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MAIN CONCLUSION: NH4+ is necessary for full functionality of reduction-based Fe deficiency response in plants. Nitrogen (N) is present in soil mainly as nitrate (NO3-) or ammonium (NH4+). Although the significance of a balanced supply of NO3- and NH4+ for optimal growth has been generally accepted, its importance for iron (Fe) acquisition has not been sufficiently investigated. In this work, hydroponically grown cucumber (Cucumis sativus L. cv. Maximus) plants were supplied with NO3- as the sole N source under -Fe conditions. Upon the appearance of chlorosis, plants were supplemented with 2 mM NH4Cl by roots or leaves. The NH4+ treatment increased leaf SPAD and the HCl-extractable Fe concentration while decreased root apoplastic Fe. A concomitant increase in the root concentration of nitric oxide and activity of FRO and its abolishment by an ethylene action inhibitor, indicated activation of the components of Strategy I in NH4+-treated plants. Ammonium-pretreated plants showed higher utilization capacity of sparingly soluble Fe(OH)3 and higher root release of H+, phenolics, and organic acids. The expression of the master regulator of Fe deficiency response (FIT) and its downstream genes (AHA1, FRO2, and IRT1) along with EIN3 and STOP1 was increased by NH4+ application. Temporal analyses and the employment of a split-root system enabled us to suggest that a permanent presence of NH4+ at concentrations lower than 2 mM is adequate to produce an unknown signal and causes a sustained upregulation of Fe deficiency-related genes, thus augmenting the Fe-acquisition machinery. The results indicate that NH4+ appears to be a widespread and previously underappreciated component of plant reduction-based Fe deficiency response.
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Compostos de Amônio , Cucumis sativus , Regulação da Expressão Gênica de Plantas , Ferro , Raízes de Plantas , Cucumis sativus/genética , Cucumis sativus/metabolismo , Cucumis sativus/fisiologia , Compostos de Amônio/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Ferro/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Transdução de Sinais , Deficiências de Ferro , Folhas de Planta/metabolismo , Folhas de Planta/genética , Folhas de Planta/efeitos dos fármacos , Nitratos/metabolismo , Nitratos/farmacologia , Óxido Nítrico/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Nitrogênio/metabolismoRESUMO
Numerous studies have shown the beneficial effects of silicon (Si) for plant growth, particularly under stress conditions, and hence a detailed understanding of the mechanisms of its uptake, subsequent transport, and accumulation in different tissues is important. Here, we provide a thorough review of our current knowledge of how plants benefit from Si supplementation. The molecular mechanisms involved in Si transport are discussed and we highlight gaps in our knowledge, particularly with regards to xylem unloading and transport into heavily silicified cells. Silicification of tissues such as sclerenchyma, fibers, storage tissues, the epidermis, and vascular tissues are described. Silicon deposition in different cell types, tissues, and intercellular spaces that affect morphological and physiological properties associated with enhanced plant resilience under various biotic and abiotic stresses are addressed in detail. Most Si-derived benefits are the result of interference in physiological processes, modulation of stress responses, and biochemical interactions. A better understanding of the versatile roles of Si in plants requires more detailed knowledge of the specific mechanisms involved in its deposition in different tissues, at different developmental stages, and under different environmental conditions.
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Plantas , Silício , Transporte Biológico , Desenvolvimento Vegetal , Estresse FisiológicoRESUMO
Lignin is currently an underutilized part of biomass; thus, further research into lignin could benefit both scientific and commercial endeavors. The present study investigated the potential of kraft lignin as a support material for the removal of hydrogen sulfide (H2S) from gaseous streams, such as biogas. The removal of H2S was enabled by copper ions that were previously adsorbed on kraft lignin. Copper adsorption was based on two different strategies: either directly on lignin particles or by precipitating lignin from a solution in the presence of copper. The H2S concentration after the adsorption column was studied using proton-transfer-reaction mass spectrometry, while the mechanisms involved in the H2S adsorption were studied with X-ray photoelectron spectroscopy. It was determined that elemental sulfur was obtained during the H2S adsorption in the presence of kraft lignin and the differences relative to the adsorption on porous silica as a control are discussed. For kraft lignin, only a relatively low removal capacity of 2 mg of H2S per gram was identified, but certain possibilities to increase the removal capacity are discussed.
