Metal Deficiency Research Articles

Alterations in tissue content of iron and zinc in mice bearing hepatoma 22a and their correction by zinc sulphate supplementation

It is known that many tumors induce iron and zinc deficiency in the organism. We studied the content of these metals, as well as the specific activity of two antioxidant metal-dependent enzymes – catalase and superoxide dismutase of three distal organs (thymus, liver and spleen) in animals bearing transplantable hepatoma 22a. These alterations were compared to weight changes of organs. On day 21 of tumor growth, as compared to control group, nonheme iron content in all three organs was decreased, and zinc content – only in the thymus. The specific activities of catalase and superoxide dismutase were both increased in the thymus, while in the liver activity of superoxide dismutase decreased. At the same time point thymic involution and splenomegaly were developed. In order to normalize metal content mice bearing hepatoma 22a were supplemented with 22 mkg of zinc sulphate per ml of drinking water during 3 weeks. Zinc sulphate supplementation partly compensated zinc deficiency in the thymus, increased zinc content in the liver and restored iron content in three organs. It also normalized superoxide dismutase activity in the liver and had no influence on enzymes in other organs. Zinc supplementation did not influence the weight of spleen and liver, but prevented the development of thymic involution. Moreover, metal deficiency in the thymus was restored while the activity of antioxidant enzymes remained unchanged. Based on this we can conclude that thymus involution in hepatoma 22a mice was associated with iron and zinc deficiency in this organ and was not linked with antioxidant enzyme activity, while splenomegaly had no relation to both types of parameters in the spleen. Thus, zinc sulphate positively influences metabolism of two vital trace elements – zinc and iron in animals bearing hepatoma 22a, what contributes to maintaining of the central immune organ – the thymus, and along with this it improves antioxidant system of the liver.

Genome-wide identification and expression analysis of the ZRT, IRT-like Protein (ZIP) family in Nicotiana tabacum.

Iron (Fe) and Zinc (Zn) are essential micronutrients for plant growth and development. ZIP (ZRT, IRT-like protein) transporters, known for their role in the regulation of Zinc and Iron uptake, are pivotal in facilitating the absorption, transport, and maintenance of Fe/Zn homeostasis in plants. Nicotiana tabacum has been widely used as a model plant for gene function analysis; however, the tobacco ZIP genes have not been identified systematically. In this study, we have identified a comprehensive set of 32 NtZIP genes, which were phylogenetically categorized into three distinct clades. The gene structures, characterized by their exon/intron organization, and the protein motifs are relatively conserved, particularly among genes within the same clade. These NtZIP genes exhibit an uneven distribution across 12 chromosomes. The gene localization analysis revealed the presence of 11 pairs of homeologous locus genes and 7 pairs of tandem duplication genes within the genome. To further explore the functionality of these genes, Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) was employed to assess their expression levels in roots subjected to metal deficiency. The results indicated that certain NtZIP genes are specifically upregulated in response to either Fe or Zn deficiency. Additionally, the presence of specific cis-elements within their promoter regions, such as the E-box associated with Fe deficiency response and the ZDRE box linked to Zn deficiency response, was identified. This study lays a foundational groundwork for future research into the biological functions of NtZIP genes in tobacco in micronutrient regulation and homeostasis.

Cause, Consequence, and Control of Ag Vacancies in BaAg2-xAs2.

The impact of transition metal (Ag) deficiencies on the structural and transport properties of ThCr2Si2-type arsenides are investigated. We experimentally confirm a partial occupancy of Ag in BaAg2-xAs2, which can be predictably controlled within 0.053(5) ≤ x ≤ 0.19(1) by varying the quenching temperature during the crystal growth. Density functional theory calculations reveal that substoichiometric concentrations of Ag lower the density of states at the Fermi level, providing an electronic cause for the tendency of Ag to form vacancies. This vacancy concentration is linked to a characteristic kink in electrical resistivity that can be substantially shifted from 22 to 125 K and is established as the metric of a low-temperature structural phase transition (SPT) in BaAg2-xAs2. Along with electrical resistivity, the Seebeck coefficient and heat capacity for selected BaAg2-xAs2 samples are presented, which also exhibit anomalies due to the SPT.

