Berlin 2018 – scientific programme
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BP: Fachverband Biologische Physik
BP 36: Cell Adhesion and Migration, Multicellular Systems II
BP 36.8: Talk
Friday, March 16, 2018, 11:30–11:45, H 1028
Temperature gradients characterize, counteract and rescue P granule segregation in C. elegans — •Anatol W. Fritsch1, Matthäus Mittasch1, Carsten Hoege1, Frank Jülicher2, Anthony Hyman1, and Moritz Kreysing1 — 1MPI-CBG, Dresden, Germany — 2MPI-PKS, Dresden, Germany
Recent studies report on membrane-less condensates in cells, that are formed by liquid-liquid phase separation. In C. elegans zygotes condensates, named P granules, segregate asymmetrically to one daughter cell during the first cell division. This process is involved in the development of a functional germ line. More specifically, the asymmetric localization of P granules depends on a protein gradient of MEX-5 along the long axis of the zygote. MEX-5 in turn, is thought to act through an mRNA competition mechanism and locally regulates the phase separation of the of the condensates.
Using a strategy based on the physical principles of phase-separation, we are able to rescue the asymmetric localization of P granules in MEX-5 RNAi mutants with defective segregation in vivo. We replace the protein gradient with a localized temperature gradient that mimics the physical mechanisms of the local regulation in phase separation. Furthermore, with this approach, we are able to invert the endogenous spatial distribution of P granules in zygotes. This enables us to study the dynamics of in vivo phase separation via controlled physical perturbations. In this study we conclude, that P granule segregation is a spatially tuned, diffusive-flux dependent, evaporation-condensation phenomenon.