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Academic literature on the topic 'Photosynthèse – Acclimatation'
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Dissertations / Theses on the topic "Photosynthèse – Acclimatation"
Fouqueray, Manuela. "Dynamique de l'acclimatation des diatomées marines aux rayonnements ultraviolets : approches physiologiques, biochimiques et moléculaires." Le Mans, 2007. http://cyberdoc.univ-lemans.fr/theses/2007/2007LEMA1004.pdf.
Full textAmong the photosynthetic aquatic organisms, marine diatoms are responsible for a quarter of the annual incorporation of inorganic carbon in the oceans. Ultraviolet radiation (UV) induces a reduction of productivity of these microalgae, which has negative impacts on the economical (shellfish industry) as on the ecologicallevel (biogeochemical cycles). This thesis focuses on the short-term acclimation to UV radiation in five marine diatoms : Amphora coffeaeformis, Entomoneis paludosa, Haslea ostrearia, Odontella aurita and Skeletonema costatum. The originality of this work was the study of the dynamics of the acclimation phase of the different species exposed to UV radiation. The UV stress consisted in 5h exposure to a combination of UV-A and UV-B radiation applied in the middle of the photoperiod, repeated on 8 consecutive days. Measurements of in vivo chlorophyll fluorescence (modulated fluorimetry), during the UV treatment, allowed to continuously record the changes in photosynthetic parameters (maximum quantum efficiency and effective maximum electron transport rate) and to quantify damage at the photosynthetic apparatus and possible repairs. Recovery (after the stress) estimated by means ofmeasured photosynthetic parameters appears to be a key factor for acclimation. The use of lincomycin demonstrated that the Dl PSII protein was a major target of UV radiation and its turn-over rate increased with exposure. The overall results indicated that S. Costatum is un able to acclimate to UV. The quantification of constants of damage and repair illustrated the capabilities of UV acclimation in the other four diatoms. Thus, in A. Coffeaeformis, E. Paludosa and H. Ostrearia, PSII acclimated to the UV stress due to the mechanism of recovery and repair, while in O. Aurita although repair was important, the absence of recovery and mechanisms of defense and / or protection did not allow to compensate for all the damages. In addition, diatoms developed protection mechanisms with respect to the formation of reactive oxygen species whose production increased under UV treatment. Among these mechanisms, the activity of antioxidant enzymes was followed during the acclimation period. Our results indicated that an overall reduction of these activities was correlated with an increase in sensitivity to UV. The phosphoenolpyruvate carboxylase (PEPCase), like the ribulose bisphosphate carboxylase (RUBISCO), participates in the inorganic carbon sequestration in diatoms. In addition, carbonic anhydrase (CA) plays an important role in the supply of inorganic carbon in diatoms. To determine at which level UV radiation acts on these enzymes (enzyme activity or at the gene transcription level), a-AC and B-AC and PEPCase genes were investigated in A. Coffeaeformis. A partial sequence (357 aa) of PEPCase was determined. It had a strong identity with PEPCases of plants but formed, with the known sequences of two other diatoms, a different group. The first tests of quantification of transcripts during the 8 days of UV exposure indicated that UV inhibited transcription of PEPCase in A. Coffeaeformis. These various approaches have helped to highlight the differences in behavior of diatoms exposed to UV radiation with a major effect at the physiological (PS II) and the molecular (PEPCase) level
Frak, Elzbieta. "Allocation de l'azote dans le feuillage d'un arbre decidu (juglans nigra x regia) aux niveaux foliaire et de la plante entière." Paris 11, 2002. http://www.theses.fr/2002PA112173.
