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Larbi, Ajmi, Fermín Morales, Anunciación Abadía, Yolanda Gogorcena, Juan J. Lucena e 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, n.º 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, e Lailiang Cheng. "Photoprotective Mechanisms of Grape Leaves (Vitis labrusca L. cv. Concord) in Relation to Iron Supply". HortScience 39, n.º 4 (julho de 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 e 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, n.º 15 (26 de março de 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 e 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, n.º 2 (17 de fevereiro de 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 e Yutaka Okumura. "Photoinhibition and Photoprotective Responses of a Brown Marine Macroalga Acclimated to Different Light and Nutrient Regimes". Antioxidants 12, n.º 2 (2 de fevereiro de 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 e Şevket Arslan. "Hearing Assessment in Adult Patients with Common Variable Immunodeficiency". Asthma Allergy Immunology 19, n.º 1 (30 de abril de 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, e 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, n.º 3 (24 de setembro de 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, n.º 10 (1 de março de 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 e Anjana Jajoo. "Structural and functional disorder in the photosynthetic apparatus of radish plants under magnesium deficiency". Functional Plant Biology 45, n.º 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 e Aaron Michael Goodman. "Predicting Responses to Checkpoint Inhibitors in Lymphoma: Are We Up to the Standards of Solid Tumors?" Clinical Medicine Insights: Oncology 14 (janeiro de 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.
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Nair, Ranjit, Samer Al Hadidi, Raphael Eric Steiner, Sairah Ahmed, Paolo Strati, Simrit Parmar, Swaminathan P. Iyer et al. "Association of Vitamin D Deficiency with Inferior Treatment Outcomes in Patients with Newly Diagnosed Classic Hodgkin Lymphoma: MD Anderson Cancer Center Experience". Blood 136, Supplement 1 (5 de novembro de 2020): 27–28. http://dx.doi.org/10.1182/blood-2020-142139.
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Introduction Vitamin D deficiency is a modifiable risk factor for multiple malignancies. There is growing evidence that associates vitamin D deficiency with progression-free survival (PFS) and overall survival (OS) in patients with classic Hodgkin lymphoma (cHL). Supplemental ergocalciferol/cholecalciferol may improve chemosensitivity of malignant cells to chemotherapy as evidenced by reduction in the rate of tumor growth in a cHL- xenograft animal model. The goal of our study is to explore the association of pretreatment vitamin D levels on survival outcomes of patients with cHL. Methods We retrospectively reviewed the records of patients who were first seen at The University of Texas MD Anderson Cancer Center between January, 2016 and May, 2020 for newly diagnosed cHL. Patient charts were reviewed to assess demographic information, clinical staging at the time of vitamin D assessment, pretreatment 25-hydroxyvitamin D (25(OH) D) level and vitamin D supplementation. Vitamin D deficiency was defined as a 25(OH)D level < 30 nmol/L. PFS and OS outcomes were evaluated for these patients. Descriptive statistics including mean, standard deviation, median, and range for continuous variables such as age, and 25(OH) D level, and frequency counts and percentages for categorical variables such as race, gender, vitamin D supplementation and response were analyzed. The Kaplan-Meier method was used for time-to-event analysis including PFS and OS. Median time to event in months with 95% confidence interval (CI) was calculated. The Log-rank test was used to evaluate the difference in time-to-event endpoints between patient groups. Statistical software SAS 9.4 (SAS, Cary, NC) and S-Plus 8.2 (TIBCO Software Inc., Palo Alto, CA) were used for statistical analyses. Results 644 patients met the inclusion criteria of which 483 patients had their vitamin D levels assessed at the time of initial visit to this center. The median patient age at diagnosis was 33 years with 52% males. Advanced stage (stages III and IV) occurred in 45% of patients of which the International Prognostic Score was ≥4 in 13% of patients. Patients received doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) based therapy (77%), brentuximab vedotin (BV) based therapy (13%) and other agentss (6%). Patient demographics are outlined in Table.1. Pretreatment 25(OH)D level was assessed in 75% of the patients. The median 25(OH)D level was 25 nmol/L (range: 2-78 nmol/L). Vitamin D deficiency was present in 320 of 483 (66%) patients. Ergocalciferol/cholecalciferol supplementation was used in 29% of patients. There was no statistically significant association of vitamin D deficiency with advanced stage (p-value: 0.64). PFS rate at 10 years was significantly longer in patients with normal 25(OH)D level (40% vs 27%, p-value: 0.0481). Ergocalciferol/cholecalciferol supplementation was associated with a 6% improvement of PFS, however this difference was not statistically significant. No OS difference was noted between vitamin D deficient and non-deficient patients, an observation that persisted in patients on vitamin D supplementation versus not on supplementation. Conclusions Vitamin D deficiency was associated with inferior PFS with a 13% difference in vitamin D deficient versus non-deficient patients. There was a numerical PFS benefit associated with ergocalciferol/cholecalciferol supplementation. An OS benefit was not observed as the duration of follow up may not have been sufficient to observe the differential impact of vitamin D levels. Vitamin D screening and replacement is done in patients with newly diagnosed cHL and should be encouraged given the potential benefit from such approach. Prospective studies are warranted to establish the relationship between vitamin D level, supplementation and outcomes in cHL patients. Figure Disclosures Parmar: Cellenkos Inc.:Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding.Nieto:Affimed:Consultancy, Other: Grant Support;Novartis:Other: Grant Support;Astra Zeneca:Other: Grant Support;Secura Bio:Other: Grant Support.Chuang:Sage-Evidence=Based Medicine & Practice:Consultancy.Wang:Lu Daopei Medical Group:Honoraria;Beijing Medical Award Foundation:Honoraria;OncLive:Honoraria;Molecular Templates:Research Funding;Verastem:Research Funding;Dava Oncology:Honoraria;Guidepoint Global:Consultancy;Nobel Insights:Consultancy;Oncternal:Consultancy, Research Funding;InnoCare:Consultancy;Acerta Pharma:Research Funding;VelosBio:Research Funding;BioInvent:Research Funding;Juno:Consultancy, Research Funding;Kite Pharma:Consultancy, Other: Travel, accommodation, expenses, Research Funding;Pulse Biosciences:Consultancy;Loxo Oncology:Consultancy, Research Funding;Targeted Oncology:Honoraria;OMI:Honoraria, Other: Travel, accommodation, expenses;Celgene:Consultancy, Other: Travel, accommodation, expenses, Research Funding;AstraZeneca:Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding;Janssen:Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding;MoreHealth:Consultancy;Pharmacyclics:Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding.Lee:Takeda:Research Funding;Seattle Genetics:Research Funding;Oncternal Therapeutics:Research Funding;Guidepoint Blogal:Consultancy;Celgene:Research Funding;Bristol-Myers Squibb:Consultancy, Research Funding;Aptitude Health:Speakers Bureau.
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Smith, Brandon R., e Lailiang Cheng. "Photoprotective Mechanisms of `Concord' Grape Leaves in Relation to Iron Supply". Journal of the American Society for Horticultural Science 130, n.º 3 (maio de 2005): 331–40. http://dx.doi.org/10.21273/jashs.130.3.331.
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The objective of this study was to quantify how photoprotective mechanisms in the leaves of `Concord' grapevines (Vitis labruscana Bailey) respond to a range of iron (Fe) supply. Own-rooted, 1-year-old container-grown vines were fertigated twice weekly for 11 weeks with a complete nutrient solution containing 1, 10, 20, 50, or 100 μm Fe from ferric ethylenediamine di (o-hydroxyphenylacetic) acid (Fe-EDDHA). Leaf total Fe content did not increase in response to Fe supply; however, “active” Fe (extracted with 2,2′-dipyridyl) and chlorophyll (Chl) increased on a leaf area basis as applied Fe increased. At the lowest active Fe level, leaf absorptance and the efficiency of excitation transfer (Fv′/Fm′) was lower, and nonphotochemical quenching (NPQ) was significantly greater. Photosystem II (PSII) quantum efficiency decreased curvilinearly, and the proportion of PSII reaction centers in the open state (qP) decreased linearly as active Fe content decreased. On a Chl basis, the xanthophyll cycle pool size [violaxanthin (V) + antheraxanthin (A) + zeaxanthin (Z)], lutein, and β-carotene increased curvilinearly as active Fe decreased, and neoxanthin (Neo) increased at the lowest Fe level. On a leaf area basis, as active Fe decreased, V+A+Z and β-carotene decreased curvilinearly, and lutein and Neo decreased linearly. At noon, conversion of V to A and Z increased as active Fe decreased. On a Chl basis, activities of antioxidant enzymes superoxide dismutase (SOD), monodehydroascorbate reductase (MDAR), and dehydroascorbate reductase (DHAR) increased curvilinearly, and glutathione reductase (GR) activity increased linearly as active Fe levels declined. Ascorbate peroxidase (APX) and catalase (CAT), on a Chl basis, were relatively constant. On a leaf area basis, a decrease in active Fe increased SOD and MDAR activity, whereas APX, CAT, DHAR and GR activity decreased. Antioxidant metabolites ascorbate (AsA), dehydroascorbate (DAsA), reduced glutathione (GSH) and oxidized glutathione (GSSG) also increased in response to Fe limitation when expressed on a Chl basis, whereas on a leaf area basis AsA and DAsA decreased and GSH increased curvilinearly. The GSH:GSSG ratio increased as active Fe declined, whereas the AsA:DAsA ratio did not change. In conclusion, both photoprotective mechanisms, xanthophyll cycle-dependent thermal dissipation and the ascorbate-glutathione antioxidant system, are enhanced in response to Fe deficiency to cope with excess absorbed light. In a low soil pH tolerant species such as V. labruscana, the foliar antioxidant system was upregulated in response to excess absorbed light from Fe deficiency-induced chlorosis, and there was no evidence of an increase in oxidative stress from high rates of applied Fe-EDDHA.
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Kilic, Nihat, Ali Kiki, Hüsamettin Oktay e Erol Selimoglu. "Effects of Rapid Maxillary Expansion on Conductive Hearing Loss". Angle Orthodontist 78, n.º 3 (1 de maio de 2008): 409–14. http://dx.doi.org/10.2319/050407-217.1.
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Abstract Objective: To test the null hypothesis that rapid maxillary expansion (RME) with a rigid bonded appliance has no effect on conductive hearing loss (CHL) in growing children. Materials and Methods: Fifteen growing subjects (mean age 13.43 ± 0.86 years) who had narrow maxillary arches and CHL participated in this study. Three pure-tone audiometric and tympanometric records were taken from each subject. The first records were taken before RME (T1), the second after maxillary expansion (T2) (mean = 0.83 months), and the third after retention (mean = 6 months) and fixed appliance treatment (approximately 2 years) periods (T3). The data were analyzed by means of analysis of variance (ANOVA) and least significant difference (LSD) tests. Results: Hearing levels of the patients were improved and air-bone gaps decreased at a statistically significant level (P < .001) during active expansion (T2–T1) and the retention and fixed appliance treatment (T2–T3) periods. Middle ear volume increased in all observation periods. However, a statistically significant increase was observed only in the T2–T3 period. No significant change was observed in the static compliance value. Conclusions: The hypothesis is rejected. RME treatment has a positive and statistically significant effect on both improvements in hearing and normal function of the eustachian tube in patients having transverse maxillary deficiency and CHL.
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Shao, Ruixin, Huifang Zheng, Shuangjie Jia, Yanping Jiang, Qinghua Yang e Guozhang Kang. "Nitric Oxide Enhancing Resistance to PEG-Induced Water Deficiency is Associated with the Primary Photosynthesis Reaction in Triticum aestivum L." International Journal of Molecular Sciences 19, n.º 9 (18 de setembro de 2018): 2819. http://dx.doi.org/10.3390/ijms19092819.
