Protein Analysis of A. halleri and N. caerulescens Hyperaccumulators When Exposed to Nano and Ionic Forms of Cd and Zn.

Hyperaccumulator plant species growing on metal-rich soils can accumulate high quantity of metals and metalloids in aerial tissues, and several proteomic studies on the molecular mechanisms at the basis of metals resistance and hyperaccumulation have been published. Hyperaccumulator are also at the basis of the phytoremediation strategy to remove metals more efficiently from polluted soils or water. Arabidopsis halleri and Noccea caerulescens are both hyperaccumulators of metals and nano-metals. In this study, the change in some proteins in A. halleri and N. caerulescens was assessed after the growth in soil with cadmium and zinc, provided as sulphate salts (CdSO4 and ZnSO4) or sulfide quantum dots (CdS QDs and ZnS QDs). The protein extracts obtained from plants after 30 days of growth were analyzed by 2D-gel electrophoresis (2D SDS-PAGE) and identified by MALDI-TOF/TOF mass spectrometry. A bioinformatics analysis was carried out on quantitative protein differences between control and treated plants. In total, 43 proteins resulted in being significatively modulated in A. halleri, while 61 resulted in being modulated in N. caerulescens. Although these two plants are hyperaccumulator of both metals and nano-metals, at protein levels the mechanisms involved do not proceed in the same way, but at the end bring a similar physiological result.

Data on the interaction of hyperaccumulating plants with nanoscale metals Zn and Cd.

The article describes: growth phenotypes of the four plant species (Noccaea caerulescens, Thlaspi perfoliatum, Arabidopsis halleri, Arabidopsis thaliana) before and after the treatment with ionic and nanoscale Zn and Cd (Fig. 1); the method of synthesis and characterization of ZnS QDs and CdS QDs (Fig. 2); the genetic characterization (performed with molecular markers) of the four plant species, their relative genecological relation (Fig. 3); a conceptual workflow designed to detect the amount of ionic Zn and Cd in the original solution/suspension used for the treatment (Fig. 4); the determination of Zn and Cd in the treatment soils after 30 days from supplement of ionic and nanoscale Zn and Cd (Fig. 5); the effect of the treatment on root elongation (Fig. 6); a workflow of a novel analytical method designed to detect the ionic and nanoscale Zn and Cd in the plant tissues after digestion with three different methods (Fig. 7); a reconstruction experiments with an exsiccated powder of plant tissue spiked with the same amount of Zn in the ionic and nanoscale forms (Fig. 8); a TEM-EDX analysis on these powdered plant tissues after removal of all soluble (ionic) Zn to show the presence of Zn in a non soluble form (nanoscale) (Fig. 9); the calculation of Bioconcentration Factor (BCF) and Translocation Factor (TF) and their ratios (Table 1); all data of the "spiking" experiments (Tables 2 and 3).

Interaction of hyperaccumulating plants with Zn and Cd nanoparticles.

Metal hyperaccumulating plant species are an interesting example of natural selection and environmental adaptation but they may also be useful to developing new technologies of environmental monitoring and remediation. Noccaea caerulescens and Arabidopsis halleri are both Brassicaceae and are known metal hyperaccumulators. This study evaluated tolerance, uptake and translocation of zinc sulfide quantum dots by N. cearulescens and cadmium sulfide quantum dots by A. halleri in direct comparison with the non-hyperaccumulator, genetically similar T. perfoliatum and A. thaliana. Growth media were supplied with two different concentrations of metal in either salt (ZnSO4 and CdSO4) or nanoscale form (ZnS QDs and CdS QDs). After 30 days of exposure, the concentration of metals in the soil, roots and leaves was determined. Uptake and localization of the metal in both nanoscale and non-nanoscale form inside plant tissues was investigated by Environmental Scanning Electron Microscopy (ESEM) equipped with an X-ray probe. Specifically, the hyperaccumulators in comparison with the non-hyperaccumulators accumulate ionic and nanoscale Zn and Cd in the aerial parts with a BCF ratio of 45.9 for Zn ion, 49.6 for nanoscale Zn, 2.64 for Cd ion and 2.54 for nanoscale Cd. Results obtained with a differential extraction analytical procedure also showed that a significant fraction of nanoscale metals remained inside the plants in a form compatible with the retention of at least a partial initial structure. The molecular consequences of the hyperaccumulation of nanoscale materials are discussed considering data obtained with hyperaccumulation of ionic metal. This is the first report of conventional hyperaccumulating plants demonstrating an ability to hyperaccumulate also engineered nanomaterials (ENMs) and suggests a potential novel strategy for not only understanding plant-nanomaterial interactions but also for potential biomonitoring in the environment to avoid their entering into the food chains.

Cadmium sulfide quantum dots impact Arabidopsis thaliana physiology and morphology.

