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21Author    SeymourSteven BrodyRequires cookie*
 Title    Flash Photolysis of Liposomes Containing Chlorophyll and Zeaxanthin, as a Function of Temperature (2 °—34 °C)  
 Abstract    The transfer o f triplet excitation from chlorophyll to zeaxanthin in lip osom es is a function o f temperature and pigment concentration. At 525 nm both chlorophyll and zeaxanthin triplet states are observed. The result is a biphasic increase in absorption. The rise time o f absorption by the chlorophyll triplet is much faster, than by the zeaxanthin triplet. With increasing temperature the contribution o f absorption by zea­ xanthin (relative to that o f chlorophyll) at 525 nm increases, and its rise tim e gets faster. At high ratios o f zeaxanthin to chlorophyll, temperature has less effect on both the rise tim e and absorption by the zeaxanthin triplet state. The chlorophyll triplet is measured at 780 nm. It decays faster with increasing temperature and or increasing ratio o f zeaxanthin to chlorophyll. The results are interpreted in terms of: increasing fluidity o f the lipid lip osom e with tem per­ ature, formation o f zeaxanthin-chlorophyll com plexes at high ratios o f zeaxanthin and chloro­ phyll, presence o f different lipid phases in the lip osom e bilayer. 
  Reference    Z. Naturforsch. 39c, 1108—1111 (1984); received June 15 1984 
  Published    1984 
  Keywords    Chlorophyll, Carotenoid, Liposomes, Triplet States, Excitation Energy Transfer 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-1108.pdf 
 Identifier    ZNC-1984-39c-1108 
 Volume    39 
22Author    Sibille Schindler, J. Thomas, H. Bach, K. Artm, LichtenthalerRequires cookie*
 Title    Differential Inhibition by Mevinolin of Prenyllipid Accumulation in Radish Seedlings  
 Abstract    We have studied in intact radish seedlings the effects o f m evinolin (at concentrations o f 0.25 to 5 [am), a specific inhibitor o f HM G -CoA reductase, and. therefore, o f m evalonate biosynthesis, on the production o f various isopentenoids and prenyllipids. Whereas the content o f free desmethyl sterols was decreased steadily, only depending on the concentration o f inhibitor present in the parts o f seedlings investigated separately (e.g. roots, hypocotyls, and cotyledons), the effect on ubiquinone accumulation^ was different. Irrespective o f the part o f seedlings being analyzed, the maximal inhibition reached was 50%. Plastidic pigm ent accum ulation, however, as well as that o f chloroplast quinones (plastoquinone and phylloquinone), appeared even to be enhanced at low inhibitor concentrations and was not significantly lowered by application o f 5 ^m mevinolin. a-Tocopherol showed a similar profile in the dose response to com pounds known to be exclusively synthesized in the plastid. The results indicate a differential accessibility o f the m evalonate synthesizing enzymes presumably present in the cytoplasm, m itochondria and plastids in respect to the inhibitory action o f mevinolin. If prenyllipid formation in the different cell compartments solely depended on cytoplasm ic m evalonate biosynthesis, all prenyllipids should be affected to the same extent as the sterols, which are exclusively synthesized by cytoplasm ic enzymes. 
  Reference    Z. Naturforsch. 40c, 208 (1985); received D ecem ber 5 1984 
  Published    1985 
  Keywords    Carotenoids, Chlorophylls M evinolin Plastoquinone-9, Sterol Accumulation 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0208.pdf 
 Identifier    ZNC-1985-40c-0208 
 Volume    40 
23Author    S. S. BrodyRequires cookie*
 Title    The Position of Carotene in the D-l/D-2 Sub-Core Complex of Photosystem II  
 Abstract    When the sub-core complex of photosystem II, D1/D2, is irradiated at 436 or 415 nm (absorp-tion by chlorophyll and pheophytin and ß-carotene) or 540 nm (absorption primarily by pheophy-tin), the low temperature fluorescence spectrum has two maxima, at 685 and 674 nm. This shows the existence of at least two different fluorescent forms of chlorophyll (chlorophyll a and perhaps pheophytin a). When carotene is irradiated at 485 nm (absorption primarily by ß-carotene), only fluorescence at 685 nm is observed: this indicates that carotene is transferring energy to only the long-wavelength form of chlorophyll in the D1/D2 sub-core complex. The band of carotene (at 485 nm) does not appear in the fluorescence excitation spectrum, measured at 674 nm. The position of the carotene molecule relative to each of the fluorescent forms of chlorophyll was determined from the excitation spectra of each of the fluorescence bands. 
