Integration and Replication of DNA of M. Iysodeikticus in DNA of Germinating Barley

WE have shown^1-8 that in germinating barley seeds (1 day old), sectioned perpendicularly to the axis and placed on a drop of bacterial DNA labelled with tritium or carbon-14, the foreign macromolecules are absorbed by the endosperm and migrate to the root, where they are immediately taken up into the cell nuclei, apparently without noticeable degradation or immediate re-utilization in endogenous synthesis. Experiments in CsCl gradients have shown that most of the radioactive molecules found in the DNA of the root cells, up to 2 h after application of the foreign labelled DNA, have the buoyant density of this labelled DNA^8,9. Other experiments have followed the fate of these molecules for long times^7,9.