Mutation/metal deficiency in the "electrostatic loop" enhanced aggregation process in apo/holo SOD1 variants: implications for ALS diseases

Despite the many mechanisms it has created to prevent unfolding and aggregation of proteins, many diseases are caused by abnormal folding of proteins, which are called misfolding diseases. During this process, proteins undergo structural changes and become stable, insoluble beta-sheet aggregates called amyloid fibrils. Mutations/disruptions in metal ion homeostasis in the ALS-associated metalloenzyme superoxide dismutase (SOD1) reduce conformational stability, consistent with the protein aggregation hypothesis for neurodegenerative diseases. However, the exact mechanism of involvement is not well understood. Hence, to understand the role of mutation/ metal deficiency in SOD1 misfolding and aggregation, we investigated the effects of apo/holo SOD1 variants on structural properties using biophysical/experimental techniques. The MD results support the idea that the mutation/metal deficiency can lead to a change in conformation. The increased content of β-sheet structures in apo/holo SOD1 variants can be attributed to the aggregation tendency, which was confirmed by FTIR spectroscopy and dictionary of secondary structure in proteins (DSSP) results. Thermodynamic studies of GdnHCl showed that metal deficiency/mutation/intramolecular S–S reduction together are required to initiate misfolding/aggregation of SOD1. The results showed that apo/holo SOD1 variants under destabilizing conditions induced amyloid aggregates at physiological pH, which were detected by ThT/ANS fluorescence, as well as further confirmation of amyloid/amorphous species by TEM. This study confirms that mutations in the electrostatic loop of SOD1 lead to structural abnormalities, including changes in hydrophobicity, reduced disulfide bonds, and an increased propensity for protein denaturation. This process facilitates the formation of amyloid/amorphous aggregates ALS-associated.

Cation-oxygen dual-defective ACu3Ti4O12 (A = Sr, Ba) perovskites enable high-performance humidity sensors for human-body related moisture monitoring

ACu3Ti4O12 (A = Sr, Ba) double perovskites are attractive dielectric materials, yet they have not been reported in the field of gas and humidity sensors. In this work, SrCu3Ti4O12 (SCTO) and BaCu3Ti4O12 (BCTO) powders were synthesized by a facile modified solid-phase sintering method with characteristic of abundant cation-oxygen dual-defects (oxygen vacancy, metal deficiencies of Cu+ and Ti3+). For the first time, SCTO and BCTO are explored as humidity sensing materials, while the SCTO sensor holds a response value of four orders of magnitude (Sr = 2.8× 104), which is over a thousand times higher than that of BCTO (Sr = 25). In addition, the SCTO sensor is featured in fast response (7 s), reliable linearity (R2 = 0.97), small hysteresis (ΔHmax = 0.8%) and good repeatability in a wide relative humidity (RH) range (11%–97%). The boosted humidity sensing performance enables the SCTO sensor to possess great potential in human-body related moisture monitoring of breath and finger detection. Finally, the complex impedance analysis reveals different majority carriers of SCTO (H+) and BCTO (H3O+) under high RH range. The enhanced humidity sensing performance of SCTO can be attributed to the synergistic effects of richer dual-defects and larger ion potential. This work provides an excellent humidity sensing material of SCTO, and furthermore, gives new insights on defect sensitization strategy of perovskites for high-performance electronic sensory devices.

