A FUNCTIONAL TEST FOR MATERNALLY INHERITED CADHERIN IN XENOPUS SHOWS ITS IMPORTANCE IN CELL-ADHESION AT THE BLASTULA STAGE

We report here on the consequences of reducing the expression of EP-ca dherin at the earliest stages of Xenopus development. Injection of oli godeoxynucleotides antisense to maternal EP-cadherin mRNA into full-gr own oocytes reduced the mRNA level in oocytes, and the protein level i n blastulae. Adhesion between blastomeres was significantly reduced, a s seen in whole embryos, and in assays of the ability of blastomeres t o reaggregate in culture. This effect was especially conspicuous in th e inner cells of the blastula and included the disruption of the blast ocoel. The severity of the EP-cadherin mRNA depletion and of the disag gregation phenotype was dose dependent. This phenotype was rescued by the injection into EP-cadherin mRNA-depleted oocytes of the mRNA codin g for a related cadherin, E-cadherin, that is normally expressed at th e gastrula stage in the embryonic ectoderm.