This proposed research program is a direct extension of our earlier program with the same 1 fundamental goals: the investigation of reproduction, and the molecular mechanisms that control genetic activity. Specific aims include: determination of the biological significance of the individual cis regulatory sites of Cyllla and SM50 genes; cloning, characterization, and studies on the localization and synthesis of the trans regulatory factor directing expression of these genes; exploration of upper levels of the regulatory control hierarchy, including search for elements shared amongst coordinately controlled genes; experiments on normal and chimeric embryos using molecular probes to investigate induction and localization in early development; extension of knowledge of specification and cell lineage in the embryo, and determination of the origin of lineage elements using imaginal rudiments; carrying out studies on transcription in oogenesis: utilizing evolutionary change and conservation in sequences important for developmental gene regulation for assessment of functional significance; development of paradigms for photoperiodic control of gonadal cycle in cultured sea urchins producing and characterizing inbred lines of laboratory sea urchins, and attempting to-induce and exploit hermaphroditism for research purposes.