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Photosynthesis is affected by water-deficiency (WD) stress, and nitric oxide (NO) is a free radical that participates in the photosynthesis process. Previous studies have suggested that NO regulates excitation-energy distribution of photosynthesis under WD stress. Here, quantitative phosphoproteomic profiling was conducted using iTRAQ. Differentially phosphorylated protein species (DEPs) were identified in leaves of NO- or polyethylene glycol (PEG)-treated wheat seedlings (D), and in control seedlings. From 1396 unique phosphoproteins, 2257 unique phosphorylated peptides and 2416 phosphorylation sites were identified. Of these, 96 DEPs displayed significant changes (≥1.50-fold, p < 0.01). These DEPs are involved in photosynthesis, signal transduction, etc. Furthermore, phosphorylation of several DEPs was upregulated by both D and NO treatments, but downregulated only in NO treatment. These differences affected the chlorophyll A–B binding protein, chloroplast post-illumination chlorophyll-fluorescence-increase protein, and SNT7, implying that NO indirectly regulated the absorption and transport of light energy in photosynthesis in response to WD stress. The significant difference of chlorophyll (Chl) content, Chl a fluorescence-transient, photosynthesis index, and trapping and transport of light energy further indicated that exogenous NO under D stress enhanced the primary photosynthesis reaction compared to D treatment. A putative pathway is proposed to elucidate NO regulation of the primary reaction of photosynthesis under WD.
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Correia, Pedro José, Florinda Gama, Teresa Saavedra, Maria Graça Miguel, José Paulo Da Silva, Anunciación Abadía, Amarilis de Varennes e Maribela Pestana. "Changes in the concentration of organic acids in roots and leaves of carob-tree under Fe deficiency". Functional Plant Biology 41, n.º 5 (2014): 496. http://dx.doi.org/10.1071/fp13204.
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Several fruit trees are able to cope with iron (Fe) deficiency when grown in calcareous soils in the Mediterranean region, although information regarding well adapted slow-growing species is scarce, and the mechanisms activated by these species are not described in the literature. A crucial issue related to tolerance is the need to transport Fe over relatively long distances inside the plant. To evaluate the possible role of organic acids in the movement of Fe in tolerant plants, we studied the concentration of low molecular weight organic acids in several organs of 1-year old carob plants grown for 55 days in nutrient solutions without Fe (0 µM Fe) or with 1 µM Fe and 10 µM Fe. Roots, stems and leaves were harvested, and the biomass, Fe and organic acid contents quantified. Total leaf chlorophyll (Chl) was evaluated in young leaves over the experimental period and the activity of root ferric chelate-reductase (FC-R; EC 1.16.1.17) was determined after 35 days, when deficiency symptoms appeared. Iron chlorosis was observed only at the end of the experiment in plants grown in the absence of Fe, and these plants had a smaller DW of leaves and also significant greater activity of root FC-R. Iron deficiency (Fe0 and Fe1 treatments) induced significant changes in the concentrations of succinic, malic, citric and fumaric acids, which increased in roots, or in basal, middle and apical leaves. There were significant correlations between most organic acids (with the exceptions of 2-oxoglutaric and tartaric acids) and leaf Chl. Analysis of each type of leaf showed that more succinic and malic acids were present in young chlorotic leaves while the reverse was true for quinic acid. These changes in organic acids followed a root-to-foliage pathway that was similar in all leaf types and particularly evident in young chlorotic leaves. We hypothesised that it was associated with Fe transport from roots to aboveground tissues, as there were significant differences in Fe contents between treatments with and without Fe.
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Kabashnikova, L. F., I. N. Domanskaya, T. S. Pilipovich, L. V. Pashkevich, H. V. Martysiuk, S. M. Motyleva, M. S. Gins e N. V. Tetyannikov. "Photosynthetic pigments content and parameters of oxidative stress in the amaranth species with increasing water deficiency". Proceedings of the National Academy of Sciences of Belarus, Biological Series 66, n.º 3 (4 de agosto de 2021): 282–94. http://dx.doi.org/10.29235/1029-8940-2021-66-3-282-294.
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The dynamics of the photosynthetic pigments content and parameters of oxidative stress with an increasing water deficit in the leaves of 40-days-old plants of two amaranth species - Amaranthus paniculatus L. (cv. Rubin) and Amaranthus caudatus L. (cv. Chyrvony aksamit), grown in a pot culture, was studied. Specific features of the development of water deficiency in amaranth leaves were revealed: amaranth plants Amaranthus paniculatus L. showed a stronger development of water deficit in leaves than Amaranthus caudatus L. after 4-days soil drought, which after 8 days increased in two species to 73.7 and 55.7 %, respectively. Under moderate drought, the amount of photosynthetic pigments (chlorophyll (Chl) and carotenoids) based on dry leaf weight increased in two amaranth species, but after 8 days of soil drought, the content of Chl (a + b) was reduced by 2.0-2.1 times, and carotenoids - 1.8-1.9 times relative to the physiological level. As a result of a 4-days soil drought in the leaves of Amaranthus paniculatus L., there was a significant decrease in the content of reactive oxygen species (ROS) and the activity of lipid peroxidation (LPO), while in Amaranthus caudatus L. an increase in the levels of ROS and LPO was observed. With an increase in the pressure of the stress factor in the leaves of amaranth of the two studied species, a decrease in the ROS content and LPO activity relative to physiological values was revealed. A conclusion was made about the different mechanisms of ROS generation and the flow of LPO processes at different stages of soil drought in the leaves of different amaranth species.
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Tseng, Y. F., J. Lin, M. Dai e S. J. Kao. "Joint effect of freshwater plume and coastal upwelling on phytoplankton growth off the Changjiang River". Biogeosciences 11, n.º 2 (28 de janeiro de 2014): 409–23. http://dx.doi.org/10.5194/bg-11-409-2014.
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Abstract. The Changjiang (Yangtze) River discharges vast amount of unbalanced nutrients (dissolved inorganic nitrogen and phosphorus with N / P ratio > 80 in general) into the East China Sea in summer. To study nutrient dynamics and P-stress potential for phytoplankton, a cruise was conducted in the Changjiang plume during summer 2011. With 3-D observations of nutrients, chlorophyll a (Chl a), and bulk alkaline phosphatase activity (APA), we concluded that the Changjiang Diluted Water and coastal upwelling significantly influenced the horizontal and vertical heterogeneities of phytoplankton P deficiency in the Changjiang plume. Allochthonous APA was detected at nutrient-enriched freshwater end. Excessive N (~ 10 to 112 μM) was observed throughout the entire plume surface. In the plume fringe featuring stratification and excess N, diapycnal phosphate supply was blocked and phytoplankton APA was stimulated for growth. We observed an upwelling just attaching to the turbidity front at seaward side where Chl a peaked yet much less APA was detected. An external phosphate supply from subsurface, which promoted phytoplankton growth but inhibited APA, was suggested to be sourced from the Nearshore Kuroshio Branch Current. In the so hydrographically complicated Changjiang plume, phosphate supply instead of its concentration may be more important in determining the expression of APA. Meanwhile, allochthonous APA may also alter the usefulness of APA as a P-stress indicator.
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Tseng, Y. F., J. Lin, M. Dai e S. J. Kao. "Joint effect of freshwater plume and coastal upwelling on phytoplankton growth off the Changjiang River". Biogeosciences Discussions 10, n.º 6 (26 de junho de 2013): 10363–97. http://dx.doi.org/10.5194/bgd-10-10363-2013.
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Abstract. Changjiang River discharges vast amount of unbalanced nutrients (dissolved inorganic nitrogen (N) and phosphorus (P) with N / P > 80 in general) into the East China Sea during summertime. To explore nutrient dynamics and P stress potential for phytoplankton, a cruise was conducted in the Changjiang plume during summer 2011. With 3-D observations of nutrients, chlorophyll a (Chl a), and bulk alkaline phosphatase activity (APA), we concluded that the Changjiang Diluted Water (CDW) and coastal upwelling significantly influenced the horizontal and vertical heterogeneities of phytoplankton P-deficiency in the plume. Allochthonous APA was detected at nutrient-enriched freshwater end. Excessive N (~10 to 112 µM) was obserevd throughout the entire plume surface. In the plume fringe where featured by stratification and excess N, diapycnal phosphate supply was blocked to stimulate APA for phytoplankton growth. We observed upwelling outcrops just attaching the turbidity front at seaward side, where Chl a peaked yet much less APA was detected. An external phosphate supply from subsurface, which stimulated phytoplankton growth but inhibited APA, was suggested and the supply was likely sourced from the Nearshore Kuroshio Branch Current. In such hydrographically complicated Changjiang plume, phosphate supply instead of its concentration was more important determining the expression of APA. Meanwhile, allochthounous APA may also alter the usefulness of APA as a P-stress indicator.
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Wójtowicz, Joanna, Adam K. Jagielski, Agnieszka Mostowska e Katarzyna B. Gieczewska. "Compensation Mechanism of the Photosynthetic Apparatus in Arabidopsis thaliana ch1 Mutants". International Journal of Molecular Sciences 22, n.º 1 (28 de dezembro de 2020): 221. http://dx.doi.org/10.3390/ijms22010221.
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The origin of chlorophyll b deficiency is a mutation (ch1) in chlorophyllide a oxygenase (CAO), the enzyme responsible for Chl b synthesis. Regulation of Chl b synthesis is essential for understanding the mechanism of plant acclimation to various conditions. Therefore, the main aim of this study was to find the strategy in plants for compensation of low chlorophyll content by characterizing and comparing the performance and spectral properties of the photosynthetic apparatus related to the lipid and protein composition in four selected Arabidopsis ch1 mutants and two Arabidopsis ecotypes. Mutation in different loci of the CAO gene, viz., NW41, ch1.1, ch1.2 and ch1.3, manifested itself in a distinct chlorina phenotype, pigment and photosynthetic protein composition. Changes in the CAO mRNA levels and chlorophyllide a (Chlide a) content in ecotypes and ch1 mutants indicated their significant role in the adjustment mechanism of the photosynthetic apparatus to low-light conditions. Exposure of mutants with a lower chlorophyll b content to short-term (1LL) and long-term low-light stress (10LL) enabled showing a shift in the structure of the PSI and PSII complexes via spectral analysis and the thylakoid composition studies. We demonstrated that both ecotypes, Col-1 and Ler-0, reacted to high-light (HL) conditions in a way remarkably resembling the response of ch1 mutants to normal (NL) conditions. We also presented possible ways of regulating the conversion of chlorophyll a to b depending on the type of light stress conditions.
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Xu, Keren, Niquelle B. Wadé, Amie E. Hwang, David V. Conti, Maryam Salehi, Thomas M. Mack, Victoria Cortessis, David J. Van Den Berg, Adam J. de Smith e Wendy Cozen. "Whole-Exome Sequencing in Multiplex Families to Identify Novel AYA Classical Hodgkin Lymphoma Predisposition Genes". Blood 138, Supplement 1 (5 de novembro de 2021): 3499. http://dx.doi.org/10.1182/blood-2021-153247.