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Biocombustíveis/análise , Cobre/química , Sulfeto de Hidrogênio/análise , Sulfeto de Hidrogênio/isolamento & purificação , Lignina/química , Cobre/metabolismo , Concentração de Íons de Hidrogênio , Lignina/metabolismoRESUMO
BACKGROUND AND AIMS: Retranslocation of iron (Fe) from source tissues enhances plant tolerance to Fe deficiency. Previous work has shown that silicon (Si) can alleviate Fe deficiency by enhancing acquisition and root to shoot translocation of Fe. Here the role of Si in Fe mobilization in older leaves and the subsequent retranslocation of Fe to young leaves of cucumber (Cucumis sativus) plants growing under Fe-limiting conditions was investigated. METHODS: Iron ((57)Fe or naturally occurring isotopes) was measured in leaves at different positions on plants hydroponically growing with or without Si supply. In parallel, the concentration of the Fe chelator nicotianamine (NA) along with the expression of nicotianamine synthase (NAS) involved in its biosynthesis and the expression of yellow stripe-like (YSL) transcripts mediating Fe-NA transport were also determined. KEY RESULTS: In plants not receiving Si, approximately half of the total Fe content remained in the oldest leaf. In contrast, Si-treated plants showed an almost even Fe distribution among leaves with four different developmental stages, thus providing evidence of enhanced Fe remobilization from source leaves. This Si-stimulated Fe export was paralleled by an increased NA accumulation and expression of the YSL1 transporter for phloem loading/unloading of the Fe-NA complex. CONCLUSIONS: The results suggest that Si enhances remobilization of Fe from older to younger leaves by a more efficient NA-mediated Fe transport via the phloem. In addition, from this and previous work, a model is proposed of how Si acts to improve Fe homeostasis under Fe deficiency in cucumber.
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Alquil e Aril Transferases/metabolismo , Cucumis sativus/efeitos dos fármacos , Deficiências de Ferro , Silício/farmacologia , Alquil e Aril Transferases/genética , Ácido Azetidinocarboxílico/análogos & derivados , Ácido Azetidinocarboxílico/metabolismo , Transporte Biológico , Cucumis sativus/metabolismo , Homeostase , Hidroponia , Modelos Biológicos , Floema/efeitos dos fármacos , Floema/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
The supplementation of monosilicic acid [Si(OH)4] to the root growing medium is known to protect plants from toxic levels of iron (Fe), copper (Cu) and manganese (Mn), but also to mitigate deficiency of Fe and Mn. However, the physicochemical bases of these alleviating mechanisms are not fully understood. Here we applied low-T electron paramagnetic resonance (EPR) spectroscopy to examine the formation of complexes of Si(OH)4 with Mn(2+), Fe(3+), and Cu(2+) in water and in xylem sap of cucumber (Cucumis sativus L.) grown without or with supply of Si(OH)4. EPR, which is also useful in establishing the redox state of these metals, was combined with measurements of total concentrations of metals in xylem sap by inductive coupled plasma. Our results show that Si(OH)4 forms coordination bonds with all three metals. The strongest interactions of Si(OH)4 appear to be with Cu(2+) (1/1 stoichiometry) which might lead to Cu precipitation. In line with this in vitro findings, Si(OH)4 supply to cucumber resulted in dramatically lower concentration of this metal in the xylem sap. Further, it was demonstrated that Si(OH)4 supplementation causes pro-reductive changes that contribute to the maintenance of Fe and, in particular, Mn in the xylem sap in bioavailable 2+ form. Our results shed more light on the intertwined reactions between Si(OH)4 and transition metals in plant fluids (e.g. xylem sap).
