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oai:www.ideals.illinois.edu:2142/77666 2023-07-11 col_2142_5131 col_2142_16357 com_2142_5130 com_2142_16356 com_2142_8913 com_2142_8903

1987 Cheeseman, John M. Lazof, Dennis Boyd 2015-05-14T15:19:18Z 2015-05-14T15:19:18Z 10000-01-01 1987 Techniques of compartmental analysis were adapted to the study of intact roots of rapidly-growing Spergularia marine and Lactuca sativa. Using large numbers of plants short time-courses of uptake and chase, $\sp{42}$K$\sp+$ and $\sp{22}$Na$\sp+$ transport could be resolved, even during a chase following a brief 10 minute labeling period. The use of intact plant systems allowed distinction of that portion of the isotope flux into the root, associated with the ion-conducting symplasms. A small compartment, which rapidly (t$\sb{.5}$ $<$ 1 min) exchanges with the external medium was implicated in the radial transport of N$\sp+$, accounting for the observed obtention of linear translocation rates within minutes of transferring to labeled solution. At the 90 mol m$\sp{-3}$ Na$\sp+$ steady-state, 90% of the contents of this compartment exchanged out to the medium during a chase, while the remaining 10% translocated to the shoot in the first few minutes of the chase. The ion contents of this compartment varied in proportion to the external ion concentration. When K$\sp+$ was at a high external concentration, labeled K$\sp+$ exchanged into this same symplasm, but chasing a short pulse indicated that K$\sp+$ transport to the xylem was not through a rapidly-exchanging compartment. At physiological concentrations of K$\sp+$ the evidence indicated that transport of K$\sp+$ across the root proceeded through a compartment which was not exchanging rapidly with the external medium. The rise to a linear rate of isotope translocation was gradual and translocation during a chase, following a brief pulse, was prolonged, indicating that this compartment retained its specific activity for a considerable period. In computer simulation modeling, it was shown that specialized ion-transporting symplasms needed to be incorporated into the compartmental model. An alternative model with specialized conducting compartments for Na$\sp+$ and K$\sp+$ was required to overcome the major difficulties. In the case of K$\sp+$, it was necessary to virtually eliminate uptake from the external medium by exchange in order to simulate the experimental results. Made available in DSpace on 2015-05-14T15:19:18Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 8803105.PDF: 4433401 bytes, checksum: 560ab3d387fa02dac79bea1cbb4744e6 (MD5) Previous issue date: 1987 Embargo set by: Seth Robbins for item 78876 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 160 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987. http://hdl.handle.net/2142/77666 (UMI)AAI8803105 eng Biology, Plant Physiology Compartmental Analysis of Roots in Intact Rapidly-Growing Spergularia Marina and Lactuca Sativa: Partial Characterization of the Symplasms Functional in the Radial Transport of Sodium Ion and Potassium Ion text Plant Biology Botany University of Illinois at Urbana-Champaign Dissertation Ph.D.