Characterization of a Light-Induced Oxygen-Uptake in Tobacco Protoplasts

1979 ◽  
Vol 34 (7-8) ◽  
pp. 570-575 ◽  
Author(s):  
Georg H. Schmid ◽  
Pierre Thibault
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Evolution ◽  
Photosystem I ◽  
Action Spectrum ◽  
Photosynthetic Oxygen Evolution ◽  
Yellow Leaf ◽  
Wild Type ◽  
In The Wild ◽  
Aurea Mutant ◽  
Yellow Pigments

Abstract Protoplasts prepared from the wild type tobacco N. tabacum var. John William’s Broadleaf exhibit photosynthetic oxygen-evolution if the suspension medium is supplemented with bicarbonate. In the absence of bicarbonate no steady state oxygen-evolution is observed with such preparations. Instead, an appreciable uptake which is mainly insensitive to DCMU and which persists over hours, and therefore is no induction phenomenon, is seen. Protoplasts of the tobacco aurea mutant Su/su, which is a plant with an exceptionally high photorespiration, show an oxygen consumption in the light which is 4 to 5 times higher per protoplast than in the wild type. Again, the uptake is practically insensitive to DCMU which means that the effect is to be associated with photosystem I. This is further substantiated by the fact that protoplasts prepared from yellow leaf1 sec­tions of the variegated tobacco mutant NC 95 also show the light induced uptake. As reported earlier, the yellow leaf sections of this mutant exhibit only photosystem I reactions.The action spectrum for this oxygen-uptake yields the spectrum of chlorophyll. Consequently, this uptake is an inherent property of the chloroplast and has nothing to do with earlier described, light-dependent oxygen consumptions, which were mainly driven by blue light and hence used some yellow pigment as the photoreceptor. No effect or contribution of yellow pigments such as carotenoids is seen since the action spectrum with the yellow tobacco mutants which have an up to 4 fold higher carotenoid/chlorophyll ratio than the wild type is identical to that of the wild type.

Light-induced inhibition of respiration in DCMU-poisoned Chlorella caused by photosystem I activity

1972 ◽  
Vol 50 (1) ◽  
pp. 13-21 ◽  
Author(s):  
D. F. Sargent ◽  
C. P. S. Taylor
Keyword(s):  
Oxygen Uptake ◽  
Chlorophyll A ◽  
Oxygen Evolution ◽  
Photosystem I ◽  
Action Spectrum ◽  
Photosynthetic Oxygen Evolution ◽  
Intracellular Atp ◽  
Respiratory Inhibition ◽  
Cyclic Photophosphorylation ◽  
Photosynthetic Oxygen

We have demonstrated that the reduced net rate of oxygen uptake observed when DCMU-poisoned Chlorella are illuminated is a result of an inhibition of respiration rather than residual photosynthetic oxygen evolution. The action spectrum of the effect demonstrates that chlorophyll a is the main photoreceptor, implicating system I of photosynthesis. Studies using PMS, which is known to stimulate cyclic photophosphorylation by photosystem I, show that the respiratory inhibition is caused by a change in the intracellular ATP/ADP balance as a result of cyclic photophosphorylation.

Evidence for a Rapid Oxygen-Uptake in Tobacco Chloroplasts

1979 ◽  
Vol 34 (5-6) ◽  
pp. 414-418 ◽  
Author(s):  
Georg H. Schmid ◽  
Pierre Thibault
Keyword(s):  
Oxygen Uptake ◽  
Photosystem I ◽  
Photosynthetic Oxygen Evolution ◽  
Wild Type ◽  
Intact Chloroplasts ◽  
Chlorophyll Mutants ◽  
Photosynthetic Oxygen ◽  
Aurea Mutant ◽  
Oxygen Yield ◽  
Fully Functioning

Abstract A fast oxygen uptake, induced by a sequence of short (5 µsec) saturating flashes was observed in chloroplasts of wild type tobacco and two chlorophyll-deficient tobacco mutants. One of the chlorophyll mutants is the earlier described variegated tobacco NC 95. Chloroplasts of this mutant exhibit only photosystem I mediated photoreactions, hence the observed oxygen uptake is to be associated with photosystem I. This is further substantiated by the fact that the oxygen uptake is insensitive to DCMU in the two chloroplast types used, which have both photosystems fully functioning. The uptake depends on the addition of electron acceptors like p-benzoquinone in intact chloroplasts or on p-benzoquinone or ferricyanide in chloroplasts that have lost the envelope. In dark adapted chloroplasts, therefore, under these conditions the overall apparent gas exchange in the first two flashes is consumption. Although the uptake is slower than photosynthetic oxygen evolution it clearly affects the oxygen yield in the flash sequences. This is demonstrated by several experiments in which the apparent oxygen consumption in the absence of DCMU oscillates with a periodicity of four. We have indications that in chloroplasts of the tobacco aurea mutant Su/su the oxygen uptake is faster than in wild type chloroplasts.