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Abstract Background: Hodgkin Lymphoma (HL) is a B-cell malignancy that mainly affects young adults in economically developed countries. Classical HL (cHL) is the most common type, comprising >95% of cases. We demonstrated strong heritability of cHL in adolescents and young adults (AYA) with a high risk to the unaffected co-twins of affected monozygotic (MZ) twins. We and others identified common risk variants by GWAS, and sequencing of familial and sporadic HL patients previously identified rare pathogenic germline variants in genes with varying functions. Few have replicated in other families. A greater understanding of the genes involved in cHL predisposition is needed. We performed germline whole-exome sequencing (WES) for 48 individuals in 14 multiplex families with AYA cHL patients to identify novel cHL predisposition genes. Methods: Index cases from multiplex families were ascertained from the USC twin registries (International Twin Registry or California Twin Program, 7 index cases, 2 additional cases, and 7 unaffected relatives) or from the USC Cancer Surveillance Program (7 index cases, 4 additional cases, and 21 unaffected relatives). Among the twin pairs, 5 were concordant MZ pairs, one was a concordant dizygotic pair and one was an MZ discordant pair with a second case occurring in the daughter of the unaffected MZ co-twin. The other 7 families included 4 with two affected siblings, one with a child/father pair, and two with child/uncle pairs; the latter 3 families had specimens available for the index child case only. All index cases were diagnosed under 50 years old, with the median age 27. DNA samples were extracted from blood or saliva of 48 individuals in 14 multiplex families, with specimens from 20 of 28 reported cases. Germline WES was performed using the Nextera® Rapid Capture Exome kit, with data pre-processing performed based on Genome Analysis Toolkit best practices guidelines, and additional filtering applied using BCFtools. Variants were annotated using ANNOVAR. We filtered out variants with an allele frequency >0.001 in population databases (gnomAD or TOPMed), and variants documented as benign/likely benign in ClinVar. We retained splicing/ncRNA variants and exonic variants with loss-of-function/missense/unknown functional consequences, and with a CADD score >10. We further limited variants to those in 1,073 candidate predisposition genes, including cancer/immunodeficiency/hematological-related genes in the Pediatric Cancer Variant Pathogenicity Information Exchange (PeCanPIE) and genes previously identified in sequencing studies or GWAS for cHL. Variants in candidate genes were visually inspected in the Integrative Genomics Viewer and were analyzed for their potential pathogenicity through the PeCanPIE MedalCeremony pipeline. Variants predicted to be tolerated by PeCanPIE were removed. Variants found only in HL patients and not in their sibling controls were considered to be potentially causal. Results: In 45 subjects that passed sequencing QC (3 controls were removed due to low mean coverage) and following variant filtering, there were 33 variants in 33 genes found only in cHL patients but not in their sibling controls, among 9 of 14 families. None of the variants appeared in more than one family. One variant in PGK1 was previously reported as pathogenic/likely pathogenic in ClinVar in patients with phosphoglycerate kinase 1 deficiency associated with hemolytic anemia. Nine variants were reported in ClinVar as variants of uncertain significance, of which 3 were previously reported in patients with immunodeficiency disorders (in genes IL2RA, MALT1, and PRKDC) and 2 were reported in patients with dyskeratosis congenita (TERT) and other anemia-associated disorders (EPB42). Of 22 variants not reported in ClinVar, one was a missense variant in NPAT, a gene previously associated with familial lymphoma; 4 were in genes associated with immune disorders (PLCG2, LIG1, C1QB, and NOD2) and 3 were in genes associated with anemia (SPTB, ALDOA, and GATA1). To our knowledge, none of these genes other than NPAT have previously been implicated in predisposition to HL. Conclusions: WES in 20 AYA cHL patients among multiplex families identified putative novel predisposition genes for HL, including genes implicated in anemia and immune function. Assessment of these genes in sequencing studies of independent HL families is required to understand their role in HL predisposition. Disclosures Wadé: Flatiron Health: Current Employment; Roche: Current equity holder in publicly-traded company.
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Ogawa, Takako, e Kintake Sonoike. "Effects of Bleaching by Nitrogen Deficiency on the Quantum Yield of Photosystem II inSynechocystissp. PCC 6803 Revealed by Chl Fluorescence Measurements". Plant and Cell Physiology 57, n.º 3 (8 de fevereiro de 2016): 558–67. http://dx.doi.org/10.1093/pcp/pcw010.
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Zhang, Ke, Xiaojun Liu, Yong Ma, Rui Zhang, Qiang Cao, Yan Zhu, Weixing Cao e Yongchao Tian. "A Comparative Assessment of Measures of Leaf Nitrogen in Rice Using Two Leaf-Clip Meters". Sensors 20, n.º 1 (27 de dezembro de 2019): 175. http://dx.doi.org/10.3390/s20010175.
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Accurate estimation and monitoring of crop nitrogen can assist in timely diagnosis and facilitate necessary technical support for fertilizer management. Four experiments, involving three cultivars and six nitrogen (N) treatments, were conducted in southeast China to compare the two leaf-clip meters (Dualex 4 Scientific+, Force-A, Orasy, France; Soil and Plant Analyzer Development (SPAD) meter, Minolta Camera Co., Osaka, Japan) for their ability to measure nitrogen nutrient-related indicators. The results indicated that Chl had a better monitoring accuracy for chlorophyll in per unit leaf area as compared to SPAD value, and there was no saturation to appear under high leaf chlorophyll concentration status. Flavonoids (Flav) presented the advantage of early diagnosis of rice N nutrition status (about one day as compared to SPAD value). As a reliable N nutrient diagnosis indicator, it also improved the estimation accuracy compared with the classical SPAD-based method. The other Dualex value also obtained good monitoring results. Flav was positively correlated with N deficiency, and with higher R2 in panicle initiation and booting stages with low RMSE, respectively; whereas SPAD value was negatively correlated with nitrogen deficiency. Therefore, the Flav-based nitrogen application model was found to provide an early rice nitrogen fertilizer application approach, especially in the panicle initiation and booting stages.
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Herrmann, Brian William, Campbell R. Hathaway e Michael Fadell. "Hearing Loss in Pediatric Septo-Optic Dysplasia". Annals of Otology, Rhinology & Laryngology 128, n.º 6 (19 de fevereiro de 2019): 485–89. http://dx.doi.org/10.1177/0003489419832629.
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Objective: To identify and characterize hearing loss (HL) in children with septo-optic dysplasia (SOD). Methods: Otologic and audiometric data for patients less than 18 years of age identified as having SOD who were seen in the Children’s Healthcare of Atlanta-Scottish Rite Hospital clinic between 2013 and 2017 were collected and reviewed through a HIPAA-compliant medical record search. Relevant literature was also reviewed with the assistance of Medline. Results: Sixty-four patients with SOD were identified, and 7 of those patients (10.9%) were diagnosed with hearing loss. Type of hearing loss was sensorineural (SNHL) in 5 patients (63%), mixed (MHL) in 1(14%), and conductive (CHL) in 1(14%). Bilateral loss presented in 60% (3/5) of SNHL patients, while the rest demonstrated unilateral loss. Unilateral findings included cochlear nerve deficiency (1) and atresia/microtia (1). Tympanostomy tubes were required in 57% (4/7) of SOD children with hearing loss. Amplification was successfully implemented in 86% (6/7). Conclusions: Hearing loss was found in nearly 11% of SOD children, and SNHL was identified as (63%) the predominant form of loss. To our knowledge, this is the first retrospective review of hearing loss in a pediatric SOD cohort and the first to report of cochlear nerve deficiency and atresia/microtia in this population. Based on these findings, early identification of hearing loss with imaging when appropriate and treatment of otitis in this population is recommended.
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Saleem, Ammara, Asma Zulfiqar, Baber Ali, Manal Ahmed Naseeb, Arwa Saad Almasaudi e Steve Harakeh. "Iron Sulfate (FeSO4) Improved Physiological Attributes and Antioxidant Capacity by Reducing Oxidative Stress of Oryza sativa L. Cultivars in Alkaline Soil". Sustainability 14, n.º 24 (15 de dezembro de 2022): 16845. http://dx.doi.org/10.3390/su142416845.
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Rice ranks second among cereals in dietary uses around the world. Rice is deficient in iron (Fe), and these are important micronutrients for infants, men, and women. Fortification of rice with iron would help to minimize nutrient deficiency disorders among humans. The current study aims to introduce nutrient-rich rice. The effects of iron on germination, growth, photosynthetic pigment, antioxidant activity, and reduction of oxidative stress were investigated in four Oryza sativa L. cultivars. O. sativa of four different cultivars (Basmati-515, PK-386, KSK-133, and Basmati-198) were grown under five treatments (100, 200, 300, 400, and 500 mM) of iron sulphate (FeSO4) in soil of pH 7.5, along with control, by using six replicates. The result revealed that Fe treatment significantly affected seed germination percentage, plant growth parameters, biomass, photosynthetic pigments (chl a, chl b, total chlorophyll, and carotenoids), antioxidant enzymatic and non-enzymatic activity, and reduced oxidative stress. The findings also showed that Fe application reduced the oxidative stress including malondialdehyde content and hydrogen peroxide, by increasing the antioxidant enzymatic activity, i.e., catalase, ascorbate peroxidase, superoxide dismutase, peroxidase, glutathione peroxidase, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), and non-enzymatic antioxidant compounds (proline, amino acid, total soluble protein, phenolics, flavonoids, reducing-non-reducing sugar, and carbohydrates) in all cultivars of O. sativa. Furthermore, FeSO4 induced a significant increase in proline, free amino acid, and total carbohydrates in the leaves of all O. sativa cultivars, but Basmati-198 showed the significantly highest content by 169, 88, and 110%, respectively, at concentration of 500 mM. The present research work showed that soil application of FeSO4 improved the seed germination, plant growth, and antioxidants enzymatic and non-enzymatic activity, denatured the ROS (reactive oxygen species) in alkaline soil. In order to understand the underlying mechanisms, long-term field investigations should be carried out at the molecular level to examine patterns of iron uptake and plant growth.
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Wienand, Kirsty, Bjoern Chapuy, Chip Stewart, Andrew Dunford, David Wu, Jaegil Kim, Atanas Kamburov et al. "Comprehensive Genomic Analysis of Flow-Sorted Hodgkin Reed Sternberg Cells Reveals Additional Genetic Bases of Immune Evasion". Blood 132, Supplement 1 (29 de novembro de 2018): 1559. http://dx.doi.org/10.1182/blood-2018-99-118453.
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Abstract Classical Hodgkin lymphoma (cHL) is composed of rare malignant Hodgkin Reed Sternberg (HRS) cells within an extensive, but ineffective, inflammatory/immune cell infiltrate. Emerging data suggests that cHLs use multiple genetic mechanisms to evade immune recognition. We previously found that HRS cells exhibit near-universal somatic copy number alterations (SCNAs) involving chromosome 9p24.1/PD-1-L1/PD-L2 and rare chromosomal rearrangements of PD-L1 or PD-L2. The 9p24.1 amplicon also includes JAK2, which increases JAK2 copy numbers, augments JAK2/STAT signaling and further induces PD-1 ligand expression. However, HRS cells also have inactivating mutations of B2M and decreased or absent MHC class I expression. In cHL, clinical responses to PD-1 blockade are unrelated to HRS cell expression of MHC class I but closely associated with HRS cell expression of MHC class II, highlighting the potential role of CD4+ T-cell effectors (J Clin Oncol 2018;36:942-50). To define genetic bases of response and resistance to PD-1 blockade and identify complementary treatment targets, we performed whole exome sequencing (WES) of HRS cells. We first used a previously described multi-color flow cytometric sorting protocol (Methods 2012; 57:368-75) to obtain highly purified CD30+ HRS cells and normal B cells from the excisional biopsies of 25 newly diagnosed cHLs. The isolated HRS cells and paired normal B cells were then subjected to WES using an optimized workflow for low input samples and an expanded bait set to capture structural variants (SVs). We used established analytical pipelines to identify significantly mutated genes (candidate cancer genes [CCGs], MutSig2CV), SCNAs (GISTIC2.0) and SVs (4 algorithms). With improved methodology and purity (median of 80%) of the isolated HRS cells, we defined 15 significantly mutated CCGs, 21 recurrent SCNAs, including 6 CN gains (4 focal and 2 arm level) and 15 CN losses (14 focal and 1 arm level), and low frequency SVs. We identified 2 cHLs as hypermutators with MSI signatures due to splice site mutations in MSH2 or missense mutations in POLE. Excluding the 2 hypermutators, the analyzed cHLs had a median mutational density of 6.4 mutations/Mb, that falls within the top quartile of reported cancer mutational frequencies (Nature 2013 499:214). We also identified a previously unappreciated high incidence of ARID1A mutations (24%) in cHL. This is noteworthy because ARID1A deficiency increases mutational load and augments the efficacy of PD-1 blockade in murine models (Nature Med 2018;24:556). Together, the observed MSI signatures, relatively high mutational burden and newly identified ARID1A mutations in cHL represent additional potential genetic bases for the efficacy of PD-1 blockade. Notably, these cHLs also exhibited recurrent 9p24.1 copy gain (80%) and multiple genetic bases of enhanced JAK/STAT signaling including JAK2 copy gain (80%), STAT6 mutations (32%) involving known hotspots (D419 and N421) in the DNA-binding domain and frequent inactivating SOCS1 mutations (68%). We also identified multiple genetic bases for immune evasion, including B2M inactivating mutations (36%), HLA-B mutations (16%) and 6p21.32/HLA-B copy loss (28%), copy loss of the larger 6p21.32 region and inactivating CIITA SVs (8%). Additional signaling pathways were perturbed by multiple genetic mechanisms in these cHLs. For example, NF-κB pathway alterations included: TNFAIP3 mutations (24%) and 6q23.2/TNFAIP3 copy loss (56%), 12% biallelic; NFKBIE mutations (24%) and 6q21.32/NFKBIE copy loss (12%); and NFKBIA mutations (16%). The gene encoding the nuclear export protein, XPO1, was perturbed by E571K mutations (24%) and frequent 2p15/XPO1 copy gain (72%). Additionally, GNA13, an activator of RHOA and modifier of PI3K signaling, was mutated in 24% of cases. Of interest, cHL recurrent alterations including B2M, TNFAIP3, STAT6, and GNA13 mutations and 6q23.2 and 9p24.1 SCNAs were also identified in > 20% of examined primary mediastinal B-cell lymphomas, highlighting shared pathogenetic mechanisms in these diseases. In summary, comprehensive genomic analyses of purified HRS cells reveal new genetic bases of immune evasion, potential mechanisms of response and resistance to PD-1 blockade and additional targetable alterations. KW, BC, CS, AD and DW contributed equally. JF, GG and MS contributed equally. Disclosures Rodig: Affimed: Research Funding; KITE: Research Funding; Merck: Research Funding; Bristol Myers Squibb: Research Funding. Shipp:Merck: Research Funding; Bayer: Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria.
