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

Abstract

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. Immunocytochemical techniques have been carried out on regenerating scales of a primitive polypterid, Calamoichthys calabaricus, with three antibodies to mammalian amelogenins. The present study provides the first evidence that ganoine contains molecules which cross-react with mammalian amelogenin proteins. 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.