The effect of metal/non-metal ratio on the microstructure and magnetic properties of (MnFe)x(P0.5Si0.5) microwires

The effects of metal/non-metal ratio (M/NM ​= ​x: 1) on the microstructure and magnetocaloric properties of promising melt-extracted Mn–Fe–P–Si microwires with short heat treatment have been investigated here. More Fe2P principal phase, which is considered favorite for magnetocaloric effect (MCE), should achieve at low M/NM ratio and the fraction of Fe2P phase increased with the reduction of x. Meanwhile, the (Mn, Fe)3Si impurity phase is formed for x ​= ​2.00–1.90 whereas change to (Mn, Fe)5Si3 structure for x ​= ​1.85. It's worth noting that a metal deficiency resulted in the thermal hysteresis (Thys) and the magnetic hysteresis loss (Wy) decreased by ∼40 ​%., The magnetic transition temperature (Ttran), peak value of isothermal magnetic entropy change (−ΔSisopeak), refrigerant capacity (RC) and effective refrigerant capacity (RCE) first increased then decreased with the decrease of x, and reached the maximums at x ​= ​1.90, i.e., 370 ​K, 26.0 ​J ​kg−1 ​K−1, 367.4 and 339.8 ​J ​kg−1, respectively. Therefore, the customizable microstructure and magnetic properties of the melt-extracted (MnFe)x(P0.5Si0.5) microwires will be achievable effectively by tuning M/NM ratio x, and optimized Mn–Fe–P–Si compounds with novel thermomagnetic properties will be obtained.

Stabilization of P2 layered oxide electrodes in sodium-ion batteries through sodium evaporation

Sodium-ion batteries are well positioned to become, in the near future, the energy storage system for stationary applications and light electromobility. However, two main drawbacks feed their underperformance, namely the irreversible sodium consumption during solid electrolyte interphase formation and the low sodiation degree of one of the most promising cathode materials: the P2-type layered oxides. Here, we show a scalable and low-cost sodiation process based on sodium thermal evaporation. This method tackles the poor sodiation degree of P2-type sodium layered oxides, thus overcoming the first irreversible capacity as demonstrated by manufacturing and testing all solid-state Na doped-Na~1Mn0.8Fe0.1Ti0.1O2 ǀǀ PEO-based polymer electrolyte ǀǀ Na full cells. The proposed sodium physical vapor deposition method opens the door for an easily scalable and low-cost strategy to incorporate any metal deficiency in the battery materials, further pushing the battery development.

Metabolic Derangement of Essential Transition Metals and Potential Antioxidant Therapies.

Essential transition metals have key roles in oxygen transport, neurotransmitter synthesis, nucleic acid repair, cellular structure maintenance and stability, oxidative phosphorylation, and metabolism. The balance between metal deficiency and excess is typically ensured by several extracellular and intracellular mechanisms involved in uptake, distribution, and excretion. However, provoked by either intrinsic or extrinsic factors, excess iron, zinc, copper, or manganese can lead to cellular damage upon chronic or acute exposure, frequently attributed to oxidative stress. Intracellularly, mitochondria are the organelles that require the tightest control concerning reactive oxygen species production, which inevitably leaves them to be one of the most vulnerable targets of metal toxicity. Current therapies to counteract metal overload are focused on chelators, which often cause secondary effects decreasing patients' quality of life. New therapeutic options based on synthetic or natural antioxidants have proven positive effects against metal intoxication. In this review, we briefly address the cellular metabolism of transition metals, consequences of their overload, and current therapies, followed by their potential role in inducing oxidative stress and remedies thereof.

Variation of trace metal minerals among different soil orders under different land use systems falling in Malwa region of Punjab in North-western India