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Sayala, Hazem A., Sheila J. O’Connor, Andrew S. Jack, Chetan Patalappa, Peter Hillmen e Roger G. Owen. "EBV Related Transformation Events in CLL." Blood 108, n.º 11 (16 de novembro de 2006): 4963. http://dx.doi.org/10.1182/blood.v108.11.4963.4963.
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Abstract Less than 5% of patients with CLL undergo histological transformation to diffuse large B cell lymphoma (DLBL) while transformation to Classical Hodgkins lymphoma (CHL) is also recognised. It has been assumed that such events reflect genetic changes in the CLL clone but there is now emerging evidence to suggest that at least some transformation events may be Epstein Barr virus (EBV) related neoplasms not clonally related to CLL. In this analysis we have reviewed the clinical and laboratory features of 15 CLL patients with biopsy proven histological transformation to DLBL and 2 patients who developed CHL. Histological sections were assessed for the expression of a wide range of immunophenotypic markers as well as EBV latent membrane protein 1 (LMP-1). Of the 15 patients developing DLBL 5 appeared on phenotypic grounds to be related to the underlying CLL clone. In the remaining patients the tumour cells appeared phenotypically distinct as they lacked CD5 and CD23 and demonstrated expression of germinal centre markers in some instances. LMP1 positivity was demonstrable in 5 patients with DLBL (1 apparently related and 4 unrelated to the underlying CLL). Of the 2 patients who developed CHL 1 was associated with EBV and lacked CD20 expression. The 6 patients with EBV+ tumours were heavily pretreated (median prior therapies 4, range 1–5) while the median time from original diagnosis to histological transformation was 74.5 months (range 17–114). Previous therapies included chlorambucil (n= 4), fludarabine monotherapy (n=3), FC (n=2), FCR (n=1 patient), high dose methyl prednisolone (n= 1) and alemtuzumab (n=2). 2 patient received only one line of therapy for CLL but one of these was heavily immunosuppressed with steroids and azathioprine for autoimmune neutropenia. 4 patients presented with nodal disease and 2 patients presented with extranodal disease (bone marrow and liver). The outcome of the EBV associated tumours in these patients was death in 2 patients (opportunistic infection and complications of intensive chemotherapy), remission with intensive combination chemotherapy in 2 patients one of whom died 10 months later of progressive CLL and spontaneous remission of nodal disease in 1 patient. 1 patient is still undergoing intensive chemotherapy and the outcome is not known yet. We would conclude that not all transformation events in CLL occur within the original clone. The majority appear to be clonally distinct and a significant proportion of these appear to be EBV associated. This presumably occurs as a result of both the underlying immune-deficiency seen in CLL as well the potent immunosuppressive agents given as therapy. This phenomenon may also be a feature of other B-cell disorders as we have recently seen a phenotypically and genotypically distinct EBV associated DLBL in a patient treated with chlorambucil, CHOP and FCR for mantle cell lymphoma. The natural history of these tumours remains uncertain at this stage but it is clear that at least a minority may resolve spontaneously. All biopsies demonstrating histological transformation in CLL patients should be assessed for the presence of EBV.
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Puglisi, Fabrizio, Enrico La Spina, Alessandro Barbato, Grazia Scandura, Cesarina Giallongo, Daniele Tibullo, Francesco Di Raimondo e Alessandra Romano. "An Integrative Unbiased Global Analysis of the Metabolic Adaptive Response to Tryptophan Deprivation in Classical Hodgkin Lymphoma". Blood 136, Supplement 1 (5 de novembro de 2020): 26–27. http://dx.doi.org/10.1182/blood-2020-139748.
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Background Tryptophan (trp) is an essential aminoacid, required for de novo NAD+ synthesis. Our previous work showed that the microenvironment in classical Hodgkin Lymphoma is characterized by dysfunctional neutrophils and myeloid derived suppressor cells that produce a trp-degrading enzyme indoelamine deoxygenase (IDO-1), lowering the amount of trp. Aims To detect metabolomics changes in human cHL cell lines exposed in vitro to tryptophan deprivation, an amino acid involved in immune dysregulation and generation of anergic and tolerogenic T- cells. Methods In order to better understand the impact of extra-cellular IDO1 increase on the metabolome of human cHL cells, three human cHL cell lines (L428, L540 and KM-H2) were individually cultured with customized complete media or media lacking tryptophan (W0), +10% dyalised fetal bovum serum, in six independent experiments. After 48 hours of culture the cells were collected for global metabolomic analysis, by gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) platforms by Metabolon Inc. Following normalization to DNA concentration, log transformation and imputation of missing values, if any, with the minimum observed value for each compound, Welch's two-sample t-test was used to identify biochemicals that differed significantly between experimental groups (Table 1). Results The lack of tryptophan in media had a profound effect on the cell metabolome in 2 cell lines, KMH2 and L428 cells, while L540 cell line was pretty resilient (Table 1). In all cell lines, the removal of tryptophan from the media resulted in significantly lower levels of tryptophan. Kynurenine, the metabolic product of IDO-1 action on tryptophan, was lower in all cells, but did not reach significance in the L540 cells, whereas it trended lower in L428 and was significantly lower in the KMH2 compared to controls. Indolelactate, another major tryptophan metabolite was also significantly lower in the L428 and KMH2 cells lines compared to controls. Glucose uptake and aerobic glycolysis are frequently upregulated in tumor cells to support energy needs and provide biosynthetic precursors (e.g. pentose phosphate pathway intermediates for nucleotide synthesis). Known as the Warburg effect, this process of reliance on glucose for energy results in high levels of lactate production. We found that trp deficiency lead to lower levels of the hexose diphosphates (fructose 1,6-diphosphate/glucose 1,6-diphosphate/myo-inositol diphosphates isobar) and dihydroxyacetone phosphate, suggesting the revert of Warburg effect due to reduced bio-energetic requirements for proliferation. In line with this observation, culture in trp deficient media resulted in increased levels of long chain saturated fatty acids and long chain polyunsaturated fatty acids (PUFAs), suggesting that specific-amino acid deficiency leads to an increase in uptake of free fatty acids from the media, to preserve membrane dynamics. Since prolonged trp deprivation (up to 10 days) delayed cell cycle length without affecting proliferation or changes in intracellular amount of NAD+, we investigated changes in mitochondrial membranes network to explain these findings. Trp deprivation induced the rearrangement of the mitochondrial network at 48 hours, with more fission than fusion, as suggested by increased expression of Fis1 and Drp1 and reduced expression of Tfam and Opa1, without affecting significantly mitochondrial mass and depolarization. This adaptive response was associated to increased oxidative stress, as suggested by of reduced glutathione (GSH) and oxidized glutathione (GSSG) in the L540 and KMH2 cells, depletion of gamma-glutamylcysteine, increased cystine, the oxidative product of cysteine, and methionine sulfoxide (an oxidation product of methionine). Conclusions The removal of trp from L428 and KMH2 resulted in changes in the specific-amino acid related metabolites. The adaptive response to trp-depleted microenvironment can revert the Warburg effect, promoting a shift in the glucose use in the futile attempt to preserve mitochondrial function, and increase oxidative stress. Quantity and function of mitochondria network can play a major role in selecting the fittest clones, a metabolic pathway that should be explored as novel non -synthetic lethal targets. Disclosures Puglisi: Amgen:Honoraria.Di Raimondo:Takeda:Consultancy, Honoraria;GILEAD, Incyte:Research Funding;Amgen, Takeda, Novartis:Honoraria;Celgene:Consultancy, Honoraria;Janssen:Consultancy, Honoraria;GSK:Consultancy, Honoraria;Amgen:Consultancy, Honoraria.Romano:Takeda:Honoraria;Novartis:Honoraria.
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Edwards, GE, e CLD Jenkins. "C4 Photosynthesis: Activities of Photosynthetic Enzymes in a Virescent Mutant of Maize Having a Low-Temperature Induced Chloroplast Ribosome Deficiency". Functional Plant Biology 15, n.º 3 (1988): 385. http://dx.doi.org/10.1071/pp9880385.
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A virescent mutant of maize (v16/v16), which has a low temperature induced deficiency in 70S ribosomes, was used to examine whether the enzymes of the C4 pathway and other photosynthetic enzymes are synthesised on chloroplast ribosomes. The mutant and control plants were grown at 20°C and 30°C and the rates of photosynthesis and enzyme activities were compared. There was no photosynthesis in v16/v16 grown at 20°C (pale yellow), while plants grown at 30°C (normal green) had rates equivalent to the wild type and normal enzyme activities. On a leaf area basis, with v16/v16 grown at 20°C, the activity of ribulose 1,5-bisphosphate (RuP2) carboxylase was only 2% that of the wild type grown at this temperature, while the activities of enzymes of the C4 cycle were much higher (as a percentage of the wild type activity: pyruvate,PI dikinase, 22%; NADP-malate dehydrogenase, 35%; NADP-malic enzyme, 47%; and phosphoenolpyruvate (PEP) carboxylase, 68%). In another experiment v16/v16 plants were grown initially at 30°C, then transferred to 20°C. After transfer to 20°C leaves previously formed under 30°C remained green and had normal rates of photosynthesis and enzyme activities, but newly formed leaves were pale yellow (only 11% as much Chl) and had low photosynthesis rates (2% of normal) and RuP2 carboxylase activity (5% of control). However, there was high activity of eight enzymes of the C4 cycle. The low activity of RuP2 carboxylase in the mutant grown at 20°C is consistent with the requirement of 70S ribosomes for its synthesis, while the high activities of enzymes of the C4 cycle, including those which are chloroplastic, suggest their synthesis is nuclear-encoded.
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El-Yazied, Ahmed Abou, Mohamed F. M. Ibrahim, Mervat A. R. Ibrahim, Ibrahim N. Nasef, Salem Mesfir Al-Qahtani, Nadi Awad Al-Harbi, Fahad Mohammed Alzuaibr et al. "Melatonin Mitigates Drought Induced Oxidative Stress in Potato Plants through Modulation of Osmolytes, Sugar Metabolism, ABA Homeostasis and Antioxidant Enzymes". Plants 11, n.º 9 (24 de abril de 2022): 1151. http://dx.doi.org/10.3390/plants11091151.
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The effect of melatonin (MT) on potato plants under drought stress is still unclear in the available literature. Here, we studied the effect of MT as a foliar application at 0, 0.05, 0.1, and 0.2 mM on potato plants grown under well-watered and drought stressed conditions during the most critical period of early tuberization stage. The results indicated that under drought stress conditions, exogenous MT significantly (p ≤ 0.05) improved shoot fresh weight, shoot dry weight, chlorophyll (Chl; a, b and a + b), leaf relative water content (RWC), free amino acids (FAA), non-reducing sugars, total soluble sugars, cell membrane stability index, superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX) compared to the untreated plants. Meanwhile, carotenoids, proline, methylglyoxal (MG), H2O2, lipid peroxidation (malondialdehyde; MDA) and abscisic acid (ABA) were significantly decreased compared to the untreated plants. These responses may reveal the protective role of MT against drought induced carbonyl/oxidative stress and enhancing the antioxidative defense systems. Furthermore, tuber yield was differentially responded to MT treatments under well-watered and drought stressed conditions. Since, applied-MT led to an obvious decrease in tuber yield under well-watered conditions. In contrast, under drought conditions, tuber yield was substantially increased by MT-treatments up to 0.1 mM. These results may imply that under water deficiency, MT can regulate the tuberization process in potato plants by hindering ABA transport from the root to shoot system, on the one hand, and by increasing the non-reducing sugars on the other hand.
