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Littérature scientifique sur le sujet « Chl-deficiency »
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Articles de revues sur le sujet "Chl-deficiency"
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Larbi, Ajmi, Fermín Morales, Anunciación Abadía, Yolanda Gogorcena, Juan J. Lucena et Javier Abadía. « Effects of Cd and Pb in sugar beet plants grown in nutrient solution : induced Fe deficiency and growth inhibition ». Functional Plant Biology 29, no 12 (2002) : 1453. http://dx.doi.org/10.1071/fp02090.
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Effects of Cd and Pb toxicity were investigated in sugar beet (Beta vulgaris L.) grown in hydroponics under growth-chamber-controlled conditions. Chemical speciation calculations were used to estimate the chemical species in equilibrium. Cd, used as chloride salt or chelated to EDTA, decreased fresh and dry mass of both root and shoot, and increased root / shoot ratios. Plants developed few brownish roots with short laterals. Cd decreased N, P, Mg, K, Mn, Cu and Zn uptake, and facilitated Ca uptake. Leaves of plants treated with 10 or 50 μM Cd–EDTA and 10 μM CdCl2 developed symptoms of Fe deficiency. These symptoms included decreased leaf chlorophyll (Chl) and carotenoid concentrations, increased carotenoid / Chl and Chl a/b ratios, de-epoxidation of violaxanthin cycle pigments, and decreased photosynthetic rates and PSII efficiency. Plants treated with 50 μM CdCl2, however, had decreased growth but did not show marked leaf Fe-deficiency symptoms. All Cd treatments increased Fe(III)-chelate reductase activity in root tips, although Fe concentrations in shoots were similar to those found in control plants. Pb chelated with EDTA induced visual symptoms only at concentrations of 2 mM. Leaves of Pb-treated plants remained green and their edges were rolled inwards. Pb increased root fresh and dry mass with no changes in shoot mass, therefore increasing the root / shoot ratio. Changes in plant nutrient concentrations with Pb were only minor, although leaf Cu levels approached critical deficiency levels. No symptoms of Fe deficiency were apparent in leaves. Root tips of Pb-treated plants, however, had increased Fe(III)-chelate reductase activities.
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Smith*, Brandon, et Lailiang Cheng. « Photoprotective Mechanisms of Grape Leaves (Vitis labrusca L. cv. Concord) in Relation to Iron Supply ». HortScience 39, no 4 (juillet 2004) : 854A—854. http://dx.doi.org/10.21273/hortsci.39.4.854a.
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One-year-old `Concord' grapevines (Vitis labrusca L.) were fertigated twice weekly for 11 weeks with a complete nutrient solution containing 1, 10, 20, 50 or 100 μmol iron (Fe) from ferric ethylenediamine di (o-hydroxyphenylacetic) acid (Fe-EDDHA). Leaf total Fe content did not increase in response to Fe supply, however both “active” Fe (extracted with 2, 2'-dipyridyl) and chlorophyll (Chl) content increased as applied Fe increased. At the lowest active Fe level, leaf absorptance and maximum PSII efficiency (Fv/Fm) were slightly decreased, and non-photochemical quenching was significantly greater. PSII quantum efficiency decreased curvilinearly as active Fe content decreased. On a Chl basis, the xanthophyll cycle pool size, lutein, and beta-carotene increased curvilinearly as active Fe decreased, and neoxanthin increased at the lowest Fe level. Activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase followed a similar trend and increased under Fe deficiency, when expressed on a Chl basis. Antioxidant metabolites also increased in response to Fe limitation. On a Chl basis, ascorbate (AsA), dehydroascorbate (DAsA), reduced glutathione (GSH) and oxidized glutathione (GSSG) content was greater at the lowest active Fe levels. We did not find a difference in the ratio of AsA to DAsA or GSH to GSSG. In conclusion, both photoprotective mechanisms, xanthophyll cyle-dependent thermal dissipation and the ascorbate-glutatione antioxidant system, are enhanced in response to iron deficiency to cope with excess absorbed light.
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Wang, Peng, Fu-Cheng Liang, Daniel Wittmann, Alex Siegel, Shu-ou Shan et Bernhard Grimm. « Chloroplast SRP43 acts as a chaperone for glutamyl-tRNA reductase, the rate-limiting enzyme in tetrapyrrole biosynthesis ». Proceedings of the National Academy of Sciences 115, no 15 (26 mars 2018) : E3588—E3596. http://dx.doi.org/10.1073/pnas.1719645115.
