A theory proposed by W. Arber to explain host-controlled restriction of bacteriophage growth. According to this model, the DNA of the bacterium contains specific nucleotide sequences that are recognized and cleaved by the restriction endonucleases carried by that cell. The bacterium also contains methylases that methylate these sequences. This chemical modification thus protects the DNA of the bacterium from its own endonucleases. However, these serve to degrade foreign DNA introduced by phages. See Chronology, 1962, Arber; 1972, Kuhnlein and Arber.
Subjects: Genetics and Genomics.