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  • 1
    Electronic Resource
    Electronic Resource
    Water- and temperature-dependence of DNA damage and repair in the fruticose lichen Cladonia arbuscula ssp. mitis exposed to UV-B radiation (2003)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 118 (2003), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The induction of cyclobutane pyrimidine dimers (CPDs) by ultraviolet-B radiation (UV-B, 280–315 nm) and repair mechanisms were studied in the lichen Cladonia arbuscula ssp. mitis exposed to different temperatures and water status conditions. In addition, the development and repair of CPDs were studied in relation to the different developmental stages of the lichen thallus podetial branches. Air-dried lichen thalli exposed to UV-B radiation combined with relatively high visible light (HL, 800 μmol m−2 s−1; 400–700 nm) for 7 days showed a progressive increase of CPDs with no substantial repair, although HL was present during and after irradiation with UV-B. Fully hydrated lichen thalli, that had not been previously exposed to UV-B radiation for 7 days, were given short-term UV-B radiation treatment at 25°C, and accumulated DNA lesions in the form of CPDs, with repair occurring when they were exposed to photoreactivating conditions (2 h of 300 μmol m−2 s−1, 400–700 nm). A different pattern was observed when fully hydrated thalli were exposed to short-term UV-B radiation at 2°C, in comparison with exposure at 25°C. High levels of CPDs were induced at 2°C under UV-B irradiation, without significant repair under subsequent photoreactivating light. Likewise, when PAR (300 μmol m−2 s−1) and UV-B radiation were given simultaneously, the CPD levels were not lowered. Throughout all experiments the youngest, less differentiated parts of the lichen thallus – namely ‘tips’, according to our arbitrary subdivision – were the parts showing the highest levels of CPD accumulation and the lowest levels of repair in comparison with the older thallus tissue (‘stems’). Thus the experiments showed that Cladonia arbuscula ssp. mitis is sensitive to UV-B irradiation in the air-dried state and is not able to completely repair the damage caused by the radiation. Furthermore, temperature plays a role in the DNA damage repairing capacity of this lichen, since even when fully hydrated, C. arbuscula ssp. mitis did not repair DNA damage at the low temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2003.00130.x
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  • 2
    Electronic Resource
    Electronic Resource
    Protein complexes of the plant plasma membrane resolved by Blue Native PAGE (2004)
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 121 (2004), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: With the characterization of the total genomes of Arabidopsis thaliana and Oryza sativa, several putative plasma membrane components have been identified. However, a lack of knowledge at the protein level, especially for hydrophobic proteins, have hampered analyses of physiological changes. To address whether protein complexes may be present in the native membrane, we subjected plasma membranes isolated from Spinacia oleracea leaves to blue-native polyacrylamide gel electrophoresis (BN-PAGE). BN-PAGE is well established in the separation of functional membrane protein complexes from mitochondria and chloroplasts, but a resolved protein complex pattern from PM of eukaryotic cells has previously not been reported. Using this method, protein complexes from Spinacia oleracea PM could be efficiently solubilized and separated, including the highly hydrophobic aquaporin (apparent molecular mass 230 kDa), a putative tetramer of H+-ATPase, and several less abundant complexes with apparent masses around or above 750 kDa. After denaturation and separation of the complexes into their subunits in a second dimension (SDS-PAGE), several of the complexes were identified as hydrophobic membrane proteins. Large amounts of protein (up to 1 mg) can be resolved in each lane, which suggests that the method could be used to study also low-abundance protein complexes, e.g. under different physiological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.2004.00354.x
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  • 3
    Electronic Resource
    Electronic Resource
