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  • 1
    Electronic Resource
    Electronic Resource
    Longitudinal leaf gradients of UV-absorbing screening pigments in barley (Hordeum vulgare) (2003)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 117 (2003), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In vivo leaf characteristics were examined to describe longitudinal gradients of UV-absorbing screening pigments in barley. Chlorophyll fluorescence properties and in vivo absorption spectra (210–750 nm) of leaves were measured from the base to the tip. Barley leaves showed strong longitudinal gradients of chlorophyll, where chlorophyll concentration increased within the first 5–8 cm from the leaf base, and did not significantly change for the remaining part of the leaf. Fluorescence microscopy was used to localize cell wall bound screening pigments different from flavonoids, since flavonoids lack a blue-green fluorescence emission (Lichtenthaler and Schweiger 1998). Measurements of in vivo chlorophyll fluorescence indicated that the ratio of UV-absorbing screening pigments per leaf area increases from the leaf base to the tip. These gradients were confirmed by in vivo absorption spectra. It is demonstrated that leaves in the early stage of development are less protected against UV-radiation than fully developed mature leaf regions. The experiments show that measurements of in vivo chlorophyll fluorescence are ideally suited as a fast non-invasive tool to estimate the epidermal UV-transmittance in different leaf sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2003.00045.x
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  • 2
    Electronic Resource
    Electronic Resource
    Photophysiology and primary production of phytoplankton in freshwater (2004)
    Oxford, UK; Malden, US : Munksgaard International Publishers
    Physiologia plantarum 120 (2004), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the last 10 years enormous progress has been made in developing new instruments to collect physiological data from natural phytoplankton. In this review we summarize the motivation which has powered this engagement and focus on new technologies used to measure fluorescence, absorption and biochemical compositions of natural phytoplankton cells from nature. Combining the knowledge of phytoplankton structure along with taxon-specific measurements of photosynthetic activity and biochemical cell composition, can lead to new models which increase the reliability of water quality prediction. Furthermore, recent progress in the analysis of photophysiological fitness of phytoplankton cells has revealed new knowledge about the phylogenetic diversity of metabolic strategies to cope with light and nutrient stress. Future progress in single cell analysing systems will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0031-9317.2004.00267.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of different light qualities on the ultrastructure, thylakoid membrane composition and assimilation metabolism of Chlorella fusca (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 64 (1985), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chlorella fusca (Shihira et Krauss) strain C-1.1.10 was grown under three different light qualities (red, white or blue light) in homocontinuous cultures. Under electron microscopy, blue light cultures showed enlarged cells, thinner cell walls and lower starch content than red light cells. Under blue light, the degree of stacking of the thylakoid membranes was significantly lower than under white or red light conditions. Changing the light from blue to red the ratio of exposed to appressed membranes was doubled. Compared to red light cells, blue light cells exhibited higher photosynthetic rates per chlorophyll molecule and contained less chlorophyll per dry weight. Blue light stimulated the content of soluble protein as well as that of soluble carbohydrates. The dry weight productivity per unit time was enhanced under blue light conditions. The thylakoid protein complexes which are generally assumed to be localized in the exposed membranes were found in higher concentrations under blue light than under red light. In blue light, both the Photosystem II/Photosystem I ratio and the ratio of light-harvesting chlorophyll protein to P-700 chlorophyll a-protein were lower than in red light. Blue light cells contained twice the concentration of cytochrome f, which correlates well with their higher photosynthetic capacity. When altering the light quality, the degree of change in the reaction center complexes was much lower than expected given the corresponding degree of change in the ratio of exposed to appressed membranes. These results are discussed in light of the question as to whether the variation in the stoichiometry of the laterally distributed complexes can be explained by changes in the degree of stacking alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1985.tb03353.x
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  • 4
    Electronic Resource
    Electronic Resource
    The light-harvesting system of Euglena gracilis during the cell cycle (1990)
    Springer
    Planta 180 (1990), S. 293-296 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast development ; Euglena ; Light-harvesting chlorophyll-protein complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The apoproteins of the light-harvesting chlorophyll-protein complexes LHCI and CP29 (apparent molecular weights of 27 kDa and 29 kDa, respectively) of Euglena gracilis were identified immunologically. Both complexes are present in the thylakoids of autotrophically cultured Euglena cells during the whole cell cycle. The relative amount of each apoprotein tends to increase towards the end of the cell cycle. The light-harvesting chlorophyll-protein complex of photosystem II, LHCII, of E. gracilis contains chlorophyll a, chlorophyll b, neoxanthin, diadinoxanthin and beta-carotene. Its chlorophyll a/b ratio is about 1.7 during the whole cell cycle. About 9 h after cell division the ratio of diadinoxanthin to chlorophyll a is doubled for a time of 3–4 h. The relevance of this increase during one developmental stage is discussed in relation to the insertion and-or assembly of newly synthesized LHCII.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194010
