Chapter 1 Lysed Chromatophores: A Model System for the Study of Bidirectional Organelle Transport

Haimo, Leah T.; Rozdzial, Moshe M.

doi:10.1016/s0091-679x(08)61599-x

Cited by 13 publications

(7 citation statements)

References 40 publications

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“…The central importance of cAMP in regulating pigment granule position is also suggested by studies conducted on dermal melanophores of tilapia ( Tilapia mossambica ) [21-25], black tetra ( Gymnocorymbus ternetzii ) [26], and angelfish ( Pterophyllum scalare ) [27] among others (reviewed in [28]). In each of these cases, increased cAMP i is associated with pigment granule dispersion and decreased cAMP i with pigment granule aggregation.…”

Section: Discussionmentioning

confidence: 99%

Activation of muscarinic acetylcholine receptors elicits pigment granule dispersion in retinal pigment epithelium isolated from bluegill

2004

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Background: In fish, melanin pigment granules in the retinal pigment epithelium disperse into apical projections as part of the suite of responses the eye makes to bright light conditions. This pigment granule dispersion serves to reduce photobleaching and occurs in response to neurochemicals secreted by the retina. Previous work has shown that acetylcholine may be involved in inducing light-adaptive pigment dispersion. Acetylcholine receptors are of two main types, nicotinic and muscarinic. Muscarinic receptors are in the G-protein coupled receptor superfamily, and five different muscarinic receptors have been molecularly cloned in human. These receptors are coupled to adenylyl cyclase, calcium mobilization and ion channel activation. To determine the receptor pathway involved in eliciting pigment granule migration, we isolated retinal pigment epithelium from bluegill and subjected it to a battery of cholinergic agents.

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Section: Discussionmentioning

confidence: 99%

Activation of muscarinic acetylcholine receptors elicits pigment granule dispersion in retinal pigment epithelium isolated from bluegill

2004

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“…ied in teleost chromophores than in amphibian melanophores (see Akiyama et al, 1990;Beckerle and Porter, 1983;Haimo and Rozdzial, 1989;McNiven et al, 1984;Obika, 1986;Schliwa, 1987;Stearns and Wang, 1987;Thylor, 1992;Yu et al, 1990). In general, however, the teleost melanophore has not been shown to respond to melatonin (Rollag and Adelman, 1992).…”

Section: Discussionmentioning

confidence: 99%

Actin and Tubulin Arrays in Cultured Xenopus Melanophores Responding to Melatonin

Rollag

Adelman

1993

Pigment Cell Research

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Melatonin induces pigment granule aggregation in amphibian melanophores. In the studies reported here, we have used fluorescence microscopic techniques to test the hypothesis that such melatonin-induced pigment movement is correlated with alterations in either the actin or tubulin cytoskeletal patterns of cultured Xenopus melanophores. In general, the cytoplasmic domains of the cultured melanophores were flat and thin except in the perinuclear region (especially when the pigment was aggregated). The microtubules and microfilaments were usually found in the same focal plane; however, on occasion, microfilaments were closer to the substratum. Microtubules were arranged in arrays radiating from what are presumed to be cytocenters. A small percentage of the melanophores were very large, had actin-rich circular perimeters and did not respond as rapidly to melatonin treatment as did the other melanophores. Melanophores with either aggregated or dispersed melanosomes had low intensity rhodamine-phalloidin staining of actin filaments compared to nonpigmented cells, whereas the FITC anti-tubulin intensities were comparable in magnitude to that seen in nonpigmented cells. When cells were fixed prior to complete melatonin-induced pigment granule aggregation there was no abrupt diminution in either the tubulin or actin staining at the boundary between pigment granule-rich and pigment granule-poor cytoplasmic domains. Nor could the actin and tubulin patterns in cells with partially aggregated melanosomes be reliably distinguished from those in melanophores in which the melanosomes were either completely dispersed or completely aggregated. These data argue against the hypothesis that melatonin causes consistent large-scale rearrangements of tubulin and actin polymers as it induces pigment aggregation in Xenopus melanophores.

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“…To determine if CN was present in the dermis on scales, dermis was prepared as described (Haimo and Rozdzial, 1989). The dermis was homogenized in 2 ml of lysis buffer with protease inhibitors (1 mM PMSF, 0.5 mM DTT, 10 ~tg/ml of leupeptin, N~-p-tosyl-L-arginine methyl ester, and aprotinin), centrifuged at 10,000 g for 1 h, and the supernatant collected and concentrated with a Centricon filter (Amicon, Inc., Danvers, MA).…”

Section: Immunoblottingmentioning

confidence: 99%

Regulation of organelle transport in melanophores by calcineurin.

Thaler

Haimo

1990

The Journal of Cell Biology

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Abstract.Previous studies have shown that pigment granule dispersion and aggregation in melanophores of the African cichlid, Tilapia mossambica, are regulated by protein phosphorylation and dephosphorylation, respectively (Rozdzial, M. M., and L. T. Haimo. 1986. Cell. 47:1061-1070. The present studies suggest that calcineurin, a Ca2÷/calmodulin-stimulated phosphatase, is the endogenous phosphatase that mediates pigment aggregation in melanophores. Aggregation, but not dispersion, is inhibited by okadaic acid at concentrations consistent with an inhibition of calcineurin activity. Inhibition of aggregation in melanophores that have been BAPTA loaded or treated with calmodulin antagonists implicate Ca 2+ and calmodulin, respectively, in this process. Moreover, addition of calcineufin rescues aggregation in lysed melanophores which are otherwise incapable of aggregating pigment. Immunoblotting with an anticalcineurin IgG reveals that calcineurin is a component of the dermis, which contains the melanophores, and indirect immunofluorescence localizes calcineurin specifically to the melanophores. Finally, this antibody, which inhibits calcineurin's phosphatase activity (Tash, J. S., M.

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Chapter 1 Lysed Chromatophores: A Model System for the Study of Bidirectional Organelle Transport

Cited by 13 publications

References 40 publications

Activation of muscarinic acetylcholine receptors elicits pigment granule dispersion in retinal pigment epithelium isolated from bluegill

Activation of muscarinic acetylcholine receptors elicits pigment granule dispersion in retinal pigment epithelium isolated from bluegill

Actin and Tubulin Arrays in Cultured Xenopus Melanophores Responding to Melatonin

Regulation of organelle transport in melanophores by calcineurin.

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