The differential mechanisms of CdS QDs (Quantum Dots) and Cd ion toxicity to Arabidopsis thaliana (L.) Heynh were investigated. Plants were exposed to 40 and 60 mg L-1 for CdS QDs and 76.9 and 115.2 mg L-1 CdSO4·7H2O and toxicity was evaluated at 5, 20, 35 (T5, T20, T35) days after exposure. Oxidative stress upon exposure was evaluated by biochemical essays targeting non-enzymatic oxidative stress physiological parameters, including respiration efficiency, total chlorophylls, carotenoids, ABTS and DPPH radicals reduction, total phenolics, GSH redox state, lipid peroxidation. Total Cd in plants was measured with AAS. Root and leaf morphology and element content were assessed in vivo utilizing low-vacuum Environmental Scanning Electron Microscopy (ESEM) with X-ray microanalysis (EDX). This integrated approach allowed identification of unique nanoscale CdS QDs toxicity to the plants that was distinct from CdSO4 exposure. The analyses highlighted that CdS QDs and Cd ions effects are modulated by the developmental stage of the plant, starting from T20 till T35 the plant development was modulated by the treatments, in particular CdS QDs induced early flowering. Both treatments induced Fe accumulation in roots, but at different intensities, while CdS QDs was associated with Mn increase into plant leaf. CdSO4 elicited higher levels of oxidative stress compared with QDs, especially the former treatment caused more intense respiration damages and reduction in chlorophyll and carotenoids than the latter. The two types of treatments impact differently on root and leaf morphology.

Structural and Functional Features of Chars From Different Biomasses as Potential Plant Amendments.

Biochars result from the pyrolysis of biomass waste of plant and animal origin. The interest in these materials stems from their potential for improving soil quality due to increased microporosity, carbon pool, water retention, and their active capacity for metal adsorption from soil and irrigation water. Applications in agriculture have been studied under different conditions, but the overall results are still unclear. Char structure, which varies widely according to the pyrolysis process and the nature of feedstock, is thought to be a major factor in the interaction of chars with soil and their metal ion adsorption/chelation properties. Furthermore, biochar nutrients and their elemental content can modify soil fertility. Therefore, the use of biochars in agricultural settings should be examined carefully by conducting experimental trials. Three key problems encountered in the use of biochar involve (i) optimizing pyrolysis for biomass conversion into energy and biochar, (ii) physicochemically characterizing biochar, and (iii) identifying the best possible conditions for biochar use in soil improvement. To investigate these issues, two types of wood pellets, plus digestate and poultry litter, were separately converted into biochar using different technologies: pyrolysis/pyrogasification or catalytic (thermo)reforming. The following physicochemical features for the different biochar batches were measured: pH, conductivity, bulk density, humidity and ash content, particle size, total organic substances, and trace element concentrations. Fine porous structure analysis and total elemental analysis were performed using environmental scanning electron microscopy along with energy-dispersive X-ray spectrometry (EDX). Phytotoxicity tests were performed for each biochar. Finally, we were able to (i) differentiate the biochars according to their physicochemical properties, microstructure, elemental contents, and original raw biomass; (ii) correlate the whole biochar features with their respective optimal concentrations when used as plant fertilizers or soil improvers; and (iii) show that biochars from animal origin were phytotoxic at lower concentrations than those from plant feedstock.

Target proteins reprogrammed by As and As + Si treatments in Solanum lycopersicum L. fruit.

BACKGROUND: Arsenic is an important contaminant of many arable soils worldwide, while silicon, one of the most abundant elements in the earth's crust, interacts with As in the context of plant metabolism. As toxicity results largely from its stimulation of reactive oxygen species, and it is believed that Si can mitigate this process through reduction of the level of oxidative stress. Experiments targeting the proteomic impact of exposure to As and Si have to date largely focused on analyses of root, shoot and seed of a range of mainly non-solanaceous species, thus it remains unclear whether oxidative stress is the most important manifestation of As toxicity in Solanum lycopersicum fruit which during ripening go through drastic physiological and molecular readjustments. The role of Si also needs to be re-evaluated. RESULTS: A comparison was drawn between the proteomic responses to As and As + Si treatments of the fruit of two tomato cultivars (cvs. Aragon and Gladis) known to contrast for their ability to take up these elements and to translocate them into fruits. Treatments were applied at the beginning of the red ripening stage, and the fruit proteomes were captured after a 14 day period of exposure. For each cultivar, a set of differentially abundant fruit proteins (from non-treated and treated plants) were isolated by 2DGE and identified using mass spectrometry. In the fruit of cv. Aragon, the As treatment reprogrammed proteins largely involved in transcription regulation (growth- regulating factor 9-like), and cell structure (actin-51), while in the cv. Gladis, the majority of differentially expressed proteins were associated with protein ubiquitination and proteolysis (E3 ubiquitin protein, and hormones (1-aminocyclopropane 1-carboxylase). CONCLUSIONS: The present experiments were intended to establish whether Si supplementation can be used to reverse the proteomic disturbance induced by the As treatment; this reprogram was only partial and more effective in the fruit of cv. Gladis than in that of cv. Aragon. Proteins responsible for the protection of the fruits' quality in the face of As-induced stress were identified. Moreover, supplementation with Si seemed to limit to a degree the accumulation of As in the tomato fruit of cv. Aragon.

