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1Author    J.J S Van Rensen, D. Wong, GovindjeeRequires cookie*
 Title    Characterization of the Inhibition of Photosynthetic Electron Transport in Pea Chloroplasts by the Herbicide 4,6-Dinitro- o-cresol by Comparative Studies with 3-(3,4-Dichlorophenyl)-l,l- dimethylurea  
 Abstract    An attempt to characterize the mechanism of inhibition of photosynthetic electron transport in isolated pea chloroplasts by the herbicide 4,6-dinitro-o-cresol (DNOC) by a comparison with the effects of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) revealed the following: 
  Reference    Z. Naturforsch. 33c, 413 (1978); received April 12 1978 
  Published    1978 
  Keywords    Photosynthesis, Electron Transport, Fluorescence, Herbicides 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0413.pdf 
 Identifier    ZNC-1978-33c-0413 
 Volume    33 
2Author    Friederike Koenig, Alfons Radunz, GeorgH. Schmid, Wilhelm MenkeRequires cookie*
 Title    Antisera to the Coupling Factor of Photophosphorylation and Its Subunits  
 Abstract    Stroma-freed chloroplasts were extracted with sucrose palmitate-stearate containing buffer. A fter the addition o f dodecyl sulfate and mercaptoethanol to the extract a series of polypeptides was isolated from the mixture by gel filtration. These polypeptides were later used for immunization. Antisera to four polypeptides reacted in the Ouchterlony double diffusion test with authentic coupling factor yielding a precipitation band. According to the observed apparent molecular weights the polypeptides are the a, ß , 8 and e subunits of the coupling factor. An antiserum to the y subunit has been obtained already previously. A ll antisera inhibit photophosphorylation reactions and electron transport considerably. Addition of gramicidin inhibits photophosphorylation com pletely whereas gramicidin restores electron transport in the assays with the antisera to the a, ß , y and 5 subunit. In the case o f the antiserum to the E subunit gramicidin does not regenerate electron transport. As in the presence of the serum to the £ subunit pH changes in the suspension medium are not observed, this serum seems to open a proton channel. Also, upon addition of dicyclohexyl carbodiimide (D C C D) pH changes in the suspension medium in the assay with antiserum do not reoccur. According to these unexpected results the identity o f the antigen with the e subunit of the coupling factor is not certain. ATP-ase reactions are only inhibited by the antisera to the a and y subunit and what is thought to be the £ subunit. The antiserum to the a subunit uncouples electron transport as the only one when used in sufficient concentrations. The dosis-effect curves o f the inhibition of the electron transport exhibits a maximum. The dosis-effect curves for the other components rise after a lag phase in an approxim ately hyperbolic manner. The inhibitory action on electron transport is exerted by all antisera in the region of the reaction center I or in its immediate vicinity. This is thought to be due to the fact that a protein of the reation center I is inhibited in its function by the increasing proton concentration inside the thylakoid. The inhibition of electron transport by the antiserum to the e subunit is considered to be a direct serum effect. Besides the increase in fluorescence yield, due to the inhibition of electron transport in the region o f photosystem I, decreases of the fluorescence yield are observed in the presence of D CM U, which do not depend on the redox state of Q but rather on the condition of the thylakoid mem­ brane. Moreover, the antisera affect in a differing manner the energy spill-over o f excitation from photosystem I I to photosystem I. 
  Reference    Z. Naturforsch. 33c, 529 (1978); received June 21 1978 
  Published    1978 
  Keywords    Coupling Factor, Antisera, Chloroplasts, Fluorescence 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0529.pdf 
 Identifier    ZNC-1978-33c-0529 
 Volume    33 
3Author    P. V. Sane, T. S. Desai, V. G. TatakeRequires cookie*
 Title    Luminescence from Photosystem I at High Temperatures  
 Abstract    The changes in the fluorescence and delayed fluorescence intensity of spinach leaf as affected by temperature were studied. It was observed that the delayed fluorescence showed a maximum at about 45 °C whereas the fluorescence maximum was at about 55 °C. An examination of the emission spectra of delayed fluorescence at different temperatures showed that at higher tem­ peratures the relative emission at 735 nm was increased. It is argued that at higher temperatures the luminescence from photosystem I contributes to delayed fluorescence. 
