The major objective of these studies has been to obtain a basic understanding of the structural arrangement of specific viral DNA sequences within several groups of oncogenic and nonocogenic human adenoviruses. A number of unique features have been described which may have implications in viral replication or carcinogenesis or both. However, also central to these studies has been the development of a technology which would allow the collection of preparative amounts of both physically and genetically defined fragments of DNA with the ultimate goals of (1) relating these DNA sequences to those biochemical activities which permit these viruses to influence or gain control of cellular functions (e.g., cell lysis and transformation and (2) of defining basic mechanisms for regulation of genetic expression (e.g., initiation of DNA synthesis).