In vitro induction of tyrosinase activity in goldfish (Carassius auratus L.) integument by ACTH and dibutyryl-cAMP.

Tyrosinase was first detected in melanoblasts by the DOPA-oxidase reaction in the presence of catalase in explants of goldfish integument after 12 hr culture with either ACTH (1IU/ml) or DB-cAMP (0.1mM). Melanin did not appear in the new melanocytes until 24 hr. The data indicate that the release of cAMP within the melanoblast in response to ACTH treatment is rapid and the tyrosinase in the melanoblast is released from inhibition and/or activated at least 12 hr prior to melanization of premelanosomes.