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Cone and rod cells have different target preferences in vitro as revealed by optical tweezers.

Clarke RJ, Högnason K, Brimacombe M, Townes-Anderson E - Mol. Vis. (2008)

Bottom Line: Cell orientation of the photoreceptor also did not affect preferences: Cells oriented away from dendritic processes could reorient their axonal pole toward the target cell.Cone cells preferred normal partners, and rod cells preferred novel partners.Further,these differences may help explain the patterns of photoreceptor sprouting seen in retinal degeneration in which rod, but not cone, cells invade the inner retinal layers where third-order neurons are located.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology and Neuroscience, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.

ABSTRACT

Purpose: When neural circuits are damaged in adulthood, regenerating and sprouting processes must distinguish appropriate targets to recreate the normal circuitry. We tested the ability of adult nerve cells to target specific cells in culture using the retina as a model system.

Methods: Under sterile culture conditions, retinal cells, isolated from tiger salamander retina, were micromanipulated with optical tweezers to create pairs of first-order photoreceptor cells with second- or third-order retinal neurons. The development of cell contact and presynaptic varicosities, the direction and amount of neuritic growth, and nerve cell polarity were assessed after seven days in vitro. Cultures were labeled for rod opsin to distinguish rod from cone cells and for the alpha subunit of the trimeric G protein Go (Go alpha) to identify cone-dominated and mixed rod-cone ON bipolar cells.

Results: Quantitative analysis of growth demonstrated that target preferences were cell-specific: Cone cells preferred second-order bipolar cells, whereas rod cells grew toward third-order neurons, which include amacrine and ganglion cells. In addition, when rod cells grew toward bipolar cells, they chose an abnormally high number of Go alpha-positive bipolar cells. These growth patterns were not affected by tweezers manipulation or the amount of growth. Cell orientation of the photoreceptor also did not affect preferences: Cells oriented away from dendritic processes could reorient their axonal pole toward the target cell.

Conclusions: Cone cells preferred normal partners, and rod cells preferred novel partners. These intrinsic preferences indicate that adult nerve cells can have differing capacities for targeting even if they come from the same cell class. Further,these differences may help explain the patterns of photoreceptor sprouting seen in retinal degeneration in which rod, but not cone, cells invade the inner retinal layers where third-order neurons are located.

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Related in: MedlinePlus

Normal and novel interactions after laser tweezers micromanipulation. The left column shows cells immediately after tweezers placement; the middle column, 3 days in vitro; and the right column, 7 days in vitro. A: An example of attraction between a rod cell and a multipolar cell. At 3 days, long filopodial processes emanating from the rod cell contacted processes of the multipolar cell. The cells grew toward each other over 7 days in culture creating a broad intercellular contact. Inset: The photoreceptor identification as a rod cell was confirmed by immunolabeling with anti-rod opsin. B: An example of attraction between a cone cell and a bipolar cell. At 3 days, a neurite bearing a varicosity (arrow) contacted the bipolar cell. A second varicosity developed by day 7. For cone cells, quantitative analysis compared the two halves of the cell for growth since cone cells grew fewer processes than rod cells. Greater numbers of neurites and varicosities (arrows) on the side facing the bipolar are indicative of attraction between the cells. C: An example of repulsion between a cone cell and a multipolar cell. The larger numbers of neurites and varicosities (arrows) on the opposite side of the cone with respect to its paired multipolar cell indicate repulsion. Scale bar equals 20 µm.
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f2: Normal and novel interactions after laser tweezers micromanipulation. The left column shows cells immediately after tweezers placement; the middle column, 3 days in vitro; and the right column, 7 days in vitro. A: An example of attraction between a rod cell and a multipolar cell. At 3 days, long filopodial processes emanating from the rod cell contacted processes of the multipolar cell. The cells grew toward each other over 7 days in culture creating a broad intercellular contact. Inset: The photoreceptor identification as a rod cell was confirmed by immunolabeling with anti-rod opsin. B: An example of attraction between a cone cell and a bipolar cell. At 3 days, a neurite bearing a varicosity (arrow) contacted the bipolar cell. A second varicosity developed by day 7. For cone cells, quantitative analysis compared the two halves of the cell for growth since cone cells grew fewer processes than rod cells. Greater numbers of neurites and varicosities (arrows) on the side facing the bipolar are indicative of attraction between the cells. C: An example of repulsion between a cone cell and a multipolar cell. The larger numbers of neurites and varicosities (arrows) on the opposite side of the cone with respect to its paired multipolar cell indicate repulsion. Scale bar equals 20 µm.

Mentions: The photoreceptors were analyzed by examining for cell contacts, and by quantifying changes in the number of presynaptic varicosities that formed toward or away from the partner, the number and total length of processes which grew toward or away from the potential postsynaptic partner, and the distance between cells over time. Although adult retinal neurons do not migrate in culture, in some cases of attraction, cells appeared to move together due to asymmetric expansion of the cell soma so that there was broad contact between cell bodies (Figure 2A). Based on these measures, a photoreceptor cell was classified as attracted to (Figures 1C, Figure 2A,B) or repulsed by (Figures 2C) its partner or undetermined. The undetermined category contained (1) photoreceptor cells that had neutral growth, i.e., equal amount of growth in all directions; (2) cells that had equal growth both toward and away from the target, i.e., cells that may have sensed multiple attractive or inhibitory molecules or may have been paired with a target cell which released weak or mixed signals; and (3) cells that responded poorly, i.e., cells that had little growth, making it difficult to assess growth patterns. We know from experience that about 1%–5% of the photoreceptors will not grow well in culture. We analyzed 203 pairs from 86 cultures derived from 55 animals.


