| Citation | Mariann Bienz has studied the way in which the transcription of key genes is regulated according to the position of cells within an embryo. She was the first to exploit the Drosophila midgut as a model experimental system: she discovered that the endodermal cells are patterned by signals from the overlying mesodermal cells, and that these signals also regulate the homeotic gene Ultrabithorax which initiates this inductive cascade. Her systematic analysis has yielded a molecular description of this entire inductive pathway, revealing how an extracellular signal is translated into a specific switch in gene activity. This work has broad significance, since the same signalling pathways are implicated in human cancer. |