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Assembly of light-harvesting complexes requires synchronization of chlorophyll (Chl) biosynthesis with biogenesis of light-harvesting Chl a/b-binding proteins (LHCPs). The chloroplast signal recognition particle (cpSRP) pathway is responsible for transport of nucleus-encoded LHCPs in the stroma of the plastid and their integration into the thylakoid membranes. Correct folding and assembly of LHCPs require the incorporation of Chls, whose biosynthesis must therefore be precisely coordinated with membrane insertion of LHCPs. How the spatiotemporal coordination between the cpSRP machinery and Chl biosynthesis is achieved is poorly understood. In this work, we demonstrate a direct interaction between cpSRP43, the chaperone that mediates LHCP targeting and insertion, and glutamyl-tRNA reductase (GluTR), a rate-limiting enzyme in tetrapyrrole biosynthesis. Concurrent deficiency for cpSRP43 and the GluTR-binding protein (GBP) additively reduces GluTR levels, indicating that cpSRP43 and GBP act nonredundantly to stabilize GluTR. The substrate-binding domain of cpSRP43 binds to the N-terminal region of GluTR, which harbors aggregation-prone motifs, and the chaperone activity of cpSRP43 efficiently prevents aggregation of these regions. Our work thus reveals a function of cpSRP43 in Chl biosynthesis and suggests a striking mechanism for posttranslational coordination of LHCP insertion with Chl biosynthesis.
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Meng, Xin, Wei-Wei Chen, Yan-Yu Wang, Zeng-Rong Huang, Xin Ye, Li-Song Chen et Lin-Tong Yang. « Effects of phosphorus deficiency on the absorption of mineral nutrients, photosynthetic system performance and antioxidant metabolism in Citrus grandis ». PLOS ONE 16, no 2 (17 février 2021) : e0246944. http://dx.doi.org/10.1371/journal.pone.0246944.
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Phosphorus (P) is an essential macronutrient for plant growth, development and production. However, little is known about the effects of P deficiency on nutrient absorption, photosynthetic apparatus performance and antioxidant metabolism in citrus. Seedlings of ‘sour pummelo’ (Citrus grandis) were irrigated with a nutrient solution containing 0.2 mM (Control) or 0 mM (P deficiency) KH2PO4 until saturated every other day for 16 weeks. P deficiency significantly decreased the dry weight (DW) of leaves and stems, and increased the root/shoot ratio in C. grandis but did not affect the DW of roots. The decreased DW of leaves and stems might be induced by the decreased chlorophyll (Chl) contents and CO2 assimilation in P deficient seedlings. P deficiency heterogeneously affected the nutrient contents of leaves, stems and roots. The analysis of Chl a fluorescence transients showed that P deficiency impaired electron transport from the donor side of photosystem II (PSII) to the end acceptor side of PSI, which showed a greater impact on the performance of the donor side of PSII than that of the acceptor side of PSII and photosystem I (PSI). P deficiency increased the contents of ascorbate (ASC), H2O2 and malondialdehyde (MDA) as well as the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in leaves. In contrast, P deficiency increased the ASC content, reduced the glutathione (GSH) content and the activities of SOD, CAT, APX and monodehydroascorbate reductase (MDHAR), but did not increase H2O2 production, anthocyanins and MDA content in roots. Taking these results together, we conclude that P deficiency affects nutrient absorption and lowers photosynthetic performance, leading to ROS production, which might be a crucial cause of the inhibited growth of C. grandis.
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Endo, Hikaru, Hikari Moriyama et Yutaka Okumura. « Photoinhibition and Photoprotective Responses of a Brown Marine Macroalga Acclimated to Different Light and Nutrient Regimes ». Antioxidants 12, no 2 (2 février 2023) : 357. http://dx.doi.org/10.3390/antiox12020357.
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Plants and brown algae avoid photoinhibition (decline in photosystem II efficiency, Fv/Fm) caused by excess light energy and oxidative stress through several photoprotective mechanisms, such as antioxidant xanthophyll production and heat dissipation. The heat dissipation can be measured as non-photochemical quenching (NPQ) and is strongly driven by de-epoxidation of xanthophyll cycle pigments (XCP). Although NPQ is known to increase under high light acclimation and nutrient-deficient conditions, a few studies have investigated the combined effects of the conditions on both NPQ and associated xanthophyll-to-chlorophyll (Chl) a ratio. The present study investigated the photosynthetic parameters of the brown alga Sargassum fusiforme acclimated to three irradiance levels combined with three nutrient levels. Elevated irradiance decreased Fv/Fm but increased NPQ, XCP/Chl a ratio, and fucoxanthin/Chl a ratio, suggesting the photoprotective role of antioxidant fucoxanthin in brown algae. Reduced nutrient availability increased NPQ but had no effect on the other variables, including XCP/Chl a ratio and its de-epoxidation state. The results indicate that NPQ can be used as a sensitive stress marker for nutrient deficiency, but cannot be used to estimate XCP pool size and state.
