The long term objective of this proposal is to understand how cytoplasmic factors interact with the genome to effect determination and differentiation during early development. Since the primary germ layers arise during the period when the maternal components of the egg are present and can effect gene expression, it is important that we understand how the components of the embryo interact to establish these layers. As a model system Dr. Showman is examining the gene coding for alkaline phosphatase in the embryonic endoderm of Spisula solidissima. Using a combination of cell marking and cell deletion studies he will determine the lineage of the cells expressing alkaline phosphatase and the role of cell interactions in the lineage determination process. Coincidentally the gene for Spisula alkaline phosphatase will be cloned and characterized in terms of time of mRNA synthesis, message prevalence, polysome association, tissue specificity and reiteration frequency. Finally the gene will be sequenced to determine its overall structure. From these studies he will learn the role played by specific cytoplasmic components in regulating the expression of a unique marker of a defined cell lineage and be in a position to begin an analysis of the cytoplasmic components themselves. %%% This study addresses the mechanism of determination and differentiation of specialized cells during the process of embryogenesis. %%%
