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This article examines the funeral customs of the Cumans from the territory of Bulgaria. The graves are mainly from North-Eastern and South-Eastern Bulgaria. During the archaeological research, graves were found that bear the characteristic marks of this ethnic group. One of the characteristic features of the burial custom is that they are buried in circular pits, some of which also have small mounds. Graves of soldiers (Pliska, Zlatna Livada, Mednikarovo) and ordinary Cumans were discovered. Swords, stirrups and bridles were found in the graves. Burial in tree trunks, only graves are known. It was unearthed during the excavations of Tumulus No. 35 in Pliska, the former capital of Bulgaria. In addition to circular pits, burials were also carried out in rectangular pits. Ceramic vessels were also found in some graves (Plovdiv). In addition to burial mounds, Cuman graves have also been found in Christian necropolises. A typical feature of Cuman burials is the presence of dogs in the graves. A characteristic feature of Cumans graves is the erection of balbals. Initially, they were accepted as part of the culture of the proto-Bulgarians, but later they were correctly attributed to the cultural circle of the Cumans. It is recorded that stone statues (balbal) were erected in only one tumulus. Besides human graves, dog graves have also been studied. Such a grave was discovered near the village of Zimnitsa in the city of Yambol. The dog plays an important role in the folklore, mythology and funeral traditions of Turkic peoples. In most of the graves, traces of burial rituals were also found - animal bones, dishes and food remains. The graves discovered in Bulgaria are dated to the second half of the XII century and the beginning of the XIII century. [ABSTRACT FROM AUTHOR]

Reactive oxygen species play a central role in the regulation of plant responses to environmental stress. Under prolonged iron (Fe) deficiency, increased levels of hydrogen peroxide (H2O2) initiate signaling events, resulting in the attenuation of Fe acquisition through the inhibition of FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT). As this H2O2 increase occurs in a FIT-dependent manner, our aim was to understand the processes involved in maintaining H2O2 levels under prolonged Fe deficiency and the role of FIT. We identified the CAT2 gene, encoding one of the three Arabidopsis catalase isoforms, as regulated by FIT. CAT2 loss-of-function plants displayed severe susceptibility to Fe deficiency and greatly increased H2O2 levels in roots. Analysis of the Fe homeostasis transcription cascade revealed that H2O2 influences the gene expression of downstream regulators FIT , BHLH genes of group Ib, and POPEYE (PYE); however, H2O2 did not affect their upstream regulators, such as BHLH104 and ILR3. Our data shows that FIT and CAT2 participate in a regulatory loop between H2O2 and prolonged Fe deficiency. [ABSTRACT FROM AUTHOR]

The removal of transmembrane proteins from the plasma membrane via endocytosis has emerged as powerful strategy in the regulation of receptor signalling and molecule transport. In the last decade, IRON‐REGULATED TRANSPORTER1 (IRT1) has been established as one of the key plant model proteins for studying endomembrane trafficking. The use of IRT1 and additional other metal transporters has uncovered novel factors involved in plant endocytosis and facilitated a better understanding of the role of endocytosis in the fine balancing of plant metal homoeostasis. In this review, we outline the specifics of plant endocytosis compared to what is known in yeast and mammals, and based on several examples, we demonstrate how studying metal transport has contributed to extending our knowledge of endocytic trafficking by shedding light on novel regulatory mechanisms and factors. [ABSTRACT FROM AUTHOR]

Eukaryotic organisms share many common features in terms of endomembrane trafficking. This fact has helped plant scientists to propose testable hypotheses on how plant intracellular membrane trafficking is achieved and regulated based on knowledge from yeast and mammals. However, when a new compartment has been identified in a plant cell that has a vesicle tethering complex located at a position which is completely different to its counterpart in yeast and mammalian cells, caution is demanded when interpreting possible interactions with other trafficking elements. This is exemplified by the recently discovered EMAC (ER and microtubule-associated compartment). It has been postulated that this compartment is the recipient of vacuolar sorting receptors (VSRs) transported retrogradely via "retromer vesicles" from a post-Golgi location. Unfortunately, this suggestion was based entirely on our knowledge of retromer from yeast and mammalian cells, and did not take into account the available literature on the composition, localization, and function of the plant retromer. It also lacked reference to recent contradictory findings on VSR trafficking. In this short article, we have tried to rectify this situation, pointing out that plant retromer may not function as a pentameric complex of two subunits: the retromer core and the sorting nexins. [ABSTRACT FROM AUTHOR]

