The investigators will determine what role cell lineage plays in the specification of cell fate during vertebrate neuronal development. They will study the early embryo of the zebrafish, in which they can mark individual cells, transplant them, and follow them as they develop in living embryos. They have shown previously that gastrula cells generate clones restricted to single tissues, yet if the cells are transplanted, they produce new lineages. The early cells, therefore, may express position- specific developmental programs that determine their early behavior, but do not restrict their potential. To further our understanding of the developmental roles of cell lineage, the investigators will study in vivo the lineages that normally arise from singly marked cells, learning the patterns of division, movements, and lineage relationships of a variety of cell types, including identified neurons. To investigate cellular commitments and clues provided by the environment, they will examine lineages and fates of cells transplanted individually between embryos.
