Let me now comment on the question "what next". Up to now we are working on the descriptive phase of molecular biology. … But the real challenge will start when we enter the synthetic phase of research in our field. We will then devise new control elements and add these new modules to the existing genomes or build up wholly new genomes. This would be a field with an unlimited expansion potential and hardly any limitations to building "new better control circuits" or ..... finally other "synthetic" organisms, like a "new better mouse". … I am not concerned that we will run out of exciting and novel ideas, … in the synthetic biology, in general.

The work on restriction nucleases not only permits us easily to construct recombinant DNA molecules and to analyze individual genes, but also has led us into the new era of synthetic biology where not only existing genes are described and analyzed but also new gene arrangements can be constructed and evaluated.