The ultimate objective of the work in my laboratory is to understand the early development of vertebrates at the molecular level. Our approaches include the isolation of genes that play a critical role, analysis of their expression and function, and examination of the mechanisms whereby patterns of gene expression are altered in early development. We have chosen to study this problem primarily in Xenopus because the embryos are large and easy to manipulate surgically, and the function of macromolecules, such as mRNA or protein, can be assayed by injection into living embryos. Furthermore, the stages of development when the dorso- ventral and antero-posterior axes form are readily accessible to biochemical and embryological analysis. In the next five years we will have two major objectives: first we will study the molecules that induce and pattern the mesoderm before and during gastrulation. Second, we will determine the molecular basis for neural induction and neural patterning. To carry out these aims we will clone peptide growth factors and signal transduction components that are used in embryonic patterning. Molecules that are used in early embryogenesis are reused, often for different purposes, later in development. Thus, increasing our understanding of early development will aid in understanding and treating diseases of the adult.