  Reference    Z. Naturforsch. 43c, 226—230 (1988); received August 21. 1987/January 11 1988 
  Published    1988 
  Keywords    Photosynthesis Photosystem II, Chlorophyll, Fluorescence, Carotenoids, Energy Transfer 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0226.pdf 
 Identifier    ZNC-1988-43c-0226 
 Volume    43 
24Author    M. Athias, O. Senge, H. Äkon, Hope, KevinM. SmithRequires cookie*
 Title    Structure and Conformation of Photosynthetic Pigments and Related Compounds 3. Crystal Structure of ß-Carotene  
 Abstract    The crystal structure o f the title compound (C40H 56, M w = 536.8) has been redetermined by X-ray diffraction methods in order to achieve a structure at higher resolu­ tion suitable for theoretical calculations. The crystal sys­ tem is monoclinic, P2 ,/«, a = 7.656(2), b = 9.445(5), c -23.536(15) Ä , ß = 93.41(2)°, V = 1698.8(15) Ä 3, Z = 2, D = 1.050 m g/m 3, 130 K. R = 0.071, R w = 0.076. 
  Reference    Z. Naturforsch. 47c, 474 (1992); received June 4 1991/February 24 1992 
  Published    1992 
  Keywords    Crystal Structure, ß-Carotene, Carotenoids, Photosynthesis 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0474_n.pdf 
 Identifier    ZNC-1992-47c-0474_n 
 Volume    47 
25Author    NavassardV. Karapetyanab, Ute Windhövel3 ', AlfredR. Holzwarthc, Peter BögeraRequires cookie*
 Title    Physiological Significance of Overproduced Carotenoids in Transformants of the Cyanobacterium Synechococcus PCC7942  
 Abstract    The functional location of carotenoids in the photosynthetic apparatus of -crtB and -pys transformants of the cyanobacterium Synechococcus PCC7942 was studied and compared with a control strain -pF P l-3. These transformants overproduce carotenoids due to the insertion of an additional foreign phytoene synthase gene. A higher carotenoid content was found for -crtB and -pys transformants both in whole cells and isolated membranes; the -crtB transformant was also enriched with chlorophyll. 77-K fluorescence emission and excita­ tion spectra of the phycobilin-free membranes were examined for a possible location of overproduced carotenoids in pigment-protein complexes in situ. A similar ratio of the ampli­ tudes of fluorescence bands at 716 and 695 nm emitted by photosystems I and II, found for the three strains, indicates that the stoichiometry between photosystems of the transformants was not changed. Overproduced carotenoids are not located in the core antenna of photosys­ tem I, since 77-K fluorescence excitation spectra for photosystem I of isolated membranes from the studied strains do not differ in the region of carotenoid absorption. When illumi­ nated with light of the same intensity but different quality, absorbed preferentially by either carotenoids, chlorophylls or phycobilins, respectively, oxygen evolution was found always higher in the transformants -crtB and -pys than in -p F P l-3 control cells. Identical kinetics of fluorescence induction of all strains under carotenoid excitation did not reveal a higher activity of photosystem II in cells enriched with carotenoids. It is suggested that overpro­ duced carotenoids of the transformants are not involved in photosynthetic light-harvesting; rather they may serve to protect the cells and its membranes against photodestruction. 