Full textDeterminants, plasticity and modalities of nitrogen (N) allocation in foliage of walnut trees (Juglans regia x nigra) at leaf or whole plant scale were investigated. At the leaf scale, we demonstrated that leaf irradiance played a key role in leaf N allocation and photosynthetic acclimation. We have shown that after a sudden change in light regime, fully expanded walnut leaves were able to acclimate their photosynthetic capacities to the new light conditions within one month. This ability was due to concurrent changes in total leaf N and N investment into different photosynthetic functions but its relative importance differed depending of the type of change in light regime. At whole plant level, N allocated to the new shoots arrived from two sources: stored N and N provided by root uptake. However, we found that the major part of total shoot N came from remobilization (92-99%). The current nitrogen availability for root uptake do not affect the absolute amount of N provided by remobilization but affects the fraction of N coming from remobilization. There is no effect of leaf "age" and light regime on the fraction of N coming, from remobilization, recovered in new shoots. However, light regime affects total amount of N in new shoots. This indicates, that at the whole plant level, the allocation of N to the new shoots is dependent on local sink strength, which is modulated by the local light environment
Navarro, Mastache Luis Cuauhtémoc. "Effet de l'intensité lumineuse, de l'aération et de l'enrichissement en CO2 au cours de la micropropagation du bananier (Musa acuminata cv. Petite Naine) sur le développement des plants in vitro et en phase d'acclimatation in vivo." Toulouse, INPT, 1990. http://www.theses.fr/1990INPT016A.
Full textPeraudeau, Sébastien. "Réponses de la respiration à l'augmentation de la température nocturne chez le riz : production de biomasse et de grains et conséquences pour les modèles de culture." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20106/document.
Full textIn tropical climate, increasing night temperature was reported to be associated with a decline in grain yield in rice. This can be partly due to an increase in night respiration rate (Rn) which causes a depletion of carbohydrate supply available for plant growth. Mitochondrial respiration is commonly divided in two functional components; - Maintenance respiration (Rm) which is associated with all biochemical reactions required to maintain existing biomass. The rate of this respiration component would double when ambient temperature increase by 10°C (Q10 = 2). - Growth respiration which is associated with all processes involved in establishment of new biomass. This respiration component is mainly driven by carbohydrate supply and thus, by the photosynthesis rate. The present work aims to (1) determine the effects of short-term (without acclimation) and long-term (with acclimation) increase in night temperature similar to that projected by future climate scenarios on vegetative biomass production and grain yield; (2) evaluate, in terms of loss of biomass, the cost of Rn at plant scale; (3) estimate the maintenance respiration rate (Rm) and its response to temperature; and (4) evaluate the impact of Q10 value on biomass production. To achieve these objectives, three experiments (one unexploitable) were conducted in greenhouses, two in growth chambers and one in the field, at Montpellier (France) or at the experimental station of IRRI (International Rice Research Institute). The moderate increase in night temperature from panicle initiation to maturity in the field by 1.9°C and in growth chambers by 3.5°C, and form transplanting to maturity in greenhouse experiments by 3.8 to 5.4°C, did affect significantly Rn that increased by 13 to 35%. In the same time, it did not affect significantly biomass production and grain yield for indica and aus cultivars, whereas grain production decline was observed for japonica. Calculated biomass losses due to increased Rn under increased night temperature were important but were not associated with a change in biomass production or grain yield. Effect of long-term exposure to increased night temperature (acclimation) was smaller (factor 1.14 to 1.67 between 21 to 31°C) than that of short-term exposure (without acclimation) (factor 2.4 between 21 to 31°C). In this work, 0.3 to 1.2% (expanded leaves) and 1.5 to 2.5% (whole seedlings) of existing dry biomass was lost daily to Rm. The Rn was composed by about 33% of Rm, which increased by factor 1.49 between 21 and 31°C. This is below the common assumption of Q10 = 2 that thus overestimates the effect of increasing night temperature on Rm.A model sensitivity analysis showed that the Q10 value is important in the prediction of biomass production in crop models. Yield is expected to decline by 9% (Q10 = 2 assumption) and by 5% (Q10 = 1.5 assumption) with increasing mean daily temperature by 2°C. Thus, taking into account the acclimation response to temperature change is important for models accuracy. Making crop models more accurate requires more knowledge thermal effect on respiration in the field
Dindaeng, Pathomchai. "Exploring the role of the conserved thylakoid proteins, Ape1 and Tlp15, in the cyanobacterium, Synechocystis sp. PCC6803." Electronic Thesis or Diss., université Paris-Saclay, 2025. http://www.theses.fr/2025UPASL005.