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  • 5
    Electronic Resource
    Electronic Resource
    The xanthophyll cycle of Mantoniella squamata converts violaxanthin into antheraxanthin but not to zeaxanthin: consequences for the mechanism of enhanced non-photochemical energy dissipation (1998)
    Springer
    Planta 205 (1998), S. 613-621 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Antheraxanthin ; Light adaptation ; Mantoniella ; Non-photochemical quenching of chlorophyll fluorescence ; Violaxanthin cycle ; Zeaxanthin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The prasinophycean alga Mantoniella squamata uses in vivo an incomplete violaxanthin cycle. Although the violaxanthin cycle in Mantoniella is capable of converting violaxanthin to zeaxanthin, in intact cells only antheraxanthin accumulates during periods of strong illumination. Antheraxanthin enhances non-photochemical quenching of chlorophyll fluorescence. Inhibition of antheraxanthin synthesis by the de-epoxidase inhibitor dithiothreitol abolishes increased thermal energy dissipation. Antheraxanthin-dependent non-photochemical quenching, like zeaxanthin-mediated non-photochemical quenching in higher plants, is uncoupler-sensitive. Mantoniella squamata cells cultivated at high light intensities contain higher amounts of violaxanthin than cells grown at low light. The increased violaxanthin-cycle pool size in high-light-grown Mantoniella cells is accompanied by higher de-epoxidation rates in the light and by a greater capacity to quench chlorophyll fluorescence non-photochemically. Antheraxanthin-dependent amplification of non-photochemical quenching is discussed in the light of recent models developed for zeaxanthin- and diatoxanthin-mediated enhanced heat dissipation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050364
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  • 6
    Electronic Resource
    Electronic Resource
    The energy distribution between the photosystems and light-induced changes in the stoichiometry of system I and II reaction centers in the chlorophyll b-containing alga Mantoniella squamata (Prasinophyceae) (1989)
    Springer
    Photosynthesis research 20 (1989), S. 221-233 
    Details
    ISSN: 1573-5079
    Keywords: green algae ; light adaptation ; photosystems ; state 1-state 2 transitions ; thylakoid stacking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chlorophyll b-containing alga Mantoniella squamata was analyzed with respect to its capacity to balance the energy distribution from the light-harvesting antenna to photosystem I or photosystem II. It was shown, that this alga is unable to alter the absorption cross section of the two photosystems in terms of short-time regulations (state transitions). The energy absorbed by the LHC, which contains 60% of total photosynthetic pigments, is transferred to both photosystems without any preference. The stoichiometry of the two photosystems is found to be extremely unequal and variable during light adaptation. In high light, the molar ratio of P-680 per P-700 is found to be two, whereas under low light conditions this ratio accounts to nearly four. This very unbalanced stoichiometry of the reaction centers gives some new insights into the concept of the photosynthetic unit as well as in the importance of the regulation of the energy distribution. It is assumed that the high concentration of photosystem II can be understood as a mechanism to prevent the overexcitation of photosystem I. In addition, the changes im membrane protein pattern are not accompanied by variations in the ratio of appressed to nonappressed membranes as probed by ultrastructural analysis. It is suggested that the thylakoids are organized like a homogenous pigment bed. The lack of state transitions can be interpreted as a consequence of this unusual membrane morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034066
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  • 7
    Electronic Resource
    Electronic Resource
    Energy transfer and pigment composition in three chlorophyll b-containing light-harvesting complexes isolated from Mantoniella squamata (Prasinophyceae), Chlorella fusca (Chlorophyceae) and Sinapis alba (1987)
    Springer
    Photosynthesis research 13 (1987), S. 101-111 
    Details
    ISSN: 1573-5079
    Keywords: Chlorella ; Light-harvesting Chl a/b-complex ; Mantoniella ; Prasinoxanthin ; Sinapis alba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light-harvesting Chl a/b protein complexes were isolated from the higher plant Sinapis alba, the green alga Chlorella fusca, and the prasinophycean alga Mantoniella squamata by mild gel electrophoresis. The energy transfer from chlorophyll b and the accessory xanthophyll was measured by means of fluoresence spectroscopy at 77 K. The pigment composition of the isolated antenna complexes was determined by high performance liquid chromatography in order to calculate the number of light absorbing molecules per chlorophyll a in the different light-harvesting complexes. These results were complemented by the quantitation of the pigments in total thylakoids as well as in the different electrophoretic fractions. On the basis of these data the in vivo ratios of