BackgroundTrace metal deficiency has become a major constraint on the productivity and sustainability of soils. Agriculture becomes more complex, advanced and intensive farming systems develop, however, the deficiency of trace metal are more frequent and extensive in different systems. MethodsThis study investigated the variation of trace metal minerals in soil profiles of diverse land use systems (LUSs), i.e. agriculture, horticulture and forestry, falling under three dominant soil orders (Entisol, Inceptisol and Aridisol) in Malwa region of Punjab. Through comprehensive analyses, we explore the intricate relationships between soil characteristics, land use practices, and the distribution of key trace metals—namely zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn). ResultsThe mean values of DTPA-extractable trace metal from soil profiles of different land uses varied from 1.75 to 2.09, 1.64–2.32, 1.18–1.69 mg kg−1 for Zn; 0.59–1.02, 0.59–0.99, 0.64–0.92 mg kg−1 for Cu; 12.12–16.49, 9.84–16.05, 7.94–11.56 mg kg−1 for Fe; 7.82–9.99, 4.66–9.39, 6.51–7.46 mg kg−1for Mn in soil orders Entisol, Inceptisol and Aridisol, respectively. The concentration of trace metals in different soil orders follows the pattern of ntisol>Inceptisol>Aridisol. In contrast, there is a considerable amount of variation and no discernible pattern in the distribution of trace metals under various LUSs in each soil order. Several LUSs were examined, and agriculture land use system (ALUS) had the greatest Fe and Mn content, while the horticulture land use system (HLUS) had the highest Zn and Cu content. The Irrespective of soil orders and LUSs, the concentration of trace metals decreased as soil depth increased. Diverse LUSs and management practices have a substantial impact on the physico-chemical characteristics of soils, which in turn influence the availability of trace metals. According to the Pearson correlation studies, trace metals were positively associated with soil OC and negatively associated with soil pH, electrical conductivity (EC), and calcium carbonate (CaCO3) and there was also a positive correlation between DTPA-Zn, Cu, Fe, and Mn in the investigated soils. The results of the principal component analysis (PCA) revealed that soil CaCO3 and organic carbon (OC) content were the most variable soil parameters influencing crop trace metal availability in different soil orders and land use systems. ConclusionThe findings contribute to a nuanced understanding of the dynamic interplay between soil properties and land use, providing valuable insights for sustainable agricultural practices and environmental management in the region.

Role of copper in central nervous system physiology and pathology.

Copper is a transition metal and an essential element for the organism, as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs, including the central nervous system. Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B, Menkes disease and Wilson's disease, respectively, and also in multifactorial neurological disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology, reports about unbalances in copper levels and/or distribution under disease, describes relevant animal models for human disorders where copper metabolism genes are dysregulated, and discusses relevant therapeutic approaches modulating copper availability. Overall, alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.

Multiomics Analysis of PCB126's Effect on a Mouse Chronic-Binge Alcohol Feeding Model.

Environmental pollutants, including polychlorinated biphenyls (PCBs) have been implicated in the pathogenesis of liver disease. Our group recently demonstrated that PCB126 promoted steatosis, hepatomegaly, and modulated intermediary metabolism in a rodent model of alcohol-associated liver disease (ALD). To better understand how PCB126 promoted ALD in our previous model, the current study adopts multiple omics approaches to elucidate potential mechanistic hypotheses. Briefly, male C57BL/6J mice were exposed to polychlorinated biphenyl (PCB) 126 or corn oil vehicle prior to ethanol (EtOH) or control diet feeding in the chronic-binge alcohol feeding model. Liver tissues were collected and prepared for mRNA sequencing, phosphoproteomics, and inductively coupled plasma mass spectrometry for metals quantification. Principal component analysis showed that PCB126 uniquely modified the transcriptome in EtOH-fed mice. EtOH feeding alone resulted in differentially expressed genes (DEGs), and PCB126 exposure resulted in more DEGs in the EtOH-fed group (907 DEGs) in comparison with the pair-fed group (503 DEGs). Top 20 significant gene ontology (GO) biological processes included "peptidyl tyrosine modifications," whereas top 25 significantly decreasing GO molecular functions included "metal/ion/zinc binding." Quantitative, label-free phosphoproteomics and western blot analysis revealed no major significant PCB126 effects on total phosphorylated tyrosine residues in EtOH-fed mice. Quantified hepatic essential metal levels were primarily significantly lower in EtOH-fed mice. PCB126-exposed mice had significantly lower magnesium, cobalt, and zinc levels in EtOH-fed mice. Previous work has demonstrated that PCB126 is a modifying factor in metabolic dysfunction-associated steatotic liver disease (MASLD), and our current work suggests that pollutants also modify ALD. PCB126 may, in part, be contributing to the malnutrition aspect of ALD, where metal deficiency is known to contribute and worsen prognosis. https://doi.org/10.1289/EHP14132.

