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  • 1
    Electronic Resource
    Electronic Resource
    Effect of cytokinins on plastid development and photosynthetic polypeptides during organogenesis ofPinus ponderosa Dougl. cotyledons culturedin vitro (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 81-89 
    Details
    ISSN: 1573-5044
    Keywords: cytokinins ; in vitro ; organogenesis ; photosynthetic polypeptides ; Pinus ponderosa ; plastid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract InPinus ponderosa Dougl., application of the cytokinins, benzyladenine and 2-isopentenyl adenine, to excised cotyledons, promoted thein vitro formation of meristematic centers which led to bud and shoot production. Meristematic cells showed plastids with poorly developed thylakoid membranes and rudimentary grana, whereas cells in non-meristematic tissues and in growth regulator free medium, had chloroplasts with well developed inner membranes, and more thylakoid membranes and grana than plastids of meristematic cells. Chlorophyll and six polypeptides associated with photosynthesis were present in lower concentrations in cytokinin-treated cotyledons than in those cultured in growth regulator free medium. Both benzyladenine and 2-isopentenyl adenine are effective in inhibiting the accumulation of at least two photosynthetic polypeptides in the first 24 h in culture. The ability of cotyledons to respond in this way to cytokinins is lost after three days in culture in growth regulator free medium prior to treatment with cytokinin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01997602
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Physiological recovery of freezer-stored white and Engelmann spruce seedlings planted following different thawing regimes (1995)
    Springer
    New forests 10 (1995), S. 55-77 
    Details
    ISSN: 1573-5095
    Keywords: Key words ; Water relations ; photosynthesis ; chlorophyll a fluorescence ; artificial forest regeneration ; cold storage ; frost hardiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Logistic problems of large-scale reforestation necessitate freezer-storage of conifer seedlings. Frozen stock is typically thawed slowly at low temperatures for up to several weeks before shipping to the plantation site, but the necessity of this practice is questionable. Experiments were conducted to study effects of different thawing regimes on photosynthetic recovery, frost hardiness, water relations and growth initiation in “interior spruce” (white spruce (Picea glauca (Moench) Voss) and Engelmann spruce (Picea engelmannii Parry) hybrid complex). One year-old container-grown seedlings were planted after 9 days post-storage thawing at 5–15 °C or still frozen, directly from the freezer. During a 29 day observation period after planting, both groups showed changes in xylem water potential (Ψw), carbon fixation (A), stomatal conductance (g s ), chlorophyll a fluorescence and xanthophyll cycle pigments. Treatment differences in fluorescence and pigments peaked within one hour after planting. All differences in Ψw, A, g s , ratio of internal to external CO2 concentration (Ci/Ca), fluorescence, pigments and root number disappeared after 5 to 8 days. Terminal bud burst occurred 2.6 days earlier in the pre-thawed seedlings. When seedlings were rapidly thawed in the dark at 21 °C they achieved maximum Ψw (−0.2 MPa) in 3–4 hour. When evaluated 45 min after planting, A, g s , Ci/Ca and fluorescence values of rapidly thawed seedlings were intermediate between those for seedlings planted frozen or after 9 days slow thawing, showing that the recovery process was well underway a few hours after removal from the freezer. These results suggested that a suitable on-site operational protocol for rapid thawing might be to lay frozen bundles on the ground at ambient temperature overnight. In field trials of this method, rapidly thawed seedlings broke bud 3.3 days later than slowly thawed stock and also had greater frost hardiness at time of planting. Height, shoot and root mass did not differ after 3 months growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034176
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  • 3
    Electronic Resource
    Electronic Resource
    Assocation of the 33 kDa extrinsic polypeptide (water-splitting) with PS II particles: immunochemical quantification of residual polypeptide after membrane extraction (1987)
    Springer
    Photosynthesis research 13 (1987), S. 69-80 
    Details
    ISSN: 1573-5079
    Keywords: H2O-splitting activity ; membrane extraction ; O2-evolving activity ; photosystem II ; 33 kDa extrinsic protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various washing procedures were tested on Triton-prepared PS II particles for their ability to remove the 33 kDa extrinsic polypeptide (33 kDa EP) associated with the water-splitting complex. Residual 33 kDa EP was evaluated by Coomassie blue staining of SDS gels of washed particles and by Western blotting with an antibody specific for the 33 kDa EP. A wash with 16 mM Tris buffer, pH 8.3, inhibited water-splitting activity but did not remove all the 33 kDa EP. Sequential washes with 30 mM octyl glucoside (pH 8.0 and 6.8), and a single wash with 0.8 M Tris were also ineffective in removing all the 33 kDa EP. Washing with 1 M CaCl2 was more effective in removing 33 kDa EP; while only a faint trace of protein was detectable by Coomassie-staining, immunoblotting revealed a considerable remainder. The treated particles retained some water-splitting activity. The two step procedure of Miyao and Murata (1984) involving 1 M NaCl and 2.3 M urea was most effective, removing all but a trace of antibody positive protein. Our finding suggests that (1) the degree of depletion of the 33 kDa EP cannot be judged on the basis of Coomassie stain alone, and (2) this extrinsic protein is very tightly associated with the membrane, perhaps via a hydrophilic portion of this otherwise hydrophilic protein. The results also suggest that the presence or absence of the 33 kDa protein per se is not the primary determinant of residual water splitting activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032266
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation of PS II reaction centre and its relationship to the minor chlorophyll-protein complexes (1983)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 23 (1983), S. 171-179 
    Details
    ISSN: 0730-2312
    Keywords: photosystem II ; reaction centre ; octyl glucoside ; spinach ; CPa -1 ; CP 47 ; chlorophyll-protein complexes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Evidence is presented for the identification of the chlorophyll- protein complex CPa-1 (CP 47) as the reaction centre of photosystem II (PS II). We have developed a simple, rapid method using octyl glucoside solubilization to obtain preparations from spinach and barley that are highly enriched in PS II reaction centre activity (measured as the light-driven reduction of diphenylcarbazide by 2,6-dichlorophen-olindophenol). These preparations contain only the two minor chlorophyll-protein complexes CPa-1 and CPa-2. During centrifugation on a sucrose density gradient, there is a partial separation of the two CPa complexes from each other, and a complete separation from other chlorophyll-protein complexes. The PS II activity comigrates with CPa-1 but not CPa-2, strongly suggesting that the former is the reaction centre complex of PS II. Reaction centre preparations are sensitive to the herbicide 3(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), but only at much higher concentrations than those required to inhibit intact thylakoid membranes.A model of PS II incorporating our current knowledge of the chlorophyll-protein complexes is presented. It is proposed that CPa-2 and the chlorophyll a + b complex CP 29 may function as internal antenna complexes surrounding the reaction centre, with the addition of variable amounts of the major chlorophyll a+b light-harvesting complex.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240230114
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    Paper (German National Licenses)
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