  Reference    Z. Naturforsch. 35c, 289—292 (1980); received November 1 1979 
  Published    1980 
  Keywords    Fluorescence, Delayed Fluorescence, Photosystem I 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0289.pdf 
 Identifier    ZNC-1980-35c-0289 
 Volume    35 
4Author    Thomas Vom Bruch, Klaus-Heinrich RöhmRequires cookie*
 Title    Fluorescence Properties of Hog Kidney Aminoacylase I  
 Abstract    The state of the tryptophan residues of porcine kidney aminoacylase I (EC 3.5.1.14) was investigated by fluorescence spectroscopy and chemical modification. The pH-dependence of the fluorescence emission spectrum of the enzyme indicates that its native conformation prevails between pH 6 and 9.5. Within this range, the ionization of a residue with an apparent pKa of 7.1 quenches the enzyme fluorescence by about 15%. A similar reduction of fluorescence intensity accompanies the inactivation of aminoacylase I by treatment with N-bromosuccinimide in low excess. This suggests that in both cases a single tryptophyl residue out of eight residues per subunit is affected. Quenching by iodide revealed that, in the native conformation of the enzyme, 5—6 tryptophans per subunit are accessible, while 2—3 are buried within the protein. 8-Anilinonaph-thalene-L-sulfonate (ANS) is tightly bound to aminoacylase I (1 mol/mol dimer, K d < 1 PM). ANS binding does not interfere with substrate turnover; the spectroscopic properties of the amino-acylase-ANS complex are consistent with bound ANS being excited by radiationless energy transfer (RET) from buried tryptophyl residues of the enzyme. 
  Reference    Z. Naturforsch. 43c, 671—678 (1988); received June 3 1988 
  Published    1988 
  Keywords    Aminoacylase, Kidney, Tryptophan, Fluorescence, ANS 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0671.pdf 
 Identifier    ZNC-1988-43c-0671 
 Volume    43 
5Author    Judit Kissim, Á. Gnes Tantos3, Annam Ária, M. Észáros3, ErzsébetJ. Ám Bor-Benczúrb, G. Ábor Horváth3Requires cookie*
 Title    Stress Alterations in Growth Parameters, Pigment Content and Photosynthetic Functions of in vitro Cultured Plants  
 Abstract    Effects of different concentrations of glucose, sucrose and the natural growth regulator, triacontanol were studied under the unfavourable stress conditions of micropropagation of two woody plants, Sorbus rotundifolia L. and Primus x davidiopersica 'Piroska'. After 4 -6 weeks of cultures, the number and length of shoots, the photosynthetic activity as well as the chlorophyll, carotenoid and anthocyanin contents were investigated. As shown by the growth parameters, the optimal carbohydrate concentration was between 1 .5 -2 .5 % , whereas in higher concentrations, a definite inhibition could be observed. A similar response was found in changes of the anthocyanin content in Prunus x davidiopersica 'Piroska', but this effect was less pronounced with the photosynthetic pigments in both species. The Fv/Fm ratio representing the quantum yield of photosynthesis was low due to the inhibitory effect of stress and altered significantly by changing the carbohydrate concentrations. In all cases, the addition of 2 -4 jig triacontanol/1 further enhanced the stimulating effect of the optimal carbohydrate concentrations, which indicated the specific importance of the appropriate hor­ mone balance under such stress conditions. 