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Cucumis sativus/química , Ácido Silícico/química , Elementos de Transição/química , Xilema/química , Sítios de Ligação , Cucumis sativus/crescimento & desenvolvimento , Espectroscopia de Ressonância de Spin Eletrônica , Oxirredução , Soluções , Água/químicaRESUMO
MAIN CONCLUSION: So far, considerable advances have been achieved in understanding the mechanisms of Si uptake and transport in vascular plants. This review presents a comprehensive update about this issue, but also provides the new insights into the role of Si against mineral stresses that occur in acid soils. Such information could be helpful to understand both the differential Si uptake ability as well as the benefits of this mineral element on plants grown under acidic conditions. Silicon (Si) has been widely recognized as a beneficial element for many plant species, especially under stress conditions. In the last few years, great efforts have been made to elucidate the mechanisms involved in uptake and transport of Si by vascular plants and recently, different Si transporters have been identified. Several researches indicate that Si can alleviate various mineral stresses in plants growing under acidic conditions, including aluminium (Al) and manganese (Mn) toxicities as well as phosphorus (P) deficiency all of which are highly detrimental to crop production. This review presents recent findings concerning the influence of uptake and transport of Si on mineral stress under acidic conditions because a knowledge of this interaction provides the basis for understanding the role of Si in mitigating mineral stress in acid soils. Currently, only four Si transporters have been identified and there is little information concerning the response of Si transporters under stress conditions. More investigations are therefore needed to establish whether there is a relationship between Si transporters and the benefits of Si to plants subjected to mineral stress. Evidence presented suggests that Si supply and its subsequent accumulation in plant tissues could be exploited as a strategy to improve crop productivity on acid soils.
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Ácidos/farmacologia , Minerais/metabolismo , Feixe Vascular de Plantas/metabolismo , Silício/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Transporte Biológico/efeitos dos fármacos , Feixe Vascular de Plantas/efeitos dos fármacosRESUMO
Vanadium speciation in the fungus Phycomyces blakesleeanus was examined by X-ray absorption near-edge structure (XANES) spectroscopy, enabling assessment of oxidation states and related molecular symmetries of this transition element in the fungus. The exposure of P. blakesleeanus to two physiologically important vanadium species (V(5+) and V(4+)) resulted in the accumulation of this metal in central compartments of 24 h old mycelia, most probably in vacuoles. Tetrahedral V(5+), octahedral V(4+), and proposed intracellular complexes of V(5+) were detected simultaneously after addition of a physiologically relevant concentration of V(5+) to the mycelium. A substantial fraction of the externally added V(4+) remained mostly in its original form. However, observable variations in the pre-edge-peak intensities in the XANES spectra indicated intracellular complexation and corresponding changes in the molecular coordination symmetry. Vanadate complexation was confirmed by (51)V NMR and Raman spectroscopy, and potential binding compounds including cell-wall constituents (chitosan and/or chitin), (poly)phosphates, DNA, and proteins are proposed. The evidenced vanadate complexation and reduction could also explain the resistance of P. blakesleeanus to high extracellular concentrations of vanadium.
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Phycomyces/fisiologia , Vanádio/química , Espectroscopia por Absorção de Raios X/métodos , Análise Espectral RamanRESUMO
Atrial fibrillation (AF) is the most common long-term arrhythmia in adults. Rhythm control in patients with AF involves efforts to restore and maintain sinus rhythm and is accomplished by medication, catheter ablation, or electrical cardioversion. Amiodarone represents one of the most commonly used antiarrhythmic medications. Prolonged use of amiodarone can lead to many side effects. One of the most severe side effects is drug-induced long QT syndrome (LQTS), which can cause malignant arrhythmias and sudden cardiac death. We presented a case of a 52-year-old male who was admitted to the Coronary Unit due to first diagnosed AF with a rapid ventricular response. After amiodarone infusion was administrated the patient lost consciousness and the monitor displayed torsades de pointes (TdP) ventricular tachycardia with rapid conversion to ventricular fibrillation (VF). Cardiac resuscitation with two direct current (DC) shocks was performed. The patient was stabilized, and restoration of sinus rhythm with significant QT prolongation on the ECG was noted. This is a rare case of short-term amiodarone administration causing LQTS, TdP, and VF. The findings or observations emphasize the significance of diligent ECG monitoring during amiodarone treatment.
