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'Carotenoid' in keywords Facet   Publication Year 1983  [X]
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1983[X]
1Author    K. H. GrumbachRequires cookie*
 Title    Interconversion of Carotenoids and Quinones after Onset of Photosynthesis in Chloroplasts of Higher Plants  
 Abstract    The interconversion of carotenoids and quinones was investigated in beech and spinach leaves as well as isolated intact spinach chloroplasts following a dark-light transition. It is shown that isolated intact chloroplasts which are preincubated for 2 h at pH 7.6 in the dark and re­ illuminated with strong white light are capable not only o f deepoxidizing violaxanthin into antheraxanthin and zeaxanthin but simultaneously change the redox state o f the plastoquinone-pool in their thylakoid membrane. At the same time as violaxanthin is deepoxidized plasto-hydroquinone-9 is oxidized to plastoquinone-9. If the light is turned off zeaxanthin is epoxidized into antheraxanthin and violaxanthin but no significant change in the redox state o f the plasto-quinone-pool occurred. It is concluded that the deepoxidation of violaxanthin is connected to the photosynthetic electron transport in that way that an acidification o f the intrathylakoidal compartment by the vectorial release of protons from the water photooxidizing enzyme system and the plastoquinone-pool is required for the activation of the violaxanthin deepoxidase. This may be taken as further evidence that violaxanthin deepoxidase is located at the inner side o f the thylakoid membrane. Additional evidence for this location site is given by the observation that neither deepoxidation of violaxanthin nor photooxidation of plastohydroquinone-9 occurred after onset o f photosyn­ thesis if non cyclic electron transport was inhibited by DCMU. 
  Reference    Z. Naturforsch. 38c, 393 (1983); received March 15 1983 
  Published    1983 
  Keywords    Carotenoids, Photosynthesis, Quinones, Xanthophyll Cycle 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0393.pdf 
 Identifier    ZNC-1983-38c-0393 
 Volume    38 
2Author    G. E. Laskay, I. M. Lehoczki, L. Aróti, SzalayRequires cookie*
 Title    Effects of Pyridazinone Herbicides during Chloroplast Development in Detached Barley Leaves I. Effects on Pigment Accumulation and Fluorescence Properties  
 Abstract    The effects o f three differently substituted pyridazinone herbicides on the accum ulation o f photosynthetic pigments and on the fluorescence properties o f greening barley leaves were studied. The two trifluoro-methyl derivatives, SAN 6706 and 9789 caused inhibition in the accumulation o f carotenes only after the First 24 h o f greening. By the 48th hour o f greening no detectable amounts o f carotenes were present in the treated leaves. Considerable am ounts o f xanthophylls however remained present, and no bleaching o f the leaves was observed. It is suggested that SAN 6706 and 9789 prevent the formation o f the enzym e(s) catalyzing the desaturation o f phytoene and phytofluene. Fluorescence spectra indicate that the organization o f pigment forms altered seriously in the treated leaves. This experimental system may be useful to study the action o f pyridazinone herbicides without causing com plete photobleaching o f the photosynthetic apparatus. SAN 9785 had only minor effects on pigment accum ulation and also on the organization o f pigment forms. The possible explanations o f the effects observed are dis­ cussed. 
  Reference    Z. Naturforsch. 38c, 736—740 (1983); received June 8 1983 
  Published    1983 
  Keywords    Pyridazinone Herbicides, Carotenoids, Fluorescence Spectrum 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0736.pdf 
 Identifier    ZNC-1983-38c-0736 
 Volume    38 
3Author    K.H G Rum BachRequires cookie*
 Title    Distribution of Chlorophylls, Carotenoids and Quinones in Chloroplasts of Higher Plants  
 Abstract    Leaves, cotyledons, isolated chloroplasts and subplastid fractions (thylakoids and envelopes) o f radish (Raphanus sativus L. cv. Saxa) and spinach (Spinacia oleracea L. cv. M atador) were assayed for their pigment and quinone content and com position. Virtually all the chlorophylls, carotenoids and quinones were contained in the thylakoids. Envelopes prepared by the method described contained very low amounts o f chlorophyll a and b, violaxanthin and neoxanthin, but no /7-carotene, lutein, zeaxanthin and antheraxanthin. Am ong the quinones trace am ounts o f plastoquinone and a-tocopherol but no plastohydroquinone, a-tocoquinone and phylloquinone were detected. Presented data may be taken as evidence that in vivo the chloroplast envelope is not a location site o f carotenoids and quinones as generally accepted. Possible im plications for the biosyntheses o f quinones and pigments are discussed. 
  Reference    Z. Naturforsch. 38c, 996—1002 (1983); received August 16 1983 
  Published    1983 
  Keywords    Carotenoids, Chlorophylls, Chloroplasts, Envelopes, Quinones, Thylakoids 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0996.pdf 
 Identifier    ZNC-1983-38c-0996 
 Volume    38 
4Author    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