title: Calcium regulation of pigment transport in vitro.
abstract: Calcium has been implicated in the regulation of many cellular motility events. In this study we have examined the role of different Ca2+ concentrations on the in vitro transport of pigment within cultured chromatophores. Cells treated with Brij detergent for 1-2 min were stripped of their plasma membranes, leaving their cytoskeleton and associated pigment granules exposed to the external milieu. We found that retrograde pigment transport (aggregation) is induced upon addition of 1 mM MgATP2- with 10(-7) M free Ca2+, while an orthograde transport (redispersal) of pigment results from lowering the concentration of free Ca2+ to 10(-8) M while maintaining 1 mM MgATP2-. These Ca2+-regulated movements are ATP dependent but are apparently independent of cAMP and insensitive to calmodulin inhibitors. The observations reported here provide novel evidence that the concentration of free Ca2+ acts to regulate the direction of intracellular organelle transport.
authors.affiliation: Department of Biological Sciences, University of Maryland Baltimore County, Catonsville 21228.
authors.forename: M A
authors.initials: MA
authors.lastname: McNiven
authors.forename: J B
authors.initials: JB
authors.lastname: Ward
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology; D002856:Chromatophores / Q000502:physiology*; D000242:Cyclic AMP / Q000502:physiology; D003594:Cytoplasmic Granules / Q000502:physiology; D005399:Fishes; D066298:In Vitro Techniques; D008274:Magnesium / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D008870:Microtubules / Q000502:physiology; D010858:Pigmentation / Q000187:drug effects*
chemical_list: D002147:Calmodulin; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D008274:Magnesium; D002118:Calcium