Full textOxygenic photosynthesis is well-conserved from cyanobacteria to chloroplast-containing organisms such as algae and plants. Using energy from light, carbon dioxide (CO₂), minerals and water, the photosynthetic organisms assimilate a large number of inorganic carbon and nitrogen to generate their biomass to be distributed to the heterotrophic organisms suggesting that they are the base of the food chain. However, the mechanism can lead to the formation of Reactive Oxygen Species (ROS) which causes irreversible damages on proteins, lipids, DNA and photosynthetic apparatus thus decreasing the photosynthesis efficiency. Therefore, photosynthetic organisms had developed various processes to deal with ROS generated directly or indirectly from photosynthesis. Some of them are conserved through the evolution of the green lineage. One of these, named the acclimation, allows adjusting the composition of photosynthetic apparatus in the thylakoid membrane to make them tolerant to fluctuating conditions. Two proteins found in thylakoids, the photosynthetic membranes, i) the Acclimation of Photosynthesis to the Environment 1 protein (Ape1) and the Thylakoid Luminal Protein 15 (TLP15) are conserved through the green lineage and thanks to genetic screening, they were considered to be involved in the acclimation process in the microalga, Chlamydomonas reinhardii, and the plant, Arabidopsis. However, the role of these proteins remained unknown and was never been studied in cyanobacteria that have evolved oxygenic photosynthesis and are considered as i) the ancestor of the chloroplast of eukaryotic photosynthetic organisms, ii) potential cell factories for sustainable production of high added values molecules for health and energy. The objective of this thesis is to analyze the role of Ape1 (Slr0575) and Tlp15 (Sll1071) in the model cyanobacterium, Synechocystis sp. PCC 6803 that is genetically manipulable and is able to grow in the absence of photosynthesis at the expense of glucose. First, single knockout mutants of the genes encoding the two proteins were constructed by replacing their corresponding genes with an antibiotic resistance cassette in all chromosome copies of Synechocystis. ape1 and tlp15 genes were shown to be dispensable in standard photoautotrophic growth. Then the mutant phenotypes were analyzed by a combination of methods (growth in various environmental and stress conditions, O₂ evolution measurements, enzymatic assays, metabolites quantification of some carbonated molecules, etc..). The Δape1 mutant was shown to be sensitive to oxidative stress induced by hydrogen peroxide and menadione and produces more ROS than the wild-type strain (WT) suggesting that APE1 protein is involved in the tolerance to oxidative stress. The Δtlp15 mutant grows as the WT strain in photoautotrophic conditions under various light intensities but produce less O₂ than the WT. Surprisingly, in the presence of glucose (mixotrophic conditions) under high light that promote oxidative stress and methylglyoxal production, the Δtlp15 is able to grow whereas the WT strain is not. This phenotype is due to the absence of tlp15 and not to a secondary mutation since the introduction of tlp15 gene (complementation) in the Δtlp15 restores the WT phenotype. The Δtlp15 mutant was also shown to be more tolerant to various oxidative stresses and is able to reorganize carbon metabolism pathways differently than the WT. A structure function analysis was performed using site-directed mutagenesis. The transmembrane domain of Tlp15 as well as the two cysteines involved in the formation of a disulfide bridge were shown to be involved in the activity of Tlp15. All these results suggest that Tlp15 participates in a redox regulation mechanism involved in photosynthesis acclimation process. A model taking into account all the results is proposed
Piel, Clément. "Diffusion du CO2 dans le mésophylle des plantes à métabolisme C3." Paris 11, 2002. https://tel.archives-ouvertes.fr/tel-00007597.
