The transfer of free deoxyribonucleic acid (DNA) into cells is a powerful tool for genetic and viral studies. The mechanism of uptake and integration of homologous DNA is, however, little understood. Its occurence in a wide variety of biological systems, including mammalian, has been inferred and it may play an important role in cancer. We propose to investigate the nature of the cell membrane involved in the uptake of DNA at the specific period of competence in the model system of transformation in Bacillus subtilis. In particular we will investigate the possibility that specific DNA binding proteins participate in DNA uptake. The role of specific deoxyribonucleases in the process of penetration and integration will also be studied. Mutants blocked in different stages of the process will be employed in these studies to identify the component stages.