Co-inoculation of rhizobia and AMF improves growth, nutrient uptake, and cadmium resistance of black locust grown in sand culture.

Rhizobia and arbuscular mycorrhizal fungi (AMF) are symbiotic microorganisms important for plants grown in nutrient-deficient and heavy metal-contaminated soils. However, it remains unclear how plants respond to the coupled stress by heavy metal and nitrogen (N) deficiency under co-inoculation. Here, we investigated the synergistic effect of Mesorhizobium huakuii QD9 and Funneliformis mosseae on the response of black locust (Robinia pseudoacacia L.) grown in sand culture to cadmium (Cd) under N deficiency conditions. The results showed that single inoculation of AMF improved the growth and Cd resistance of black locust, co-inoculation improved the most. Compared to non-inoculated controls, co-inoculation mediated higher biomass and antioxidant enzyme activity, reduced oxidative stress, and promoted nodulation, mycorrhizal colonization, photosynthetic capacity, and N, P, Fe and Mg acquisition when exposed to Cd. This increase was significantly higher under N deficiency compared to N sufficiency. In addition, the uptake of Cd by co-inoculated black locust roots increased, but Cd translocation to the above-ground decreased under both N deficiency and sufficiency. Thus, in the tripartite symbiotic system, not merely metabolic processes but also Cd uptake increased under N deficiency. However, enhanced Cd detoxification in the roots and reduced allocation to the shoot likely prevent Cd toxicity and rather stimulated growth under these conditions.

Effect of nano-hydroxyapatite and phosphate on thorium toxicity – Arabidopsis transcriptomic study

Thorium (Th) is a ubiquitous element but elevated concentrations caused by anthropogenic or natural activities pose health and environmental risks. Plants may be exposed accidentally or during the remediation of contaminated sites. Therefore, in this study, we analyzed the effect of thorium on Arabidopsis plants by RNA-seq profiling. Since Th and phosphorus form insoluble phosphates, we focused on the effect of Th in the presence/absence of phosphate in wild-type and mutants with altered phosphate management. Furthermore, we investigated the effect of hydroxyapatite nanoparticles, which are considered as material for in situ remediation, on Th toxicity. The highest number of DEGs was recorded in the combination of P absence and Th presence while the lowest in the presence of Th together with hydroxyapatite. Besides a high number of genes involved in stress response, Th also induced the transcription of genes involved in response to P starvation, indicating that Th decreased the availability of P. P deficiency caused by Th contributed to the phytotoxic effect of Th. We observed that nano-hydroxyapatite significantly reduced Th toxicity. Nano-hydroxyapatite also served as a source of inorganic P for the plants, but caused deficiency of essential metals indicated by up-regulation of genes involved in their acquisition.

Association of prenatal essential metal exposure with newborn mitochondrial DNA copy number: Results from a birth cohort study

Imbalance or deficiencies of essential metals can lead to oxidative stress, that can damage mitochondrial DNA (mtDNA) molecule. Knowledge on effects of exposure to essential metals and their mixture remains limited. We aimed to evaluate individual and joint associations of prenatal essential metals with neonatal mtDNA copy number. We recruited 746 mother-newborn pairs from a birth cohort study conducted in Wuhan City, China, and collected trimester-specific urine and cord blood samples. We measured the concentrations of seven urinary essential metals, include zinc (Zn), iron (Fe), selenium (Se), cobalt (Co), manganese (Mn), copper (Cu), and chromium (Cr), using inductively coupled plasma mass spectrometry, and measured cord blood mtDNA copy number using real-time quantitative polymerase chain reaction. We estimated the trimester-specific associations of individual essential metal concentrations with mtDNA copy number using a multiple informant model, and assessed their joint association using weighted quantile sum (WQS) regression. For individual essential metal, a doubling of maternal urinary Zn concentrations during the second trimester was associated with a 7.47% (95% CI: 1.17–14.17%) higher level of neonatal mtDNA copy number. For the essential metal mixture, one-unit increased in the WQS index of the essential metals mixture during the second trimester resulted in a 10.41% (95% CI: 3.04–18.30%) increase in neonatal mtDNA copy number. Our findings suggest that exposure to both Zn and essential metal mixture during the second trimester is associated with a higher neonatal mtDNA copy number. Further research should assess whether mtDNA copy number is associated with child health.