  Reference    Z. Naturforsch. 54c, 191—198 (1999); received December 18 1998 
  Published    1999 
  Keywords    Carotenoid, Chlorophyll, Cyanobacterium, Fluorescence, Oxygen Evolution 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0191.pdf 
 Identifier    ZNC-1999-54c-0191 
 Volume    54 
26Author    Karl-JosefK. Unert, Peter BögerRequires cookie*
 Title    Influence of Bleaching Herbicides on Chlorophyll and Carotenoids  
 Abstract    Over 24 and 48 hour cultivation periods the influence of SAN 9789 (norflurazon), EMD-IT 5914 (difunon) and fluridone on growth, photosynthetic oxygen evolution and pigment content of the green alga Scenedesmus acutus was determined. Four effects were observed: a) Both carotenoid and chlorophyll formation were inhibited. b) Carotenoids were destroyed in the presence of air, but not nitrogen. The level of chlorophyll, however, did not change. c) ß-(and a-) carotene was markedly decreased in the presence of oxygen. d) Photosynthetic oxygen evolution was decreased with the disappearance of carotenoids. These effects, which are accompanied by reduced growth, are believed to represent primary herbicidal modes of action. The decrease of oxygen evolution is not due to a direct inhibition of photosynthetic electron transport by the herbicides applied. 
  Reference    Z. Naturforsch. 34c, 1047 (1979); received June 30 1979 
  Published    1979 
  Keywords    Bleaching Herbicides, Algae, Scenedesmus acutus, Carotenoids, Chlorophyll, Air/Nitrogen Gassing 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1047.pdf 
 Identifier    ZNC-1979-34c-1047 
 Volume    34 
27Author    K. H. Grumbach, M. DrollingerRequires cookie*
 Title    The Effect of Phytochrome and Proteinsynthesis-Inhibitors on the Formation of Chlorophylls and Carotenoids in Radish Seedlings Treated with Photosystem II and Bleaching Herbicides  
 Abstract    Etioplasts of radish seedlings treated with photosystem II (DCM U, bentazon) and chlorotic herbicides (amitrole, SAN 6706) were tested on their ability to perform the phytochrome mediated chlorophyll and carotenoid biosynthesis. The cytoplasmic influence on the chloroplastic action o f herbicides was also investigated by inhibition of protein synthesis either in the chloro­ plast with chloramphenicol or in the cytoplasm with actidion. In all herbicide treated radish seedlings a phytochrome mediated chlorophyll and carotenoid biosynthesis was obtained as found in control plants. In plants treated with DCM U the bio­ synthesis o f carotenoids is enhanced compared to the control plants, while SAN 6706 significantly suppresses the carotenoid formation. It is concluded, that photosystem II and chlorotic herbicides do not interfere with the primary action o f phytochrome but rather do develope their effects on the terpenoid metabolism through phytochrome. Chloramphenicol applied at the time o f sowing very strongly suppresses the formation of chlorophylls and carotenoids in control plants. The sensitivity towards actidion is, however, very much lower. If chloramphenicol and actidion treated plants were also supplied with herbicides, the pigment pattern is completely different In SAN 6706-treated plants chloramphenicol acts synergistic, resulting in an even lower chlorophyll and carotenoid content than in plants supplied only with chloramphenicol. On the other hand SAN 6706 in combination with actidion enhances the formation of pigments, leading to a much higher chlorophyll and carotenoid content as in plants treated only with actidion. A stimulatory effect on the formation o f chlorophylls and carotenoids was also found for DCMU-treated plants in combination with actidion. The observation, that in plants treated with SAN 6706 together with actidion, which inhibits protein synthesis in the cytoplasm, the herbicidal response in the chloroplast is completely abolished, gives evidence that the photooxidative action of SAN 6706 in the chloroplast is developed by the cytoplasm. 