The functional importance of nuclear protein condensation remains often unclear. The bHLH FER-like iron deficiency-induced transcription factor (FIT) controls iron acquisition and growth in plants. Previously described C-terminal serine residues allow FIT to interact and form active transcription factor complexes with subgroup Ib bHLH factors such as bHLH039. FIT has lower nuclear mobility than mutant FITmSS271AA. Here, we show that FIT undergoes a light-inducible subnuclear partitioning into FIT nuclear bodies (NBs). Using quantitative and qualitative microscopy-based approaches, we characterized FIT NBs as condensates that were reversible and likely formed by liquid-liquid phase separation. FIT accumulated preferentially in NBs versus nucleoplasm when engaged in protein complexes with itself and with bHLH039. FITmSS271AA, instead, localized to NBs with different dynamics. FIT colocalized with splicing and light signaling NB markers. The NB-inducing light conditions were linked with active FIT and elevated FIT target gene expression in roots. FIT condensation may affect nuclear mobility and be relevant for integrating environmental and Fe nutrition signals. [ABSTRACT FROM AUTHOR]

Protein sorting in the endomembrane system is responsible for the coordination of cellular functions. Plant intracellular trafficking has its own unique features, which include specific regulatory aspects of endosomal sorting and recycling of cargo proteins, mediated by the retromer complex. Recent work has led to significant progress in understanding the role of Arabidopsis retromer subunits in recycling vacuolar sorting receptors and plasma membrane proteins. As a consequence, members of the sorting nexin (SNX) protein family and their interaction partners have emerged as critical protein trafficking regulators, in particular with regard to adaptation to environmental change, such as temperature fluctuations and nutrient deficiency. In this Review, we discuss the known and proposed functions of the comparatively small Arabidopsis SNX protein family. We review the available information on the role of the three Bin-Amphiphysin-Rvs (BAR)-domain-containing Arabidopsis thaliana (At)SNX proteins and discuss their function in the context of their potential participation in the plant retromer complex. We also summarize the role of AtSNX1- interacting proteins in different aspects of SNX-dependent protein trafficking and comment on the potential function of three novel, as yet unexplored, Arabidopsis SNX proteins. [ABSTRACT FROM AUTHOR]

In this paper, the front detection (also called inverse configuration) photopyroelectric method for thermal effusivity measurement in liquids is improved by adding a viscous liquid to the front face of the pyroelectric sensor, on which the intensity modulated excitation light beam impinges, while the sample is attached to the rear side of the sensor. This viscous liquid will act as an optical transparent window. This configuration avoids problems related with the piezoelectric contribution to the photopyroelectric signal at high modulation frequencies that can be present in conventional approaches due to thermoelastic waves generated in the heated sample or by thermally induced deformations of the detector material itself. The theoretical and experimental principles behind the proposed method are presented and its usefulness is demonstrated with measurements on test samples. [ABSTRACT FROM AUTHOR]

Background and aims: Dicotyledonous plants, such as Arabidopsis, acquire soil iron using a reduction-based mechanism, named Strategy I, where the final step involves Fe import by the ZIP-family transporter AtIRT1. The universal presence of IRT1-like genes, suggests that Strategy I represents a basic process in the green lineage. However, for some green organisms, like Chlamydomonas and rice, alternative iron-acquisition mechanisms are known. We aimed to outline potential interactions between Strategy I and alternative iron acquisition mechanisms. Methods: We investigated gene-coexpression networks in Chlamydomonas, rice and Arabidopsis, and used the sequences of the variable regions of the selected IRT proteins to identify the conservation of key amino acids. Results: IRT genes in Chlamydomonas and rice were found to be closely coexpressed with components of alternative available iron-acquisition systems. On protein level, we could observe conservation of potential phosphorylation sites in close proximity to predicted or experimentally-demonstrated ubiquitination sites. Conclusions: Data suggest that the regulation of Strategy I is closely connected to alternative existing iron-acquisition strategies. Transciptional control, together with potential post-transcriptional modifications of IRT transporters, may be involved in fine-tuning iron import. This study provides a basis for experimentally analyzing the regulation of iron acquisition in an evolutionary context. [ABSTRACT FROM AUTHOR]