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Alexanin, Anatoly, Vasilii Kachur, Anastasiya Khramtsova e Tatiana Orlova. "Methodology and Results of Satellite Monitoring of Karenia Microalgae Blooms, That Caused the Ecological Disaster off Kamchatka Peninsula". Remote Sensing 15, n.º 5 (22 de fevereiro de 2023): 1197. http://dx.doi.org/10.3390/rs15051197.
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The environmental disaster in Kamchatka in the autumn of 2020 was caused by an extensive bloom of harmful microalgae of the genus Karenia. A spectral shape algorithm was used to detect algae on satellite imagery. The algorithm calibration of in situ species composition data made it possible to identify areas where harmful algae dominated in biomass. The algorithm allowed evaluation of the dynamics of the distribution of the algae. The state of phytoplankton was estimated based on images of the specific capacity of photosynthesis. Specific fluorescence is the ratio of the height of the fluorescence line (flh) to the concentration of chlorophyll-a (chl-a). The parameter was used to recognize the stages of the algal bloom: intensive growth, blooming, and change in the dominant algal species. In addition, an increase in the concentration of harmful substances in the coastal zone due to wind impact was analyzed. After analyzing the available data, the events that caused the ecological disaster can be summarized as follows. After the stage of intensive growth of microalgae, nutrient deficiency stimulated the production of metabolites that have a harmful effect on the environment. The change of the dominant alga species in the second half of September and the past storm contributed to a sharp increase in the concentration of metabolites and dead organic matter in the coastal zone, which caused an ecological disaster. The subsequent mass bloom of alga species of the same genus, and the regular wind impact leading to the concentration of harmful substances in the coastal zone, contributed to the development of this catastrophic phenomenon.
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Puglisi, Fabrizio, Antonella Padella, Nunziatina Laura Parrinello, Grazia Scandura, Daniela Cambria, Enrico La Spina, Alessandro Barbato et al. "Dissecting the Adaptive Response to Arginine Deprivation in Hodgkin Lymphoma". Blood 138, Supplement 1 (5 de novembro de 2021): 4497. http://dx.doi.org/10.1182/blood-2021-151006.
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Abstract Background In Hodgkin Lymphoma (HL), neoplastic cells orchestrate an inflammatory microenvironment leading to sterile inflammation, T-cell anergy, and immune deficiency. Our group showed that in HL patients the aminoacid degrading enzyme Arginase-1 is increased, associated with poor outcome, and leads to arginine (Arg) deprivation. However, how the reduction of Arg in the extracellular milieu of the tumor microenvironment can contribute to neoplastic cell fitness is largely unknown. Aims To detect the adaptive response (via evaluation of global transcriptome and metabolome changes) in human HL cell lines exposed to Arg deprivation. Methods To better understand the impact of extra-cellular Arg1 deprivation on the metabolome of human cHL cells, four human cHL cell lines (L428, L540, HDMYZ and KM-H2) were individually cultured with customized complete media or lacking or Arg (R0), supplemented with 10% dialyzed fetal bovine serum, in six independent experiments. After 48 hours of culture, the cells were collected for global metabolomic analysis, by gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) platforms by Metabolon Inc and transcriptome profiling by Illumina platform. Following normalization to DNA concentration, log transformation, and imputation of missing values, if any, with the minimum observed value for each compound, Welch's two-sample t-test was used to identify biochemicals that differed significantly between experimental groups. Results While Arg deprivation did not affect cell viability but delayed cell cycle due to arrest in G2 phase in all tested cell lines, the effect of Arg deficiency on the cellular metabolome depended largely on the cell type examined with L428 and KMH2 cells having significantly changed metabolomes. Pyruvate was significantly higher in the KMH2 cells deprived of Arg compared to controls. Conversely, lactate was significantly lower, with increased levels of long-chain saturated fatty acids and long-chain polyunsaturated fatty acids (PUFAs). Taken together the metabolomics changes suggested that specific-amino acid deficiency can lead to an increase in free fatty acids synthases to preserve cytoplasmatic and mitochondrial membrane dynamics. Consistent with a metabolic rewiring to maintain mitochondrial integrity (the pyruvate is an important intermediary in the conversion of carbohydrates into fatty acids), the adaptive response was associated to increased oxidative stress, as suggested by of reduced glutathione in KMH2 cells, depletion of gamma-glutamylcysteine, increased cystine, the oxidative product of cysteine, and methionine sulfoxide (an oxidation product of methionine). Gene set enrichment analysis (GSEA) showed deep transcriptome rearrangements in KMH2 and HDMYZ cell lines, involving upregulation of genes required for the unfolded protein response (UPR, including XBP1, EIF2S1, EIF4A2, EIF4A3, ATF3, ATF4, DDIT4, EDEM1, GADD45B, SQSTM1, HMOX), NF-kB response to TNF (including RAF1, TNF, LIF, NKBIA, SGK1, BIRC3, ICAM1, BCL6, IL6, RELA, CDKN1A), p53 pathway and networks (including CDKN2B, STOM, TRAF4, RRAD, SESN1, FOXO3, SERPINB5, JAG2) and proteosome degradation (HSPA4, PSMD11, PSMD13, PSMD2, PSMA5, PSMA7, PSMC4), with a minimal effect on metabolism features, except the upregulation of genes involved in lactate generation and degradation. All lines tested showed down-regulation of CCNI2, LCROL, MKI67, NCAPG, PEX10 and UFSP2, suggesting that early response to arginine deprivation includes modulation of UFMylation pathway, the most recently discovered post-translational protein modification system, whose biological function is largely unknown. Conclusions The removal of Arg from L428 and KMH2 resulted in changes in the specific-amino acid-related metabolites. The adaptive response to Arg-depleted environment increases oxidative stress and promotes a shift in glucose use in the attempt to preserve mitochondrial function. The cell-cycle arrest in G2, the increase of pyruvate availability and the upregulation of proteasome function via upregulation of the UFMylation pathway suggest the dependency of HL cell lines on mitochondrial function integrity. Quantity and function of mitochondria network can play a major role in selecting the fittest clones, a metabolic pathway that should be explored as novel non -synthetic lethal targets. Disclosures Martinelli: Stemline Therapeutics: Consultancy; Roche: Consultancy; Astellas: Consultancy, Speakers Bureau; Daichii Sankyo: Consultancy; Pfizer: Consultancy, Speakers Bureau; Incyte: Consultancy; Abbvie: Consultancy; Celgene /BMS: Consultancy, Speakers Bureau; Jazz Pharmaceuticals: Consultancy. Di Raimondo: Pfizer: Honoraria; Jazz Pharmaceutical: Honoraria; Amgen: Honoraria; AbbVie: Honoraria; Bristol Myers Squibb: Honoraria; Janssen Pharmaceuticals: Honoraria.
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Leblanc, K., C. E. Hare, Y. Feng, G. M. Berg, G. R. DiTullio, A. Neeley, I. Benner et al. "Distribution of calcifying and silicifying phytoplankton in relation to environmental and biogeochemical parameters during the late stages of the 2005 North East Atlantic Spring Bloom". Biogeosciences Discussions 6, n.º 3 (19 de junho de 2009): 5789–847. http://dx.doi.org/10.5194/bgd-6-5789-2009.
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Abstract. The late stage of the North East Atlantic (NEA) spring bloom was investigated during June 2005 along a transect section from 45 to 66° N between 15 and 20° W in order to characterize the contribution of siliceous and calcareous phytoplankton groups and describe their distribution in relation to environmental factors. We measured several biogeochemical parameters such as nutrients, surface trace metals, algal pigments, biogenic silica (BSi), particulate inorganic carbon (PIC) or calcium carbonate, particulate organic carbon, nitrogen and phosphorus (POC, PON and POP, respectively), as well as transparent exopolymer particles (TEP). Results were compared with other studies undertaken in this area since the JGOFS NABE program. Characteristics of the spring bloom generally agreed well with the accepted scenario for the development of the autotrophic community. The NEA seasonal diatom bloom was in the late stages when we sampled the area and diatoms were constrained to the northern part of our transect, over the Icelandic Basin (IB) and Icelandic Shelf (IS). Coccolithophores dominated the phytoplankton community, with a large distribution over the Rockall-Hatton Plateau (RHP) and IB. The Porcupine Abyssal Plain (PAP) region at the southern end of our transect was the region with the lowest biomass, as demonstrated by very low chl-a concentrations and a community dominated by picophytoplankton. Early depletion of dissolved silicic acid (DSi) and increased stratification of the surface layer most likely triggered the end of the diatom bloom, leading to coccolithophore dominance. The chronic Si deficiency observed in the NEA could be linked to moderate Fe limitation, which increases the efficiency of the Si pump. TEP closely mirrored the distribution of both biogenic silica at depth and prymnesiophytes in the surface layer suggesting the sedimentation of the diatom bloom in the form of aggregates, but the relative contribution of diatoms and coccolithophores to carbon export in this area still needs to be resolved.
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Grovenstein, Phillip B., Darryel A. Wilson, Kathryn D. Lankford, Kelsey A. Gaston, Surangi Perera e Mautusi Mitra. "Identification and molecular characterization of a Chlamydomonas reinhardtii mutant that shows a light intensity dependent progressive chlorophyll deficiency". F1000Research 2 (19 de junho de 2013): 142. http://dx.doi.org/10.12688/f1000research.2-142.v1.
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The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms. These tetrapyrroles are synthesized via a common branched pathway that involves mainly nuclear encoded enzymes. One of the enzymes in the pathway is Mg chelatase (MgChel) which inserts Mg2+ into protoporphyrin IX (PPIX, proto) to form Magnesium-protoporphyrin IX (MgPPIX, Mgproto), the first biosynthetic intermediate in the Chl branch. The GUN4 (genomes uncoupled 4) protein is not essential for the MgChel activity but has been shown to significantly stimulate its activity. We have isolated a light sensitive mutant, 6F14, by random DNA insertional mutagenesis. 6F14 cannot tolerate light intensities higher than 90-100 μmol photons m-2 s-1. It shows a light intensity dependent progressive photo-bleaching. 6F14 is incapable of photo-autotrophic growth under light intensity higher than 100 μmol photons m-2 s-1. PCR based analyses show that in 6F14 the insertion of the plasmid outside the GUN4 locus has resulted in a genetic rearrangement of the GUN4 gene and possible deletions in the genomic region flanking the GUN4 gene. Our gun4 mutant has a Chl content very similar to that in the wild type in the dark and is very sensitive to fluctuations in the light intensity in the environment unlike the earlier identified Chlamydomonas gun4 mutant. Complementation with a functional copy of the GUN4 gene restored light tolerance, Chl biosynthesis and photo-autotrophic growth under high light intensities in 6F14. 6F14 is the second gun4 mutant to be identified in C. reinhardtii. Additionally, we show that our two gun4 complements over-express the GUN4 protein and show a higher Chl content per cell compared to that in the wild type strain.
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Naz, Arshi, Tehmina nafees sonia Khan, Noman A. Malik, Shahla Tariq, Nazish Saqlain e Tahir Shamsi. "Characterization of Phenotypic Expression of Inherited Fibrinogen Coagulopathy in Pakistani Index Patients". Blood 126, n.º 23 (3 de dezembro de 2015): 4667. http://dx.doi.org/10.1182/blood.v126.23.4667.4667.
