THE NA-ATPASE ALPHA-SUBUNIT REQUIRES GASTRULATION IN THE XENOPUS EMBRYO(, K+)

Na+, K+-ATPase participates in reabsorption of ions and water and prod uces an electrochemical gradient between the intra-and extracellular s paces across the cell membrane. It also plays an important role in man y developmental phenomena such as a blastocoele formation and neural f ormation. To elucidate the expression pattern of Na+, K+-ATPase in the Xenopus embryo, the spatial expression patterns of the Na+, K+-ATPase a subunit were studied in a normal embryo by whole-mount in situ hybr idization. These transcripts were localized around the dorsal blastopo re at the gastrula stage, in the neural tube at the neurula stage, and then in the pronephros and cloaca at the tail-bud stage. To study the function of Na+, K+-ATPase in embryogenesis after mid-blastula transi tion, the expression of the Nat, K+-ATPase a subunit was inhibited by the injection of specific antisense RNA. Embryos injected with Na+, K-ATPase antisense RNA showed inhibition of gastrulation. When antisens e RNA was injected into the dorsal blastomeres, head differentiation w as markedly inhibited. These results suggest that this transcript play s an important role during gastrulation and head differentiation.