scholarly journals TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

2020 ◽  
Author(s):  
Azeez Beebo ◽  
Ahmad Zia ◽  
Christopher R. Kinzel ◽  
Andrei Herdean ◽  
Karim Bouhidel ◽  
...  
Keyword(s):  
Electron Transport ◽  
Oxygen Evolution ◽  
Photosynthetic Electron Transport ◽  
Chloroplast Envelope ◽  
Photosynthetic Oxygen Evolution ◽  
Wild Type ◽  
Thylakoid Lumen ◽  
Photosynthetic Oxygen ◽  
Osmotic Treatment ◽  
Envelope Membranes

SUMMARYPhotosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of Arabidopsis thaliana. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both thylakoid and envelope membranes. Mutants lacking TIP1;2 and/or TIP2;1 did not display a macroscopic phenotype when grown under standard conditions. The mutant chloroplasts and thylakoids underwent less volume changes than the corresponding wild type preparations upon osmotic treatment and in the light. Significantly reduced rates of photosynthetic electron transport were obtained in the mutant leaves, with implications on the CO2 fixation rates. However, electron transport rates did not significantly differ between mutants and wild type when isolated thylakoids were examined. Less acidification of the thylakoid lumen was measured in mutants thylakoids, resulting in a slower induction of delta pH-dependent photoprotective mechanisms. These results identify TIP1;2 and TIP2;1 as chloroplast proteins and highlight their importance for osmoregulation and optimal photosynthesis. A third aquaporin, TIP1;1, is present in the chloroplast envelope, and may play role in photosynthesis under excessive light conditions, as based on the weak photosynthetic phenotype of its mutant.

Blue Light Enhanced Respiratory Activity Under Photosynthetic Conditions In Chlorella; A Mass Spectrometric Analysis

1992 ◽  
Vol 47 (11-12) ◽  
pp. 881-888 ◽  
Author(s):  
Klaus P. Bader ◽  
Georg H. Schmid ◽  
Günter Ruyters ◽  
Wolfgang Kowallikb
Keyword(s):  
Oxygen Uptake ◽  
Blue Light ◽  
Red Light ◽  
Wavelength Dependence ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Wild Type ◽  
Carbohydrate Degradation ◽  
In The Wild

Mass spectrometric analysis shows that blue light enhances oxygen uptake during photosynthesis in Chlorella fusca. Assays in which all of the normal 16O2 of air has been substituted by 18O2 permit discrimination between photosynthetic O2-evolution (measured as 16O2, i.e. mass 32) and O2-uptake (measured as 18O2, i.e. mass 36). A chlorophyll-free Chlorella kessleri mutant for which in earlier studies the occurrence of blue light enhanced oxidative carbohydrate degradation has been demonstrated (W. Kowallik, H. Gaffron, Planta 69, 9 2 -9 5 (1966); W. Kowallik, Ann. Rev. Plant Physiol. 33, 5 7 -7 2 (1982)) has been used for comparison in the present study. The light intensity dependencies of the observed effect seem to differ in mutant and wild type cells. In the mutant a fluence rate of 1 .5 -2 .0 (μE m -2·s-1 of blue light yields saturation, whereas in the wild type even ten times this value does not. A wavelength dependence of the effect measured with equal fluence rates at 422 nm, 457 nm, 488 nm, 555 nm and 649 nm shows maximal efficiency around 460 nm and no significant effect of red light. This agrees with earlier studies on the chlorophyll- free mutant. As a result of this correspondence, we think that the enhanced oxygen uptake during photosynthesis concerns oxidative carbohydrate degradation. The putative mechanism and significance of the observed blue light enhanced respiration in photosynthesizing Chlorella are discussed

scholarly journals The Action Spectrum of Photosynthesis in Euglena Gracilis at Different Stages of Chloroplast Development

1970 ◽  
Vol 23 (1) ◽  
pp. 33 ◽  
Author(s):  
JT O Kirk ◽  
JA Reade
Keyword(s):  
Oxygen Evolution ◽  
Euglena Gracilis ◽  
Chloroplast Development ◽  
Platinum Electrode ◽  
Action Spectrum ◽  
Thin Strip ◽  
Agarose Gel ◽  
Photosynthetic Oxygen Evolution ◽  
Unicellular Algae ◽  
Photosynthetic Oxygen

A method for measuring the action spectra of photosynthetic oxygen evolution in unicellular algae is described. This involves embedding the cells in a thin strip of agarose gel. These gel strips can then be used for action spectrum measurements, with a bare platinum electrode of the Haxo and Blinks type in the same way as measure� ments are made with a piece of multicellular algal thallus.