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Abstract Background: Congenital afibrinogenemia is inherited as an autosomal recessive trait and consanguinity is common among affected families. Phenotypic expression of this particular factor deficiency is still not unanimously established in research literature globally as the disease manifests with variability in symptoms which may ranges from minimal bleeding to catastrophic hemorrhage. Aim: To characterize the clinical manifestations of patients to set a standard parameter of bleeding severity in our local population. Materials and Methods: This descriptive and cross sectional study was conducted at NIBD Karachi in collaboration with Chugtai's Lab and CHL Lahore in conformance with the Helsinki declaration. Consent was signed from all participants. Inclusion criteria for index patients specifically encompass the diagnosed cases of congenital afibrinogenemia excluding all acquired causes of this condition. Initially all the samples were processed at collection centers and platelet poor plasma and serum was separated and collected in labeled aliquots. Samples were transported to NIBD Karachi by maintaining cold chain. First line investigations including prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen levels by clauss method were performed to reconfirm the results. Grading of every individual's signs and symptoms depends upon severity of the disease and define here as per bleeding score [Tossetto et al] Results: Total 18 patients were evaluated with mean age group10±2 yrs and 11 were males. Two patients were sibling. PT was >120s, APTT >180s and fibrinogen levels were (<0.2g/l).The most common symptom is umbilical bleeding (95%) followed by circumcision hemorrhage (90%) in males, cutaneous manifestations (85%) and epistaxis (68%). Grading of bleeding was done by WHO bleeding scale criteria and very well correlated with bleeding score and haemorrhagic manifestations exhibiting by patients. Severe bleeding patients were shown to have high bleeding scores along with II and III grades of bleeding . Conclusion:The clinical manifestations of congenital afibrinogenemia in our local population are more or less same as reported in global literature. Due to the low prevalence rate of RBDs and the variability of bleeding manifestations are not well characterized clinically so far. Few exceptions do exists as we didn't find most of the rare complications in our set of patients. Disclosures No relevant conflicts of interest to declare.
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Cisternas-Novoa, Carolina, Frédéric A. C. Le Moigne e Anja Engel. "Composition and vertical flux of particulate organic matter to the oxygen minimum zone of the central Baltic Sea: impact of a sporadic North Sea inflow". Biogeosciences 16, n.º 4 (27 de fevereiro de 2019): 927–47. http://dx.doi.org/10.5194/bg-16-927-2019.
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Abstract. Particle sinking is a major form of transport for photosynthetically fixed carbon to below the euphotic zone via the biological carbon pump (BCP). Oxygen (O2) depletion may improve the efficiency of the BCP. However, the mechanisms by which O2 deficiency can enhance particulate organic matter (POM) vertical fluxes are not well understood. Here, we investigate the composition and vertical fluxes of POM in two deep basins of the Baltic Sea (GB: Gotland Basin and LD: Landsort Deep). The two basins showed different O2 regimes resulting from the intrusion of oxygen-rich water from the North Sea that ventilated the water column below 140 m in GB, but not in LD, during the time of sampling. In June 2015, we deployed surface-tethered drifting sediment traps in oxic surface waters (GB: 40 and 60 m; LD: 40 and 55 m), within the oxygen minimum zone (OMZ; GB: 110 m and LD: 110 and 180 m) and at recently oxygenated waters by the North Sea inflow in GB (180 m). The primary objective of this study was to test the hypothesis that the different O2 conditions in the water column of GB and LD affected the composition and vertical flux of sinking particles and caused differences in export efficiency between those two basins. The composition and vertical flux of sinking particles were different in GB and LD. In GB, particulate organic carbon (POC) flux was 18 % lower in the shallowest trap (40 m) than in the deepest sediment trap (at 180 m). Particulate nitrogen (PN) and Coomassie stainable particle (CSP) fluxes decreased with depth, while particulate organic phosphorus (POP), biogenic silicate (BSi), chlorophyll a (Chl a) and transparent exopolymeric particle (TEP) fluxes peaked within the core of the OMZ (110 m); this coincided with the presence of manganese oxide-like (MnOx-like) particles aggregated with organic matter. In LD, vertical fluxes of POC, PN and CSPs decreased by 28 %, 42 % and 56 %, respectively, from the surface to deep waters. POP, BSi and TEP fluxes did not decrease continuously with depth, but they were higher at 110 m. Although we observe a higher vertical flux of POP, BSi and TEPs coinciding with abundant MnOx-like particles at 110 m in both basins, the peak in the vertical flux of POM and MnOx-like particles was much higher in GB than in LD. Sinking particles were remarkably enriched in BSi, indicating that diatoms were preferentially included in sinking aggregates and/or there was an inclusion of lithogenic Si (scavenged into sinking particles) in our analysis. During this study, the POC transfer efficiency (POC flux at 180 m over 40 m) was higher in GB (115 %) than in LD (69 %), suggesting that under anoxic conditions a smaller portion of the POC exported below the euphotic zone was transferred to 180 m than under reoxygenated conditions present in GB. In addition, the vertical fluxes of MnOx-like particles were 2 orders of magnitude higher in GB than LD. Our results suggest that POM aggregates with MnOx-like particles formed after the inflow of oxygen-rich water into GB, and the formation of those MnOx–OM-rich particles may alter the composition and vertical flux of POM, potentially contributing to a higher transfer efficiency of POC in GB. This idea is consistent with observations of fresher and less degraded organic matter in deep waters of GB than LD.
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Pánisová, Elena, Anna Lünemann, Simone Bürgler, Monika Kotur, Julien Lazarovici, Alina Danu, Meike Kaulfuss et al. "Reduced frequency of cytotoxic CD56dim CD16+ NK cells leads to impaired antibody-dependent degranulation in EBV-positive classical Hodgkin lymphoma". Cancer Immunology, Immunotherapy, 15 de maio de 2021. http://dx.doi.org/10.1007/s00262-021-02956-x.
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AbstractAround 30–50% of classical Hodgkin lymphoma (cHL) cases in immunocompetent individuals from industrialized countries are associated with the B-lymphotropic Epstein-Barr virus (EBV). Although natural killer (NK) cells exhibit anti-viral and anti-tumoral functions, virtually nothing is known about quantitative and qualitative differences in NK cells in patients with EBV+ cHL vs. EBV- cHL. Here, we prospectively investigated 36 cHL patients without known immune suppression or overt immunodeficiency at diagnosis. All 10 EBV+ cHL patients and 25 out 26 EBV- cHL were seropositive for EBV antibodies, and EBV+ cHL patients presented with higher plasma EBV DNA levels compared to EBV- cHL patients. We show that the CD56dim CD16+ NK cell subset was decreased in frequency in EBV+ cHL patients compared to EBV- cHL patients. This quantitative deficiency translates into an impaired CD56dim NK cell mediated degranulation toward rituximab-coated HLA class 1 negative lymphoblastoid cells in EBV+ compared to EBV- cHL patients. We finally observed a trend to a decrease in the rituximab-associated degranulation and ADCC of in vitro expanded NK cells of EBV+ cHL compared to healthy controls. Our findings may impact on the design of adjunctive treatment targeting antibody-dependent cellular cytotoxicity in EBV+ cHL.
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Nie, Libing, Yushan Zheng, Liting Zhang, Ying Wu, Shidong Zhu, Jinfeng Hou, Guohu Chen, Xiaoyan Tang, Chenggang Wang e Lingyun Yuan. "Characterization and transcriptomic analysis of a novel yellow-green leaf wucai (Brassica campestris L.) germplasm". BMC Genomics 22, n.º 1 (12 de abril de 2021). http://dx.doi.org/10.1186/s12864-021-07573-7.
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Abstract Background Leaf color mutants are the ideal materials to explore the pathways of chlorophyll (Chl) metabolism, chloroplast development, and photosynthesis system. In this study, a spontaneous yellow-green leaf wucai (Brassica campestris L.) mutant “WY16–13” was identified, which exhibited yellow-green leaf color during its entire growth period. However, current understanding of the molecular mechanism underlying Chl metabolism and chloroplast development of “WY16–13” is limited. Results Total Chl and carotenoid content in WY16–13 was reduced by 60.92 and 58.82%, respectively, as compared with its wild type parental line W16–13. Electron microscopic investigation revealed fewer chloroplasts per cell and looser stroma lamellae in WY16–13 than in W16–13. A comparative transcriptome profiling was performed using leaves from the yellow-green leaf type (WY16–13) and normal green-leaf type (W16–13). A total of 54.12 million (M) (WY16–13) and 56.17 M (W16–13) reads were generated. A total of 40,578 genes were identified from the mapped libraries. We identified 3882 differentially expressed genes (DEGs) in WY16–13 compared with W16–13 (i.e., 1603 upregulated genes and 2279 downregulated genes). According to the Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, these DEGs are involved in porphyrin and Chl metabolism [i.e., chlorophyllase (CLH), heme oxygenase (HO), chlorophyll (ide) b reductase (NYC), and protochlorophyllide oxidoreductase (POR) genes], carbohydrate metabolism, photosynthesis, and carbon fixation in photosynthetic organisms. Moreover, deficiency in Chl biosynthetic intermediates in WY16–13 revealed that the formation of the yellow-green phenotype was related to the disorder of heme metabolism. Conclusions Our results provide valuable insights into Chl deficiency in the yellow-green leaf mutant and a bioinformatics resource for further functional identification of key allelic genes responsible for differences in Chl content.
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Jia, Anqi, Yanli Zheng, Hui Chen e Qiang Wang. "Regulation and Functional Complexity of the Chlorophyll-Binding Protein IsiA". Frontiers in Microbiology 12 (17 de novembro de 2021). http://dx.doi.org/10.3389/fmicb.2021.774107.
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As the oldest known lineage of oxygen-releasing photosynthetic organisms, cyanobacteria play the key roles in helping shaping the ecology of Earth. Iron is an ideal transition metal for redox reactions in biological systems. Cyanobacteria frequently encounter iron deficiency due to the environmental oxidation of ferrous ions to ferric ions, which are highly insoluble at physiological pH. A series of responses, including architectural changes to the photosynthetic membranes, allow cyanobacteria to withstand this condition and maintain photosynthesis. Iron-stress-induced protein A (IsiA) is homologous to the cyanobacterial chlorophyll (Chl)-binding protein, photosystem II core antenna protein CP43. IsiA is the major Chl-containing protein in iron-starved cyanobacteria, binding up to 50% of the Chl in these cells, and this Chl can be released from IsiA for the reconstruction of photosystems during the recovery from iron limitation. The pigment–protein complex (CPVI-4) encoded by isiA was identified and found to be expressed under iron-deficient conditions nearly 30years ago. However, its precise function is unknown, partially due to its complex regulation; isiA expression is induced by various types of stresses and abnormal physiological states besides iron deficiency. Furthermore, IsiA forms a range of complexes that perform different functions. In this article, we describe progress in understanding the regulation and functions of IsiA based on laboratory research using model cyanobacteria.
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Karalewitz, Andrew P. A., e Samuel I. Miller. "Multidrug-ResistantAcinetobacter baumanniiChloramphenicol Resistance Requires an Inner Membrane Permease". Antimicrobial Agents and Chemotherapy 62, n.º 8 (11 de junho de 2018). http://dx.doi.org/10.1128/aac.00513-18.
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ABSTRACTAcinetobacter baumanniiis a Gram-negative organism that is a cause of hospital-acquired multidrug-resistant (MDR) infections.A. baumanniihas a unique cell surface compared to those of many other Gram-negative pathogens in that it can live without lipopolysaccharide (LPS) and it has a high content of cardiolipin in the outer membrane. Therefore, to better understand the cell envelope and mechanisms of MDRA. baumannii, we screened a transposon library for mutants with defective permeability barrier function, defined as a deficiency in the ability to exclude the phosphatase chromogenic substrate 5-bromo-4-chloro-3-indolylphosphate (XP). We identified multiple mutants with mutations in the ABUW_0982 gene, predicted to encode a permease broadly present inA. baumanniiisolates with increased susceptibility to the ribosome-targeting antibiotic chloramphenicol (CHL). Moreover, compared to other known CHL resistance genes, such as chloramphenicol acyltransferase genes, we found that ABUW_0982 is the primary determinant of intrinsic CHL resistance inA. baumanniistrain 5075 (Ab5075), an important isolate responsible for severe MDR infections in humans. Finally, studies measuring the efflux of chloramphenicol and expression of ABUW_0982 in CHL-susceptibleEscherichia colisupport the conclusion that ABUW_0982 encodes a single-component efflux protein with specificity for small, hydrophobic molecules, including CHL.
