The ability to regulate gene expression is a fundamental property of all life forms from the simplest virus to the most complex mamammal. To understand how the overall developement of an organism is programmed, it is crucial to understand the different mechanisms which control the expression of individual genes. Our group concentrates on mechanisms controlling mRNA levels. There are two major ways RNA levels are controlled, either by a control of their synthesis (transcription initiation and elongation) or their degradation (by mRNA nucleases). The different projects use either E. coli or B. subtilis as model organisms and can be divided into two major subjects.