The objective of this proposal is to investigate the molecular mechanisms underlying the determination of cell fate in embryonic development. In this study the engrailed gene of Drosophila, a gene that is essential for the determination of the anterior and posterior cell lineages of body segments, will be analyzed. Dr. O'Farrell has proposed to develop a new assay which will enable him to follow and analyze the fate of individual cells in early development. The second major specific aim is to investigate regulatory elements of the engrailed gene as defined by other genes that interact with engrailed. By applying both approaches this study will define when and where determination of patterns of engrailed expression occurs and will define events controlling pattern regulation. Identification of the developmental fate of the descendants of the cells that express the engrailed gene at the blastoderm stage of the Drosophila embryo is important for an understanding of the genetic regulation of segmentation. The method of marking cells will be a useful technique which will benefit all developmental biologists studying Drosophila.