Consequences of High CO2-Concentrations in Air on Growth and Gas-Exchange Rates in Tobacco Mutants

1995 ◽  
Vol 50 (11-12) ◽  
pp. 781-788 ◽  
Author(s):  
P He ◽  
K. P Bader ◽  
A Radunz ◽  
G.H Schmid
Keyword(s):  
Gas Exchange ◽  
Photosynthetic Apparatus ◽  
Wild Type ◽  
Induction Kinetics ◽  
Partial Pressures ◽  
In The Wild ◽  
Rate Of Photosynthesis ◽  
Aurea Mutant ◽  
Kinetics Of

Abstract Wild type tobacco N. tabacum var. John William’s Broadleaf and the tobacco aurea mutant Su/su were permanently grown under 700 ppm CO2 in air. In comparison to plants grown under 350 ppm CO2 in air but under otherwise identical conditions growth was substantially enhanced. Gas exchange measurements carried out by mass spectrometry show that the rate of photosynthesis in the wild type and in the mutant is increased by more than 100%. The photorespiratory rate in the wild type measured as 18O2-uptake in the light in the “700 ppm CO2-plants” is not reduced to the extent expected or deduced from experiments in which the 350 ppm system responds under in vitro conditions to 700 ppm CO2. An analysis of the induction kinetics of room temperature fluorescence kinetics of the adapted (700 ppm CO2) system and the control system (350 ppm CO2) under various CO2-partial pressures shows that permanent growth under the elevated CO2-partial pressure leads to a structural modification of the photosynthetic apparatus.

scholarly journals The plastome-encoded PsaJ subunit is required for efficient Photosystem I excitation, but not for plastocyanin oxidation in tobacco

2007 ◽  
Vol 403 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Mark A. Schöttler ◽  
Claudia Flügel ◽  
Wolfram Thiele ◽  
Sandra Stegemann ◽  
Ralph Bock
Keyword(s):  
Chlorophyll A ◽  
Photosystem I ◽  
Fluorescence Emission ◽  
Reaction Centre ◽  
Wild Type ◽  
Fluorescence Emission Spectra ◽  
Light Intensities ◽  
In The Wild ◽  
Assimilation Capacity

The functions of several small subunits of the large photosynthetic multiprotein complex PSI (Photosystem I) are not yet understood. To elucidate the function of the small plastome-encoded PsaJ subunit, we have produced knockout mutants by chloroplast transformation in tobacco (Nicotiana tabacum). PsaJ binds two chlorophyll-a molecules and is localized at the periphery of PSI, close to both the Lhca2- and Lhca3-docking sites and the plastocyanin-binding site. Tobacco psaJ-knockout lines do not display a visible phenotype. Despite a 25% reduction in the content of redox-active PSI, neither growth rate nor assimilation capacity are altered in the mutants. In vivo, redox equilibration of plastocyanin and PSI is as efficient as in the wild-type, indicating that PsaJ is not required for fast plastocyanin oxidation. However, PsaJ is involved in PSI excitation: altered 77 K chlorophyll-a fluorescence emission spectra and reduced accumulation of Lhca3 indicate that antenna binding and exciton transfer to the PSI reaction centre are impaired in ΔpsaJ mutants. Under limiting light intensities, growth of ΔpsaJ plants is retarded and the electron-transport chain is far more reduced than in the wild-type, indicating that PSI excitation might limit electron flux at sub-saturating light intensities. In addition to defining in vivo functions of PsaJ, our data may also have implications for the interpretation of the crystal structure of PSI.

scholarly journals Two Mutants Affecting Adaptative Responses to Abiotic Stresses in Barley Seedlings

