Cloning and expression analysis of myostatin, fibroblast growth factor 6, insulin-like growth factor I and II in liver and muscle of sea bass (Dicentrarchus labrax, L.) during long-term fasting and refeeding

Abstract

The exceptionally fast growth that fish experience after periods of fasting has been called “compensatory growth”. This phenomenon has been studied in intensive aquaculture as a means of enhancing growth rates, but the mechanisms by which food intake activates an increase in somatic growth, and especially in muscle growth, are complex and not yet fully understood. In the present paper, we describe the molecular cloning and sequencing of sea bass (Dicentrarchus labrax) myostatin (MSTN) and fibroblast growth factor 6 (FGF6), which have been shown to be major genetic determinants of skeletal muscle growth, together with insulin-like growth factor I (IGF-I) and IGF-II, which are potent mitogens known to play important roles in growth and development.We then report the pattern of expression of the four aforementioned genes, in liver and myotomal muscle in response to prolonged fasting and refeeding. Nutritional status significantly influenced the expression of IGF-I, IGF-II and MSTN, whereas the muscular FGF6 expression levels were not affected by the feeding status of the animals. Taken together these data indicate that IGF-I, IGF-II and MSTN are involved in the sea bass muscle compensatory growth induced by refeeding, whereas FGF6 probably has not a role in this phenomenon.