    The association of actin and tubulin with plasma membranes: Characterization using inside-out vesicles formed by Brij 58 (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Most processes of eukaryotic cells depend on the cortical cytoskeleton (CS), a protein filament structure associated to the plasma membrane (PM). With animal cells, much information has been collected on the mechanisms behind CS-PM interactions, but for plant cells the CS-PM links are poorly characterized. To allow investigations on these links, isolated PM from cauliflower were here treated with Brij 58, a detergent that causes the PM vesicles to turn inside-out (cytoplasmic side-out), thereby exposing the CS components. When actin and tubulin co-pelleted with inside-out PM were separated using sucrose gradient centrifugation, actin and tubulin were recovered with PM-marker activities, supporting intact links between these CS proteins and the Brij-treated PM. Inside-out PM was also treated with different media to learn more about the CS-PM interaction. Extensive dialysis against a low ionic strength medium released actin but not tubulin from these PM, while dialysis against 0.7 M NaCl had no effect. Neither 50 mM DTT, 10 mM CaCl2 nor 2 M NaCl had any effect on the release of either actin or tubulin from PM, but actin was completely released with 6 M urea or 0.6 M KI. Tubulin was also released by urea but not by KI. Incubation of PM in sodium carbonate at increasing pH led to a total release of actin at pH 10, of α-tubulin at pH 11 and of β-tubulin at pH 11.4. In many respects, these characteristics agree with reported findings using e.g., fluorescence microscopy with protoplast ghosts, suggesting that inside-out vesicles obtained with Brij 58 can be used in investigations aimed at understanding the role of the cortical CS in regulating PM-bound components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030308.x
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  • 4
    Electronic Resource
    Electronic Resource
    Purification of endoplasmic reticulum from wheat roots and shoots (Triticum aestivum). Comparison of their blue light-sensitive redox components with those of highly purified plasma membrane (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 82 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plasma mebranes (PM) and endoplasmic reticulum (ER) were prepared from 4.5-day-old, light-grown wheat (Triticum aestivum L. cv. Drabant) shoots and roots, using phase partitioning for the PM, which yields very pure PM preparations, and sucrose gradient centrifugation for the ER. Also the ER fractions were highly purified, being totally free from mitochondria (cytochrome c oxidase, EC 1.9.3.1), PM (glucan synthase II, EC 2.4.1.34) and thylakoid membranes (chlorophyll), and with a low content of tonoplast (nitrate-sensitive ATPase) and Golgi (latent IDPase). Sodium dodecyl sulphate polyacrylmide gel electrophoresis of root ER resulted in a similar polypeptide pattern as for shoot ER, but very different from the crude fraction from which the ER fractions were purified, also indicative of a high purity. The PM and ER preparations were compared with respect to their blue light-sensitive flavoprotein-cytochrome b. About half of the dithionite-reducible cytochrome b of shoots (PM as well as ER) and root PM was light-sensitive, compared to only 10–20% of that of root ER. Shoot PM needed 2–3 times less light compared to the other membranes, for half saturation of the reaction. NADH-cytochrome c reductase activity was found with all four membrane fractions, with ER having activities 5–10 times higher than PM. The relevance of photoreducible components in the PM and the ER is discussed in connection with blue light photobiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02896.x
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution of ATPases in wheat root membranes separated by phase partition (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 52 (1981), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The distribution of divalent cation stimulated ATPase activity in relation to the distribution of other enzyme activities was studied for membrane fractions from wheat roots (Tritium aestivum L. cv. Svenno). A homogenate from dark grown plants was fractionated by differential centrifugation at 1000 g, 10,000 g, 30,000 g and 60,000 g (1, 10, 30 and 60 KP fractions), followed by partition in an aqueous polymer two-phase system, using polyethylene glycol 4000/dextran T500 concentrations of 5.7/5.7, 5.9/5.9, 6.1/6.1, 6.3/6.3 and 6.5/6.5% (w/w). The 30 KP fraction was also separated by counter-current distribution id a 6.3/6.3% two-phase system. Protein and activities of Ca2+, Mg2+, and Mn2+ stimulated ATPases. cytochrome oxidase, light induced absorbance change (LIAC) related to cyt b reductions, inosine diphosphatase and NADH dependent antimycin A insensitive cytochrome c reductase were measured.The partition of ATPase activities stimulated by Ca2+, Mg2+ or Mn2+ was similar at all polymer concentrations tested, indicating: a low cation specificity of the dominating ATPases. The distribution of ATPases. agreed with different marker enzymes in different centrifuge fractions. Divalent cation stimulated ATPases were evidently related to several of the organelles. In the different fractions the distribution of ATPase activity should then follow that of the marker enzyme of the dominant organelle. From studies with different polymer concentrations the 6.3/6.3-system was selected for further separation of the membranes in the 30 KP fraction by counter-current distribution. By this method one fraction was obtained, which probably consisted of plasmalemma and was free from mitochondrial material. Indications for plasmalemma in this fraction were a) similar partition as protoplasts and b) high LIAC activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1981.tb06039.x