xanthophylls per chlorophyll a could be estimated. The results show that the light-harvesting complexes from Chlorella and from Sinapis exhibit identical ratios of total xanthophylls per chlorophyll a. By contrast, in the prasinophycean alga Mantoniella, the light-harvesting complex markedly differs from the other chlorophyll b containing proteins. It contains, in addition to neoxanthin and violaxanthin, high amounts of prasinoxanthin and its epoxide, which contribute significantly to light absorption. The concentration of chlorophyll b in the complex is very much higher in the antenna of Mantoniella than in those of Chlorella and Sinapis. Furthermore, it must be emphasized that in addition to chlorophyll b, a third chlorophyll species acts in the energy transfer to chlorophyll a. This chlorophyll c-like pigment is found to be present in a concentration which improves very efficiently the absorption in blue light. In light of these results it can be concluded that the absorption cross section in Mantoniella is higher not only because of an enhanced number of light-harvesting particles in the membrane, but also because of a higher ratio of accessory pigments to chlorophyll a.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035234
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  • 8
    Electronic Resource
    Electronic Resource
    Stimulation of the diadinoxanthin cycle by UV-B radiation in the diatom Phaeodactylum tricornutum (1999)
    Springer
    Photosynthesis research 59 (1999), S. 73-80 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll fluorescence quenching ; diatoxanthin ; light adaptation ; photoprotection ; UV-B effects ; xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study we show that the diadinoxanthin cycle in the diatom Phaeodactylum tricornutum is stimulated by mild UV-B radiation. High steady state concentrations of diatoxanthin established during a period of strong actinic illumination with white light (300 μmol photons m-2 s-1 PAR) are further increased if weak UV-B (3 μmol photons m-2 s-1) is additionally applied. Short term increases in the diatoxanthin concentration caused by UV-B strongly correlate with a stoichiometric decrease in diadinoxanthin. The UV-B dependent increase in diatoxanthin is correlated with a concommitant enhancement of non-photochemical quenching of chlorophyll fluorescence and a decrease in the quantum efficiency of oxygen evolution. This indicates that UV-B induced diatoxanthin functions in thermal energy dissipation. Possible scenarios for a stimulation of the diadinoxanthin cycle by UV-B are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006169901482
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  • 9
    Electronic Resource
    Electronic Resource
    Isolation of chlorophyll-protein complexes and quantification of electron transport components in Synura petersenil and Tribonema aequale (1983)
    Springer
    Photosynthesis research 4 (1983), S. 317-329 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll-protein complexes ; cytochrome c-553 ; eytechrome f ; lightharvesting Chl a/c-protein ; P-700 chlorophyll a-protein ; Synura petersenii ; Tribonema acquale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chlorophyll-protein complexes of the yellow alga Synura petersenii (Chrysophyceae) and the yellow-green alga Tribonema aequale (Xanthophyceae) were studied. The sodiumdodecylsulfate/sodiumdesoxycholate solubilized photosynthetic membranes of these species yielded three distinct pigment-protein complexes and a non-proteinous zone of free pigments, when subjected to SDS polyacrylamid gel electrophoresis. The slowest migrating protein was identical to complex I (CP I), the P-700 chlorophyll a-protein, which possessed 60 chlorophyll a molecules per reaction center in Tribonema and 108 in Synura. The zone of intermediate mobility contained chlorophyll a and carotenoids. The absorption spectrum of this complex was very similar to the chlorophyll a-protein of photosystem II (CP a), which is known from green plants. The fastest migrating pigment protein zone was identified as a light-harvesting chlorophyll-protein complex. In Synura this protein was characterized by the content of chlorophyll c and of fucoxanthin. Therefore this complex will be named as LH Chl a/c-fucocanthin protein. In addition to the separation of the chlorophyll-protein complexes the cellular contents of P-700, cytochrome f (bound cytochrome) and cytochrome c-553 (soluble cytochrome) were measured. The stoichiometry of cytochrome f: cytochrome c-553:P-700 was found to be 1:4:2.4 in Tribonema and 1:6:3.4 in Synurá.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041829
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  • 10
    Electronic Resource
    Electronic Resource
    Polypeptide sequence of the chlorophyll a/b/c-binding protein of the prasinophycean alga Mantoniella squamata (1994)
    Springer
    Photosynthesis research 40 (1994), S. 269-277 
    Details
    ISSN: 1573-5079
    Keywords: light-harvesting complex ; chlorophyll-binding protein ; protein sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The primary structure of the Chla/b/c-binding protein from Mantoniella squamata is determined. This is the first report that protein sequencing reveals one modified amino acid resulting in a LHCP-specific TFA-cleavage site. The comparison of the sequence of Mantoniella with other Chla/b-and Chla/c-binding proteins shows that the modified amino acid is located in a region which is highly conserved in all these proteins. The alignment also reveals that the LHCP of Mantoniella is related to the Chla/b-binding proteins. Finally, possible Chl-binding regions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034776
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