Role of the polyamines in germ cell differentiation and in early embryonic development.

The physiological function of the polyamines in germ cell differentiation and in early embryonic development was studied with the aid of the highly specific polyamine synthesis inhibitors DL-alpha-methylornithine (MO) and DL-alpha-difluoromethylornithine (DFMO). In the invertebrate Ophryotrocha labronica DFMO-induced polyamine deficiency severely affected nucleolar formation and activity in germ cell differentiation as revealed by RNA-labelling experiments and by ultrastructural analysis. Both in an invertebrate (Ophryotrocha labronica) and in a vertebrate (chick), inhibitor-induced polyamine deficiency caused a block of embryonic development at gastrulation. The major ultrastructural effect observed in the arrested embryos was an interference with nucleolar formation. Our data suggest that polyamine synthesis is essential for the ribosomal gene expression that is associated with oogenesis and embryogenesis.