Cloning of European eel (Anguilla anguilla) FSH-β subunit, and expression of FSH-β and LH-β in males and females after sex determination

The European eel (Anguilla anguilla) is a catadromic teleost species with a complex life cycle, both in sea and freshwater environments. The sex determination phase of gonadal development occurs in a freshwater environment. Polymorphism occurs in increasing rates with respect to gender. While males stop growing at approximately 150 g, females continue to grow to being much larger. In this study, we cloned the cDNA FSH-β subunit of the European eel (A. anguilla), and measured the mRNA levels of FSH-β and LH-β in males and females after sex determination. The FSH-β subunit cDNA consisted of 1068 bp, encoding a 127 amino acid peptide. A comparison between European and Japanese eels of the FSH-β amino acid sequence showed 98% similarity.