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Silicon (Si) is a widely recognized beneficial element in plants. With the emergence of nanotechnology in agriculture, silicon nanoparticles (SiNPs) demonstrate promising applicability in sustainable agriculture. Particularly, the application of SiNPs has proven to be a high-efficiency and cost-effective strategy for protecting plant against various biotic and abiotic stresses such as insect pests, pathogen diseases, metal stress, drought stress, and salt stress. To date, rapid progress has been made in unveiling the multiple functions and related mechanisms of SiNPs in promoting the sustainability of agricultural production in the recent decade, while a comprehensive summary is still lacking. Here, the review provides an up-to-date overview of the synthesis, uptake and translocation, and application of SiNPs in alleviating stresses aiming for the reasonable usage of SiNPs in nano-enabled agriculture. The major points are listed as following: (1) SiNPs can be synthesized by using physical, chemical, and biological (green synthesis) approaches, while green synthesis using agricultural wastes as raw materials is more suitable for large-scale production and recycling agriculture. (2) The uptake and translocation of SiNPs in plants differs significantly from that of Si, which is determined by plant factors and the properties of SiNPs. (3) Under stressful conditions, SiNPs can regulate plant stress acclimation at morphological, physiological, and molecular levels as growth stimulator; as well as deliver pesticides and plant growth regulating chemicals as nanocarrier, thereby enhancing plant growth and yield. (4) Several key issues deserve further investigation including effective approaches of SiNPs synthesis and modification, molecular basis of SiNPs-induced plant stress resistance, and systematic effects of SiNPs on agricultural ecosystem.
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Serbia preserves a high number of local grape varieties, which have been cultivated across the country for centuries. Now, these ancient varieties are in the spotlight, and there is a global trend towards their recovery and characterization because they can revitalize regional, national and international grape and wine sectors. In addition, their genetic study can be useful to find new pedigree relationships to reveal how local varietal assortment evolved over time. Here, the genetic characterization of 138 grapevines from old Serbian vineyards revealed 59 different genetic profiles, 49 of which were identified as grapevine varieties whose origin in the country could be linked to some major Serbian historical periods. Most of the genetic profiles found in this work arranged in a complex pedigree network that integrates numerous grapevine varieties from diverse Balkan countries, agreeing with an intense exchange of plant material among Balkan regions for centuries. This analysis identified some varieties as important founders of Balkan genetic resources, like 'Alba Imputotato', 'Braghina Rosie', 'Coarna Alba', and 'Vulpea'. After deepening into their genealogy, these major direct founders might have ultimately derived from 'Visparola', an ancient variety of likely Balkan origin with a major founding role in some European regions. Our results also indicated the genetic singularity of the grapevine resources from the Balkans when compared to those from other relevant winemaking regions, supporting the interest of their detailed study to evaluate their oenological potential and for the eventual identification of useful traits to counteract current viticulture challenges.