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  • 6
    Electronic Resource
    Electronic Resource
    Overexpression of the Ca2+-binding protein calreticulin in the endoplasmic reticulum improves growth of tobacco cell suspensions (Nicotiana tabacum) in high-Ca2+ medium (2005)
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 123 (2005), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Calreticulin (CRT) is a eukaryotic, highly conserved, Ca2+-binding protein predominantly located in the endoplasmic reticulum (ER) lumen. In addition to being involved in the regulation of cellular Ca2+, calreticulin is a key quality control element during protein folding in the ER lumen. Tobacco (Nicotiana tabacum L.) suspension cells overexpressing a maize CRT (CRT1a) were used here to examine the properties of CRT in growing plant cells with respect to stress exposure. The endogenous CRT gene was induced rapidly after subculturing of the cells to new medium. In accordance, the CRT protein levels increased, peaking at days 3–4. At day 5, when the CRT transcript levels had levelled off, a further increase in endogenous CRT expression was obtained when the cells were treated with excess Ca2+ or the N-linked glycosylation inhibitor tunicamycin. Whereas the response to Ca2+ occurred within 30 min, the induction by tunicamycin took several hours to be established. Transforming tobacco cells with maize CRT1a, under a constitutive mannopine synthase promoter, resulted in a stable level of expressed CRT1a during the growth cycle compared with endogenous CRT. The CRTs showed differences in attached glycans, but both contained the high mannose-rich-type glycans characteristic of ER proteins. In agreement with an ER location, both tobacco CRT and the transgene product CRT1a codistributed with the ER marker NADH cytochrome c reductase after density gradient centrifugation of microsomal fractions from tobacco cells. Increased production of CRT, as was obtained in the transgenic tobacco cell lines, made cells more tolerant than wild-type cells to high Ca2+ during growth. These data suggest that overexpression of CRT1a in plant cells results in a more efficient calcium buffering capacity in the ER.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.2004.00434.x
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of UV-B radiation and nitrogen starvation on daily rhythms in phototaxis and cell shape of Euglena gracilis (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 92 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The flagellate Euglena gracilis Klebs strain Z shows phototaxis and changes cell shape between oblong and round. Both cell events show daily rhythmicity. Phototaxis was highest about 2 h after light onset with a second peak of activity 9 h later. At the same times, the cells were in their most oblong shape. During the night phase the cells were phototactically inactive and round. These rhythms were altered by environmental stress, e.g. UV-B radiation (280–320 nm) and nitrogen deficiency. Artificial UV-B radiation of 0.5 W m−2 caused a loss in phototaxis hut the peak of activity occurred at the same time as for control cells. The transition from round to oblong cell shape was slower after UV-B radiation, but the difference between the roundest and the most oblong cell shape was unchanged. Nitrogen deficiency caused a total loss of phototaxis and the cells remained round all the time. The cells lost all their chlorophyll and were, therefore, photosynthetically inactive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb08842.x
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  • 8
    Electronic Resource
    Electronic Resource
