Dimorfismo sexual en el crecimiento somático del pez cíclido Cichlasoma dimerus

FOSSATI, MARIANA; KARP, PAOLA; PÉREZ SIRKIN DANIELA IRINA; DELGADÍN, TOMÁS; SOMOZA, GM; VISSIO, P

Ciudad Autónoma de Buenos Aires

Jornada; XIV JORNADAS DE LA SOCIEDAD ARGENTINA DE BIOLOGIA; 2012

Sociedad Argentina de Biología

In all vertebrates, growth is regulated by the GH/IGF-I axis. Growth hormone is synthesized and released from the pituitary gland under regulation by the hypothalamus. In many teleost fish, there is a sexually dimorphic pattern in body growth. In Cichlasoma dimerus, we observed that males growing faster and larger than females when placed in community tanks of three couples but not of four couples or in individual tanks. In this context, the objective of this study is to analyze if the differential growth depend on the differential food intake. Six fishes (three couples) were kept for two months in a common tank and the reproductive behavior was analyzed. At the end of the experiment all the parameters of somatic growth were significantly higher in males than females . Also we measured by PCR the levels of IGF-I in males and females. In order to test if that the difference in growth between males and females is due to a differential food intake we analyze the hepatosomatic index (as an indirect indicator of metabolic status) and the levels of CRH and orexin (anorexigenic and orexigenic peptides respectively). In none of these parameters we observed significant differences concluding that the differential somatic growth is not due a differential food intake. In future experiments the role of sexual hormones in somatic growth will be analyzed.