  Reference    Z. Naturforsch. 35c, 445 (1980); received February 8 1980 
  Published    1980 
  Keywords    Photosystem II Herbicides, Chlorotic Herbicides, Chlorophylls, Carotenoids, Phytochrome, Inhibitors 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0445.pdf 
 Identifier    ZNC-1980-35c-0445 
 Volume    35 
28Author    H. Erm, Ann Bothe, Gislene Barbosa, JohannaD.Requires cookie*
 Title    Nitrogen Fixation and Nitrate Respiration by A zospirillum brasilense  
 Abstract    Azospirillum The 0 2-sensitivitiy of N 2-fixation by the carotenoid forming strain Azospirillum brasilense Cd and the colourless strain Sp 7 is com pared in the present communication. As no difference in the reaction is observed with both strains, it is concluded that carotenoids do not protect nitrogenase from damage by 0 2. Azospirillum spp. have also been shown to perform N O '-dependent ^ -f i x ­ ation. The physiological properties of this reaction are described in more detail in the present communication. Evidence is presented that NO^-dependent N 2-fixation is a transitory reaction, proceeding only as long as the enzymes o f assimilatory nitrate reduction are synthesized by the cells. 
  Reference    Z. Naturforsch. 38c, 571—577 (1983); received March 31 1983 
  Published    1983 
  Keywords    Nitrogen Fixation, N itrate Respiration, Denitrification, Nitrogenase Protection, Carotenoids 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0571.pdf 
 Identifier    ZNC-1983-38c-0571 
 Volume    38 
29Author    Jürgen FeierabendRequires cookie*
 Title    Comparison of the Action of Bleaching Herbicides  
 Abstract    Among chlorosis-inducing herbicides that interfere with carotenoid synthesis two groups o f different potency can be discriminated (group 1; aminotriazole amd haloxidine; group 2 with more extensive photodestructions: pyridazinone herbicides and difunon). After application o f herbicides o f group 2 colored carotenoids were com pletely absent and preexisting chlorophyll was degraded by photochem ical reactions requiring high light intensity and 0 2, that occurred also at 0 °C . In treatments with group 1 herbicides direct photodegradation o f chlorophyll was not sufficient to generate the chlorosis. Light-induced interference with constituents o f the chloroplast protein synthesis apparatus being more sensitive to ph otooxidative dam age than chlorophyll, appeared to indirectly m ediate the chlorosis. In the absence o f chloroplast protein synthesis further chlorophyll accum ulation is prevented. Photodegradation o f chlorophyll in the presence o f group 2 herbicides involved the participation o f 0 2~ radicals and was accom panied by lipid peroxidation. In all herbicide treatments the catalase activity o f the leaves was very low. Only in the presence o f group 2 herbicides chloroplast enzym es o f cytoplasm ic origin (e.g. NADP-glyceraldehyde-3-phosphate dehydrogenase) were also inactivated. Rapid inactivation o f catalase as well as o f N A D P-glyceraldehyde-3-phosphate dehydrogenase was induced by exposure o f dim-light-grown herbicide-treated leaves to bright light, also at 0 ° C . In treatments with herbicides o f group 2 also other peroxisom al enzymes (e.g. glycolate oxidate, hydroxy-pyruvate reductase) were affected. The elim ination o f these peroxisom al enzym es also appeared to depend on photooxidative processes o f the chloroplast. 