Full textL'activité photosynthétique foliaire est fonction de la disponibilité en CO2 au niveau de la Rubisco dans le chloroplaste. La disponibilité en CO2 est déterminée par une série de limitations au transfert du CO2 entre l'air ambiant et les sites enzymatiques de la Rubisco, qui sont à l'origine d'un gradient de concentration. La limitation à la diffusion du CO2 dans le mésophylle, d'abord dans le réseau des espaces gazeux intercellulaires puis dans la cellule, contribue de manière très significative à ce gradient. Cette limitation est quantifiée sous la forme d'une conductance au transfert du CO2 : la conductance interne (g-i). Ce travail de thèse a été consacré à l'étude de la diffusion du CO2 dans le mésophylle des plantes ayant un métabolisme photosynthétique de type C3. Nous avons tout d'abord amélioré l'estimation de g-i grâce une méthode d'analyse simultanée des échanges gazeux et de la fluorescence chlorophyllienne. Nous avons ensuite analysé les deux composantes déterminant g-i : la limitation dans les espaces gazeux intercellulaires du mésophylle, et la limitation en phase liquide cellulaire. Nous montrons, grâce à une approche originale d'estimation de g-i dans une atmosphère à base d'hélium, chez le peuplier, le rosier, le chêne vert et le laurier rose, que la totalité de g-i est déterminée par la limitation en phase liquide cellulaire. Enfin, nous avons étudié la variabilité interspécifique et phénotypique de g-i. Nous confirmons l'existence d'une corrélation entre g-i et l'assimilation maximale pour les différentes espèces étudiées (espèces citées ci-dessus, et chez le noyer et le lamier), et nous montrons que la présumée distinction entre ligneux présentant une faible g-i et herbacées présentant une forte g-i n'est pas pertinente. Nous montrons également que chez le noyer, une réponse de g-i accompagne l'acclimatation foliaire à l'environnement lumineux, et proposons une paramétrisation de g-i pour modéliser la photosynthèse
Flori, Serena. "Light utilization in microalgae : the marine diatom Phaeodactylum tricornutum and the green algae Chlamydomonas reinhardtii." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV080/document.
Full textMicroalgae have developed distinct approaches to modulate light absorption and utilization by their photosystems in response to environmental stimuli. In this Ph.D Thesis, I characterised different strategies employed by freshwater (Chlamydomonas reinhardtii) and marine algae (Phaeodactylum tricornutum) to optimise their acclimation to the environment.In the first part of this work, I used spectroscopic, biochemical, electron microscopy analysis and 3-dimentional reconstitution to generate a model of the entire cell of the marine diatom Phaeodactylum tricornutum. This model has been used to address the following questions: i. how is a secondary chloroplast structured to facilitate exchanges with the cytosol via its four membranes envelope barrier ii. how have diatoms shaped their photosynthetic membranes to optimise light absorption and downstream electron flow and iii. how the cellular organelles interact to optimise CO2 assimilation via ATP/NADPH exchanges.In the second part, I have focused on the regulation of light harvesting and dissipation in Chlamydomonas by studying the role of perception of light colour and metabolism on excess light dissipation via the Non-Photochemical Quenching of energy (NPQ). Using biochemical and spectroscopic approaches, I found a molecular link between photoreception, photosynthesis and photoprotection in Chlamydomonas via the role of the photoreceptor phototropin on excess absorbed energy dissipation (NPQ) and also demonstrated that besides light, downstream metabolism can also affect this acclimation process.Overall this Ph.D work reveals the existence and integration of different signal pathways in the regulation of photoprotective responses by microalgae living in the ocean and in the land
Dumont, Estelle. "Tolérance au gel après acclimatation au froid chez le pois : identification de protéines et cartographie de PQL et QTL." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10037/document.
Full textCoId acclimation is the process whereby plants, previously exposed to low positive temperatures, are sUbsequently able to tolerate frost. This phenomenon was studied under controlled conditions in pea (Pisum sativum L.) in two Iines: Champagne, frost tolerant after cold acclimation and Terese, frost sensitive even if previously submitted to a cold acclimation period. Leaf, stem and root proteomes were analysed. Thirty five per cent of the identified differentially expressed proteins in leaves and stems during the cold acclimation period were involved in photosynthesis and glycolysis. ln stems, 25% were identified as folding proteins and ir roots, 47% were involved in the defense response. The raffinose, sucrose, glucose and citrate contents increased in Champagne leaves, stems and roots during the cold acclimation. ln contrast, the levels of these compounds were low in non-acclimated Champagne as weil as in Terese submitted to the cold acclimation period or not. Metabolite levels were also determined on the recombinant inbred lines (RIL) resulting from the cross between Champagne and Terese. Subsequent analyses permitted the detection of potential cold acclimation explicative OTL. ln particular, raffinose content QTL were colocalized with frost da mage QTL on the linkage groups 5 and 6. POL were also detected with the study of RtL leaf proteome. A number of these PQL colocalized with the previously detected QTL. The data obtained using these different approaches allowed us to propose hypothezises potentially explaining the mechanisms used by Champagne to tolerate frost
Talhouët, Anne-Claire. "Stratégies d’acclimatation de deux plantes alpines, Soldanella alpina et Geum montanum, à deux points clefs de leur developpement Dynamic acclimation to sunlight in an alpine plant, Soldanella alpina L.” Epidermal UVA screening capacity measured in situ as an indicator of light acclimation state of leaves of a very plastic alpine plant Soldanella alpina L." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS018.