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Aytekin, Gökhan, Fatih Çölkesen, Eray Yıldız, Mitat Arıcıgil et Şevket Arslan. « Hearing Assessment in Adult Patients with Common Variable Immunodeficiency ». Asthma Allergy Immunology 19, no 1 (30 avril 2021) : 38–45. http://dx.doi.org/10.21911/aai.600.
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ABSTRACT Objective: Common Variable Immunodeficiency (CVID) is a primary antibody disorder characterized by impaired B cell differentiation. Patients commonly present with acute and chronic sinusitis as well as otitis media, which may lead to hearing loss. Materials and Methods: Thirty-three CVID patients (20 male /13 female) with a mean age of 35 years (range 19-65 years) and 33 healthy individuals as a control group were included. Results: Among CVID patients, 17 (51.5%) had conductive hearing loss (CHL) , being unilateral in 4 (12.1%) and bilateral in 13 (39.4%). Unilateral and bilateral sensorineural hearing loss (SNHL) were detected in 2 (6.1%) and 5 (15.2%) respectively. CD4/CD8 cell ratio was significantly lower while CD8+ T lymphocyte ratio was significantly higher in those with CHL than in those without it (p=0.045 and p=0.009). Elevated CD8+ T cell ratio was an independent risk factor for CHL (p=0.015). Patients with SNHL were significantly older than those without it (p=0.040). CD16-56+ cell count was significantly lower in those with SNHL (p=0.031). Conclusion: CVID patients have an increased occurrence of CHL and SNHL, regardless of the cause. They provide evidence for the notion that these two types of hearing loss are not unrelated, immune dysregulation also plays a role in the process, and SNHL is not independent of CHL. Keywords: Common variable immune deficiency, conductive hearing loss, sensorineural hearing loss
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JUNWAL, MANJU, et BHAI ISMAIL. « A case study of Human iron deficiency Anaemia in different age groups from Ujjain (M.P.) India ». Journal of Ultra Scientist of Physical Sciences Section B 33, no 3 (24 septembre 2021) : 12–18. http://dx.doi.org/10.22147/jusps-b/330301.
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Iron deficiency Anaemia is the most common case of nutritional Anaemia worldwide and is a public health problem in developing countries; characterized by abnormal red cell count (MCV, MCHC). Iron deficiency Anaemia associated with fatigue, skin paleness, weakness etc. The aim of the study is to determine the risk factors for iron deficiency Anaemia among population of Ujjain district (M.P.). Both male and female iron deficient patients were studied from the SS hospital and CHL applo hospitals during Jan. 2012 to Dec. 2012. A group of 6828 patients were studied for iron deficiency Anaemia in different age groups. A total of 4549 female and 2279 males were studied. Information was collected about sex, socioeconomic level. It is inferred that the percentage of anaemia is more in women compared to men.
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Chen, Guangyu E., Andrew Hitchcock, Jan Mareš, Yanhai Gong, Martin Tichý, Jan Pilný, Lucie Kovářová et al. « Evolution of Ycf54-independent chlorophyll biosynthesis in cyanobacteria ». Proceedings of the National Academy of Sciences 118, no 10 (1 mars 2021) : e2024633118. http://dx.doi.org/10.1073/pnas.2024633118.
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Chlorophylls (Chls) are essential cofactors for photosynthesis. One of the least understood steps of Chl biosynthesis is formation of the fifth (E) ring, where the red substrate, magnesium protoporphyrin IX monomethyl ester, is converted to the green product, 3,8-divinyl protochlorophyllide a. In oxygenic phototrophs, this reaction is catalyzed by an oxygen-dependent cyclase, consisting of a catalytic subunit (AcsF/CycI) and an auxiliary protein, Ycf54. Deletion of Ycf54 impairs cyclase activity and results in severe Chl deficiency, but its exact role is not clear. Here, we used a Δycf54 mutant of the model cyanobacterium Synechocystis sp. PCC 6803 to generate suppressor mutations that restore normal levels of Chl. Sequencing Δycf54 revertants identified a single D219G amino acid substitution in CycI and frameshifts in slr1916, which encodes a putative esterase. Introduction of these mutations to the original Δycf54 mutant validated the suppressor effect, especially in combination. However, comprehensive analysis of the Δycf54 suppressor strains revealed that the D219G-substituted CycI is only partially active and its accumulation is misregulated, suggesting that Ycf54 controls both the level and activity of CycI. We also show that Slr1916 has Chl dephytylase activity in vitro and its inactivation up-regulates the entire Chl biosynthetic pathway, resulting in improved cyclase activity. Finally, large-scale bioinformatic analysis indicates that our laboratory evolution of Ycf54-independent CycI mimics natural evolution of AcsF in low-light–adapted ecotypes of the oceanic cyanobacteria Prochlorococcus, which lack Ycf54, providing insight into the evolutionary history of the cyclase enzyme.
