The control of pigment migration in isolated erythrophores of Holocentrus ascensionis (Osbeck). I. Energy requirements

Erythrophores isolated from the scales of the marine teleost, Holocentrus ascensionis (Osbeck), are capable of rapidly aggregating or dispersing numerous red pigment granules within their cytoplasm by translocating them along radial paths delineated by bundles of radially oriented microtubules. Pigment translocation is accompanied by transformations in the morphology of the cytoplasmic matrix, or microtrabecular lattice (MTL), in which the pigment granules are suspended. It appears that the MTL as a whole contracts toward the cell center during aggregation, carrying the pigment granules inward along with it, and is restructured during dispersion, using the radial microtubules as guides. We examined the energy requirements of pigment migration and the accompanying MTL transformations. Cellular ATP was depleted using the specific metabolic inhibitors 2,4 dinitrophenol, NaCN and oligomycin, All three of these drugs, which inhibit oxidative phosphorylation by different mechanisms, prevent both pigment dispersion and MTL transformation to dispersed morphology, while aggregation is unaffected. Inhibitor-treated cells recover normal pigment movements and MTL morphology when inhibitor is washed out of the cells with fresh medium. Potential energy apparently is stored in the MTL by some ATP-dependent process during dispersion and is converted to kinetic energy during aggregation. The results of this study strengthen the hypothesis that the MTL, working in concert with the radial microtubules, is the vehicle for pigment translocation in the erythrophore system.