  Reference    Z. Naturforsch. 54c, 834—8 (1999); received November 28 1998/March 18 1999 
  Published    1999 
  Keywords    Anthocyanin, Fluorescence, Huckberry, Peach, Triacontanol 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0834.pdf 
 Identifier    ZNC-1999-54c-0834 
 Volume    54 
6Author    GeoffreyA. Codd, G. Eorg, H. SchmidRequires cookie*
 Title    Effects of S-^^-DichlorophenyO-N-N'-Dimethylurea on Oxygen Evolution and Fluorescence by Whole Filaments and Isolated Thylakoids of the Cyanobacterium Anabaena cylindrica  
 Abstract    The site of inhibition of DCM U against photosystem II in the cyanobacterium (Blue-green alga) Anabaena cylindrica was examined in electron transport and fluorescence studies. Isolated thylakoids catalyzed silicomolybdate photoreduction using H zO as electron donor; the steady-state reaction was completely inhibited by DCM U. This reaction is insensitive to DCM U in chloro­ plasts, since silicomolybdate accepts electrons from the prim ary photosystem II acceptor, and thus before the site of action o f D CM U in higher plants. DCM U did not increase the steady-state level of fluorescence by inact A. cylindrica, nor affect the monophasic fluorescence induction, with 
  Reference    Z. Naturforsch. 35c, 649—655 (1980); received April 18 1980 
  Published    1980 
  Keywords    Oxygen-Evolving Side, Cyanobacteria, D CM U-Sensitivity, Fluorescence 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0649.pdf 
 Identifier    ZNC-1980-35c-0649 
 Volume    35 
7Author    Klaus Pfister, U. Lrich, S. ChreiberRequires cookie*
 Title    Comparison of Diuron-and Phenol-Type Inhibitors: Additional Inhibitory Action at the Photosystem II Donor Site  
 Abstract    Inhibitors o f photosystem II reactions from the "diuron-type" and "phenol-type" have been compared regarding their m echanism o f action. "Diuron-" as well as "phenol-type" inhibitors act at the acceptor site o f photosystem II by displacing the secondary acceptor quinone Q B from its binding site. "Phenol-type" inhibitors additionally interfere with the donor site, which is demonstrated in studies o f chlorophyll fluorescence and lum inescence. This m echanism o f action is shown to be similar but not identical to that reported for hydroxylam ine. 
  Reference    Z. Naturforsch. 39c, 389 (1984); received D ecem ber 1 1983 
  Published    1984 
  Keywords    Herbicides, Photosynthesis, Fluorescence, Lum inescence, Inhibitors 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0389.pdf 
 Identifier    ZNC-1984-39c-0389 
 Volume    39 
8Author    T. B. Melø, G. Reisaeter, A. Johnsson, M. JohnssonRequires cookie*
 Title    Photodestruction of Propionibacterium acnes Porphyrins  
 Abstract    The fluorescence spectra o f colonies o f Propionibacterium acnes were studied under various experimental conditions. The spectra contained peaks at 580 nm and 620 nm. These bands were due to two different components; the 580 nm component was likely to be a m etalloporphyrin, and there are ind ica­ tions that the 620 nm component could be a coproporphyrin. The 580 nm fluorescence was destroyed by the com bined action o f light and oxygen (no destruction under strict anaerobic conditions). A dark period interrupting the bleaching light stopped the destruction o f this component for the time o f the dark period. The initial production o f the 620 nm com ponent was due to the oxygen exposure. U pon light irradiation this component was later destroyed by the com bined action o f oxygen and light. 
  Reference    Z. Naturforsch. 40c, 125—128 (1985); received October 22 1984 
  Published    1985 
  Keywords    Propionibacterium acnes, Fluorescence, Porphyrin, Photobleaching, Singlet-O xygen 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0125.pdf 
 Identifier    ZNC-1985-40c-0125 
 Volume    40 
9Author    B. Ernd, F. Ussm, Ann, P. Ete, D. AnRequires cookie*
 Title    Polymerization of Actin in the Absence and Presence of Cytochalasin B: Problems of Determining "Critical Concentration"  
 Abstract    A Various concentrations o f actin (0.3 or 1 mM MgCl2, 1 mM A T P , 1 mM E G T A) reached their final degree o f polym erization (m easured by a pyrene dye attached to actin) earlier in the pres­ ence o f cytochalasin B than in its absence. The curves relating concentrations o f polym eric F-actin to total actin concentration were under these conditions highly nonlinear making an unam biguous extrapolation to zero F-actin concentration (to deduce the "critical concentration" o f actin poly­ m erization) im possible. The concentration o f actin, above which polym erization occurred, was unaltered by cytochalasin B (although for reasons not yet understood the specific fluorescence intensity of polym erized actin was lower in the presence of cytochalasin B than in its absence). The results show that a distinct "critical concentration" o f actin polymerization must not always be well defined. 