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Introduction: Spontaneous coronary artery dissection (SCAD) is a non-traumatic and non-iatrogenic separation of the coronary arterial wall. Materials and methods: This systematic review and meta-analysis is reported following the PRISMA guidelines and is registered in the PROSPERO database. A literature search was focused on female patients in generative period (16-55 of age) with acute coronary syndrome (ACS) caused by SCAD, and comparison from that database NP-SCAD (spontaneous coronary artery dissection in non pregnant women) and P-SCAD (spontaneous coronary artery dissection in pregnant women). Results: 14 studies with 2,145 females in the generative period with ACS caused by SCAD were analyzed. The median age was 41 years (33.4-52.3 years). The most common risk factor was previous smoking history in 24.9% cases. The most common clinical presentation of ACS was STEMI in 47.4%. Conservative treatment was reported in 41.1%. PCI was performed in 32.7%, and 3.8% of patients had CABG surgery. LAD was the most frequently affected (50.5%). The prevalence of composite clinical outcomes including mortality, non-fatal MI and recurrent SCAD was 3.3% (95% CI: 1.4-5.1), 37.7% (95% CI: 1.9-73.4) and 15.2% (95% CI: 9.1-21.3) of patients. P-SCAD compared to NP-SCAD patients more frequently had STEMI (OR = 3.16; 95% CI: 2.30-4.34; I2 = 64%); with the left main and LAD more frequently affected [(OR = 14.34; 95% CI: 7.71-26.67; I2 = 54%) and (OR = 1.57; 95% CI: 1.06-2.32; I2 = 23%)]; P-SCAD patients more frequently underwent CABG surgery (OR = 6.29; 95% CI: 4.08-9.70; I2 = 0%). NP-SCAD compared to P-SCAD patients were more frequently treated conservatevly (OR = 0.61; 95% CI: 0.37-0.98; I2 = 0%). In P-SCAD compared to NP-SCAD mortality rates (OR = 1.13; 95% CI: 0.06-21.16; I2 = not applicable) and reccurence of coronary artery dissection (OR = 2.54; 95% CI: 0.97-6.61; I2 = 0%) were not more prevalent. Conclusion: The results of this meta-analysis indicated that patients with P-SCAD more frequently had STEMI, and events more frequently involved left main and LAD compared to NP-SCAD patients. Women with NP-SCAD were significantly more often treated conservatively compared to P-SCAD patients. P-SCAD compared to NP-SCAD patients did not have significantly higher mortality rates or recurrent coronary dissection.
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· Root responses to lack of iron (Fe) have mainly been studied in nutrient solution experiments devoid of silicon (Si). Here we investigated how Si ameliorates Fe deficiency in cucumber (Cucumis sativus) with focus on the storage and utilization of Fe in the root apoplast. · A combined approach was performed including analyses of apoplastic Fe, reduction-based Fe acquisition and Fe-mobilizing compounds in roots along with the expression of related genes. · Si-treated plants accumulated higher concentrations of root apoplastic Fe, which rapidly decreased when Fe was withheld from the nutrient solution. Under Fe-deficient conditions, Si also increased the accumulation of Fe-mobilizing compounds in roots. Si supply stimulated root activity of Fe acquisition at the early stage of Fe deficiency stress through regulation of gene expression levels of proteins involved in Fe acquisition. However, when the period of Fe deprivation was extended, these reactions further decreased as a consequence of Si-induced enhancement of the Fe status of the plants. · This work provides new evidence for the beneficial role of Si in plant nutrition and clearly indicates that Si-mediated alleviation of Fe deficiency includes an increase of the apoplastic Fe pool in roots and an enhancement of Fe acquisition.
