INTEGRATION EFFICIENCY AND GENETIC RECOMBINATION IN PNEUMOCOCCAL TRANSFORMATION

Abstract

CONSIDERABLE progress has been made toward an understanding of the molecular basis of transformation in pneumococcus. DNA particles outside the cell compete for entry (HOTCHKISS 1957a). Competent cells indiscriminately take up this DNA at a steady rate to the extent of as much as 5% of their own genetic material (Fox and HOTCHKISS 1957). Immediately following uptake, donor DNA loses its ability to transform other cells This appears to result from the conversion of native donor DNA to single strands upon uptake Within one quarter of a generation donor material recovers its activity, apparently as a consequence of insertion of single-stranded segments into native DNA of the host (LACKS 1969; Simultaneous with this recovery, genetically recombinant DNA appears