  Reference    Z. Naturforsch. 39c, 450 (1984); received N ovem ber 4 1983 
  Published    1984 
  Keywords    Bleaching Herbicides, Carotenoids, Catalase, Chlorosis, Leaf Peroxisom es, Photooxidation 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0450.pdf 
 Identifier    ZNC-1984-39c-0450 
 Volume    39 
30Author    K. H. GrumbachRequires cookie*
 Title    Herbicides which Interfere with the Biosynthesis of Carotenoids and Their Effect on Pigment Excitation, Chlorophyll Fluorescence and Pigment Composition of the Thylakoid Membrane  
 Abstract    Plants grown in the presence o f the herbicides assayed synthesized chlorophylls during growth at low fluence rates. Subsequent irradiation with higher fluence rates o f red light induced a strong chlorosis with SAN 6706 being a much stronger herbicide than J 852 or am ino-triazole. All herbicides assayed also changed the content and com position o f chlorophylls, carotenoids and pigment-protein-complexes o f the thylakoid m em brane and therefore the pigm ent excitation and chlorophyll fluorescence em ission spectra o f the plastid. W ith increasing herbicide toxicity the main characteristic em ission bands at 690 and 730 nm disappeared and new em ission bands at 715 (J 852) and 700 nm (SA N 6706) appeared. Such "artificial" m em branes with a changed pigment composition were very susceptible to light. Presented data m ay be taken as evidence, that the lack o f photoprotective cyclic carotenoids caused by the specific action o f a bleaching herbicide is the primary event that m ay lead to a disturbed form ation o f the thylakoid membrane and its destruction by light and oxygen. 
  Reference    Z. Naturforsch. 39c, 455—458 (1984); received N ovem ber 29 1983 
  Published    1984 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophylls, F luorescence, Pigm ent Excitation 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0455.pdf 
 Identifier    ZNC-1984-39c-0455 
 Volume    39 
31Author    W. I. Gruszecki3, K. Strzałkab, A. Radunzc, G. H. SchmidcRequires cookie*
 Title    Cyclic Electron Flow Around Photosystem II as Examined by Photosynthetic Oxygen Evolution Induced by Short Light Flashes  
 Abstract    Photosynthetic oxygen evolution from photosystem II particles was analyzed as conse­ quence o f a train o f short (5 ^is) flashes of different light quality and different intensities to study cyclic electron flow around photosystem II. Damped oscillations of the amplitudes of 0 2-evolution corresponding to a flash sequence were fitted numerically and analyzed in terms o f a nonhomogeneous distribution of misses, represented by the probability parameter ctj. Application o f red light, known to promote cyclic electron flow around photosystem II (Grus­ zecki et al., 1995) results in a considerable increase of all a{, indicating that at the molecular level the misses may be interpreted as resulting from a competition for the reduction of oxidized P680 between cyclic electron flow and the electron flow coming from the water splitting enzyme. In accordance with previous findings, application of light flashes of the spectrum covering the absorption region of carotenoids resulted in an inhibition o f cyclic electron flow and a pronounced decrease of the level of the miss parameter. Possible molecu­ lar mechanisms for the activity control of this cyclic electron transport around photosystem II by carotenoids are discussed. 
  Reference    Z. Naturforsch. 52c, 175—179 (1997); received November 24 1996/ 
  Published    1997 
  Keywords    Cyclic Electron Transport, Photosystem II Oxygen Evolution, Light Flashes, Carotenoids 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0175.pdf 
 Identifier    ZNC-1997-52c-0175 
 Volume    52 
32Author    K. H. Grumbach, T. J. BachRequires cookie*
 Title    The Effect of PS II Herbicides, Amitrol and SAN 6706 on the Activity of 3-Hydroxy-3-methylglutaryl-coenzyme-A-reductase and the Incorporation of [2-14C]Acetate and [2-3H]Mevalonate into Chloroplast Pigments of Radish Seedlings  
  Reference    Z. Naturforsch. 34c, 941 (1979); received June 5 1979 
  Published    1979 
  Keywords    DC M U, Bentazone, SAN 6706, Am itrol, Chlorophylls, Carotenoids, HM G-CoA-Reductase 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0941.pdf 
 Identifier    ZNC-1979-34c-0941 
 Volume    34 
33Author    E. Interschick-Niebler, H. K. LichtenthalerRequires cookie*
 Title    Partition of Phylloquinone Kx between Digitonin Particles and Chlorophyll-Proteins of Chloroplast Membranes from Nicotiana tabacum  