Assuntos
Cucumis sativus/metabolismo , Espaço Extracelular/metabolismo , Deficiências de Ferro , Ferro/metabolismo , Raízes de Plantas/metabolismo , Silício/farmacologia , Citratos/metabolismo , Cucumis sativus/efeitos dos fármacos , Cucumis sativus/genética , Cucumis sativus/crescimento & desenvolvimento , Espaço Extracelular/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Malatos/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Xilema/efeitos dos fármacos , Xilema/metabolismoRESUMO
Trivalent chromium [Cr(III)] is a threat to the environment and crop production. Silicon (Si) has been shown to be effective in mitigating Cr(III) toxicity in rice. However, the mechanisms by which Si reduces Cr(III) uptake in rice are unclear. Herein, we hypothesized that the ability of Si to obstruct Cr(III) diffusion via apoplastic bypass is related to silicic acid polymerization, which may be affected by Cr(III) in rice roots. To test this hypothesis, we employed hydroponics experiments on rice (Oryza sativa L.) and utilized apoplastic bypass tracer techniques, as well as model simulations, to investigate 1) the effect of Si on Cr(III) toxicity and its obstruction capacity via apoplastic bypass, 2) the effect of Cr(III) on silicic acid polymerization, and 3) the relationship between the degree of silicic acid polymerization and its Cr(III) obstruction capacity. We found that Si reversed the damage caused by Cr(III) stress in rice. Si exerted an obstruction effect in the apoplast, significantly decreasing the share of Cr(III) uptake via the apoplastic bypass from 18% to 11%. Moreover, Cr(III) reduced silica particles' radii and increased Si concentration in roots. Modeling revealed that a 5-fold reduction in their radii decreased the diffusion of Cr(III) in apoplast by approximately 17%. We revealed that Cr(III) promoted silicic acid polymerization, resulting in the formation of a higher number of Si particles with a smaller radius in roots, which in turn increased the ability of Si to obstruct Cr(III) diffusion. This negative feedback regulatory mechanism is novel and crucially important for maintaining homeostasis in rice, unveiling the unique role of Si under Cr(III) ion stress and providing a theoretical basis for promoting the use of Si fertilizer in the field.
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Oryza , Silício/farmacologia , Ácido Silícico/farmacologia , Cromo/toxicidade , Retroalimentação , Raízes de PlantasRESUMO
Monocots and dicots differ in their boron (B) requirement, but also in their capacity to accumulate silicon (Si). Although an ameliorative effect of Si on B toxicity has been reported in various crops, differences among monocots and dicots are not clear, in particular in light of their ability to retain B in the leaf apoplast. In hydroponic experiments under controlled conditions, we studied the role of Si in the compartmentation of B within the leaves of wheat (Triticum vulgare L.) as a model of a high-Si monocot and sunflower (Helianthus annuus L.) as a model of a low-Si dicot, with the focus on the leaf apoplast. The stable isotopes 10B and 11B were used to investigate the dynamics of cell wall B binding capacity. In both crops, the application of Si did not affect B concentration in the root, but significantly decreased the B concentration in the leaves. However, the application of Si differently influenced the binding capacity of the leaf apoplast for excess B in wheat and sunflower. In wheat, whose capacity to retain B in the leaf cell walls is lower than in sunflower, the continuous supply of Si is crucial for an enhancement of high B tolerance in the shoot. On the other hand, the supply of Si did not contribute significantly in the extension of the B binding sites in sunflower leaves.
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Beneficial effects of silicon (Si) on plants have primarily been studied in crop species under single stress. Moreover, nutrient acquisition-based responses to combination of biotic and abiotic stresses (a common situation in natural habitats) have rarely been reported, in particular in conjunction with soil amendments with Si. Pedunculate oak (Quercus robur L.), one of the ecologically and economically most important tree species in Europe, is facing a severe decline due to combined stresses, but also problems in assisted regeneration in nurseries. Here, we studied the effect of Si supply on the leaf nutriome, root traits and overall growth of 12-weeks-old oak seedlings exposed to abiotic stress [low phosphorus (P) supply], biotic stress (Phytophthora plurivora root infection), and their combination. The application of Si had the strongest ameliorative effect on growth, root health and root phenome under the most severe stress conditions (i.e., combination of P deficiency and P. plurivora root infection), where it differentially affected the uptake and leaf accumulation in 11 out of 13 analysed nutrients. Silicon supply tended to reverse the pattern of change of some, but not all, leaf nutrients affected by stresses: P, boron (B) and magnesium (Mg) under P deficiency, and P, B and sulphur (S) under pathogen attack, but also nickel (Ni) and molybdenum (Mo) under all three stresses. Surprisingly, Si affected some nutrients that were not changed by a particular stress itself and decreased leaf Mg levels under all the stresses. On the other hand, pathogen attack increased leaf accumulation of Si. This exploratory work presents the complexity of nutrient crosstalk under three stresses, and opens more questions about genetic networks that control plant physiological responses. Practically, we show a potential of Si application to improve P status and root health in oak seedlings, particularly in nurseries.