Asbestos and Iron.

Theories of disease pathogenesis following asbestos exposure have focused on the participation of iron. After exposure, an open network of negatively charged functional groups on the fiber surface complexes host metals with a preference for iron. Competition for iron between the host and the asbestos results in a functional metal deficiency. The homeostasis of iron in the host is modified by the cell response, including increased import to correct the loss of the metal to the fiber surface. The biological effects of asbestos develop in response to and are associated with the disruption of iron homeostasis. Cell iron deficiency in the host following fiber exposure activates kinases and transcription factors, which are associated with the release of mediators coordinating both inflammatory and fibrotic responses. Relative to serpentine chrysotile, the clearance of amphiboles is incomplete, resulting in translocation to the mesothelial surface of the pleura. Since the biological effect of asbestos is dependent on retention of the fiber, the sequestration of iron by the surface, and functional iron deficiency in the cell, the greater clearance (i.e., decreased persistence) of chrysotile results in its diminished impact. An inability to clear asbestos from the lower respiratory tract initiates a host process of iron biomineralization (i.e., asbestos body formation). Host cells attempt to mobilize the metal sequestered by the fiber surface by producing superoxide at the phagosome membrane. The subsequent ferrous cation is oxidized and undergoes hydrolysis, creating poorly crystalline iron oxyhydroxide (i.e., ferrihydrite) included in the coat of the asbestos body.

Metal Deficiency Tailored by the 18-Electron Rule Stabilizes Metal-Based Inorganic Compounds

Metal Deficiency Tailored by the 18-Electron Rule Stabilizes Metal-Based Inorganic Compounds

Nicotianamine: A Key Player in Metal Homeostasis and Hyperaccumulation in Plants

Nicotianamine (NA) is a low-molecular-weight N-containing metal-binding ligand, whose accumulation in plant organs changes under metal deficiency or excess. Although NA biosynthesis can be induced in vivo by various metals, this non-proteinogenic amino acid is mainly involved in the detoxification and transport of iron, zinc, nickel, copper and manganese. This review summarizes the current knowledge on NA biosynthesis and its regulation, considers the mechanisms of NA secretion by plant roots, as well as the mechanisms of intracellular transport of NA and its complexes with metals, and its role in radial and long-distance metal transport. Its role in metal tolerance is also discussed. The NA contents in excluders, storing metals primarily in roots, and in hyperaccumulators, accumulating metals mainly in shoots, are compared. The available data suggest that NA plays an important role in maintaining metal homeostasis and hyperaccumulation mechanisms. The study of metal-binding compounds is of interdisciplinary significance, not only regarding their effects on metal toxicity in plants, but also in connection with the development of biofortification approaches to increase the metal contents, primarily of iron and zinc, in agricultural plants, since the deficiency of these elements in food crops seriously affects human health.

Co-planting alters plant iron deficiency in heavy metals contaminated soil amended with sludge

Heavy metals (HMs)-induced iron (Fe) deficiency severely inhibits plant growth and thus hampers phytoremediation and revegetation in HMs-contaminated soil. We conducted a 12-month pot experiment to investigate the effects and mechanisms of co-planting on altering plant HM-induced Fe deficiency. The landscape tree Ilex rotunda was co-planted with Ficus microcarpa and Talipariti tiliaceum in sludge-amended soil. The responses of I. rotunda growth, elements uptake, and rhizosphere microbial community and metabolites were analyzed. The addition of sludge increased cadmium (Cd), zinc (Zn), and nickel (Ni) uptake and induced Fe deficiency-induced chlorosis in I. rotunda. This chlorosis was exacerbated when I. rotunda was co-planted with F. macrocarpa due to the increase in the abundance of sulfate reduction or Fe immobilization-associated bacteria and the relative level of isoprenyl alcohol and atropine in I. rotunda rhizosphere but the decrease in the contents of soil diethylenetriaminepentaacetic acid Fe (DTPA-Fe) (−16.19 %). Co-planting with T. tiliaceum or F. macrocarpa and T. tiliaceum decreased the contents of total or DTPA Zn/Cd/Ni in the soil while increased the contents of soil DTPA-Fe by 13.24 % or 11.34 % and the abundance of microbes which contributed to immobilizing HMs or activating Fe reduction, and then alleviated the chlorosis and the growth inhibition of I. rotunda. These results provide a new perspective on the phytoremediation and revegetation of HMs-contaminated soil.

