An Improved Photoelectric Method for Recording Motile Responses of Individual Leucophores

Abstract

An improved photoelectric method for recording motile responses of individual leucophores was developed. Leucophores from scales of the medaka, Oryzias latipes, were used as a model. The intensity of light scattering from the peripheral dendritic zone (Sp) and that from the cell body (Sc) of each leucophore were separately transduced to the current changes, which were then converted to voltages, and appropriately amplified. Output voltages of both channels were represented as "Vp = A1 × Sp", and "Vc = A2 × Sc", where A1 and A2 were the overall amplification coefficients for these channels, respectively. When leucosomes dispersed from the cell body into the dendrites, the Vp increased and the Vc decreased, while the reverse changes occurred when the leucosomes aggregated. Using a simple electronic circuit, the remainder of the two outputs, namely, Vp - Vc, could easily be obtained and recorded. As alternative expressions of the response, the ratio of the outputs (Vp/Vc), its square root (√Vp/Vc), or √(Vp + vp)/(Vc + vc) could also be recorded using integrated circuits developed for such purposes (vp, vc: voltage biases applied to Vp and Vc). The relative merits of these types of analysis are discussed. Similar analysis should also be applicable to the motile activities of iridophores of the dendritic type, such as those of some gobiid fish.