  Reference    Z. Naturforsch. 41c, 781 (1986); received April 23 1986 
  Published    1986 
  Keywords    ctin, Cytochalasin B, Critical Concentration, Fluorescence, Polymerization 
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 TEI-XML for    default:Reihe_C/41/ZNC-1986-41c-0781.pdf 
 Identifier    ZNC-1986-41c-0781 
 Volume    41 
10Author    ThorB. Melø, Gro ReisaeterRequires cookie*
 Title    Photodestruction of Endogenous Porphyrins in Relation to Cellular Inactivation of Propionibacterium acnes  
 Abstract    of Propionibacterium acnes on Eagles medium protoporphyrin was accumulated inside the cells and coproporphyrin, both as a free base as metalcontaining, outside the cells. The photochemical processes in the endogenous porphyrins were studied by fluorescence spectroscopy during continuous irradiation of Propionibacterium acnes in suspension. The irradiation caused initially an increase in the content of protoporphyrin in the cells in comparison to that which had been accumulated during growth. Maximum light induced protoporphyrin production was achieved in 5 days old cultures. In old cultures where there was practically no initial protoporphy­ rin release, the fluorescence intensities from all the porphyrins present in the culture vanished exponentially with the irradiation time. The metal containing form of fluorescent coproporphyrin, with a maximum emission at 580 nm, was photobleached about ten times faster than the free base forms of coproporphyrin and protoporphyrin. Among these three fluorescent substances in the cell culture only the free base forms of the porphyrins have longer lifetimes than the cells themselves irradiated at the same conditions. 
  Reference    Z. Naturforsch. 41c, 867 (1986); received February 28/June 3 1986 
  Published    1986 
  Keywords    Propionibacterium acnes, Porphyrins, Photooxidation, Fluorescence, Survival During growth 
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 TEI-XML for    default:Reihe_C/41/ZNC-1986-41c-0867.pdf 
 Identifier    ZNC-1986-41c-0867 
 Volume    41 
11Author    S. S. BrodyRequires cookie*
 Title    The Position of Carotene in the D-l/D-2 Sub-Core Complex of Photosystem II  
 Abstract    When the sub-core complex of photosystem II, D1/D2, is irradiated at 436 or 415 nm (absorp-tion by chlorophyll and pheophytin and ß-carotene) or 540 nm (absorption primarily by pheophy-tin), the low temperature fluorescence spectrum has two maxima, at 685 and 674 nm. This shows the existence of at least two different fluorescent forms of chlorophyll (chlorophyll a and perhaps pheophytin a). When carotene is irradiated at 485 nm (absorption primarily by ß-carotene), only fluorescence at 685 nm is observed: this indicates that carotene is transferring energy to only the long-wavelength form of chlorophyll in the D1/D2 sub-core complex. The band of carotene (at 485 nm) does not appear in the fluorescence excitation spectrum, measured at 674 nm. The position of the carotene molecule relative to each of the fluorescent forms of chlorophyll was determined from the excitation spectra of each of the fluorescence bands. 
  Reference    Z. Naturforsch. 43c, 226—230 (1988); received August 21. 1987/January 11 1988 
  Published    1988 
  Keywords    Photosynthesis Photosystem II, Chlorophyll, Fluorescence, Carotenoids, Energy Transfer 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0226.pdf 
 Identifier    ZNC-1988-43c-0226 
 Volume    43 
12Author    SeymourSteven BrodyRequires cookie*
 Title    Rebinding of the 33 kDalton Polypeptide of Photosystem II to the D-l/D-2 Sub-Core Complex  
 Abstract    Specific and stoichiometric binding is shown between the D-l/D-2 sub-core complex and the 33 kDa polypeptide of photosystem II. Fluorescence from chlorophyll is used as an endogenous probe. When binding occurs there is an increase in fluorescence yield, as well as changes in both the fluorescence spectrum and excitation spectrum. 
