The Conservation of VIT1-Dependent Iron Distribution in Seeds

One third of people suffer from anemia, with iron (Fe) deficiency being the most common reason. The human diet includes seeds of staple crops, which contain Fe that is poorly bioavailable. One reason for low bioavailability is that these seeds store Fe in cellular compartments that also contain antinutrients, such as phytate. Thus, several studies have focused on decreasing phytate concentrations. In theory, as an alternative approach, Fe reserves might be directed to cellular compartments that are free of phytate, such as plastids. However, it is not known if seed plastid can represent a major Fe storage compartment in nature. To discover distinct types of Fe storage in nature, we investigated metal localizations in the seeds of more than twenty species using histochemical or X-ray based techniques. Results showed that in Rosids, the largest clade of eudicots, Fe reserves were primarily confined to the embryo of the seeds. Furthermore, inside the embryos, Fe accumulated specifically in the endodermal cell layer, a well-known feature that is mediated by VACUOLAR IRON TRANSPORTER1 (VIT1) in model plant Arabidopsis thaliana. In rice, Fe enrichment is lost around the provasculature in the mutants of VIT1 orthologs. Finally, in Carica papaya, Fe accumulated in numerous organelles resembling plastids; however, these organelles accumulated reserve proteins but not ferritin, failing to prove to be plastids. By investigating Fe distribution in distinct plant lineages, this study failed to discover distinct Fe storage patterns that can be useful for biofortification. However, it revealed Fe enrichment is widely conserved in the endodermal cell layer in a VIT1-dependent manner in the plant kingdom

Detention and mapping of iron and toxic environmental elements in human ovarian endometriosis: A suggested combined role

Background: Endometriosis is a disease affecting 10-15 % of women worldwide, consisting in the ectopic growth of endometrial cells outside the uterine cavity. Whist the pathogenetic mechanisms of endometriosis remain elusive and contemplating even environmental causes, iron deposits are common in endometrial lesions, indicating an altered iron metabolism at this level. This study was undertaken to reveal a possible relationship between iron dysmetabolism and accumulation of environmental metals. Methods: By combining histological and histochemical analysis (H&E and Perl's staining) with μ- and nano- synchrotron-based (SR-based) X-ray Fluorescence (XRF) microscopy, we investigated the distribution of iron and other elements in the ovarian endometriomas of 12 endometriosis patients and in 7 healthy endometrium samples. Results: XRF microscopy expanded the findings obtained by Perl's staining, revealing with an exceptional sensitivity intracellular features of iron accumulation in the epithelial endometrium, stroma and macrophages of the endometriotic lesions. XRF evidenced that iron was specifically accumulated in multiple micro aggregates, reaching concentrations up to 10-20 % p/p. Moreover, by XRF analysis we revealed for the first time the retention of a number of exogenous and potentially toxic metals such as Pb, Br, Ti, Al Cr, Si and Rb partially or totally co-localizing with iron. Conclusion: μXRF reveals accumulation and colocalization of iron and environmental metals in human ovarian endometriosis, suggesting a role in the pathogenesis of endometriosis

Micro-XANES analysis of metal accumulation in plants on sub-cellular level

There is a growing need to develop powerful analytical tools for monitoring concentrations and chemical state of trace element in the biosphere and its abiotic environment, due to pollution and degradation of ecosystems worldwide. Increased metal concentrations present in the environment pose a threat to all living organisms from microorganisms and plants to animals and humans, because they interfere with vital biological processes. The goal is to efficiently assess metal bioavailability and toxicity, and gain more knowledge on the mechanisms of metal uptake, accumulation and detoxification in living organisms [1]. In this work we demonstrate that a combination of micro-XRF imaging and micro-XANES and EXAFS analysis represents a powerful and indispensable tool for characterization of metal pollutants on subcellular level. The methodological approaches for efficient micro-XAS experiments are presented, the limitations and sources of potential systematic errors in XANES and EXAFS analysis (especially at low energies) due to self-absorption effects and strong energy dependent penetration depth of X-ray beam in the sample are discussed. Some typical examples of such combined micro-spectroscopy analysis are selected from the following research fields: Cd/Zn hyper-accumulating plants, that can be used for phytoremediation of Cd/Zn polluted and degraded ecosystems, including investigation of the role of externally supplied sulphur compounds in the nutrient solution of the Cd/Zn hyperaccumulator Thlaspi praecox, that may alter leaf Cd distribution and Cd ligand environment [2]; biofortification, which aims to increase essential elements (Fe) concentrations in the edible plant parts [3]; microbial regulation of metal (Fe, Pd) uptake and formation of Fe-oxide and Pd nanoparticles, encapsulated in exopolysaccharide to avoid iron toxicity under anaerobic conditions, discovered on a strain of Klebsiella oxytoca, isolated from acid pyrite-mine drainage[4]