Metal ion content of internal organs in the calorically restricted Wistar rat

BackgroundDespite the agreed principle that access to food is a human right, undernourishment and metal ion deficiencies are public health problems worldwide, exacerbated in impoverished or war-affected areas. It is known that maternal malnutrition causes growth retardation and affects behavioral and cognitive development of the newborn. Here we ask whether severe caloric restriction leads per se to disrupted metal accumulation in different organs of the Wistar rat. MethodsInductively coupled plasma optical emission spectroscopy was used to determine the concentration of multiple elements in the small and large intestine, heart, lung, liver, kidney, pancreas, spleen, brain, spinal cord, and three skeletal muscles from control and calorically restricted Wistar rats. The caloric restriction protocol was initiated from the mothers prior to mating and continued throughout gestation, lactation, and post-weaning up to sixty days of age. ResultsBoth sexes were analyzed but dimorphism was rare. The pancreas was the most affected organ presenting a higher concentration of all the elements analyzed. Copper concentration decreased in the kidney and increased in the liver. Each skeletal muscle responded to the treatment differentially: Extensor Digitorum Longus accumulated calcium and manganese, gastrocnemius decreased copper and manganese, whereas soleus decreased iron concentrations. Differences were also observed in the concentration of elements between organs independently of treatment: The soleus muscle presents a higher concentration of Zn compared to the other muscles and the rest of the organs. Notably, the spinal cord showed large accumulations of calcium and half the concentration of zinc compared to brain. X-ray fluorescence imaging suggests that the extra calcium is attributable to the presence of ossifications whereas the latter finding is attributable to the low abundance of zinc synapses in the spinal cord. ConclusionSevere caloric restriction did not lead to systemic metal deficiencies but caused instead specific metal responses in few organs.

Concomitant Activation of OsNAS2 and OsNAS3 Contributes to the Enhanced Accumulation of Iron and Zinc in Rice

Nicotianamine (NA) is produced by NA synthase (NAS), which contains three genes in rice and is responsible for chelating metals such as iron (Fe) and zinc (Zn), as well as preserving metal homeostasis. In this study, we generated a transgenic plant (23D) that shows simultaneous activation of OsNAS2 and OsNAS3 by crossing two previously identified activation-tagged mutants, OsNAS2-D1 (2D) and OsNAS3-D1 (3D). Concomitant activation of both genes resulted in the highest Fe and Zn concentrations in shoots and roots of the 23D plants grown under normal conditions and Fe and Zn limited growth conditions. Expression of genes for the biosynthesis of mugineic acid family phytosiderophores (MAs) and Fe and Zn uptake were enhanced in 23D roots. Additionally, 23D plants displayed superior growth to other plants at higher pH levels. Importantly, 23D seeds had NA and 2'-deoxymugineic acid (DMA) concentrations that were 50.6- and 10.0-fold higher than those of the WT. As a result, the mature grain Fe and Zn concentrations of the 23D plant were 4.0 and 3.5 times greater, respectively, than those of the WT. Furthermore, 23D plants exhibited the greatest resistance to excess metals. Our research suggests that simultaneous activation of OsNAS2 and OsNAS3 can enhance Fe and Zn accumulation in rice grains while also increasing plant tolerance to growing situations with metal deficiency and excess metal availability.