 Abstract    The partition of phylloquinone (vitamin K J, o f chlorophylls a and b and of the two main carotenoids, /?-carotene and lutein, in subthylakoid particles (digitonin treatment) and chlorophyll protein complexes (sodium dodecylsulfate polyamide-gel electrophoresis) isolated from tobacco chloroplasts (Nicotiana tabacum L.) is described. 1. The "light particle" fractions (S 90000, S 150000) of digitonin fragmented chloroplasts are enriched in CP I and contain a higher proportion o f phylloquinone, chorophyll a and /?-carotene as compared to whole chloroplasts. This is visualized by high values for the ratio a/b (6 -8) and for /?-carotene/lutein (1.7) as well as about 3 mol of Kx per 100 mol o f total chlorophyll. The "heavy digitonin particle" fraction (10000 x g sediment), in turn, contains a higher proportion of chlorophyll b and lutein, but a lower level of phylloquinone than whole chloroplasts. 2. The chlorophyll a-protein CP I o f pigmentsystem I, isolated by preparative gel electro­ phoresis using 0.5% and 4% SDS, is characterized by a stable level of phylloquinone (1 mol Kt per 100 mol o f total chlorophyll), high chlorophyll a/b ratios (7 -1 0) and high values for ß-carotene/lutein (~ 6.0). The light-harvesting chlorophyll a/b-protein LHCP o f photosystem II (chlorophyll a/b = 1.1 — 1.5, ^-carotene/lutein = < 0.1) contains either low amounts of phylloquinone (0.5% SDS) or only trace amounts o f Kj (4% SDS). The free pigment fraction (FP) contains at 0.5% SDS 57% of the total phylloquinone of thylakoid membranes. At 4% SDS the K? amount in the free pigment fraction increases to 84%. 3. The phylloquinone partition studies in digitonin particles and SDS chlorophyll proteins indicate that there exist at least two localization sites for phylloquinone Kj in the photosynthetic membrane. The CP I complex and a second site, presumably near photosystem II (CPa?). 
  Reference    Z. Naturforsch. 36c, 276 (1981); received January 131981 
  Published    1981 
  Keywords    Phylloquinone, Thylakoid Composition, Chlorophyll-Proteins, Chlorophyll a/b Ratio, Carotenoids, Digitonin Particles 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0276.pdf 
 Identifier    ZNC-1981-36c-0276 
 Volume    36 
34Author    C. Buschm, K.H G RuRequires cookie*
 Title    Herbicides which Inhibit Electron Transport or Produce Chlorosis and Their Effect on Chloroplast Development in Radish Seedlings II. Pigment Excitation, Chlorophyll Fluorescence and Pigment-Protein Complexes  
 Abstract    DCM U, bentazon, amitrole and SA N 6706 affected the form ation o f the pigm ent-protein com ­ plexes and caused drastic alterations in the absorption o f light and in the transfer o f the absorbed energy in the antennae systems. Bentazon and D C M U , photosystem II inhibitors, did not change the pigment absorption and fluorescence excitation spectra. After application o f both herbicides the long wavelength fluorescence em ission band at 740 nm was reduced sim ilar as in young d e ­ veloping leaves. Although D C M U and bentazon inhibit the photosynthetic electron transport at the same site, bentazon mainly suppressed the form ation o f the photosystem I com plexes C P Ia and CPI while DC M U mainly reduced the photosystem II com plex CPa. Bentazon specifically en­ hanced the formation o f LHCP3. This may be im portant for the increased grana stacking in plas-tids from bentazon treated plants. The bleaching herbicides amitrole and SA N 6706 inhibited the form ation o f carotenoids lead ­ ing to an accumulation o f lycopene, phytofluene and phytoene, w hile the accum ulation o f chloro­ phylls was suppressed. This bleaching effect was m ost pronounced during growth under higher intensities o f light. In weak light (100 lux) am itrole reduced the long wavelength fluorescence maximum but the fluorescence excitation was not affected. W ith am itrole at 2000 lux and SAN 6706 at 100 lux the long wavelength em ission band was further decreased and the fluores­ cence excitation spectra point to a less efficient energy transfer to chlorophyll a. The fluorescence spectra changed due to herbicide treatment resem bled those o f not yet fully developed leaves. In contrast to the photosystem II herbicides the bleaching herbicides am itrole and SA N 6706 had a similar effect on the formation o f pigm ent-protein com plexes. After growth at 2000 lux both herbicides suppressed the formation o f the photosystem I com plex C P Ia and the photosystem II complex CPa. At 100 lux only the formation o f C P Ia was affected. Except for D C M U all herbicides assayed primarily changed the form ation o f photosystem I. 
