Seminars of the Focus Area Complex Systems

Prof. Dr. C. Beta, Prof. Dr. K. Dethloff, Prof. Dr. R. Engbert, Prof. Dr. M. Holschneider, Prof. Dr. W. Huisinga, Prof. Dr. Ralf Metzler, Prof. Dr. A. Pikovsky, Prof. Dr. S. Reich, Prof. Dr. M. Rosenblum, Prof. Dr. G. Rüdiger, Prof. Dr. T. Scheffer, Prof. Dr. F. Scherbaum, Prof. Dr. J. Selbig, Prof. Dr. F. Spahn

Seminar

Speaker: Gustavo Martínez-Mekler, Instituto de Ciencias Fisicas, UNAM, Cuernavaca, Morelos. México Centro de Ciencias de la Complejidad, UNAM, D.F., México, and Dípartimento di Física, Università degli Studi di Firenze, Italy

Title: Sperms in Quest of the Holy Egg * Colloquium on Complex and Biological Systems

Time: Fri, Nov 30, 2012, 10:15am

Place: bldg 28, room 0.108

Abstract:
Fertilization is one of the fundamental processes of living systems. In this talk I describe how sea urchin sperms swim towards the egg. Experiments, some performed within our research group, have shown that Ca2+ oscillations triggered by the binding to the sperm flagellum of chemicals secreted by the oocyte, modify sperm navigation and in some cases produce chemotaxis. For a better understanding of this process, we construct a logical regulatory network for the Ca2+ signaling pathway [1]. This Boolean type model reproduces behaviors previously observed and provides predictions, some of which we have confirmed with new experiments. I present several sperm swimming videos that corroborate these findings. The encounter that the discrete network dynamics operates at criticality is a matter for reflection. I also introduce semi-continuous and continuous formalisms for the dynamics, as well as a space-time proposal. The models provide a clue for the presence or absence of chemotaxis observed in different sea urchin species [2] , as well as some insight on the operation of drugs that disorient the spermatozoa [3,4]. These results may be relevant to fertility issues. Finally, as an overview, I comment on some aspects of sperm motility related to other levels of description, such as molecular machines present in the flagellum and hydrodynamic considerations. A proper understanding and integration of these levels of description is an open challenge.

[1]Espinal, J., Aldana, M., Guerrero, A., Wood, C. D., Darszon, A., and Martinez-Mekler, G. (2011). Discrete dynamics model for the speract-activated Ca2+ signaling network relevant to sperm motility. PloS ONE 6(8): e22619.

[2] Guerrero, A., Nishigaki, T., Carneiro, J., Yoshiro Tatsu, Wood, C. D., and Darszon, A. (2010). Tuning sperm chemotaxis by calcium burst timing. Dev Biol, 344(1):52

[3] Guerrero, A., Espinal, J., Wood, C.D., Rendon, J.M., Carneiro, J., Martínez-Mekler, G., Darszon, A., Niflumic acid disrupts marine spermatozoan chemotaxis without impairing the spatiotemporal detection of chemoattractant gradients (submitted to Journal of Cell Science).

[4] Espinal J, Darszon, A., Wood, C., Guerreo A, Martínez-Mekler G, In silico determination of the effect of multi-target drugs on sea urchin spermatozoa motility (to be submitted)

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Past NLD Seminars (1994-2007) & (2008 ...)

Students' seminar: Theoretical Physics, PIK, Modeling & TSA Berlin-Potsdam-Colloquia: PhysGesellschaft Berlin, TU Berlin, Pro Physik, AIP, AEI, MPI-KGF, GFZ, HMI, PIK, AWI, Max Planck Institute for the History of Science, Mathematik, DPG Disputationen, & Vorschau UP

Udo Schwarz, Zentrum für Dynamik komplexer Systeme,
Universität Potsdam, Campus Golm Karl-Liebknecht-Str. 24, 14476 Potsdam, building 28, room 2.107
Phone: (+49-331) 977-1658, Fax : (+49-331) 977-1045

Email: Udo.Schwarz AT uni-potsdam.de

DFG SFB 1294

DFG Sonderforschungsbereich 1294 Data assimilation

DFG SPP 1488

DFG Schwerpunktprogramm 1488 Planetmag


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