La photorespiration se déroulant dans un air sans CO2 a-t-elle une fonction?

1978 ◽  
Vol 56 (17) ◽  
pp. 2128-2137 ◽  
Author(s):  
Gabriel Cornic
Keyword(s):  
Light Intensity ◽  
Photosynthetic Apparatus ◽  
Qualitative Change ◽  
Sinapis Alba ◽  
Inhibitory Effect ◽  
High Light Intensity ◽  
Long Term Effects ◽  
Net Assimilation ◽  
The Warburg Effect

Long-term effects of a low O2 and CO2, atmosphere on photosynthesis were studied on Sinapis alba L. It was shown that this could induce strong and durable changes on the subsequent photosynthesis measured at different CO2 and O2 concentrations. Two mains effects were observed: (1) an inhibition of net assimilation measured at 21% or 0.1% O2; (2) a qualitative change of the Warburg effect. After the treatment, high CO2 concentrations did not reverse the inhibitory effect of O2 on photosynthesis.The effect of the low O2 and CO2 atmosphere, characterized by the inhibition of net assimilation, was analyzed by varying the following factors during plants treatment: light intensity, temperature, and CO2 and O2 concentrations. The inhibition was higher under high light intensity, increased with temperature, and was apparent within the following limits of CO2 and O2 concentration, respectively, 0 to 0.018% CO2 and 0.1 to 4% O2.The results are discussed to determine if they showed that an inhibition of photorespiration in a low CO2 atmosphere has a function in the photosynthetic apparatus.

High light intensity protects photosynthetic apparatus of pea plants against exposure to lead

2006 ◽  
Vol 44 (5-6) ◽  
pp. 387-394 ◽  
Author(s):  
E. Romanowska ◽  
B. Wróblewska ◽  
A. Droƶak ◽  
M. Siedlecka
Keyword(s):  
Light Intensity ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
High Light

scholarly journals Freezing and low temperature photoinhibition tolerance in cultivated potato and potato hybrids

2001 ◽  
Vol 10 (3) ◽  
pp. 153-163 ◽  
Author(s):  
M.M. SEPPÄNEN ◽  
O. NISSINEN ◽  
S. PERÄLÄ
Keyword(s):  
Low Temperature ◽  
Light Intensity ◽  
Field Experiments ◽  
Photosynthetic Apparatus ◽  
Ground Level ◽  
High Light Intensity ◽  
High Light ◽  
Freezing Stress ◽  
Ion Leakage ◽  
Frost Injury

Four Solanum tuberosum L. cultivars (Nicola, Pito, Puikula, Timo) and somatic hybrids between freezing tolerant S. commersonii and freezing sensitive S. tuberosum were evaluated for their tolerance to freezing and low temperature photoinhibition. Cellular freezing tolerance was studied using ion leakage tests and the sensitivity of the photosynthetic apparatus to freezing and high light intensity stress by measuring changes in chlorophyll fluorescence (FV/FM) and oxygen evolution. Exposure to high light intensities after freezing stress increased frost injury significantly in all genotypes studied. Compared with S. tuberosum cultivars, the hybrids were more tolerant both of freezing and intense light stresses. In field experiments the mechanism of frost injury varied according to the severity of night frosts. During night frosts in 1999, the temperature inside the potato canopy was significantly higher than at ground level, and did not fall below the lethal temperature for potato cultivars (from -2.5 to -3.0°C). As a result, frost injury developed slowly, indicating that damage occurred to the photosynthetic apparatus. However, as the temperature at ground level and inside the canopy fell below -4°C, cellular freezing occurred and the canopy was rapidly destroyed. This suggests that in the field visual frost damage can follow from freezing or non-freezing temperatures accompanied with high light intensity. Therefore, in an attempt to improve low temperature tolerance in potato, it is important to increase tolerance to both freezing and chilling stresses.

scholarly journals Effect of Increased Influent COD on Relieving the Toxicity of CeO2 NPs on Aerobic Granular Sludge

2019 ◽  
Vol 16 (19) ◽  
pp. 3609 ◽  
Author(s):  
Xiaoying Zheng ◽  
Yuan Zhang ◽  
Wei Chen ◽  
Weihong Wang ◽  
Hang Xu ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Inhibitory Effect ◽  
Environmental Risks ◽  
Pollutant Removal ◽  
Aerobic Granular Sludge ◽  
Long Term Effects ◽  
Negative Effects

Due to the increased use of cerium oxide nanoparticles (CeO2 NPs), their potential environmental risks have caused concern. However, their effects on the aerobic granular sludge (AGS) process and the later recovery of AGS are still unclear. In this study, we comprehensively determined the changes in pollutant removal and the levels of extracellular polymeric substances (EPS) in AGS that were exposed to CeO2 NP treatments (0 (the control, R0), 1 (R1), and 5 (R5) mg/L), following an increase in the influent chemical oxygen demand (COD). An increase in the CeO2 NP concentration enhanced their inhibitory effect on the removal of total nitrogen (TN) and total phosphorus (TP), and promoted the production of polysaccharides (PS) and proteins (PN) in loosely bound EPS (LB-EPS) or tightly bound EPS (TB-EPS), as well as the dissolved organic carbon (DOC) components in EPS, but had no long-term effects on the removal of organic matter. When the addition of CeO2 NPs was stopped and the concentration of influent COD increased, the TN and TP removal efficiencies in R1 and R5 slowly increased and recovered. In R1, they were only 4.55 ± 0.55% and 2.71 ± 0.58% lower than in R0, respectively, while the corresponding values for R5 were 5.06 ± 0.46% and 6.20 ± 0.63%. Despite the LB-EPS and TB-EPS concentrations in the R1 and R5 treatments recovering and being similar to the levels in the control when no CeO2 NPs were added, they were still slightly higher than in the R0, which indicating that the negative effects of CeO2 NPs could not be completely eliminated due to the residual CeO2 NP levels in AGS.

