LAG PERIOD CHARACTERIZING THE ENTRY OF TRANSFORMING DEOXYRIBONUCLEIC ACID INTO BACILLUS SUBTILIS.

Levine, James S. (Yale University, New Haven, Conn.), and Norman Strauss. Lag period characterizing the entry of transforming deoxyribonucleic acid into Bacillus subtilis. J. Bacteriol. 89:281-287. 1965.-The kinetics of appearance of transformants as a function of time of exposure to deoxyribonucleic acid (DNA) has been studied in Bacillus subtilis. A short lag period of approximately 1 min at 37 C is evident when the transformation is terminated with deoxyribonuclease. The length of this lag is independent of the genetic trait transferred. Moreover, the lag is unaffected by transforming DNA concentration, by the presence of homologous unmarked DNA, and by shearing and cross-linking of the transforming DNA. The lag shows a strong inverse temperature dependence. The energy of activation is 13.9 kcal. The lag is abolished when the transformation is terminated by washing instead of by addition of deoxyribonuclease. These results are taken to indicate an immediate adsorption of DNA to cells, followed by a deoxyribonuclease-sensitive period of 1 min, during which time the genetic trait is entering the cell. These results make feasible an investigation of the configuration assumed by the DNA molecule during entry into the cell.