Cone and rod cells have different target preferences in vitro as revealed by optical tweezers.

Clarke RJ, Högnason K, Brimacombe M, Townes-Anderson E - Mol. Vis. (2008)

Normal and novel interactions after laser tweezers micromanipulation. The left column shows cells immediately after tweezers placement; the middle column, 3 days in vitro; and the right column, 7 days in vitro. A: An example of attraction between a rod cell and a multipolar cell. At 3 days, long filopodial processes emanating from the rod cell contacted processes of the multipolar cell. The cells grew toward each other over 7 days in culture creating a broad intercellular contact. Inset: The photoreceptor identification as a rod cell was confirmed by immunolabeling with anti-rod opsin. B: An example of attraction between a cone cell and a bipolar cell. At 3 days, a neurite bearing a varicosity (arrow) contacted the bipolar cell. A second varicosity developed by day 7. For cone cells, quantitative analysis compared the two halves of the cell for growth since cone cells grew fewer processes than rod cells. Greater numbers of neurites and varicosities (arrows) on the side facing the bipolar are indicative of attraction between the cells. C: An example of repulsion between a cone cell and a multipolar cell. The larger numbers of neurites and varicosities (arrows) on the opposite side of the cone with respect to its paired multipolar cell indicate repulsion. Scale bar equals 20 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2383278&req=5

f2: Normal and novel interactions after laser tweezers micromanipulation. The left column shows cells immediately after tweezers placement; the middle column, 3 days in vitro; and the right column, 7 days in vitro. A: An example of attraction between a rod cell and a multipolar cell. At 3 days, long filopodial processes emanating from the rod cell contacted processes of the multipolar cell. The cells grew toward each other over 7 days in culture creating a broad intercellular contact. Inset: The photoreceptor identification as a rod cell was confirmed by immunolabeling with anti-rod opsin. B: An example of attraction between a cone cell and a bipolar cell. At 3 days, a neurite bearing a varicosity (arrow) contacted the bipolar cell. A second varicosity developed by day 7. For cone cells, quantitative analysis compared the two halves of the cell for growth since cone cells grew fewer processes than rod cells. Greater numbers of neurites and varicosities (arrows) on the side facing the bipolar are indicative of attraction between the cells. C: An example of repulsion between a cone cell and a multipolar cell. The larger numbers of neurites and varicosities (arrows) on the opposite side of the cone with respect to its paired multipolar cell indicate repulsion. Scale bar equals 20 µm.
Mentions: The photoreceptors were analyzed by examining for cell contacts, and by quantifying changes in the number of presynaptic varicosities that formed toward or away from the partner, the number and total length of processes which grew toward or away from the potential postsynaptic partner, and the distance between cells over time. Although adult retinal neurons do not migrate in culture, in some cases of attraction, cells appeared to move together due to asymmetric expansion of the cell soma so that there was broad contact between cell bodies (Figure 2A). Based on these measures, a photoreceptor cell was classified as attracted to (Figures 1C, Figure 2A,B) or repulsed by (Figures 2C) its partner or undetermined. The undetermined category contained (1) photoreceptor cells that had neutral growth, i.e., equal amount of growth in all directions; (2) cells that had equal growth both toward and away from the target, i.e., cells that may have sensed multiple attractive or inhibitory molecules or may have been paired with a target cell which released weak or mixed signals; and (3) cells that responded poorly, i.e., cells that had little growth, making it difficult to assess growth patterns. We know from experience that about 1%–5% of the photoreceptors will not grow well in culture. We analyzed 203 pairs from 86 cultures derived from 55 animals.

Bottom Line: Cell orientation of the photoreceptor also did not affect preferences: Cells oriented away from dendritic processes could reorient their axonal pole toward the target cell.Cone cells preferred normal partners, and rod cells preferred novel partners.Further,these differences may help explain the patterns of photoreceptor sprouting seen in retinal degeneration in which rod, but not cone, cells invade the inner retinal layers where third-order neurons are located.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology and Neuroscience, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.

ABSTRACT

Purpose: When neural circuits are damaged in adulthood, regenerating and sprouting processes must distinguish appropriate targets to recreate the normal circuitry. We tested the ability of adult nerve cells to target specific cells in culture using the retina as a model system.

Methods: Under sterile culture conditions, retinal cells, isolated from tiger salamander retina, were micromanipulated with optical tweezers to create pairs of first-order photoreceptor cells with second- or third-order retinal neurons. The development of cell contact and presynaptic varicosities, the direction and amount of neuritic growth, and nerve cell polarity were assessed after seven days in vitro. Cultures were labeled for rod opsin to distinguish rod from cone cells and for the alpha subunit of the trimeric G protein Go (Go alpha) to identify cone-dominated and mixed rod-cone ON bipolar cells.

Results: Quantitative analysis of growth demonstrated that target preferences were cell-specific: Cone cells preferred second-order bipolar cells, whereas rod cells grew toward third-order neurons, which include amacrine and ganglion cells. In addition, when rod cells grew toward bipolar cells, they chose an abnormally high number of Go alpha-positive bipolar cells. These growth patterns were not affected by tweezers manipulation or the amount of growth. Cell orientation of the photoreceptor also did not affect preferences: Cells oriented away from dendritic processes could reorient their axonal pole toward the target cell.

Conclusions: Cone cells preferred normal partners, and rod cells preferred novel partners. These intrinsic preferences indicate that adult nerve cells can have differing capacities for targeting even if they come from the same cell class. Further,these differences may help explain the patterns of photoreceptor sprouting seen in retinal degeneration in which rod, but not cone, cells invade the inner retinal layers where third-order neurons are located.

Show MeSH
Related in: MedlinePlus