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  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Overwintering needles of the evergreen conifer Douglas fir exhibited an association between arrest of the xanthophyll cycle in the dissipating state (as zeaxanthin +  antheraxanthin; Z + A) with a strongly elevated predawn phosphorylation state of the D1 protein of the photosystem II (PSII) core. Furthermore, the high predawn phosphorylation state of PSII core proteins was associated with strongly increased levels of TLP40, the cyclophilin-like inhibitor of PSII core protein phosphatase, in winter versus summer. In turn, decreases in predawn PSII efficiency, Fv/Fm, in winter were positively correlated with pronounced decreases in the non-phosphorylated form of D1. In contrast to PSII core proteins, the light-harvesting complex of photosystem II (LHCII) did not exhibit any nocturnally sustained phosphorylation. The total level of the D1 protein was found to be the same in summer and winter in Douglas fir when proteins were extracted in a single step from whole needles. In contrast, total D1 protein levels were lower in thylakoid preparations of overwintering needles versus needles collected in summer, indicating that D1 was lost during thylakoid preparation from overwintering Douglas fir needles. In contrast to total D1, the ratio of phosphorylated to non-phosphorylated D1 as well as the levels of the PsbS protein were similar in thylakoid versus whole needle preparations. The level of the PsbS protein, that is required for pH-dependent thermal dissipation, exhibited an increase in winter, whereas LHCII levels remained unchanged.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 22 (1966), S. 436-437 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Avidin vermindert die Biosynthese von Fettsäuren inAspergillus flavus, die nur von Biotin überwunden wird. Ähnliche Phänomene werden in anderen Pilzen gefunden.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: D1 protein (turnover, modification) ; Drought ; High irradiance ; Photosystem II (core phosphorylation) ; Pisum sativum (drought stress) ; Stress syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Long-term drought stress on photosystem II (PSII) was studied in pea (Pisum sativum L.) seedlings. Drought stress (reduction of water content by 35–80%) led to a considerable depletion of the PSII core, and the remaining PSII complex appeared to be functional and reorganized, with a unit size (LHCP/PSII core) twofold greater than that of well-irrigated plants. By immunoblotting analysis of the PSII proteins from grana and stroma lamellae, the enhanced degradation of CP43 and D1 proteins was observed in water-stressed plants. Also, water stress caused increased phosphorylation of the PSII core and increased D1 protein synthesis. Water-stress-mediated increase in D1 synthesis did not occur when plants were exposed to photoinhibitory light. The depletion of the PSII core was essentially reversed when water-stressed plants grown at low visible irradiance were watered. We suggest that the syndrome caused by the effect of long-term water stress on photosynthesis is a combination of at least two events: a reduction in the number of active PSII centres caused by a physical destabilization of the PSII core and a PSII reorganization with enhanced D1 turnover to counteract the core depletion.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5028
    Keywords: bean ; leaf senescence ; protein degradation ; protein synthesis ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During senescence of primary bean leaves (Phaseolus vulgaris), there are differential changes in the rates at which thylakoid proteins are synthesized. In particular, synthesis of the 32 kD herbicide-binding protein continues throughout senescence, whereas formation of the α and β subunits of ATPase, the 68 kD photosystem I reaction center polypeptide, cytochrome f, cytochrome b6 and the structural apoprotein of the lightharvesting chlorophyll protein complex (LHCP) declines. Pulse-chase experiments with intact leaves indicated rapid degradation of the 32 kD protein, which is consistent with its known rapid rate of turnover. This degradation was light-dependent and inhibited by DCMU, and the kinetics of degradation were similar for young and senescent membranes. In Coomassie-stained gels, the 68 kD reaction center polypeptide of photosystem I, the α and β subunits of ATPase and the LHCP were the dominant proteins for all ages of membranes. Western blot analysis indicated that cytochrome f and cytochrome b6 are selectively depleted during senescence. The data have been interpreted as indicating that translational disruptions in both the cytoplasmic and chloroplastic compartments may contribute to the decline in photosynthetic electron transport in the senescing leaf.
    Type of Medium: Electronic Resource
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