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BP: Fachverband Biologische Physik

BP 30: Posters: Physics of Cells

BP 30.12: Poster

Thursday, March 17, 2011, 17:15–20:00, P3

Growth dynamics of Physarum polycephalum on different length scales — •Christina Oettmeier, Erik Bernitt, and Hans-Günther Döbereiner — Institut für Biophysik, Universität Bremen, Germany

The amoeboid slime mold Physarum polycephalum is a big single-celled organism with several hundred or thousands of nuclei. It can reach sizes of 10 to 100 cm or larger. Physarum exhibits a wide range of movement patterns, ranging from amoeboid crawling to oscillations with different amplitudes and periods. The most prominent example is the so-called shuttle streaming, the contraction and relaxation of the organism’s veins. This rhythmic pattern of contraction and relaxation serves to transport cytoplasm throughout the network and is caused by the contraction of acto-myosin structures.
Microplasmodia, a special growth form characterized by its spherical shape, were used as the starting form to grow networks. High-resolution movies were taken under a bright-field microscope and provide insights into the spatio-temporal dynamics. Pronounced oscillations could be observed and analysed quantitatively: A fast oscillation with a period of 1 to 2 minutes as well as a superimposed slow oscillation with a period of about 20 minutes were found. Lateral contraction waves running along the periphery with a speed of about 10 m/s could also be observed. Additionally, the morphology of the microplasmodia was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) pictures. Pores with a diameter of about 2 µm were located together with a system of corresponding channels.