    NAD(P)H oxidase and peroxidase activities in purified plasma membranes from cauliflower inflorescences (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 71 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An NAD(P)H oxidase activity stimulated by phenolic compounds has been investigated in purified plasma membranes (pm) and in an intracellular membrane (icm) fraction depleted in plasma membranes, both obtained from a microsomal fraction from cauliflower inflorescences (Brassica oleracea L.). The phenolic compounds salicylhydroxamic acid (SHAM), ferulic acid, coniferyl alcohol, n-propyl gallate, naringenin, kaempferol and caffeic acid all strongly stimulated the activity. Peroxidase (EC 1.11.1.7), or a peroxidase-like enzyme, was responsible for the NAD(P)H oxidase activity, which proceeded through a free-radical chain reaction and was inhibited by catalase (EC 1.11.1.6), superoxide dismutase (EC 1.15.1.1) and KCN. Most of the total activity was soluble; however, the membrane-bound activity was highly enriched in the pm compared to the icm. The catalase activity was 6 times higher in the icm-fraction than in the pm-fraction, but this was not the reason for the much lower phenol-stimulated NADH oxidase activity in the icm. Peroxidase activity measured with o-dianisidine and H2O2 had about the same specific activities in the pm-and icm-fractions.Neither the phenol-stimulated NADH oxidase nor the peroxidase activity could be washed away from the pm even by 0.7 M NaCl, indicating that these activities are truly membrane-bound. SHAM as well as the other phenolic compounds capable of stimulating the NADH oxidase reaction were potent inhibitors of blue light-induced cytochrome b-reduction in the pm fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb04610.x
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  • 9
    Electronic Resource
    Electronic Resource
    Fluorescence properties of plasma membranes from oats and cauliflower in relation to blue light physiology (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 70 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Fluorescence properties of plasma membranes from dark-grown oat shoots (Avena saliva L. cv. Sol II) and from cauliflower inflorescences (Brassica oleracea L.) were investigated. Along with a flavin (with a possible connection to blue light physiology), a blue fluorescing component was present. The effect of NaN3, phenyl acetic acid (PAA), KI (flavin inhibitors) and salicylhydroxamic acid (SHAM; inhibitor of e.g. the blue light-induced cytochrome b reduction) were followed with regard to the fluorescence properties of the two components as well as with regard to the light-induced cytochrome b reduction (LIAC). A change in flavin fluorescence and LIAC occurred at about the same concentration of PAA and SHAM, while LIAC was much more sensitive to KI and NaN3 than was the fluorescence. Rapid freezing and thawing did not change the relative fluorescence emission from the flavin and blue fluorescing component, respectively, but storage at -20°C for one or two days increased the fluorescence, especially from the latter. There did not seem to be a tight coupling between the fluorescence properties of the blue fluorescing component (spectrally similar to a pteridine) and the flavin. Therefore, no conclusions could be drawn concerning their connection in blue light physiology, i.e. in processes such as phototropism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb08692.x
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  • 10
    Electronic Resource
    Electronic Resource
    Binding of phytochrome to plasma membranes in vivo (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 61 (1984), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A microsomal fraction was prepared by differential centrifugation from the homogenate of dark grown shoots of oats (Avena sativa L. cv. Sol II). Plasma membranes were prepared from the microsomal fraction by means of an aqueous polymer two phase partition method. The content of phytochrome in the microsomal fraction and the plasma membrane fraction, respectively, were studied after different irradiation treatments of the intact shoots. Red irradiation increased the content of phytochrome in both the microsomal and plasma membrane fraction, especially in the presence of Mg2+. The increase induced by red light was fully reversible by far-red light for the plasma membrane fraction both in the presence and absence of Mg2+, in contrast to the microsomal fraction where Mg2+ had to be omitted. KI treatment of the membranes destroyed the binding of phytochrome whereas agents such as KCI, EDTA, CaCl2 and Triton X-100, did not have this effect, indicating that the phytochrome attachment to the membrane is hydrophobic. This in vivo binding resembles to a large extent the one obtained in vitro by Sundqvist and Widell (Physiol. Plant. 59: 35–41, 1983) even though some differences between the phytochrome species and the membrane side exposed probably occur; so that the present interaction between phytochrome and the plasma membrane does not necessarily reflect the interaction that leads to physiological responses, and there could be more than one type of interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb06095.x
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