Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 38: Active cell and tissue mechanics (focus session) II

BP 38.3: Talk

Thursday, April 3, 2014, 15:45–16:00, HÜL 386

Mechanical properties of syncytial Drosophila embryos by high-speed video microrheology — •Alok D. Weßel and Christoph F. Schmidt — Drittes Physikalisches Institut, Georg-August-Universität Göttingen, Germany

In the early syncytial stage Drosophila melanogaster embryos nuclei are duplicating, but are not yet separated by membranes. They are interconnected by cytoskeletal polymer networks consisting of actin and microtubules. Between division stages 9 and 13, nuclei and the cytoskeletal networks form a well-ordered 2D cortical layer. To understand the underlying mechanical properties and dynamics of this self-organizing "pre-tissue", we have measured shear elastic moduli of the interior of the embryo and its cortical layer by high-speed video microrheology. We have recorded position fluctuations of injected micron-sized fluorescent beads with a high-speed camera at kHz sampling frequencies. In that manner we can analyze the local mechanics of the embryo in time and space. The interior of syncytial embryos shows a homogeneous, viscously dominated character with a viscosity approximately 300 times higher than water. In the actin-rich outer layers, near the nuclei, we measured a viscoelastic response. Furthermore we were able to resolve temporal variations of the shear modulus inside the layer.