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Yang, Ying, Qiong Li, Yanan Xiao, Yulu Liu, Kangning Sun, Bo Li e Qingyin Zheng. "Auditory Discrimination Elicited by Nonspeech and Speech Stimuli in Children With Congenital Hearing Loss". Journal of Speech, Language, and Hearing Research, 12 de setembro de 2022, 1–15. http://dx.doi.org/10.1044/2022_jslhr-22-00008.
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Purpose: Congenital deafness not only delays auditory development but also hampers the ability to perceive nonspeech and speech signals. This study aimed to use auditory event-related potentials to explore the mismatch negativity (MMN), P3a, negative wave (Nc), and late discriminative negativity (LDN) components in children with and without hearing loss. Method: Nineteen children with normal hearing (CNH) and 17 children with hearing loss (CHL) participated in this study. Two sets of pure tones (1 kHz vs. 1.1 kHz) and lexical tones (/ba2/ vs. /ba4/) were used to examine the auditory discrimination process. Results: MMN could be elicited by the pure tone and the lexical tone in both groups. The MMN latency elicited by nonspeech and speech was later in CHL than in CNH. Additionally, the MMN latency induced by speech occurred later in the left than in the right hemisphere in CNH, and the MMN amplitude elicited by speech in CHL produced a discriminative deficiency compared with that in CNH. Although the P3a latency and amplitude elicited by nonspeech in CHL and CNH were not significantly different, the Nc amplitude elicited by speech performed much lower in CHL than in CNH. Furthermore, the LDN latency elicited by nonspeech was later in CHL than in CNH, and the LDN amplitude induced by speech showed higher dominance in the right hemisphere in both CNH and CHL. Conclusion: By incorporating nonspeech and speech auditory conditions, we propose using MMN, Nc, and LDN as potential indices to investigate auditory perception, memory, and discrimination.
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Lin, Zheng-He, Chang-Song Chen, Shui-Qing Zhao, Yuan Liu, Qiu-Sheng Zhong, Qi-Chun Ruan, Zhi-Hui Chen et al. "Molecular and physiological mechanisms of tea (Camellia sinensis (L.) O. Kuntze) leaf and root in response to nitrogen deficiency". BMC Genomics 24, n.º 1 (17 de janeiro de 2023). http://dx.doi.org/10.1186/s12864-023-09112-y.
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Abstract Background As an economically important crop, tea is strongly nitrogen (N)-dependent. However, the physiological and molecular mechanisms underlying the response of N deficiency in tea are not fully understood. Tea cultivar “Chunlv2” [Camellia sinensis (L.) O. Kuntze] were cultured with a nutrient solution with 0 mM [N-deficiency] or 3 mM (Control) NH4NO3 in 6 L pottery pots containing clean river sands. Results N deficiency significantly decreased N content, dry weight, chlorophyll (Chl) content, L-theanine and the activities of N metabolism-related enzymes, but increased the content of total flavonoids and polyphenols in tea leaves. N deficiency delayed the sprouting time of tea buds. By using the RNA-seq technique and subsequent bioinformatics analysis, 3050 up-regulated and 2688 down-regulated differentially expressed genes (DEGs) were isolated in tea leaves in response to N deficiency. However, only 1025 genes were up-regulated and 744 down-regulated in roots. Gene ontology (GO) term enrichment analysis showed that 205 DEGs in tea leaves were enriched in seven GO terms and 152 DEGs in tea roots were enriched in 11 GO items based on P < 0.05. In tea leaves, most GO-enriched DEGs were involved in chlorophyll a/b binding activities, photosynthetic performance, and transport activities. But most of the DEGs in tea roots were involved in the metabolism of carbohydrates and plant hormones with regard to the GO terms of biological processes. N deficiency significantly increased the expression level of phosphate transporter genes, which indicated that N deficiency might impair phosphorus metabolism in tea leaves. Furthermore, some DEGs, such as probable anion transporter 3 and high-affinity nitrate transporter 2.7, might be of great potential in improving the tolerance of N deficiency in tea plants and further study could work on this area in the future. Conclusions Our results indicated N deficiency inhibited the growth of tea plant, which might be due to altered N metabolism and expression levels of DEGs involved in the photosynthetic performance, transport activity and oxidation–reduction processes.
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Zakari, Shamsu Ado, Syed Hassan Raza Zaidi, Mustapha Sunusi e Kabiru Dawaki Dauda. "Nitrogen deficiency regulates premature senescence by modulating flag leaf function, ROS homeostasis, and intercellular sugar concentration in rice during grain filling". Journal of Genetic Engineering and Biotechnology 19, n.º 1 (23 de novembro de 2021). http://dx.doi.org/10.1186/s43141-021-00275-3.
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Abstract Background Leaf senescence occurs in an age-dependent manner, but the rate and timing of leaf senescence may be influenced by various biotic and abiotic factors. In the course of stress, the function, composition, and different components of photosynthetic apparatus occur to be synthesized homogeneously or degraded paradoxically due to different senescence-related processes. Nitrogen (N) deficiency is one of the critical environmental factors that induce leaf senescence, and its incidence may curtail leaf photosynthetic function and markedly alter the genetic information of plants that might result in low grain yield. However, the physiological and genetic mechanism underlying N deficiency regulates premature senescence, and flag leaf function, ROS homeostasis, and intercellular sugar concentration in rice during grain filling are not well understood. In this paper, Zhehui7954 an excellent indica restorer line (wildtype) and its corresponding mutant (psf) with the premature senescence of flag leaves were used to study the effect of different N supplies in the alteration of physiological and biochemical components of flag leaf organ and its functions during grain filling. Results The results showed that the psf mutant appeared to be more susceptible to the varying N supply levels than WT. For instance, the psf mutant showed considerably lower Pn, Chl a, Chl b, and Car contents than its WT. N deficiency (LN) decreased leaves photosynthetic activities, N metabolites, but significantly burst O2•−, H2O2, and relative conductivity (R1/R2) concentrations, which was consistent with the expression levels of senescence-associated genes. Sucrose, glucose, and C/N ratio concentrations increased with a decrease in N level, which was closely associated with N and non-structural carbohydrate translocation rates. Increases in POD activity were positively linked with the senescence-related enhancement of ROS generation under LN conditions, whereas, SOD, CAT, and APX activities showed opposite trends. High N (HN) supply significantly inhibits the transcripts of carbohydrate biosynthesis genes, while N assimilation gene transcripts gradually increased along with leaf senescence. The psf mutant had a relatively higher grain yield under HN treatment than LN, while WT had a higher grain yield under MN than HN and LN. Conclusions This work revealed that the C/N ratio and ROS undergo a gradual increase driven by interlinking positive feedback, providing a physiological framework connecting the participation of sugars and N assimilation in the regulation of leaf senescence. These results could be useful for achieving a higher yield of rice production by appropriate N supply and plant senescence regulation.
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Li, Chunmei, Xin Liu, Jihong Pan, Jia Guo, Qian Wang, Congping Chen, Na Li et al. "A lil3 chlp double mutant with exclusive accumulation of geranylgeranyl chlorophyll displays a lethal phenotype in rice". BMC Plant Biology 19, n.º 1 (29 de outubro de 2019). http://dx.doi.org/10.1186/s12870-019-2028-z.
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Abstract Background Phytyl residues are the common side chains of chlorophyll (Chl) and tocopherols. Geranylgeranyl reductase (GGR), which is encoded by CHLP gene, is responsible for phytyl biosynthesis. The light-harvesting like protein LIL3 was suggested to be required for stability of GGR and protochlorophyllide oxidoreductase in Arabidopsis. Results In this study, we isolated a yellow-green leaf mutant, 637ys, in rice (Oryza sativa). The mutant accumulated majority of Chls with unsaturated geranylgeraniol side chains and displayed a yellow-green leaf phenotype through the whole growth period. The development of chloroplasts was suppressed, and the major agronomic traits, especially No. of productive panicles per plant and of spikelets per panicle, dramatically decreased in 637ys. Besides, the mutant exhibited to be sensitive to light intensity and deficiency of tocopherols without obvious alteration in tocotrienols in leaves and grains. Map-based cloning and complementation experiment demonstrated that a point mutation on the OsLIL3 gene accounted for the mutant phenotype of 637ys. OsLIL3 is mainly expressed in green tissues, and its encoded protein is targeted to the chloroplast. Furthermore, the 637ys 502ys (lil3 chlp) double mutant exclusively accumulated geranylgeranyl Chl and exhibited lethality at the three-leaf stage. Conclusions We identified the OsLIL3 gene through a map-based cloning approach. Meanwhile, we demonstrated that OsLIL3 is of extreme importance to the function of OsGGR, and that the complete replacement of phytyl side chain of chlorophyll by geranylgeranyl chain could be fatal to plant survival in rice.
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El Moukhtari, Ahmed, Nadia Lamsaadi, Omar Farssi, Aziz Oubenali, Ismail El Bzar, Qamar Lahlimi Alami, Zine El Abidine Triqui, Mohamed Lazali e Mohamed Farissi. "Silicon- and Phosphate-Solubilizing Pseudomonas alkylphenolica PF9 Alleviate Low Phosphorus Availability Stress in Alfalfa (Medicago sativa L.)". Frontiers in Agronomy 4 (2 de março de 2022). http://dx.doi.org/10.3389/fagro.2022.823396.
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Low phosphorus (P) availability is a major limiting factor facing current agriculture in several agricultural areas. Many P fertilizers are applied to enhance P availability; however, the major part is likely to lose due to various processes related to P cycle. Silicon (Si) treatment and P-solubilizing bacteria inoculation have been emerged as a promising way to improve plant P nutrition. This study aimed to investigate the synergistic effects of Si treatment and Pseudomonas alkylphenolica PF9 strain inoculation on plant growth, P nutrition, acid phosphatase (APase) activity, oxidative stress markers, and antioxidant metabolism in the Moroccan alfalfa population Oued Lmalah (OL) under low P availability. Results revealed a significant reduction in dry biomass, plant height, leaf number, and area under low P conditions. P deficiency also altered P nutrition and chlorophyll (Chl) content. However, P-deficient alfalfa plants treated with Si or inoculated with PF9 strain displayed higher plant growth, Chl content, and remarkably the effect was much higher when Si was applied together with PF9 strain. Moreover, the simultaneous application of Si and PF9 strain to the P-deficient alfalfa plants improved APase activity and as a result, P contents in both the shoots and roots. Results also showed that the application of both the Si and PF9 counteracted the low P availability stress-induced oxidative damage by lowering the accumulation of reactive oxygen species (ROS), electrolyte leakage, and lipid peroxidation. This seems to be related to the ability of both the Si and PF9 strain to modulate both the enzymatic and non-enzymatic antioxidant molecules including superoxide dismutase activity, total polyphenols, flavonoids, and proline contents. Our findings suggest that the combined application of Si and P. alkylphenolica PF9 strain could be a promising way for improving growth of alfalfa under low-P availability.
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Li, Jian, Muhammad Atif Muneer, Aihua Sun, Qinyu Guo, Yuemin Wang, Zhenrui Huang, Wenqing Li e Chaoyuan Zheng. "Magnesium application improves the morphology, nutrients uptake, photosynthetic traits, and quality of tobacco (Nicotiana tabacum L.) under cold stress". Frontiers in Plant Science 14 (6 de fevereiro de 2023). http://dx.doi.org/10.3389/fpls.2023.1078128.