Nickel coordination in hyperaccumulator plants studied by XANES and EXAFS

Soils derived from ultramafic or serpentine rocks are characterized by elevated concentrations of Ni, Cr and Co. About 2% of plants on ultramafic soils accumulate metals in their shoots: a phenomenon known as hyperaccumulation. Ni coordination in plant organs of a Ni hyperaccumulator (HA), Berkheya zeyheri subsp. rehmannii var. rogersiana, and its non-hyperaccumulating (NHA) counterpart Berkheya zeyheri subsp. rehmannii var. rehmannii was studied by EXAFS and XANES. Both varieties originate from the vicinity of Barberton Mpumalanga, South Africa. Ni K-edge spectra of HA and NHA leaves, veins, stems and roots were measured at BM23 beamline of ESRF synchrotron facility, Grenoble, France and at P64 beamline of PETRA III, Hamburg, Germany. Samples were rapidly frozen against a metal plate cooled with liquid nitrogen, put into a windowless cryostat and evacuated. The spectra were collected in fluorescence mode. For comparison, spectra of soil and Ni standards i.e. nickel bound in citrate, malate, methionine, proline, catecholate and histidine complexes were measured in transmission mode. IFEFFIT program package [1] was used for data evaluation.The shape and position of the Ni K edge strongly indicate that nickel is in the form of Ni2+ ion in all samples. Spectra of HA leaves, veins and stem are almost identical and consistent with spectra of Ni bound to organic acid complexes, while Principal Component Analysis of the roots spectra exhibits a mixture of Ni coordinated as in the soil structure, to the organic acids and to histidine. NHA plants accumulate much lower amount of Ni, from which only the roots spectra give enough signal for analysis: there, Ni is predominantly bound as in the soil, and in a lesser amount to histidine. Results show that - in comparison with the NHA plant - HA roots not only uptake more Ni but they transform its chemical environment to a higher degree, enabling transport of the metal ions to higher parts of the plan

The Conservation of VIT1-Dependent Iron Distribution in Seeds

WOS: 000475430000002PubMed ID: 31354774One third of people suffer from anemia, with iron (Fe) deficiency being the most common reason. The human diet includes seeds of staple crops, which contain Fe that is poorly bioavailable. One reason for low bioavailability is that these seeds store Fe in cellular compartments that also contain antinutrients, such as phytate. Thus, several studies have focused on decreasing phytate concentrations. In theory, as an alternative approach, Fe reserves might be directed to cellular compartments that are free of phytate, such as plastids. However, it is not known if seed plastid can represent a major Fe storage compartment in nature. To discover distinct types of Fe storage in nature, we investigated metal localizations in the seeds of more than twenty species using histochemical or X-ray based techniques. Results showed that in Rosids, the largest clade of eudicots, Fe reserves were primarily confined to the embryo of the seeds. Furthermore, inside the embryos, Fe accumulated specifically in the endodermal cell layer, a well-known feature that is mediated by VACUOLAR IRON TRANSPORTER1 (VIT1) in model plant Arabidopsis thaliana. In rice, Fe enrichment is lost around the provasculature in the mutants of VIT1 orthologs. Finally, in Carica papaya, Fe accumulated in numerous organelles resembling plastids; however, these organelles accumulated reserve proteins but not ferritin, failing to prove to be plastids. By investigating Fe distribution in distinct plant lineages, this study failed to discover distinct Fe storage patterns that can be useful for biofortification. However, it revealed Fe enrichment is widely conserved in the endodermal cell layer in a VIT1-dependent manner in the plant kingdom.ARRS (Slovenian Research Agency)Slovenian Research Agency - Slovenia [P1-0212, J7-9418, J7-9398]This study was partially supported by the ARRS (Slovenian Research Agency) (P1-0212, J7-9418, and J7-9398) and internal fundings

The Conservation of VIT1-Dependent Iron Distribution in Seeds (vol 10, 907, 2019)

[Abstract Not Available]project CALIPSOplus under EU Framework Programme for Research and Innovation HORIZON 2020The research leading to this result has been supported by the project CALIPSOplus under Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020.The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.WOS:0005615437000012-s2.0-85088963794PubMed: 3276557

Soft X -rays radiation damage on plunge -frozen and freeze -dried maize root s evaluated by FTIR spectromicroscopy

.The radiation damage issue consequent to soft X-rays’ exposure is still an important aspect to be contemplated in soft X-ray microscopy. The work presented here is part of a more extended investigation on the topic and targets the effects of soft X-rays exposure on plant tissues. The aftermaths of soft X-rays’ exposure were evaluated by FTIR spectromicroscopy by comparing irradiated and non-irradiated areas on similar plant structural features, one day and ten days after irradiation, to highlight also a possible time-dependent behavior consequent to air exposure. Our results show partial degradation of lignocellulosic complex and oxidation of cellulose and most probably of hemicellulose; lignin moiety of cell walls in vascular tissue however remains stable. Comparing the current study with our previous works it appears that, as expected, plant tissues seem less prone to soft X-rays radiation damage compared to mammalian cells or tissues

Metallophyte status of violets of the section Melanium

Violets from metal-enriched soils have controversially been described as both heavy-metal accumulators and excluders in the literature. The present study solves the issue for violets of the section Melanium (zinc violets, Viola lutea ssp. calaminaria and V. lutea ssp. westfalica; hartsease or wild pansy, Viola tricolor; and mountain pansy, V. lutea). The aims were to determine the concentrations of heavy metals in the soil and in the roots and shoots of field-collected plants, to evaluate the potential impact of colonisation by arbuscular mycorrhizal fungi on heavy-metal concentrations in the plant tissues, and to quantitatively define the localisation of the elements in root cross-sections. When these violets grow in low-metal soils, higher concentrations of the heavy metals were found in the roots and shoots than in the soil, whereas the opposite was seen in samples from high-metal soils. Under all field conditions examined, the roots of all of these species were colonised by arbuscular mycorrhizal fungi. However, V. tricolor was marginally colonised when the concentrations of Zn and P were higher in the soil. Determination of the spatial distribution of the elements in root cross-sections of these violets indicates tissue-specific deposition of elements within the vascular tissue, the cortex, and the rhizodermis. These data indicate that violets of the section Melanium are heavy-metal excluders. (C) 2013 Elsevier Ltd. All rights reserved