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BP: Fachverband Biologische Physik

BP 10: Posters: Tissue Dynamics \& Developmental Processes

BP 10.4: Poster

Montag, 14. März 2011, 17:15–20:00, P3

Two redundant negative feedback loops in the zebrafish segmentation clock — •Saul Ares¹, Luis G. Morelli², Christian Schröter², Korneel J. I. Hens³, Sebastian J. Maerkl³, Bart Deplancke³, Andrew C. Oates², and Frank Jülicher¹ — ¹Max Planck Institute for the Physics of Complex Systems, Dresden — ²Max Planck Institute of Molecular Cell Biology and Genetics, Dresden — ³École Polytechnique Fédérale de Lausanne, Switzerland

Rhythmic processes are widespread in biology and organisms have evolved different mechanisms to control them. The segmentation clock is a transcriptional oscillator that operates during development and organizes the segmentation of the vertebrate body axis. The hes6 gene has recently been shown to control the clock's period. However, its interaction with other components of the clock, as the cyclic genes her1 and her7, is not known. To study the role of hes6 in the zebrafish segmentation clock, we propose a theory of the gene network controlling the expression of cyclic genes her1 and her7. This gene network is motivated by experimental evidence from genetics, yeast one-hybrid and in vitro assays. The theory comprises two distinct, redundant negative feedback loops. One of these loops relies on a Her7/Hes6 heterodimer, and the other on a Her1 homodimer. Intercellular communication is mediated by two different Hes6 heterodimers and a Her1 protein homodimer. An intriguing finding in our experiments is the rescue of the strong her7 mutant phenotype by further mutating hes6. The theory describes this rescue as an effect of restoring the balance in intercellular communication, which is perturbed in the her7 mutant.