  Reference    Z. Naturforsch. 43c, 727—730 (1988); received January 28/May 31 1988 
  Published    1988 
  Keywords    Photosynthesis, Reaction Center, Photosystem II, Chlorophyll, Fluorescence 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0727.pdf 
 Identifier    ZNC-1988-43c-0727 
 Volume    43 
13Author    M. Suwalsky, M. A. Espinoza, M. Bagnara, C. P. SotomayorRequires cookie*
 Title    X-Ray and Fluorescence Studies on Phospholipid Bilayers. IX. Interactions with Pentachlorophenol  
 Abstract    Pentachlorophenol (PCP) is a widely used and highly toxic fungicide. Its toxicity is mainly expressed at the cell membrane level. It is, therefore, o f interest to test its ability to alter the lipid bilayer organization. The present study was performed by X-ray diffraction techniques on dimyristoylphosphatidylethanolam ine (D M PE) and dim yristoylphosphatidylcholine (D M P C) bilayers and by fluorescence on DM PC liposomes. These two phospholipids are re­ spectively found at the inner and outer monolayers o f human erythrocyte membranes. Each type o f phospholipid was made to interact with different concentrations o f the sodium form o f PCP in absence and in presence o f water. It was found that PCP significatively affected the structure o f both phospholipids, being the damage much higher in DM PC bilayers. 
  Reference    Z. Naturforsch. 45c, 265 (1990); received September 18 1989 
  Published    1990 
  Keywords    X -R ay Diffraction, Fluorescence, Phospholipid Bilayers, Pentachlorophenol, Toxicity 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0265.pdf 
 Identifier    ZNC-1990-45c-0265 
 Volume    45 
14Author    MarcelA K Jansen3, Shmuel Malkinb, Marvin EdelmanaRequires cookie*
 Title    Differential Sensitivity of 32 kDa-D 1 Protein Degradation and Photosynthetic Electron Flow to Photosystem II Herbicides  
 Abstract    Degradation of the 32 kDa-D 1 protein, a photosystem II reaction centre component, was studied as a function of linear electron flow in visible light in the presence of various photosys­ tem II herbicides. Under these conditions, herbicide specific effects on protein degradation were clearly evident. 32 kDa-D 1 protein degradation and electron flow between Q a and Q b proved to be only partially correlated. We conclude that inhibition of protein degradation by PS II herbicides in visible light is not simply correlated to displacement of Q b. 
  Reference    Z. Naturforsch. 45c, 408—411 (1990); received December 12 1989 
  Published    1990 
  Keywords    Diuron, Bromoxynil, Dinoseb, Oxygen, Evolution, Chlorophyll, Fluorescence 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0408.pdf 
 Identifier    ZNC-1990-45c-0408 
 Volume    45 
15Author    Z. NaturforschRequires cookie*
 Title    Propagation of Voltage Transients in Arborized Neurites of Retzius Cells of the Leech in Culture  
 Abstract    Propagation o f electrical signals is studied in Retzius cells o f the leech in culture using volt­ age-sensitive fluorescent dyes at a spatial resolution o f 8 x 8 (am2 and 1 4 x 1 4 |im 2 and at a sam ­ pling interval o f 0.12 ms. The neurons are stimulated by a microelectrode impaled in the soma. Action potentials o f a halfwidth o f 2 -3 ms are triggered close to the end o f the primary neurite dissociated from the leech. They propagate back to the soma at invariant halfwidth at a veloci­ ty o f 5 0 -2 3 0 jam/ms. They pervade extended arborized secondary neurites which are grown on extracellular matrix protein. Their width is enhanced up to a factor two. The velocity is around 1 0 0 -150 (im/ms such that delays up to 3.5 ms are observed. Accordingly the neuritic trees are not isopotential. The features o f propagation are found to be incompatible with passive spread. 
