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Modeling the Aux/IAA Pathway . Presentation by Labeed Ben-Ghaly. Overview: . Motivation Background The Project Future Work. Motivation. To provide provide a quantitative and cellular description of plant development . Confocal microscope, Zeiss LSM-510.
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Modeling the Aux/IAA Pathway Presentation by Labeed Ben-Ghaly
Overview: • Motivation • Background • The Project • Future Work
Motivation • To provide provide a quantitative and cellular description of plant development
Phyllotaxis, pattern formation in plants • New plant organs appear at the SAM in a remarkably symmetric fashion • The spiral pattern and the connection to the Fibonacci series and Golden angle have attracted theoreticians • Lots of models exist and new experimental data have illuminated molecular connections to the patterns
Introduction to Auxins • Concentrations of the plant hormone Auxin play a major role in plant development.
How is Auxin activity regulated? • Lateral inhibition between primordia. • Reaction-diffusion inhibitor model. • Depletion of primordium promoting factor. Jönsson H, et al 2006
Aux/IAA • Indole-3-acetic acid (IAA) • Capable of creating new primordium when added to developing tissues. Reinhardt et al 2003
Modeling the Pathway • Signal from older/incipient primordia • Auxin flux • Auxin concentration Simple model Active vs. Passive transport A- + H+ AH
degradation passive transport active transport production Modeling the Pathway ai – auxin concentration Pij –PIN1
Analysis of Auxin Model • Analysis predicts when the model will spontaneously create auxin peaks • Also predicts distance between peaks T - active transport D - inactive transport Kd - degradation
Concluding remarks • Models can be used to indicate what players and interactions might be sufficient for driving phyllotaxis • Experiments to test the auxin model
Thank-you • SoCalBSI • Bruce Shapiro • Elliot Meyerowitz • BNMC • WaterTree • NIH
References • (2006) Mjolsness E. Modeling transcriptional regulation with equilibrium molecular complex composition, 5th International Conference on the Bioinformatics of Genome Regulation and Function (BGRS-2006), Volume 1, pp. 118-121. • (2006) Jönsson H, Heisler M, Shapiro BE, Meyerowitz EM, Mjolsness ED. An Auxin-driven polarized transport model for phyllotaxis. Proc. Natl. Acad. Sci., U.S.A., 103(5):1633-1638. • (2006) Alon, Uri An Introduction to Systems Biology: Design Principles of Biological Circuits. CRC