 For example, in PBR322 methylation at the tetracyclin resistant gene makes the plasmid liable to tetracyclin; after methylation at the tetracyclin resistant gene if the plasmid is exposed to antibiotic tetracyclin, it does not survive.Diversity of T cell receptor (TCR) genes is generated by nucleotide insertions upon V(D)J recombination from their germline-encoded V, D and J segments.Nucleotide insertions at V-D and D-J junctions are random, but some small subsets of these insertions are exceptional, in that one to three base pairs inversely repeat the sequence of the germline DNA.