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Soil-borne wheat mosaic virus (SBWMV) and Soil-borne cereal mosaic virus (SBCMV), genus Furovirus, family Virgaviridae, cause significant crop losses in cereals. The viruses are transmitted by the soil-borne plasmodiophorid Polymyxa graminis. Inside P. graminis resting spores, the viruses persist in the soil for long time, which makes the disease difficult to combat. To open up novel possibilities for virus control, we explored the influence of physical and chemical soil properties on infection of wheat with SBWMV and SBCMV. Moreover, we investigated, whether infection rates are influenced by the nutritional state of the plants. Infection rates of susceptible wheat lines were correlated to soil structure parameters and nutrient contents in soil and plants. Our results show that SBWMV and SBCMV infection rates decrease the more water-impermeable the soil is and that virus transmission depends on pH. Moreover, we found that contents of several nutrients in the soil (e.g. phosphorous, magnesium, zinc) and in planta (e.g. nitrogen, carbon, boron, sulfur, calcium) affect SBWMV and SBCMV infection rates. The knowledge generated may help paving the way towards development of a microenvironment-adapted agriculture.
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Increased availability of toxic Al3+ is the main constraint limiting plant growth on acid soils. Plants adapted to acid soils, however, tolerate toxic Al3+, and some can accumulate Al in their aerial parts to a significant degree. Studies on Al-tolerant and Al-accumulating species have mainly focused on the vegetation of acid soils distributed as two global belts in the northern and southern hemispheres, while acid soils formed outside these regions have been largely neglected. The acid soils (pH 3.4-4.2) of the tea plantations in the south Caspian region of Northern Iran were surveyed over three seasons at two main locations. Aluminum and other mineral elements (including nutrients) were measured in 499 plant specimens representing 86 species from 43 families. Al accumulation exceeding the criterion for accumulator species (>1000 µg g-1 DW) was found in 36 species belonging to 23 families of herbaceous annual or perennial angiosperms, in addition to three bryophyte species. Besides Al, Fe accumulation (1026-5155 µg g-1 DW) was also observed in the accumulator species that exceeded the critical toxicity concentration, whereas no such accumulation was observed for Mn. The majority of analyzed accumulator plants (64%) were cosmopolitan or pluriregional species, with a considerable rate of Euro-Siberian elements (37%). Our findings, which may contribute to phylogenetic studies of Al accumulators, also suggest suitable accumulator and excluder species for the rehabilitation of acid-eroded soils and introduce new model species for investigating Al accumulation and exclusion mechanisms.
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Introduction: SCAD involves a sudden tear or separation within the layers of the coronary artery wall, resulting in blood flow obstruction and subsequent myocardial ischemia. Materials and methods: A comprehensive literature search was conducted to identify relevant published cases of cutting balloon use in patients diagnosed with spontaneous coronary artery dissection. Electronic databases including PubMed, MEDLINE, Embase, Cochrane Library and Google Scholar were systematically searched from inception until the present using terms "cutting balloon," "SCAD," "acute coronary syndrome," "intramural hematoma," and "angioplasty." Results: A total of 32 published cases of cutting balloon use in spontaneous coronary artery dissection were analyzed in this study. The majority of the patients included in the analysis were female without prior history of cardiovascular disease. The median age of the SCAD population was approximately 46 years. The most frequently affected artery in SCAD cases was the Left Anterior Descending artery. Intravascular ultrasound was utilized more frequently than other modalities of adjunctive imaging techniques. The most frequent complication was the distal propagation of hematoma. Despite the successful dilation achieved with the cutting balloon, in some cases stenting was required to provide additional support. Conclusion: The results of this analysis demonstrate that cutting balloon use in SCAD cases yields favorable outcomes.
