexiform Layer ◽  
Bipolar Cells ◽  
Mouse Retina ◽  
Connectivity Map ◽  
Dendritic Field ◽  
Electron Microscopy Data ◽  
Different Types ◽  
Microscopy Data ◽  
Anatomical Evidence

AbstractVisual processing begins at the first synapse of the visual system. In the mouse retina, three different types of photoreceptors provide input to 14 bipolar cell (BC) types. Classically, most BC types are thought to contact all cones within their dendritic field; ON BCs would contact cones exclusively via so-called invaginating synapses, while OFF BCs would form basal synapses. By mining publically available electron microscopy data, we discovered interesting violations of these rules of outer retinal connectivity: ON BC type X contacted only ~20% of the cones in its dendritic field and made mostly atypical non-invaginating contacts. Types 5T, 5O and 8 also contacted fewer cones than expected. In addition, we found that rod BCs received input from cones, providing anatomical evidence that rod and cone pathways are interconnected in both directions. This suggests that the organization of the outer plexiform layer is more complex than classically thought.

scholarly journals Characterization of NGF, trkANGFR, and p75NTRin Retina of Mice Lacking Reelin Glycoprotein

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Bijorn Omar Balzamino ◽  
Filippo Biamonte ◽  
Graziana Esposito ◽  
Ramona Marino ◽  
Francesca Fanelli ◽  
...  
Keyword(s):  
Real Time ◽  
Cross Talk ◽  
Real Time Pcr ◽  
Fluorescent Protein ◽  
Information Source ◽  
Bipolar Cells ◽  
Pcr Analysis ◽  
Additional Information ◽  
Ngf Receptor ◽  
Green Fluorescent

Both Reelin and Nerve Growth Factor (NGF) exert crucial roles in retinal development. Retinogenesis is severely impaired inE-reelermice, a model of Reelin deficiency showing specific Green Fluorescent Protein expression in Rod Bipolar Cells (RBCs). Since no data are available on Reelin and NGF cross-talk, NGF andtrkANGFR/p75NTRexpression was investigated in retinas fromE-reelerversus control mice, by confocal microscopy, Western blotting, and real time PCR analysis. A scattered increase of NGF protein was observed in the Ganglion Cell Layer and more pronounced in the Inner Nuclear Layer (INL). A selective increase ofp75NTRwas detected in most of RBCs and in other cell subtypes of INL. On the contrary, a slight trend towards a decrease was detected fortrkANGFR, albeit not significant. Confocal data were validated by Western blot and real time PCR. Finally, the decreasedtrkANGFR/p75NTRratio, representative ofp75NTRincrease, significantly correlated withE-reelerversus E-control. These data indicate that NGF-trkANGFR/p75NTRis affected inE-reelerretina and thatp75NTRmight represent the main NGF receptor involved in the process. This first NGF-trkANGFR/p75NTRcharacterization suggests thatE-reelermight be suitable for exploring Reelin-NGF cross-talk, representing an additional information source in those pathologies characterized by retinal degeneration.

A Unified Model for Photophysical and Electro-Optical Properties of Green Fluorescent Proteins

2019 ◽  
Author(s):  
Chi-Yun Lin ◽  
Matthew Romei ◽  
Luke Oltrogge ◽  
Irimpan Mathews ◽  
Steven Boxer
Keyword(s):  
Driving Force ◽  
Fluorescent Protein ◽  
Charge Transfer Band ◽  
Photophysical Properties ◽  
Polymethine Dyes ◽  
Emission Rates ◽  
Unified Framework ◽  
Underlying Factor ◽  
Green Fluorescent ◽  
Protein Environment

Green fluorescent protein (GFPs) have become indispensable imaging and optogenetic tools. Their absorption and emission properties can be optimized for specific applications. Currently, no unified framework exists to comprehensively describe these photophysical properties, namely the absorption maxima, emission maxima, Stokes shifts, vibronic progressions, extinction coefficients, Stark tuning rates, and spontaneous emission rates, especially one that includes the effects of the protein environment. In this work, we study the correlations among these properties from systematically tuned GFP environmental mutants and chromophore variants. Correlation plots reveal monotonic trends, suggesting all these properties are governed by one underlying factor dependent on the chromophore's environment. By treating the anionic GFP chromophore as a mixed-valence compound existing as a superposition of two resonance forms, we argue that this underlying factor is defined as the difference in energy between the two forms, or the driving force, which is tuned by the environment. We then introduce a Marcus-Hush model with the bond length alternation vibrational mode, treating the GFP absorption band as an intervalence charge transfer band. This model explains all the observed strong correlations among photophysical properties; related subtopics are extensively discussed in Supporting Information. Finally, we demonstrate the model's predictive power by utilizing the additivity of the driving force. The model described here elucidates the role of the protein environment in modulating photophysical properties of the chromophore, providing insights and limitations for designing new GFPs with desired phenotypes. We argue this model should also be generally applicable to both biological and non-biological polymethine dyes.<br>

Structural Evidence of Photoisomerization Pathways in Fluorescent Proteins

2019 ◽  
Author(s):  
Jeffrey Chang ◽  
Matthew Romei ◽  
Steven Boxer
Keyword(s):  
Rational Design ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Super Resolution ◽  
Unit Cell Size ◽  
Chlorine Substituent ◽  
Gfp Chromophore ◽  
The One ◽  
Green Fluorescent ◽  
Super Resolution Microscopy

<p>Double-bond photoisomerization in molecules such as the green fluorescent protein (GFP) chromophore can occur either via a volume-demanding one-bond-flip pathway or via a volume-conserving hula-twist pathway. Understanding the factors that determine the pathway of photoisomerization would inform the rational design of photoswitchable GFPs as improved tools for super-resolution microscopy. In this communication, we reveal the photoisomerization pathway of a photoswitchable GFP, rsEGFP2, by solving crystal structures of <i>cis</i> and <i>trans</i> rsEGFP2 containing a monochlorinated chromophore. The position of the chlorine substituent in the <i>trans</i> state breaks the symmetry of the phenolate ring of the chromophore and allows us to distinguish the two pathways. Surprisingly, we find that the pathway depends on the arrangement of protein monomers within the crystal lattice: in a looser packing, the one-bond-flip occurs, whereas in a tighter packing (7% smaller unit cell size), the hula-twist occurs.</p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p> <p> </p>

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