2011 ◽  
Vol 41 (No. 1) ◽  
pp. 1-10 ◽  
Author(s):  
A.E. Martínez ◽  
A. Landau ◽  
P.T. García ◽  
G. Polenta ◽  
M.C. Arias ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Photosystem I ◽  
Abiotic Stresses ◽  
Higher Plants ◽  
Nuclear Gene ◽  
The Other ◽  
Wild Type ◽  
Seedling Roots ◽  
In The Wild ◽  
Photosystem I And Ii

Two novel mutants which affect the adaptative responses of barley seedlings to different abiotic stresses are described. They allow us to explore some aspects of adaptative phenomena that are little known in higher plants. One of these mutants corresponds to a nuclear gene which under certain circumstances in the wild type barley induces additional ethylene production in the seedling roots. This mechanism seems to be involved in inducing a negative hydrotropic growth of the roots, a phenomenon that we interpret as a response avoiding waterlogging. The other mutant corresponds to a plastid encoded gene which is involved in photosystem I and II stability and, probably, indirectly affects the acclimation of the seedlings to higher temperatures, a fact which seems to occur through the control of unsaturation/saturation levels of the thylakoid membrane fatty acids.  

The pigmentary system of developing axolotls

Development ◽  
1986 ◽  
Vol 92 (1) ◽  
pp. 255-268
Author(s):  
S. K. Frost ◽  
L. G. Epp ◽  
S. J. Robinson
Keyword(s):  
Developmental Stages ◽  
Structural Characteristics ◽  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Pigment Cells ◽  
Wild Type ◽  
Transmission Electron ◽  
In The Wild ◽  
Yellow Pigments ◽  
First Time

The albino mutant in the Mexican axolotl (Ambystoma mexicanum) is analysed with respect to the differentiation of pigment cells. Pigment cells were observed with the transmission electron microscope in order to determine any unusual structural characteristics and to determine what happens to each of the cell types as development proceeds. Chemical analyses of pteridine pigments were also carried out, and the pattern of pteridines in albino animals was found to be more complex than, and quantitatively enhanced (at all developmental stages examined) over, the pattern observed in comparable wild-type axolotls. The golden colour of albino axolotls is due primarily to sepiapterin (a yellow pteridine) and secondarily to riboflavin (and other flavins). Coincident with enhanced levels of yellow pigments, xanthophore pigment organelles (pterinosomes) in albino skin reach a mature state earlier than they do in wild-type axolotl skin. This morphology is conserved throughout development in albino animals whereas it is gradually lost in the wild type. Unpigmented melanophores from albino axolotls are illustrated for the first time, and in larval albino axolotls the morphology of these cells is shown to be very similar to xanthophore morphology. In older albino animals xanthophores are easily distinguished from unpigmented melanophores. Iridophores seem to appear in albino skin at an earlier stage than they have been observed in wild-type skin. Morphologically, wild-type and albino iridophores are identical.

Freeze-substituted fungal cells of Nectria haematococca: A comparison of the macroconidial walls of the adhesion-competent wild type with an adhesion-reduced mutant

1990 ◽  
Vol 48 (3) ◽  
pp. 688-689
Author(s):  
Thecan Caesar-Ton That ◽  
Lynn Epstein
Keyword(s):  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Wild Type ◽  
Nectria Haematococca ◽  
Fruit Extract ◽  
Dialysis Tubing ◽  
Tube Emergence ◽  
Contrast Microscopy ◽  
In The Wild ◽  
Freeze Damage

Nectria haematococca mating population I (anamorph, Fusarium solani) macroconidia attach to its host (squash) and non-host surfaces prior to germ tube emergence. The macroconidia become adhesive after a brief period of protein synthesis. Recently, Hickman et al. (1989) isolated N. haematococca adhesion-reduced mutants. Using freeze substitution, we compared the development of the macroconidial wall in the wild type in comparison to one of the mutants, LEI.Macroconidia were harvested at 1C, washed by centrifugation, resuspended in a dilute zucchini fruit extract and incubated from 0 - 5 h. During the incubation period, wild type macroconidia attached to uncoated dialysis tubing. Mutant macroconidia did not attach and were collected on poly-L-lysine coated dialysis tubing just prior to freezing. Conidia on the tubing were frozen in liquid propane at 191 - 193C, substituted in acetone with 2% OsO4 and 0.05% uranyl acetate, washed with acetone, and flat-embedded in Epon-Araldite. Using phase contrast microscopy at 1000X, cells without freeze damage were selected, remounted, sectioned and post-stained sequentially with 1% Ba(MnO4)2 2% uranyl acetate and Reynold’s lead citrate. At least 30 cells/treatment were examined.

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