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BACKGROUND: The mechanisms by which nitrate is transported into the roots have been characterized both at physiological and molecular levels. It has been demonstrated that nitrate is taken up in an energy-dependent way by a four-component uptake machinery involving high- and low- affinity transport systems. In contrast very little is known about the physiology of nitrate transport towards different plant tissues and in particular at the leaf level. RESULTS: The mechanism of nitrate uptake in leaves of cucumber (Cucumis sativus L. cv. Chinese long) plants was studied and compared with that of the root. Net nitrate uptake by roots of nitrate-depleted cucumber plants proved to be substrate-inducible and biphasic showing a saturable kinetics with a clear linear non saturable component at an anion concentration higher than 2 mM. Nitrate uptake by leaf discs of cucumber plants showed some similarities with that operating in the roots (e.g. electrogenic H+ dependence via involvement of proton pump, a certain degree of induction). However, it did not exhibit typical biphasic kinetics and was characterized by a higher Km with values out of the range usually recorded in roots of several different plant species. The quantity and activity of plasma membrane (PM) H+-ATPase of the vesicles isolated from leaf tissues of nitrate-treated plants for 12 h (peak of nitrate foliar uptake rate) increased with respect to that observed in the vesicles isolated from N-deprived control plants, thus suggesting an involvement of this enzyme in the leaf nitrate uptake process similar to that described in roots. Molecular analyses suggest the involvement of a specific isoform of PM H+-ATPase (CsHA1) and NRT2 transporter (CsNRT2) in root nitrate uptake. At the leaf level, nitrate treatment modulated the expression of CsHA2, highlighting a main putative role of this isogene in the process. CONCLUSIONS: Obtained results provide for the first time evidence that a saturable and substrate-inducible nitrate uptake mechanism operates in cucumber leaves. Its activity appears to be related to that of PM H+-ATPase activity and in particular to the induction of CsHA2 isoform. However the question about the molecular entity responsible for the transport of nitrate into leaf cells therefore still remains unresolved.
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Membrana Celular/enzimologia , Cucumis sativus/enzimologia , Nitratos/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Transporte Biológico , Membrana Celular/genética , Membrana Celular/metabolismo , Cucumis sativus/genética , Cucumis sativus/metabolismo , Regulação da Expressão Gênica de Plantas , Folhas de Planta/enzimologia , Folhas de Planta/genética , Proteínas de Plantas/genética , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , ATPases Translocadoras de Prótons/genética , Regulação para CimaRESUMO
This work was focused on the role of silicon (Si) in amelioration of manganese (Mn) toxicity caused by elevated production of hydroxyl radicals (·OH) in the leaf apoplast of cucumber (Cucumis sativus L.). The plants were grown in nutrient solutions with adequate (0.5 µM) or excessive (100 µM) Mn concentrations with or without Si being supplied. The symptoms of Mn toxicity were absent in the leaves of Si-treated plants subjected to excess Mn, although the leaf Mn concentration remained extremely high. The apoplastic concentration of free Mn(2+) and H(2)O(2) of high Mn-treated plants was significantly decreased by Si treatment. Si supply suppressed the Mn-induced increased abundance of peroxidase (POD) isoforms in the leaf apoplastic fluid, and led to a rapid suppression of guaiacol-POD activity under excess Mn. The spin-trapping reagent 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide was used to detect ·OH by electron paramagnetic resonance spectroscopy. Although supplying Si markedly decreased the accumulation of ·OH in the leaf apoplast with excess Mn, adding monosilicic acid to the Mn(2+)/H(2)O(2) reaction mixture did not directly affect the Fenton reaction in vitro. The results indicate that Si contributes indirectly to a decrease in ·OH in the leaf apoplast by decreasing the free apoplastic Mn(2+), thus regulating the Fenton reaction. A direct inhibitory effect of Si on guaiacol-POD activity (demonstrated in vitro) may also contribute to decreasing the POD-mediated generation of ·OH.