Kinetics of C-14 Translocation in Soybean: III. Theoretical Considerations
1Department of Biochemistry and Biophysics, Iowa State University, Ames, Iowa.
Abstract:
Based largely on data from soybean, some mathematical models are derived to describe the transport kinetics of (14)C-photosynthate. The effects of leaf size, leaf shape, and translocation velocity on the rate of tracer efflux from the leaf are considered, and it is shown that the duration of these effects will approximate the time required for tracer to reach the petiole from the farthest point of the leaf. This duration is designated as the "kinetic size" of the leaf. Although its effect will be slight in the case of soybean (about 2 to 3 minutes), a considerable effect of the kinetic size will be found in the case of large leaves, or when the translocation velocity is low.Source pool kinetics in soybean are described by a two-compartment model, one compartment representing a photosynthetic compartment and the second (the source pool) a nonphotosynthetic compartment next to the veins. The kinetics in the petiole are approximated by a two-compartment model representing the translocation stream and tissues outside the translocation stream. A combination of the models predicts fairly accurately the translocation kinetics observed in soybean.The models are compared with others in the literature. Although the assumptions are in substantial agreement with those made by Evans, Ebert, and Moorby, they are inconsistent with the model based on the movement of transcellular strands presented by Canny and Phillips.
Related Concept Videos
Short-distance Transport of Resources
Protein Diffusion in the Membrane
Directionality of Nuclear Transport
Transport Across the Golgi
Protein Transport to the Inner Chloroplast Membrane
Protein Dynamics in Living Cells
Fluorescent recovery after photobleaching (FRAP) is a fluorescent-protein-based detection technique used to quantify protein movement rates within the cell. This method exposes a small portion of the cell to an intense laser beam. The laser beam causes permanent photobleaching of the fluorophore-tagged proteins in the exposed region. As the bleached...


