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Study of Phototropism in Arabidopsis thaliana in Microgravity on the ISS.  B.A. Butler, P. Kumar, and J.Z. Kiss.  Department of Botany, Miami University, Oxford, OH 45056.

   Phototropism is a fundamental and essential process in plants that is influenced by the presence of certain phytochromes as well as other tropisms.  The process is not fully understood because it is difficult to distinguish the combined roles that phototropism and gravitropism play in the direction that a plant grows.  To free plants from the influence of gravity, the Arabidopsis seedlings were grown in the European Modular Cultivation System (EMCS) on board the International Space Station (ISS).  The seedlings were placed within experimental unique equipment (EUE) that was designed specifically for this experiment that was termed TROPI for tropisms.  The EUE contains an experimental container (EC) that includes many cassettes that hold the seedlings and provide white, blue and red LEDs for the photostimulation of the seedlings.  Three different phy mutants (phyA, phyB, and phyAB) as well as the Ler WT were used in this experiment.  The progression of the seedlings from germination to 6 day old seedlings was captured by a high resolution camera that is located within the EMCS.  The TROPI experiment contained three Runs that took place between October and December 2006.  The tropic responses of the seedlings were recorded on video tapes and returned to Earth in December 2006 and June 2007.  The original NASA tapes were then converted into digital video tapes that then were copied onto the hard drive of a computer and downloaded into still images.  The remaining images were then selected and sorted by the cassette number (1- 160) and placed in separate folders.  Once the seedling cassettes were arranged, the time of each still image of the cassettes will then be viewed in chronological order.  The preliminary organization of the data will then be followed by the measurement of the angle curvature of the shoots and roots of the Arabidopsis seedlings.  The expected result of this experiment is that phototropism in roots and shoots should be greater in microgravity compared to the ground-based controls.  This project will give insight into the interaction between phototropism and gravitropism in plant development.