The laboratory for Genetics and Microbiology works on selected model systems which appear suitable to approach general questions of molecular biology. The main emphasis is on mechanisms of regulation in prokaryotes (model Bacteria as Escherichia coli and extremophilic Bacteria and Archaea). The pursuit of these objectives has produced acknowledged contributions in the fields of DNA-protein interactions, the mechanisms of chromosomal rearrangements and their consequences for gene expression, the mechanisms of allosteric transitions and bacterial and archaeal genetic regulatory mechanisms. Those investigations have provided us with an extensive background of fundamental and practical knowledge concerning a number of genes and enzymes which we now use as experimental systems to probe the molecular basis of adaptation to extreme of temperatures and pressure in selected bacterial and archaeal species. In addition, the earlier studies have shed new light on the complex mechanisms which regulate carbamoylphosphate biosynthesis and utilisation in E.coli and revealed unexpected evolutionary relationships between regulation and recombination.