GLYCOCONJUGATE EXPRESSION CHANGES DURING RANA-DALMATINA EARLY DEVELOPMENT

Glycoconjugates are generally involved in cell adhesion and morphogene tic movements. To investigate their distribution and expression change s during amphibian development, several FITC- or HRP-labeled lectins w ere used in Rana dalmatina embryos and larvae. During gastrulation, WG A, ConA, HPA, GSA-I, PNA and RCA-I labeled either the envelopes on the perivitelline space-contained substances, while ectodermal cells and/ or extracellular matrix were mainly labeled by WGA, GSA-I, DBA and LTA . In these structures, fibronectin-like molecules were also found. Con A, HPA, RCA-I, SEA also labeled ectoderm, but with lower affinity. At larval stages, ectodermal derivatives, such as larval skin, central ne rvous system, eye and ear, were also strongly labeled by WGA, DBA and LTA, while the affinity to ConA, HPA, GSA-I, SEA, appeared less visibl e; the affinity sites to RCA-I and PNA were totally lacking. Fibronect in-like immunoreactivity was hardly present at the larval stages. Thes e results point out that glycoconjugate expression changes in cell sur face and in extracellular matrix might be developmentally regulated. F or this reason the different glycoconjugates seem to play stage-specif ic roles in early development.