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  • 1
    Electronic Resource
    Electronic Resource
    Biosynthesis of vitamin E and of the plastoquinones in chloroplasts: Steric course of the decarboxylation
    Amsterdam : Elsevier
    Bioorganic Chemistry 13 (1985), S. 187-196 
    Details
    ISSN: 0045-2068
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0045-2068(85)90021-5
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  • 2
    Electronic Resource
    Electronic Resource
    Biosynthesis of acyclic and cyclic carotenoids in higher plants and the control by phytochrome (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 60 (1984), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Radish plants (Raphanus sativus L. cv. Saxa treib) were grown in the presence of three different herbicides interfering with the biosynthesis of cyclic carotenoids. The herbicides caused an accumulation of acyclic biosynthetic intermediates. Plants were then irradiated using four different light programs in order to gain more insight into the first steps of carotenoid biosynthesis and their control by light and phytochrome. Plants grown in the dark in the presence of SAN 6706 or aminotriazole accumulated the acyclic intermediate phytoene, and those treated with J 852, the intermediates phytoene, phytofluene and zeta-carotene. In herbicide-treated plants short time irradiation with red light enhanced the formation of phytoene, phytofluene, zeta-carotene or lycopene, consistent with an effect of phytochrome on the early steps of carotenoid biosynthesis. Biosynthesis of cyclic carotenoids was also enhanced by red light in the untreated controls. In amitrole-treated plants formation of β-carotene, but not that of xanthophylls was stimulated by red light. In many cases neither the red light-induced biosynthesis of cyclic carotenoids nor the formation of acyclic intermediates could be prevented by a subsequent irradiation with far-red light. Similar enhancement as with red light was also obtained after treatment with far-red light only. Presented data may be taken as evidence that the biosynthesis and dehydrogenation of phytoene and the cyclization of lycopene are activated by a low threshold of active phytochrome. This may be further supported by the observation that far-red light itself stimulated carotenoid biosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb06081.x
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  • 3
    Electronic Resource
    Electronic Resource
    Does the chloroplast envelope contain carotenoids and quinones in vivo? (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 60 (1984), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leaves, cotyledons, isolated chloroplasts and subplastid fractions (thylakoids and envelopes) of radish (Raphanus sativus L. cv. Saxa) and spinach (Spinacia oleracea L. cv. Matador) were assayed for their pigment and quinone content and composition. Evidence is presented suggesting that the chloroplast envelope does not contain carotenoids and quinones in vivo. Envelopes prepared by the method described contained very low amounts of chlorophyll a and b, violaxanthin and neoxanthin, but no β-carotene, lutein, zeaxanthin and antheraxanthin. Among the quinones, trace amounts of plastoquinone and α-tocopherol but no plastohydroquinone, α-tocoquinone and phylloquinone were detected. The data presented suggest that, contrary to previous findings, carotenoids and quinones are not located in the chloroplast envelope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb04561.x
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  • 4
    Electronic Resource
    Electronic Resource
    Differences in phytochrome action on the formation of carotenoids and quinones during chloroplast development in seedlings of barley (Hordeum vulgare) (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 57 (1983), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The influence of phytochrome on the light induced formation of carotenoids and quinones was investigated using etiolated seedlings of barley (Hordeum vulgare L. cv. Villa). The biosynthesis of both the quinones and the carotenoids was enhanced by active phytochrome, but the formation of the individual carotenoids and quinones was influenced by quite different thresholds. In both younger and older plants the biosynthesis of β-carotene, lutein and violaxanthin was promoted by a low Pfr threshold. The formation of plastoquinone-9, plastohydroquinone-9, α-tocoquinone and phylloquinone was also influenced by a low Pfr threshold. The biosynthesis of zeaxanthin and neoxanthin required a much higher amount of Pfr. Only antheraxanthin-likeα-tocopherol, desmethylphylloquinone and, in older leaves, α-tocoquinone exhibited a complete reversibility of the phytochrome action in their biosynthesis. The effect of phytochrome on the biosynthesis of carotenoids and quinones was different in seedlings of different age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1983.tb02301.x
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  • 5
    Electronic Resource
    Electronic Resource
    Pigment and quinone content of two photosynthetic barley mutants (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 63 (1985), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The pigment and quinone content of wild-type barley (Hordeum vulgare L., cv. Svalöfs Bonus) and of two photosynthetic mutants was assayed. Wild type plants and the photosystem Hacking mutant viridis zb63 contained chlorophyll a and b. whereas chlorina-f2 contained only chlorophyll a The inability of the mutant chlorina-f2 to convert chlorophyll a into chlorophyll a appears to he the primary effect of the mutation. In both mutants, the carotenoid composition was virtually identical to that of the wild type. As compared to the wild type. chlorina-f2 contained less lutein and neoxanthin. The mutant viridis-zb63 contained less β-carotene but more antheraxanthin and xeaxanthin than the wild type. The quinone content and composition of the wild type and the photosynthetic mutants was similar, and both mutants biosynthesized plastid quinones and chromanols starting from [14C]-labeled tyrosine. The data indicate that carotenoid and quinone biosynthesis are not altered in the two mutants as compared to the wild type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1985.tb04263.x