  Reference    Z. Naturforsch. 46c, 687—6 (1991); received March 5 1991 
  Published    1991 
  Keywords    Leech, Neuron, Arborization, A ction Potential, Fluorescence 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0687.pdf 
 Identifier    ZNC-1991-46c-0687 
 Volume    46 
16Author    V. Ictor, B. Curw, G. Ert, S. Chan Sk Er, O. Scar, J. De, V. Os, J. S. Van RensenRequires cookie*
 Title    Comparison of Photosynthetic Activities in Triazine-Resistant and Susceptible Biotypes of Chenopodium album  
 Abstract    Triazine-resistant and susceptible Chenopodium album plants were grown at low and at high light irradiances. A t the lower light irradiance the dry m atter production of the resistant and the susceptible plants were almost similar. At the higher irradiance the resistant biotype had a significantly lower production. Fluorescence studies showed that the photochemical yield and the photosystem II electron transport rate were lower in the resistant biotype. It could be demonstrated in intact leaves that the lower productivity of the resistant biotype is caused by a higher sensitivity to photoinhibition. However, when studying effects of photoinhibition on electron flow and photophosphorylation in isolated thylakoids o f the two biotypes, no signifi­ cant differences between resistant and susceptible plant materials were observed. It is suggest­ ed that the difference between resistant and susceptible biotypes connected with processes pro­ tective against photoinhibition in intact leaves, are lost during the isolation of thylakoids. 
  Reference    Z. Naturforsch. 48c, 278 (1993); received November 26 1992 
  Published    1993 
  Keywords    Chloroplasts, Triazine-Resistance, Photosystem II, Photoinhibition, Fluorescence 
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 Identifier    ZNC-1993-48c-0278 
 Volume    48 
17Author    NavassardV. Karapetyanab, Ute Windhövel3 ', AlfredR. Holzwarthc, Peter BögeraRequires cookie*
 Title    Physiological Significance of Overproduced Carotenoids in Transformants of the Cyanobacterium Synechococcus PCC7942  
 Abstract    The functional location of carotenoids in the photosynthetic apparatus of -crtB and -pys transformants of the cyanobacterium Synechococcus PCC7942 was studied and compared with a control strain -pF P l-3. These transformants overproduce carotenoids due to the insertion of an additional foreign phytoene synthase gene. A higher carotenoid content was found for -crtB and -pys transformants both in whole cells and isolated membranes; the -crtB transformant was also enriched with chlorophyll. 77-K fluorescence emission and excita­ tion spectra of the phycobilin-free membranes were examined for a possible location of overproduced carotenoids in pigment-protein complexes in situ. A similar ratio of the ampli­ tudes of fluorescence bands at 716 and 695 nm emitted by photosystems I and II, found for the three strains, indicates that the stoichiometry between photosystems of the transformants was not changed. Overproduced carotenoids are not located in the core antenna of photosys­ tem I, since 77-K fluorescence excitation spectra for photosystem I of isolated membranes from the studied strains do not differ in the region of carotenoid absorption. When illumi­ nated with light of the same intensity but different quality, absorbed preferentially by either carotenoids, chlorophylls or phycobilins, respectively, oxygen evolution was found always higher in the transformants -crtB and -pys than in -p F P l-3 control cells. Identical kinetics of fluorescence induction of all strains under carotenoid excitation did not reveal a higher activity of photosystem II in cells enriched with carotenoids. It is suggested that overpro­ duced carotenoids of the transformants are not involved in photosynthetic light-harvesting; rather they may serve to protect the cells and its membranes against photodestruction. 
  Reference    Z. Naturforsch. 54c, 191—198 (1999); received December 18 1998 
  Published    1999 
  Keywords    Carotenoid, Chlorophyll, Cyanobacterium, Fluorescence, Oxygen Evolution 
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 Identifier    ZNC-1999-54c-0191 
 Volume    54 
18Author    Zoltán Takács, Zsolt Csintalan, Zoltán TubaRequires cookie*
 Title    Responses of the Lichen Cladonia convoluta to High C 0 2 Level and Heavy Metal Treatment  
 Abstract    Despite of the downward acclimation of photosynthesis in C. convoluta, increased net photosynthesis and carbon balance can be anticipated in response to elevated atmospheric C 0 2 level. C 0 2 exchange measurement seems to be m ore indicative when detecting heavy metal stress than fluorescence parameters. Among these, the relative fluorescence decrease ratio (R F d 690) shows damage first, suggesting that the primary attack site for heavy metal ions is C 0 2 fixation and reaction centres are harmed last. Long-term elevated C 0 2 amelio­ rates partly this damage by improving C-balance to a greater extent in the heavy-metal stressed lichens. 
