Immunodetection of amelogenin-like proteins in the ganoine of experimentally regenerating scales ofCalamoichthys calabaricus, a primitive actinopterygian fish

BACKGROUND: The account of the present study is to test our previous hypothesis that ganoine, a highly mineralized layer found at the scale surface of primitive actinopterygian fish, could be homologous with the enamel covering the crown of vertebrate teeth. METHODS: Immunocytochemical techniques have been carried out on regenerating scales of a primitive polypterid, Calamoichthys calabaricus, with three antibodies to mammalian amelogenins. RESULTS: The present study provides the first evidence that ganoine contains molecules which cross-react with mammalian amelogenin proteins. CONCLUSIONS: This result is consistent with our previous findings that ganoine and enamel can be considered as homologous tissues. Moreover, the presence in ganoine of a primitive actinopterygian of amelogenin-like proteins, which share epitopes with amelogenins of mammalian enamel, indicates that the gene(s) coding for these proteins appeared earlier than previously suggested and supports the hypothesis that amelogenins show a highly conserved structure through vertebrate evolution.