Full textAlpine plants are subject to stressful conditions, with extreme temperatures, intense light, and UV radiation. The majority of these plants therefore develop over a short growing period. But some exceptions exist: Soldanella alpina and Geum montanum keep their leaves during several vegetation periods. They are thus confronted with brutal variations of their environment, in particular during the changes of season, which is a source of oxidative stress. Thus in spring, the snow melts and the leaf temperature quickly goes from -10 to 40 ° C coupled with an increase in light intensity and in autumn the leaves, hitherto covered by the surrounding vegetation and therefore acclimated to shade, have to face strong lights. To tolerate these rapid changes, we can assume that S. alpina and G. montanum have developed unique acclimation strategies that I sought to understand during my thesis.In autumn and spring, the main concern for the leaves of S. alpina and G. montanum comes from the fact that they are acclimated to low light intensities.We have shown that the leaves acclimate to the change in light intensity through morphological changes and by improving their photoprotection thanks to an increase in the concentration of flavonoids for the 23 major flavonoids found in the epidermis and mesophyll of the leaves in S. alpina. However, there is no acclimation of photosynthesis to changes in light intensities in the fall: the leaves confronted with strong lights cannot manage to use all of the light energy. This excess energy creates an imbalance between the total electronic flux and the electronic flux used for photochemical processes which result in exacerbated oxidative stress, in the spring, when in addition to light stress there are extreme temperatures. After having succeeded in estimating the various electronic fluxes, we observe in S. alpina and G. montanum the existence of a flux of excess electrons, not dissipated by photosynthesis. The dissipation of energy in the form of heat and a strong capacity of the malate valve and the antioxidant system allow respectively to limit and partly consume the excess electrons
De, Mia Marcello. "The Role of nitric oxide in the remodeling of the photosynthetic apparatus under abiotic stress in Chlamydomonas reinhardtii." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS516/document.
Full textThe regulation of photosynthesis is crucial for photoautotrophic organisms and is usually operated by the modulation of light absorption or by redirection of electrons towards alternative sinks, in order to redistribute energy among several metabolic pathways. Between different mechanisms described, the remodeling of the photosynthetic apparatus is crucial under conditions of nutrient starvation or light fluctuations. It is well known that nitric oxide (NO) plays a signaling role in many abiotic stress responses, acting as a second messenger and/or modifying target proteins through redox post translational modifications. Its involvement has been recently described during nitrogen starvation in Chlamydomonas reinhardtii. This work focuses on the remodeling of the photosynthetic apparatus upon sulfur starvation and light fluctuations in Chlamydomonas reinhardtii, with particular interest for the signaling pathway involved in the responses. First we characterized sulfur starvation under heterotrophy and photo-autotrophy. Photosynthetic inactivation under low light and darkness is achieved through specific degradation of Rubisco and cytochrome b₆f and occurs only in the presence of reduced carbon in the medium. We have also shown a strong NO production after the onset of starvation, with NO-sensitive fluorescence probes visualized by confocal microscopy. We provide pharmacological evidence that intracellular NO production governs this degradation pathway using NO scavengers, NO synthesis inhibitors and NO donors. Furthermore, here, we provide clear evidence for a regulatory circuit that controls cytosolic LHCII translation in response to light quantity changes. This circuit requires the cytosolic RNA-binding protein NAB1 to repress translation of certain LHCII mRNAs. Specific nitrosylation of Cys-226 decreases NAB1 activity and could be demonstrated in vitro and in vivo. The less active, nitrosylated form of NAB1 is found in cells acclimated to limiting light supply, which permits accumulation of light harvesting proteins and efficient light capture. In contrast, elevated light supply causes NAB1 denitrosylation, thereby activating the repression of light-harvesting protein synthesis and decreasing the light pressure at the level of PSII. Denitrosylation of NAB1 is efficiently performed by the cytosolic thioredoxin system in vitro. To our knowledge, NAB1 is the first example of stimulus-induced denitrosylation in the context of photosynthetic acclimation. Taken together, our data suggest a pivotal role for NO-signaling in the control of environmental stress responses