  Reference    Z. Naturforsch. 37c, 632 (1982); received April 2 1982 
  Published    1982 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophylls, C hlorophyll Fluorescence, Photosystem II Herbicides, Pigm ent-Protein-Complexes 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0632.pdf 
 Identifier    ZNC-1982-37c-0632 
 Volume    37 
35Author    Peter Gölz, Jürgen FeierabendRequires cookie*
 Title    Isoprenoid Biosynthesis and Stability in Developing Green and Achlorophyllous Leaves of Rye (Secale cereale L.)  
 Abstract    Formation o f major prenylquinones and carotenoids was investigated by comparing the incorporation o f [14C]mevalonate into segments o f different age from green and etiolated leaves o f 22 °C-grown rye seedlings (Secale cereale L.) and from 32 °C-grown rye leaves which contained bleached and proplastid-like ribosome-deficient plastids, due to a heat-sensitivity o f 70S ribosome formation. The contents o f plastidic isoprenoids were much lower (between 2 -3 0 %) in the achlorophyllous than in green leaves. In green leaves [l4C]mevalonate incor­ poration into non-polar lipids and into plastoquinone was partially inhibited in the presence o f gabaculin, an inhibitor o f chlorophyll synthesis. However, except for ß-carotene, [,4C]mevalonate incorporation into isoprenoids continuously increased with age also in achlorophyllous etiolated or 32 °C-grown, as in green, leaves and was, except for ß-carotene and plastoquinone, higher in etiolated than in green leaves. In bleached 32 °C-grown leaves [l4C]mevalonate incorporation into all plastidic isoprenoids was strikingly (up to 45-fold) higher than in green control leaves. While degradation o f ß-carotene was greatly enhanced in bleached 32 °C-grown leaves, relative to green control leaves, and could thus compensate for a higher apparent synthesis, chase experiments did not reveal any marked differences o f the turnover o f other isoprenoids. The half times o f plastoquinone, phylloquinone and lutein were in the order o f 2 -3 days. W ithin a 24 h chase period a-tocopherol degradation did not become apparent. U ptake o f [14C]mevalonate and [l4C]isopentenyl pyrophosphate by isolated bleached plastids from 32 °C-grown leaves was much more rapid than by chloroplasts and resulted in higher precursor accumulation within the organelle. While mevalonate incorporation into iso­ prenoid lipids was not detected, isopentenyl pyrophosphate was incorporated into isoprenoid lipids, including plastoquinone. Rates o f incorporation by isolated chloroplasts or bleached plastids were o f similar order. The results illustrate that divergent types o f plastid differentia­ tion are associated with fundamental developmental changes o f the metabolic flow o f iso­ prenoid precursors between different products and compartments and, in particular, with changes o f import into the plastid compartment. 
  Reference    Z. Naturforsch. 48c, 886—8 (1993); received May 14/September 27 1993 
  Published    1993 
  Keywords    Carotenoids, Chlorophyll Form ation, Heat-Bleaching (o f Plastids), Isoprenoids, M evalonic Acid Incorporation 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0886.pdf 
 Identifier    ZNC-1993-48c-0886 
 Volume    48