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Cold stress is one of the major constraints limiting the productivity of many important crops, including tobacco (Nicotiana tabacum L.) production and quality worldwide. However, the role of magnesium (Mg) nutrition in plants has been frequently overlooked, especially under cold stress, and Mg deficiency adversely affects plant growth and development. Here, we evaluated the influence of Mg under cold stress on tobacco morphology, nutrient uptake, photosynthetic and quality attributes. The tobacco plants were grown under different levels of cold stress, i.e., 8°C, 12°C, 16°C, including with a controlled temperature of 25°C, and evaluated their effects with Mg (+Mg) and without Mg (–Mg) application. Cold stress resulted in reduced plant growth. However, the +Mg alleviated the cold stress and significantly increased the plant biomass on an average of 17.8% for shoot fresh weight, 20.9% for root fresh weight, 15.7% for shoot dry weight, and 15.5% for root dry weight. Similarly, the nutrients uptake also increased on average for shoot-N (28.7%), root-N (22.4%), shoot-P (46.9%), root-P (7.2%), shoot-K (5.4%), root-K (28.9%), shoot-Mg (191.4%), root-Mg (187.2%) under cold stress with +Mg compared to –Mg. Mg application significantly boosted the photosynthetic activity (Pn 24.6%) and increased the chlorophyll contents (Chl-a (18.8%), Chl-b (25%), carotenoids (22.2%)) in the leaves under cold stress in comparison with –Mg treatment. Meanwhile, Mg application also improved the quality of tobacco, including starch and sucrose contents, on an average of 18.3% and 20.8%, respectively, compared to –Mg. The principal component analysis revealed that tobacco performance was optimum under +Mg treatment at 16°C. This study confirms that Mg application alleviates cold stress and substantially improves tobacco morphological indices, nutrient absorption, photosynthetic traits, and quality attributes. In short, the current findings suggest that Mg application may alleviate cold stress and improve tobacco growth and quality.
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Wang, Chunli, Jianli Yang, Wenjie Chen, Xiaoguang Zhao e Zhouli Wang. "Contribution of the leaf and silique photosynthesis to the seeds yield and quality of oilseed rape (Brassica napus L.) in reproductive stage". Scientific Reports 13, n.º 1 (23 de março de 2023). http://dx.doi.org/10.1038/s41598-023-31872-6.
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AbstractInfluences of photosynthesis of leaf and silique on seeds yield and quality of oilseed rape (Brassica napus L.) were explored in this study. A field comparing experiment with several rapeseed varieties was conducted and the results showed, that the leaf area index (LAI), silique surface area index (SAI), siliques number per plant, and biological yield were statistically classified as the first principal factors which greatly influenced seeds yield, the leaf net photosynthetic rate (Pn) and silique Pn were the second principal factors; the stomatal conductance (Gs) and chlorophyll a (Chl a) content were the first principal factors which influenced leaf Pn and silique Pn. A shading experiment was conducted and the results showed that, under treatments of the ZH1, ZH2, and ZH3 (shading rapeseed plants during flowering stage, during time from initial flowering until seeds ripening, and during time from flowering ending until seeds ripening, respectively), respectively the seeds yield per plant was reduced by 34.6%, 84.3%, and 86.1%, the seed protein content was significantly increased. The treatment ZH1 Not, but the ZH2 and ZH3 caused significant decrease in both seed oil content and oleic acid (C18:1) content in seed oil, and the contents of linoleic acid (C18:2), linolenic acid (C18:3) in oil were significantly increased, gene expression of the ACCase (Acetyl-CoA carboxylase), FAD2 (fatty acid desaturase), and FAD3 (ω-3 fatty acid dehydrogenase) in green seeds was restrained/changed. Thus the LAI, SAI, siliques number per plant, biological yield per plant, leaf Pn, silique Pn, and the Gs, Chl a content of leaf and silique formed an indexes system to be used in screening rapeseed variety with higher light efficiency and seeds yield; the silique photosynthesis inhibition and the photosynthates deficiency in rapeseed plant after flowering stage predominately influenced seeds yield and quality.
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Schansker, Gert, Miho Ohnishi, Riu Furutani e Chikahiro Miyake. "Identification of Twelve Different Mineral Deficiencies in Hydroponically Grown Sunflower Plants on the Basis of Short Measurements of the Fluorescence and P700 Oxidation/Reduction Kinetics". Frontiers in Plant Science 13 (2 de junho de 2022). http://dx.doi.org/10.3389/fpls.2022.894607.
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The photosynthetic electron transport chain is mineral rich. Specific mineral deficiencies can modify the electron transport chain specifically. Here, it is shown that on the basis of 2 short Chl fluorescence and P700+ measurements (approx. 1 s each), it is possible to discriminate between 10 out of 12 different mineral deficiencies: B, Ca, Cu, Fe, K, Mg, Mn, Mo, N, P, S, and Zn. B- and Mo-deficient plants require somewhat longer measurements to detect the feedback inhibition they induce. Eight out of twelve deficiencies mainly affect PS I and NIR measurements are, therefore, very important for this analysis. In Cu- and P-deficient plants, electron flow from the plastoquinone pool to PS I, is affected. In the case of Cu-deficiency due to the loss of plastocyanin and in the case of P-deficiency probably due to a fast and strong generation of Photosynthetic Control. For several Ca-, K-, and Zn-deficient plant species, higher levels of reactive oxygen species have been measured in the literature. Here, it is shown that this not only leads to a loss of Pm (maximum P700 redox change) reflecting a lower PS I content, but also to much faster P700+ re-reduction kinetics during the I2-P (~30–200 ms) fluorescence rise phase. The different mineral deficiencies affect the relation between the I2-P and P700+ kinetics in different ways and this is used to discuss the nature of the relationship between these two parameters.
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Painting, Suzanne J., Paul Nelson, Andy J. Smith, Carolyn A. Graves, Andy Powell, Philippe Bersuder, Samuel Bullen e Simeon Archer-Rand. "Marine Water Quality at Diego Garcia: A Preliminary Study of Pollution Levels in Coastal and Lagoon Waters". Frontiers in Marine Science 8 (21 de julho de 2021). http://dx.doi.org/10.3389/fmars.2021.671319.
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Diego Garcia is the largest atoll within the Chagos Archipelago in the Indian Ocean. Since the 1960s it has been a military base, populated only by military and support personnel. Infrastructure includes sewage treatment works, a waste disposal facility and an airbase. Lagoon use includes boating and large vessel anchorage. Current pollution levels by inorganic nutrients and other contaminants are unknown. A field study was undertaken in March 2019 to obtain baseline information on key environmental parameters and pollutants for assessing the state of marine water quality. Outside the atoll, three stations were sampled where human impacts were likely to be lowest (two off the north coast, considered as ‘near-pristine’; one on the east coast); one station was sampled in the lagoon mouth; 10 stations were sampled downstream from two sewage outflows. Inside the lagoon, 10 stations were sampled at near-shore sites likely to be directly impacted by activities such as boating and waste management; six stations were sampled in the central or eastern lagoon. In situ sensors were used to estimate temperature, salinity, chlorophyll (as fluorescence) and dissolved oxygen. Discrete water samples were analyzed for nutrients, chemical contaminants, heavy metals and fecal indicator bacteria. Sea surface temperatures were highest (29.5–35 °C) inside the lagoon; salinities were generally higher (> 34.1) outside the lagoon (vs 33.8–34.1 inside). Surface nutrient concentrations at near-pristine stations were undetectable for nitrate and phosphate and averaged 1.39 μM for dissolved inorganic nitrogen (DIN) and 1.73 μM for silicate. Concentrations were higher at most other stations (maximum 5.7 μM DIN, 0.38 μM phosphate, and 9.93 μM silicate), with ammonium contributing most to DIN. In the lagoon, chlorophyll concentrations were relatively low (0.3 – 0.6 μg chl l–1) near the surface and higher (max 0.9 μg chl l–1) at depth. Results suggested low levels of pollution overall. However, levels of nutrients, oxygen deficiency, chemical contaminants (e.g., solvents and DEET) and heavy metals (cadmium, nickel, zinc and copper) at some sites inside the lagoon are a concern due to slow flushing rates and will be used to inform future monitoring and assessment of environmental health at Diego Garcia.
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Loudari, Aicha, Asmae Mayane, Youssef Zeroual, Gilles Colinet e Abdallah Oukarroum. "Photosynthetic performance and nutrient uptake under salt stress: Differential responses of wheat plants to contrasting phosphorus forms and rates". Frontiers in Plant Science 13 (10 de novembro de 2022). http://dx.doi.org/10.3389/fpls.2022.1038672.
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Salt stress impacts phosphorus (P) bioavailability, mobility, and its uptake by plants. Since P is involved in many key processes in plants, salinity and P deficiency could significantly cause serious damage to photosynthesis, the most essential physiological process for the growth and development of all green plants. Different approaches have been proposed and adopted to minimize the harmful effects of their combined effect. Optimising phosphorus nutrition seems to bring positive results to improve photosynthetic efficiency and nutrient uptake. The present work posed the question if soluble fertilizers allow wheat plants to counter the adverse effect of salt stress. A pot experiment was performed using a Moroccan cultivar of durum wheat: Karim. This study focused on different growth and physiological responses of wheat plants grown under the combined effect of salinity and P-availability. Two Orthophosphates (Ortho-A & Ortho-B) and one polyphosphate (Poly-B) were applied at different P levels (0, 30 and 45 ppm). Plant growth was analysed on some physiological parameters (stomatal conductance (SC), chlorophyll content index (CCI), chlorophyll a fluorescence, shoot and root biomass, and mineral uptake). Fertilized wheat plants showed a significant increase in photosynthetic performance and nutrient uptake. Compared to salt-stressed and unfertilized plants (C+), CCI increased by 93%, 81% and 71% at 30 ppm of P in plants fertilized by Poly-B, Ortho-B and Ortho-A, respectively. The highest significant SC was obtained at 45 ppm using Ortho-B fertilizer with an increase of 232% followed by 217% and 157% for both Poly-B and Ortho-A, respectively. The Photosynthetic performance index (PItot) was also increased by 128.5%, 90.2% and 38.8% for Ortho-B, Ortho-A and Poly B, respectively. In addition, Poly-B showed a significant enhancement in roots and shoots biomass (49.4% and 156.8%, respectively) compared to C+. Fertilized and salt-stressed plants absorbed more phosphorus. The P content significantly increased mainly at 45 ppm of P. Positive correlations were found between phosphorus uptake, biomass, and photosynthetic yield. The increased photochemical activity could be due to a significant enhancement in light energy absorbed by the enhanced Chl antenna. The positive effect of adequate P fertilization under salt stress was therefore evident in durum wheat plants.
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Sun, Xiying, Zhaohui Chen, Chao Zhang e Siyu Meng. "Latitudinal-dependent emergence of phytoplankton seasonal blooms in the Kuroshio Extension". Frontiers in Marine Science 10 (25 de janeiro de 2023). http://dx.doi.org/10.3389/fmars.2023.1027710.
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The bimodal and unimodal seasonal cycles of surface Chlorophyll-a (Chl-a) concentration (SCC) are ubiquitous in the mid-latitude oceans. The nutrient and light are regarded as two key factors affecting such seasonal differences. However, our quantitative knowledge of distinguishing these two factors is still inadequate in mid-latitude regions where they limit primary productivity simultaneously. It hinders the full understanding of the underlying mechanisms of seasonal blooms. In this study, the bimodal and unimodal variations of SCC in the Kuroshio Extension (KE) region have been investigated, with a special focus on the emergence latitudes of the secondary peak, i.e., the phytoplankton fall bloom. Based on satellite observations, we have found that the SCC bloom emerges in spring and fall in the northern region, and that spring (fall) bloom starts later (earlier) as the latitude gets higher. In the southern part of KE, by contrast, the SCC tends to peak in late winter or early spring with its bloom time delaying gradually with increasing latitude. A regression model regarding the role of the nutrient and light has been proposed to reconstruct the seasonal variations of the observed SCC, and the relative contributions of the two factors have been assessed quantitatively. It is shown that the regression model has reasonably captured the seasonal variations of SCC in terms of the bimodal/unimodal feature as well as the time of occurrence. Specifically, we have found the boundary between bimodality and unimodality areas moves northward as KE flows eastward, which corresponds to the equivalent contribution of the nutrient and light to the SCC variation and the eastward-decreasing nutrient at the same latitude. Moreover, we have used the model to explore the lag effect of light on regulating the seasonal cycle of SCC, which is associated with the light-heating process, the resultant ocean vertical stratification and the nutrient deficiency, the time interval between the growth rate and SCC, as well as light attenuation within the mixed layer. In the context of global warming, our study has provided insights into the switch pattern between bimodality and unimodality of SCC in mid-latitude oceans.