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1Author    Eckhard Loos, Ernst KellnerRequires cookie*
 Title    Influence of Magnesium Ions on the Action of Photosystems I and II at Different Wavelengths Experiments with Barley Chloroplasts of Different Chlorophyll b Content  
 Abstract    Barley leaves grown under a natural light/dark regime have a chlorophyll content o f 1300 [ig/g fresh weight and a chlorophyll a /b ratio of 2 .5 -3 . W hen the plants are grown under cycles of 2 min lig h t/1 18 min dark, the respective values are 50 and 5 — 9. W ith chloroplasts with low chlo­ rophyll b content variable fluorescence is depressed by about 30% by MgCl2; with those o f high chlorophyll b content a threefold increase is seen instead. Action spectra for variable fluorescence o f chloroplasts o f high chlorophylll b content show enhancement by Mg2+ around 475 and 650 nm; for the system I-mediated methyl viologen reduction, a depression is seen at these wavelengths. These effects are practically absent in chloroplasts with low chlorophyll b content. The data corro­ borate the hypothesis that a chlorophyll b-containing pigment protein complex is required for re­ gulation of energy transfer to system I and II by magnesium ions. 
  Reference    Z. Naturforsch. 35c, 298—302 (1980); received October 17 1979/January 23 1980 
  Published    1980 
  Keywords    Chlorophyll b, Barley, Magnesium Ions, Wavelength Action 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0298.pdf 
 Identifier    ZNC-1980-35c-0298 
 Volume    35 
2Author    Grzegorz JackowskiRequires cookie*
 Title    The Subcomplex Organization of the Major Chlorophyll «/6-Protein Light- Harvesting Complex of Photosystem II (LHCII) in Barley Thylakoid Membrane  
 Abstract    The major chlorophyll «/b-protein light-harvesting complex o f photosystem II (LHCII) isolated form barley photosynthetic membrane was shown to contain five major polypeptides only two o f which (26.7 and 25.6 kDa) were found to be its true constituents as judged by the ability to migrate as oligomers in various analytical systems. When analyzed by a vertical-bed non-denaturing isoelectric focusing the LHCII was resolved into five trimeric subcom­ plexes (designated 1 -5 in order of decreasing p i) containing either only 26.7 kDa polypep­ tide (subcom plexes 1 and 2) or 26.7 and 25.6 kDa ones associated at 2:1 ratio (subcom plexes 3 -5) . The polypeptide of 26.7 kDa could be split by denaturing isoelectric focusing into fifteen molecular forms while nine molecular species were found to be constituents of 25.6 kDa polypeptide. The subcom plexes 1 -5 contained molecular forms of one or both polypep­ tides associated in sets of 7 -9 . Our findings favour the view that the apoproteins of LHCII are much more heterogenous than thought before. 
  Reference    Z. Naturforsch. 51c, 454 (1996); received November 23 1995/March 4 1996 
  Published    1996 
  Keywords    Barley, Isoelectric Focusing Light Harvesting Complex Polypeptide Subcomplex, Trimer 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0454.pdf 
 Identifier    ZNC-1996-51c-0454 
 Volume    51 
3Author    Grzegorz JackowskiRequires cookie*
 Title    Senescence-Related Changes in the Subcomplex Arrangement of the Major Light-Harvesting Chlorophyll a/b-Protein Complex of Photosystem II (LHCII) as Influenced by Cytokinin  
 Abstract    The major light-harvesting chlorophyll a /b -protein complex of photosystem II (LHCII) from fresh barley leaves could be resolved by non-denaturing IEF into five trimeric subcom­ plexes designated 1 -5 in order of decrasing pi value. IEF-based analysis of PSII particles isolated from leaves in which the processes of senescence were induced by detachement and dark-incubation in the presence of water for 0 -8 days let us reveal that substantial rearrangements of LHCII organization took place throughout the course of senescence com ­ prising a step-wise decline in relative abundance of subcom plexes 1 -3 (down to 0-58% of the initial abundance during 8 days of aging) and an increase in the relative abundance of the subcom plexes 4 and 5. Using SDS-PAGE and immunoblot analysis it was shown that the rearrangements were linked to the changes in the relative levels of LHCII apoproteins i.e. 26.7 and 25.6 kDa ones. The changes comprised the preferential disappearance of the 26.7 kDa polypeptide and an enrichment of 25.6 kD a one and most probably reflect the hetero­ geneity among LHCII apoproteins concerning their stability under the conditions of chi loss. Kinetin was able to repress the senescence-related rearrangements in LHCII subcomplex organization at late stages of aging (5 -8 days) by preventing over this time period the disap­ pearance of 26.7 kD a polypeptide and the enrichement of 25.6 kDa one. 
