A program was established in 1984 to study several aspects of cell motility in developing systems. These systems now include 1) chemotaxis in Dictyostelium, 2) the migration of sea urchin primary mesenchyme cells, 3) the molecular basis of cell motility in vertebrate cells. and 4) growth cone and neuronal activity in Drosophila. A core facility has been established in the program which not only provides image processing and motion analysis technologies for participants, but which has evolved into a developmental facility for 2D and 3D dynamic image analyzing systems. The program also sponsors the Motility Seminar 6 times a semester in which invited speakers present seminars on current subjects of interest in cell motility and the cytoskeleton, and the Junior Motility Symposium which meets at least once each semester, in which graduate students and postdocs present formal seminars on their ongoing research. In the next program period, individual projects will investigate the following major questions: 1) how Dictyostelium amoebae behave in 3D in the natural chemotactic wave, and the defects exhibited by mutants selectively lacking sensory transduction and cytoskeletal molecules (Soll); 2) how a recently identified cell surface glycoprotein initiates migratory behavior in primary sea urchin mesenchyme cells and avian corneal fibroblasts (Solursh); 3) how the different tropomyosin isoforms and caldesmon regulate the interaction of actin and myosin in nonmuscle cell motility (Lin); and 4) how electric activity, intracellular Ca++, and protein kineses regulate Drosophila growth cone motility and neural growth, and the roles of adhesion molecules and ion channels (Wu). In addition, we will continue to develop new software packages for motion analysis in the core facility, continue the Motility Seminar and Junior Motility Symposium, and initiate a new yearly Senior Motility Symposium which will include outside speakers and project directors, and a biannual Core Facility Training and Demonstration Course for motion analysis technology. The core facility will also continue to serve all participants for microscopy, image processing and 2 and 3D motion analysis. This program project focuses on the central theme of cell motility and obtains its vitality from the intense interactions of the participants.