[Instability of recombinant molecules]

The regions and mechanisms of recombinant DNAs instability are reviewed, in particular, the mechanisms of the replication instability expressed as elimination of recombinant DNA from cells and the mechanisms of structural instability revealed as spontaneous alteration of the chemical structure of these DNAs. The replication instability is subdivided into that induced by ineffective replication systems, and that induced by disturbances in the process of correct partitioning of the plasmids between dividing cells. The structural instability is subdivided into topological one occurring due to formation in the hybrid plasmids of the anomalous elements of the secondary structure-"loops", the regulatory instability caused by nonbalanced transcription streams and metabolic instability induced because of the protein superproduction which is energy capacious and not necessary for normal cell growth.