| Modeling light-induced currents in the eye of Chlamydomonas reinhardtii. | |
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MedLine Citation:
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PMID: 12235485 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Rhodopsin-mediated electrical events in green algae have been recorded in the past from the eyes of numerous micro-algae like Haematococcus pluvialis, Chlamydomonas reinhardtii and Volvox carteri. However, the electrical data gathered by suction-pipette techniques could be interpreted in qualitative terms only. Here we present two models that allow a quantitative analysis of such results: First, an electrical analog circuit for the cell in suction pipette configuration is established. Applying this model to experimental data from unilluminated cells of C. reinhardtii yields a membrane conductance of about 3 Sm(-2). Furthermore, an analog circuit allows the determination of the photocurrent fraction that is recorded under experimental conditions. Second, a reaction scheme of a rhodopsin-type photocycle with an early Ca(2+) conductance and a later H(+) conductance is presented. The combination of both models provides good fits to light-induced currents recorded from C. reinhardtii. Finally, it allowed the calculation of the impact of each model parameter on the time courses of observable photocurrent and of inferred transmembrane voltage. The reduction of the flash-to-peak times at increasing light intensities are explained by superposition of two kinetically distinct rhodopsins and by assuming that the Ca(2+)-conducting state decays faster at more positive membrane voltages. |
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Authors:
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D Gradmann; S Ehlenbeck; P Hegemann |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of membrane biology Volume: 189 ISSN: 0022-2631 ISO Abbreviation: J. Membr. Biol. Publication Date: 2002 Sep |
Date Detail:
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Created Date: 2002-09-17 Completed Date: 2003-04-04 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0211301 Medline TA: J Membr Biol Country: United States |
Other Details:
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Languages: eng Pagination: 93-104 Citation Subset: IM |
Affiliation:
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Abteilung Biophysik der Pflanze, Albrecht-von-Haller-Institut für Pflanzenwissenschaften der Universität, Untere Karspüle 2, D-37073 Göttingen, Germany. dgradma@gwdg.de |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Algorithms Animals Chlamydomonas reinhardtii / physiology*, radiation effects* Computer Simulation Dose-Response Relationship, Radiation Electric Conductivity Light* Membrane Potentials / physiology, radiation effects Models, Biological* Photobiology / methods Photoperiod Photoreceptor Cells, Invertebrate / physiology*, radiation effects* Rhodopsins, Microbial / physiology* Sensitivity and Specificity |
| Chemical | |
Reg. No./Substance:
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0/Rhodopsins, Microbial |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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