The long term objective of this project is to define the relationship between the events of embryonic development and regulated gene expression in the sea urchin, Strongylocentrotus purpuratus. The specific goals are to characterize the molecular details of the regulation of expression of particular actin genes which are differentially expressed in development. Analysis of transcription in isolated nuclei has indicated that the expression of two cytoskeletal actin genes and the single muscle actin gene is transcriptionally regulated in embryos. Dr. Crain will determine whether the expression of these three actin genes is correctly regulated in interspecific hybrid embryos. The temporal expression of these genes will be assayed by protection of gene and species specific riboprobes from RNase digestion and the spatial expression will be determined by in situ hybridization analysis. Interspecific hybrid embryos of the sea urchin species A. purpuratus and Lytechinus pictus will be constructed in both directions to assess the effect of maternal trans-acting factors on expression of these genes. Mapping of the position of transcription initiation for the muscle actin gene will be done. This information will allow the use of this gene to ask what sequences are important for the muscle specific expression and to ask whether and RNA polymerase III/SINE, which is located within the first intron, plays a role in regulating its expression. Understanding the differential regulation of genes during embryogenesis is basic to an understanding of development at a molecular level. Dr. Crain is using a well established model system, the developing sea urchin, to study this question.
