A comparison of the effects of temperature on melanophore in vitro responses to noradrenalin in two teleost species adapted to cold ocean and tropical conditions

Abstract

Melanosome‐aggregating responses to noradrenalin in winter flounder, Pseudopleuronectes americanm Walbaum, manifest different in vitro temperature characteristics compared with such activity in sailfln molly, Poecilia velifera Regan. Winter flounder off St John's are adapted to cold ocean temperatures between − 1° C and + 15° C associated with the Labrador current, whilst sailfin molly is a tropical species adapted to temperatures up to about 30° C. The experimental data indicate that melanophores from these two species are physiologically adapted to function in contrasting thermal environments. Consequently, the optimum temperature for melanosome aggregation in winter flounder is approximately 20° C, and that of the tropical species approximately 40° C. Also, flounder melanophore In vitro responses are relatively uninfluenced by low temperatures, which drastically inhibit sailfin molly melanophore activity.