  Reference    Z. Naturforsch. 54c, 797—8 (1999); received November 15 1998/M arch 5 1999 
  Published    1999 
  Keywords    Cadmium, Lead, Fluorescence, Respiration, Photosystem II 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0797.pdf 
 Identifier    ZNC-1999-54c-0797 
 Volume    54 
19Author    StuartM. Ridley, Peter HortonRequires cookie*
 Title    DCMU-Induced Fluorescence Changes and Photodestruction of Pigments Associated with an Inhibition of Photosystem I Cyclic Electron Flow  
 Abstract    Diuron (DCM U) induces the photodestruction o f pigm ents, w hich is the initial herbicidal symptom. As a working hypothesis, it is proposed that this sym ptom can only be produced when the herbicide dose is sufficiently high to inhibit not only photosystem II electron transport alm ost completely, but also inhibit (through over oxidation) the natural cyclic electron flow associated with photosystem I as well. Using freshly prepared chloroplasts, studies o f D C M U -induced fluorescence changes, and dose responses for inhibition o f electron transport, have been com ­ pared with a dose response for the photodestruction o f pigm ents in chloroplasts during 24 h illumination. Photodestruction o f pigm ents coincides with the inhibition o f cyclic flow. 
  Reference    Z. Naturforsch. 39c, 351 (1984); received October 10 1983 
  Published    1984 
  Keywords    Diuron (DCM U), Photodestruction, Fluorescence, Photosystem I, Cyclic Electron Flow 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0351.pdf 
 Identifier    ZNC-1984-39c-0351 
 Volume    39 
20Author    G. Renger, R. H. Agem Ann, W.F J V Erm AasRequires cookie*
 Title    Studies on the Functional Mechanism of System II Herbicides in Isolated Chloroplasts  
 Abstract    The effect o f specific proteolytic enzymes on variable fluorescence, p-benzoquinone-m ediated oxygen evolution, PS II herbicide (atrazine and brom oxynil) binding, and protein degradation has been analyzed in isolated class II pea chloroplasts. It was found that: 1. Trypsin and a lysine-specific protease effectively reduce the m axim um chlorophyll-a flu o­ rescence yield, whereas the initial fluorescence remains alm ost constant. At the sam e number o f enzymatic activity units both proteases have practically the sam e effect. 2 Trypsin and a lysine-specific protease inhibit the /»-benzoquinone-m ediated flash-induced oxygen evolution with trypsin being markedly more effective at the sam e num ber o f activity units o f both enzymes. Unstacked thylakoids exhibit a higher sensitivity to proteolytic degrada­ tion by both enzymes. 3. Trypsin and a lysine-specific protease reduce the binding capacity o f [14C]atrazine, but enhance that o f [l4C]bromoxynil (at long incubation tim es trypsin treatm ent also impairs bromoxynil binding). At the same specific activity a m arkedly longer treatm ent is required for the lysine-specific protease in order to achieve the same degree o f m odification as w ith trypsin. 4. Trypsin was found to attack the rapidly-turned-over 32 kD a-protein severely, whereas the lysine-specific protease does not m odify this polypeptide. On the other hand, the lysine-specific protease attacks the light harvesting com plex II. 5. Under our experimental conditions an arginine-specific protease did not affect chlorophyll-a fluorescence yield, /?-benzoquinone-mediated oxygen evolution, herbicide binding and the p oly­ peptide pattern. Based on these results a m echanism is proposed in w hich an as yet unidentified polypeptide with exposable lysine residues, as well as the lysine-free "Q B-protein" regulate the electron transfer from Q ^ to Q B and are involved in herbicide binding. 
  Reference    Z. Naturforsch. 39c, 362—367 (1984); received Decem ber 1 1983 
  Published    1984 
  Keywords    Chloroplasts, Proteolytic Enzymes, Fluorescence, Oxygen Evolution, H erbicide Binding 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0362.pdf 
 Identifier    ZNC-1984-39c-0362 
 Volume    39 
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