With the advent of Pulsed Field Gel Electrophoresis (PFGE) large stretches of DNA can now be readily manipulated thereby facilitating MAR mapping. Three independent research projects within Massachusetts General Hospital are embarking on such mapping. The first, headed by Carl S. Shelley, will identify the MARs associated with the CD43 gene, the second, headed by M. Amin Arnaout will map those associated with the genes encoding the, 2 integrin family and the third, headed by Mason W. Freeman, will map the MARs which flank the scavenger receptor gene. The CD43 and alpha chain 2 integrin genes encode molecules which mediate the adhesive functions of leukocytes. Since these genes are clustered on the pll.2 region of chromosome 16, PFGE will also be used by Dr. Shelley's and Dr. Arnaout's groups to generate a physical map of this cluster. It is anticipated that mapping of the MARs within this cluster will define transcriptional domains and provide the basis for determining the molecular mechanisms which in vivo control the coordinate and differential regulation of these functionally related genes. Drs. Shelley, Arnaout and Freeman currently do not have access to a PFGE system and here funding is requested of the National Science Foundation for its purchase.