High light intensity aggravates latent manganese deficiency in maize

2020 ◽  
Vol 71 (19) ◽  
pp. 6116-6127 ◽  
Author(s):  
Lizhi Long ◽  
Pai R Pedas ◽  
Rebekka K Kristensen ◽  
Waltraud X Schulze ◽  
Søren Husted ◽  
...  
Keyword(s):  
Light Intensity ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
Photosynthetic Performance ◽  
High Light ◽  
Oxygen Evolving Complex ◽  
Mn Deficiency ◽  
Two Factors ◽  
Genes Encoding ◽  
Underlying Mechanisms

Abstract Manganese (Mn) plays an important role in the oxygen-evolving complex, where energy from light absorption is used for water splitting. Although changes in light intensity and Mn status can interfere with the functionality of the photosynthetic apparatus, the interaction between these two factors and the underlying mechanisms remain largely unknown. Here, maize seedlings were grown hydroponically and exposed to two different light intensities under Mn-sufficient or -deficient conditions. No visual Mn deficiency symptoms appeared even though the foliar Mn concentration in the Mn-deficient treatments was reduced to 2 µg g–1. However, the maximum quantum yield efficiency of PSII and the net photosynthetic rate declined significantly, indicating latent Mn deficiency. The reduction in photosynthetic performance by Mn depletion was further aggravated when plants were exposed to high light intensity. Integrated transcriptomic and proteomic analyses showed that a considerable number of genes encoding proteins in the photosynthetic apparatus were only suppressed by a combination of Mn deficiency and high light, thus indicating interactions between changes in Mn nutritional status and light intensity. We conclude that high light intensity aggravates latent Mn deficiency in maize by interfering with the abundance of PSII proteins.

scholarly journals THE FINE STRUCTURE OF RHODOSPIRILLUM RUBRUM

1963 ◽  
Vol 16 (2) ◽  
pp. 401-419 ◽  
Author(s):  
Germaine Cohen-Bazire ◽  
Riyo Kunisawa
Keyword(s):  
Fine Structure ◽  
Light Intensity ◽  
Chlorophyll Content ◽  
Rhodospirillum Rubrum ◽  
Photosynthetic Pigment ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
Thin Sections ◽  
Lead Hydroxide ◽  
In Cells

The fine structure of Rhodospirillum rubrum grown under a series of defined conditions has been examined in thin sections prepared by the methods of Ryter and Kellenberger. In cells grown anaerobically at different light intensities, the abundance of 500 A membrane-bounded vesicles in the cytoplasm is inversely related to light intensity, and directly related to cellular chlorophyll content. When the chlorophyll content of the cell is low, the vesicles are exclusively peripheral in location; they extend more deeply into the cytoplasm when the chlorophyll content is high. Typical vesicles also occur, though rarely, in cells grown aerobically in the dark, which have a negligible chlorophyll content. When synthesis of the photosynthetic pigment system is induced in a population of aerobically grown cells by incubation under semianaerobic conditions in the dark, the vesicles become increasingly abundant with increasing cellular chlorophyll content, and the cells eventually acquire the cytoplasmic structure that is characteristic of cells growing anaerobically at a high light intensity. Poststaining with lead hydroxide reveals that the membranes surrounding the 500 A vesicles are indistinguishable in structure from the cytoplasmic membrane, and continuous with it in some areas of the sections. The bearing of these observations on current notions concerning the organization of the bacterial photosynthetic apparatus is discussed.

Differential Changes in the Photosynthetic Pigments and Polyamine Content during Photoadaptation and Photoinhibition in the Unicellular Green Alga Scenedesmus obliquus

1998 ◽  
Vol 53 (9-10) ◽  
pp. 833-840 ◽  
Author(s):  
Kiriakos Kotzabasis ◽  
Dieter Dörnem
Keyword(s):  
Light Intensity ◽  
Green Alga ◽  
Scenedesmus Obliquus ◽  
Photosynthetic Pigment ◽  
Photosynthetic Apparatus ◽  
High Light Intensity ◽  
High Light ◽  
Light Conditions ◽  
Unicellular Green Alga ◽  
Polyamine Level

In the unicellular green alga Scenedesmus obliquus the level of photoinhibition and the recovery of the cells after reversal to the initial light conditions in relation to the pre-photoadaptation of the culture to low, medium and high light intensity was determined. The changes in the photosynthetic pigment content and in the intracellular polyamine concentration allowed to distinguish between photoadaptation and photoinhibition. In particular, the level of chlorophylls, xanthophylls and carotenoids decreased inversely proportional to the light intensity applied during photoadaptation, whereas their concentrations remained constant during photoinhibition. The violaxanthin/zeaxanthin and the loroxanthin/lutein cycle work only under photoinhibitory conditions, but not under photoadaptive premises. Changes in the level of these carotenoids in relation to the changes in the photosynthetic apparatus during photoadaptation are discussed. In addition, it was found that the intracellular polyamine level increased only under stress conditions, i. e. during photoinhibition, and decreased during recovery of the cells after reversal to the initial light conditions. The increase of the putrescine level during photoinhibition is inversely proportional to the light intensity used for pre-adaptation. This rise of the polyamine level in the cells photoadapted to high light conditions is an additional indication for the finding that photoadaptation and photoinhibition are different phenomena which are clearly distinguishable from each other. Finally, the changes of the chlorophyll, violaxanthin, zeaxanthin, loroxanthin, lutein and polyamine levels under photoadaptation in high light intensity (50 W m -2) in relation to the range of photoadaptation in Scenedesmus obliquus are discussed.

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