  Reference    Z. Naturforsch. 51c, 464 (1996); received Novem ber 23 1995/ 
  Published    1996 
  Keywords    Aging, Barley, Isoelectric Focusing, Polypeptide, Rearrangement 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0464.pdf 
 Identifier    ZNC-1996-51c-0464 
 Volume    51 
4Author    Sunkar Ramanjulu3, Werner Kaiser3, Karl-Josef Dietz3-Requires cookie*
 Title    Salt and Drought Stress Differentially Affect the Accumulation of Extracellular Proteins in Barley  
 Abstract    Barley (Hordeum vulgare) was grown for eight days in the presence of a range of salt concentrations or subjected to repeated cycles of wilting and rehydration. Changes in apoplastic protein content, protein pattern, enzymic activities and ion composition were in­ vestigated under salinity and drought. The protein content of intercellular washing fluid (IW F) increased 2.5-to 3.0-fold when the NaCl concentration in the growth medium was increased from 0 to 100 mM. The elevated protein content was the result of a general increase in most polypeptides and a pronounced increase in the abundance of specific polypeptides of apparent molecular masses of 15, 21, 22, 26, 36, 40 and 62 kDa. Conversely, the IW F protein content decreased during wilting similar as after application of colchicin, cytochalasin B or cycloheximide suggesting that inihibition of protein synthesis or vesicle transport may be the cause for the decrease in apoplastic protein content and enzyme activities in dehydrat­ ing plant tissue. The changes in apoplastic protein content were accompanied by stress-spe-cific alterations in activities of apoplastic enzymes. The greater apoplastic protein content was the consequence of stimulated protein synthesis in the presence of NaCl, as evidenced by increased incorporation of [35S]-methionine into IW F protein. The results demonstrate that the leaf apoplast is a compartment which sensitively and differentially responds to drought and salinity with consequences for plant growth. 
  Reference    Z. Naturforsch. 54c, 337—347 (1999); received February 5/February 23 1999 
  Published    1999 
  Keywords    Apoplast, Barley, Drought, Hydrolytic Enzymes, Polypeptide, Salinity 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0337.pdf 
 Identifier    ZNC-1999-54c-0337 
 Volume    54 
5Author    Michael Bender, Ulrich Heber, K. Arl-, Josef DietzRequires cookie*
 Title    Saline Growth Conditions Favour Supercooling and Increase the Freezing Tolerance of Leaves of Barley and Wheat  
 Abstract    When young plants o f barley and wheat grown in hydroponic culture were subjected to salt stress, their freezing tolerance increased with increasing severity o f salt stress. Detached leaves from salt-stressed plants also exhibited an increased ability to supercool. A voidance o f ice for­ mation permitted leaf survival at subzero temperatures which were no longer tolerated when ice nucleation resulted in extracellular freezing. The increased freezing tolerance under salt stress is attributed to osm otic adjustment o f the plants. Increased cellular solute concentra­ tions decrease the extent o f cellular dehydration at freezing temperatures, thereby decreasing mechanical and chemical stresses on biomembranes during freezing and thawing. 
  Reference    Z. Naturforsch. 47c, 695—7 (1992); received M ay 14/July 9 1992 
  Published    1992 
  Keywords    Barley, Chlorophyll a, Fluorescence, Freezing Tolerance (Leaves), Salt Stress, Supercooling 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0695.pdf 
 Identifier    ZNC-1992-47c-0695 
 Volume    47