Plant and Cell Physiology, 1987, Vol. 28, No. 6 1101-1108
© 1987
Article |
Chlorophyll-Protein Complexes and other Thylakoid Components at the Low Intensity Threshold in Euglena Chloroplast Development
Institute for Photobiology of Cells and Organelles, Brandeis University Waltham, MA 02254, U.S.A.
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The plastids of dark-grown resting cells of Euglena gracilis Klebs var. bacillaris Cori undergo only limited development when illuminated at the developmental threshold for light intensity 7 foot-candles (ft-c) (27 µW/cm2). In the present work, we have found that these low intensity cells have substantial amounts of electron transport components such as ferredoxin-NADP reductase and Cyt c-552 but only trace amounts of the major antenna components such as the light-harvesting Chl-protein complex (LHCP), the LHCP oligomer, CP la, Chi b and the 26.5 kDa apo-LHCP; CP I and CPa are at levels comparable to the electron transport components. Exposure of the low intensity cells to normal light intensity causes large increases in major antenna components and small increases in electron transport components. The kinetics of accumulation of the antenna components Chi b and apo-LHCP during greening of dark-grown resting cells at normal intensities are the same as for Chi a. The low intensity wild-type cells strongly resemble mutants of Euglena low in Chi b grown at normal intensities in lacking major antenna components.
(Received April 7, 1987; Accepted June 19, 1987)
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