Effect of background colour on somatic growth in Cichlasoma dimerus.

CÁNEPA, MAXIMILIANO; PEREZ SIRKIN, DANIELA; PANDOLFI, MATÍAS; MAGGESE, M. CRISTINA; VISSIO, PAULA G.

Calgary, Cánada

Simposio; 6TH INTERNATIONAL SYMPOSIUM ON FISH ENDOCRINOLOGY (6ISFE); 2008

Melanin-concentrating hormone (MCH) is a cyclic hepta-decapeptide synthetized in the hypothalamus. It was first isolated from the pituitary of chum salmon. Its original name is related with its first described function in teleost: making the skin pale through the aggregation of melanin granules. In mammals, the most studied MCH function is its central role on feeding behaviour. Recently, the effect of MCH in teleost food intake was studied in goldfish and barfin flounder. This MCH biological function can be very useful for aquaculture, so increasing this knowledge in divergent teleost species is very important. In teleost fish MCH expression can be increased or decreased by manipulating background colour. HYPOTHESIS: In Cichlasoma dimerus MCH increases food intake like in mammals so that a somatic growth will be observed in white-reared animals. METHODS & RESULTS:  The cichlid fish C. dimerus was chosen as experimental model. They show a marked colour display during stress, mating and environmental changes. Three independent experiments were first carried out in order to validate the use of the heterologous systems that will be used to perform feeding experiments: 1) The deduced aminoacid sequence of C. dimerus MCH was similar to other teleost species; 2) In vitro culture scales produced melanin aggregation in a dose dependent manner with MCH 3) Intramuscular injections of increasing MCH concentrations produced skin paling in a dose dependent manner (p