MELANOPHORE POTENTIALS OF THE CHROMATICALLY INTACT SPINAL STONELOACH (NOEMACHEILUS-BARBATULUS L) FOLLOWING ADAPTATION TO VARYING BACKGROUNDS

1. The transient colour response of the stoneloach (Noemacheilus barbatulus) is similar to that described for some other freshwater teleosts. 2. A method is described for measuring the melanophore transmembrane potentials resulting from direct activity of the intact chromatic system. 3. Using this method the melanophore index and the melanophore potential at the cell centrosphere were measured in fish adapted to black and white backgrounds and during background reversal (Figs. 5, 6). 4. The amount of pigment movement for the same change in centrosphere potential is greater in melanophores that are aggregating than in those that are dispersing. 5. The melanophore index and the melanophore potential at the cell centrosphere were measured in fish subjected to darkness following adaptation to black and white backgrounds (Fig. 7), and in fish subjected to illumination on black and white backgrounds after adaptation in darkness (Fig. 8). 6. The melanophore index and the melanophore potential both at the cell centrosphere and at the edge of the pigment were measured in fish adapted to backgrounds of varying reflectivity (Table 1). In all positions of the pigment the sum of these potentials remained nearly constant, although the potentials themselves varied (Figs. 9, 10). © 1979 Springer-Verlag.