Abiotic Stress Response to As and As+Si, Composite Reprogramming of Fruit Metabolites in Tomato Cultivars.

The toxic element arsenic interacts with the beneficial element silicon at many levels of the plant metabolism. The ability of the tomato plant to take up and translocate As into its fruit has risen concerns that it could facilitate the entry of this element into the human food chain above the admitted level. Here, the fruit of two contrasting tomato cultivars, Aragon and Gladis, were evaluated following exposures of either 48 h or 14 days to As-contaminated irrigation water, with or without supplementary Si. The focus was on selected biochemical stress response indicators to dissect metabolic fruit reprogramming induced by As and Si. A multivariate statistical approach was utilized to establish the relationship between tissue As and Si concentrations and selected biochemical aspects of the stress response mechanisms to identify a set of relevant stress response descriptors. This resulted in the recognition of strong cultivar and temporal effects on metabolic and biochemical stress parameters following the treatments. In this paper the metabolic changes in H2O2 content, lipid peroxidation, lycopene and carotenoids content, ascorbate and GSH redox state, total phenolics, ABTS and DPPH radicals inhibition were in favor of an oxidative stress. The significance of some of these parameters as reliable arsenic exposition biomarkers is discussed in the context of the limited knowledge on the As-induced stress response mechanisms at the level of the ripening fruit which presents a distinctive molecular background dissimilar from roots and shoots.

The Proteomic Response of Arabidopsis thaliana to Cadmium Sulfide Quantum Dots, and Its Correlation with the Transcriptomic Response.

A fuller understanding of the interaction between plants and engineered nanomaterials is of topical relevance because the latter are beginning to find applications in agriculture and the food industry. There is a growing need to establish objective safety criteria for their use. The recognition of two independent Arabidopsis thaliana mutants displaying a greater level of tolerance than the wild type plant to exposure to cadmium sulfide quantum dots (CdS QDs) has offered the opportunity to characterize the tolerance response at the physiological, transcriptomic, and proteomic levels. Here, a proteomics-based comparison confirmed the conclusions drawn from an earlier transcriptomic analysis that the two mutants responded to CdS QD exposure differently both to the wild type and to each other. Just over half of the proteomic changes mirrored documented changes at the level of gene transcription, but a substantial number of transcript/gene product pairs were altered in the opposite direction. An interpretation of the discrepancies is given, along with some considerations regarding the use and significance of -omics when monitoring the potential toxicity of ENMs for health and environment.

The response of Populus spp. to cadmium stress: chemical, morphological and proteomics study.

Poplar (Populus) species are seen as candidates for removing heavy metal contamination from polluted soil. A bottom-up multidisciplinary approach was utilized to compare the performances of clones 58-861 and Poli (Populus nigra) and A4A, a Populus nigra × Populus deltoides hybrid to Cd toxicity. Qualitative and quantitative differences in their tolerance to Cd exposure and the uptake, accumulation and translocation of Cd were noted following the hydroponic exposure of rooted cuttings to 20 µM CdSO4 for either 48 h or 14 d. Cadmium was less toxic for the hybrid clone A4A as compared to Poli and 58-861. Cd uptake and root to shoot translocation were determined by AAS, and its compartmentation was analyzed using SEM/EDX. A comparative proteomic approach was utilized to identify changes in proteins expression according to dose and time of exposure. Toxicity to Cd mainly influenced proteins related to general defense, stress response and carbohydrate metabolism.

Endothelial colony-forming cells from patients with chronic myeloproliferative disorders lack the disease-specific molecular clonality marker.

Two putative types of circulating endothelial progenitor cells have been recently identified in vitro: (1) endothelial colony-forming cell (ECFC) and (2) colony-forming unit-endothelial cell (CFU-EC). Only the former is now recognized to belong to endothelial lineage. We have used the ECFC and CFU-EC assays to readdress the issue of the clonal relation between endothelial progenitor cells and hematopoietic stem cells in patients with Philadelphia-positive and Philadelphia-negative chronic myeloproliferative disorders. Both ECFCs and CFU-ECs were cultured from peripheral blood mononuclear cells, and either BCR-ABL rearrangement or JAK2-V617F mutation were assessed in both types of endothelial colonies. We found that ECFCs lack the disease-specific markers, which are otherwise present in CFU-ECs, thus reinforcing the concept that the latter belongs to the hematopoietic lineage, and showing that in chronic myeloproliferative disorders the cell that gives rise to circulating ECFC has a distinct origin from the cell of the hematopoietic malignant clone.