Ontologies are well applicable for the description of scientific databases and thus provide appropriate means to link different databases. In a first step it is useful to generate initial ontologies from the respective database schemas. They can be completed with more specific information later on. If the database schemas change, however, these changes should now automatically be propagated to the respective ontologies. Using a realistic example from the biological field of signal transduction pathways, we demonstrate that the suggested approach is both, feasible and reasonable.