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Samborska, Izabela A., Hazem M. Kalaji, Leszek Sieczko, Vasilij Goltsev, Wojciech Borucki et Anjana Jajoo. « Structural and functional disorder in the photosynthetic apparatus of radish plants under magnesium deficiency ». Functional Plant Biology 45, no 6 (2018) : 668. http://dx.doi.org/10.1071/fp17241.
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Magnesium (Mg) is one of the significant macronutrients which is involved in the structural stabilisation of plant tissues and many enzymes such as PSII. The latter efficiency and performance were analysed, using chlorophyll (Chl) a fluorescence induction kinetics and microscopic images, to detect the changes in structure and function of photosynthetic apparatus of radish plants grown under Mg deficiency (Mgdef). Plants grown under Mgdef showed less PSII connectivity and fewer active primary electron acceptors (QA) oxidizing reaction centres than control plants. Confocal and electron microscopy analyses showed an increased amount of starch in chloroplasts, and 3,3ʹ-diaminobenzidine (DAB)-uptake method revealed higher H2O2 accumulation under Mgdef. Prominent changes in the Chl a fluorescence parameters such as dissipated energy flux per reaction centre (DIo/RC), relative variable fluorescence at 150 μs (Vl), and the sum of the partial driving forces for the events involved in OJIP fluorescence rise (DFabs) were observed under Mg deficiency. The latter also significantly affected some other parameters such as dissipated energy fluxes per cross-section (DIo/CSo), performance index for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors (PItotal), and relative variable fluorescence at 300 μs (Vk). This work emphasises the use of chlorophyll fluorescence in combination with microscopic and statistical analyses to diagnose the effects of nutrients deficiency stress on plants at an early stage of its development as demonstrated for the example of Mgdef. Due to the short growth period and simple cultivation conditions of radish plant we recommend it as a new standard (model) plant to study nutrients deficiency and changes in plant photosynthetic efficiency under stress conditions.
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Jeong, Ah-Reum, Edward D. Ball et Aaron Michael Goodman. « Predicting Responses to Checkpoint Inhibitors in Lymphoma : Are We Up to the Standards of Solid Tumors ? » Clinical Medicine Insights : Oncology 14 (janvier 2020) : 117955492097636. http://dx.doi.org/10.1177/1179554920976366.
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Treatment of cancer has transformed with the introduction of checkpoint inhibitors. However, the majority of solid tumor patients do not respond to checkpoint blockade. In contrast, the response rate to programmed cell death 1 (PD-1) blockade in relapsed/refractory classical Hodgkin lymphoma (cHL) is 65% to 84% which is the highest among all cancers. Currently, checkpoint inhibitors are only approved for cHL and primary mediastinal B-cell lymphoma as the responses to single-agent checkpoint blockade in other hematologic malignancies is disappointingly low. Various established biomarkers such as programmed cell death 1 ligand 1 (PD-L1) protein surface expression, mismatch repair (MMR) status, and tumor mutational burden (TMB) are routinely used in clinical decision-making in solid tumors. In this review, we will explore these biomarkers in the context of hematologic malignancies. We review characteristic 9p24.1 structural alteration in cHL and primary mediastinal B-cell lymphoma (PMBCL) as a basis for response to PD-1 inhibition, as well as the role of antigen presentation pathways. We also explore the reported frequencies of MMR deficiency in various hematologic malignancies and investigate TMB as a predictive marker.
Livres sur le sujet "Chl-deficiency"
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Carton, James. Haematopathology. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198759584.003.0015.
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This chapter discusses haematopathology, including iron deficiency anaemia, anaemia of chronic disease, megaloblastic anaemias, hereditary spherocytosis, glucose-6-phosphate dehydrogenase deficiency, thalassaemias, sickle-cell disorders, idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), von Willebrand disease, haemophilia, thrombophilia, acute B-lymphoblastic leukaemia, acute myeloid leukaemias, chronic lymphocytic leukaemia (CLL), chronic myelogenous leukaemia, polycythaemia vera (PV), essential thrombocythaemia (ET), primary myelofibrosis (PMF), myelodysplastic syndromes (MDS), follicular lymphoma, diffuse large B-cell lymphoma, Burkitt’s lymphoma (BL), extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), mantle cell lymphoma, classical Hodgkin’s lymphoma (cHL), lymphoplasmacytic lymphoma (LPL), plasma cell myeloma, primary amyloidosis, and mature T-cell non-Hodgkin’s lymphomas.