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  • 6
    Electronic Resource
    Electronic Resource
    Incorporation of 14CO2 in prenylquinones of Chlorella pyrenoidosa (1978)
    Springer
    Planta 141 (1978), S. 253-258 
    Details
    ISSN: 1432-2048
    Keywords: Chlorella ; Photosynthesis (prenylquinone synthesis) ; Prenylquinones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Incorporation and release of 14C-label in prenylquinones of Chlorella was investigated under steady state conditions. After one hour of 14CO2-photosynthesis all plastid quinones investigated were labeled. The highest label was found in phylloquinone (18%) while α-tocopherol exhibits the lowest label (0.38%). Among the plastoquinones, plastohydroquinone-9 shows a higher labeling degree (5.1%) and a faster labeling kinetic than plastoquinone-9 (1.6%). After replacement of 14CO2 against 12CO2 the total radioactivity in plastohydroquinone-9, α-tocopherol and phylloquinone decreases but in α-tocoquinone and plastoquinone-9 proceeds further. From this labeling kinetic we conclude, that newly synthesized [14C]α-tocopherol molecules are converted to [14C]α-tocoquinone and [14C]plastohydroquinone-9 molecules to [14C]plastoquinone-9. From their 14C-incorporation kinetic half-lives could be calculated for all prenylquinones in the same ranges as previously found for the chlorophylls and carotenoids (Grumbach et al., 1978). Half-lives are shorter in plastohydroquinone-9 (30 min) and plastoquinone-9 (40 min) than in phylloquinone (55 min), α-tocoquinone (50 min) and α-tocopherol (220 min). This means that all prenyl-lipids such as chlorophyll a, α-and β-carotene, plastohydroquinone-9 and plastoquinone-9 which are more directly involved in the process of photosynthesis are subject to a continuous and higher turnover than the xanthophyll and α-tocopherol. From the fast labeling kinetic and short half-lives of α-tocoquinone and especially phylloquinone with a labeling degree of 12% after one hour of 14CO2 photosynthesis we suppose that perhaps these two prenylquinones are also involved in the photosynthetic activity of chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388340
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  • 7
    Electronic Resource
    Electronic Resource
    Incorporation of 14CO2 in photosynthetic pigments of Chlorella pyrenoidosa (1978)
    Springer
    Planta 140 (1978), S. 37-43 
    Details
    ISSN: 1432-2048
    Keywords: Carotenoids ; Chlorophylls ; Chlorella ; Photosynthetic pigments ; Turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tracer kinetic studies of chloroplast pigments of Chlorella pyrenoidosa were carried out in a special steady-state apparatus which allowed the simultaneous recording of oxygen evolution, CO2-fixation and 14CO2-incorporation. A special cylindrical vessel which permits labeling experiments with larger algae suspensions (800 ml) is described.-1. After 2 h of 14CO2-photosynthesis (fixation rate 100–160 μmol CO2/μmol chlorophyllxh) 3.3% of the total 14C-uptake (5.66 mCi) was found in the Chlorella lipid fraction. Total and specific radioactivity were higher in total carotenoids than in the chlorophylls. Chlorophyll a gave a higher labeling degree (2.4%) than chlorophyll b (1.3%).-2. Among the carotenoids α-and β-carotene were labeled after 2 h 14CO2 exposure with the same specific radioactivity and with a particular high labeling degree of c. 19%. The xanthophylls exhibit lower labeling degree (violaxanthin 5.1%, zeaxanthin 1.9%, lutein 1.4%, antheraxanthin 1.3%, and neoxanthin 0.7%).-3. During the 4 h 12CO2-exposure period, which followed the 2 h 14CO2-incorporation time, the specific and total radioactivity of the α-and β-carotene pools decrease with a concomitant increase in the α-ionone-(lutein) and β-ionone xanthophylls (violaxanthin, zeaxanthin, antheraxanthin). The possibility, that the decrease of 14C label in the carotenes may in part be due to a photo-oxidative degradation, is discussed.-4. Calculation of biological half-life-times from the 14C-incorporation kinetics during the first hour of the experiment, when the pigment concentration is almost unchanged, results in times from 30 to 60 min. Half lives are shorter in the precursor pools such as chlorophyll a (30 min), α-carotene (40 min) and β-carotene (50 min) and violaxanthin (60 min) respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389377
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  • 8
    Electronic Resource
    Electronic Resource
    Physiological effects of photosystem II-herbicides on the development of the photosynthetic apparatus (1980)
    Springer
    Photosynthesis research 1 (1980), S. 29-43 
    Details
    ISSN: 1573-5079
    Keywords: bentazone ; chloroplast development ; herbicide action ; prenyllipids ; shade-type chloroplast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosystem II-herbicides (bentazone*, diuron) not only block photosynthetic electron transport, but have additional effects on the cell metabolism of Raphanus seedlings. They induce the formation of shade-type chloroplasts with a different ultrastructure and prenyllipid composition. This is shown by higher grana stacks as well as by higher chlorophyll b and lutein amounts with reference to chlorophyll a, and lower levels of the plastidic prenylquinones (plastoquinone, phylloquinone, α-tocoquinone) and β-carotene as compared to the controls. The two herbicides bentazone and diuron change the labelling pattern of the chloroplast pigments from 3H-mevalonic acid and 2-14C-acetate and also reduce the accumulation of anthocyanin (pelargonidin), which is a further indication of a shade-type growth response. The level of ubiquinone, an indicator for mitochondrial activity, is, however, increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020073
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