In this paper a measurement methodology is proposed to avoid some limitations of conventional front photopyroelectric technique for thermal effusivity measurements, related to the necessity of calibration using a reference sample. The same pyroelectric sensor heated at high frequencies acts as a reference sample. The proposed method is tested with measurements of thermal effusivity in liquid samples. [ABSTRACT FROM AUTHOR]

A novel differential technique of femtoseconds pump-probe laser beam to test energy transport properties of nanomaterials, based on an electro-optic device, is presented. As opposed to the standard methods, ours allows the modulation of the probe-beam. As will be shown, the differential method overcomes the drawbacks of the existing technologies for nanomaterials. These drawbacks includes the time resolution of the collected data, the signal to noise ratio and the time to record the reflectance data. [ABSTRACT FROM AUTHOR]

Dicotyledonous plants growing under limited iron availability initiate a response resulting in the solubilization, reduction, and uptake of soil iron. The protein factors responsible for these steps are transmembrane proteins, suggesting that the intracellular trafficking machinery may be involved in iron acquisition. In search for components involved in the regulation of Arabidopsis thaliana iron deficiency responses, we identified the members of the SORTING NEXIN (SNX) protein family. SNX loss-of-function plants display enhanced susceptibility to iron deficiency in comparison to the wild type. The absence of SNX led to reduced iron import efficiency into the root. SNX1 showed partial colocalization with the principal root iron importer IRON-REGULATED TRANSPORTER1 (IRT1). In SNX loss-of-function plants, IRT1 protein levels were decreased compared with the wild type due to enhanced IRT1 degradation. This resulted in diminished amounts of the IRT1 protein at the plasma membrane. snx mutants exhibited enhanced iron deficiency responses compared with the wild type, presumably due to the lower iron uptake through IRT1. Our results reveal a role of SNX1 for the correct trafficking of IRT1 and, thus, for modulating the activity of the iron uptake machinery. [ABSTRACT FROM AUTHOR]

A novel differential technique of femtoseconds pump-probe laser beam to test energy transport properties of nanomaterials, based on an electro-optic device, is presented. As opposed to the standard methods, ours allows the modulation of the probe-beam. As will be shown, the differential method overcomes the drawbacks of the existing technologies for nanomaterials. These drawbacks includes the time resolution of the collected data, the signal to noise ratio and the time to record the reflectance data. [ABSTRACT FROM AUTHOR]

A novel differential technique of femtoseconds pump-probe laser beam to test energy transport properties of nanomaterials, based on an electro-optic device, is presented. As opposed to the standard methods, ours allows the modulation of the probe-beam. As will be shown, the differential method overcomes the drawbacks of the existing technologies for nanomaterials. These drawbacks includes the time resolution of the collected data, the signal to noise ratio and the time to record the reflectance data. [ABSTRACT FROM AUTHOR]

Abstract: During the late stages of seed development, the embryo patterning program is completed and maturation is initiated. One of the main events during the maturation phase is the acquisition of dormancy, characterized by the failure of a normally developed seed to germinate precociously. Dormancy is controlled by a complex regulatory mechanism that involves the phytohormone gibberellin (GA) and the transcription factor FUSCA3 (FUS3). Here, we demonstrate the importance of the previously characterized GA regulator EFFECTOR OF TRANSCRIPTION2 (AtET2) for correct seed development. We show that entering the maturation phase, seeds of the et2-1 mutant, which contain a non-functional AtET2 gene, fail to induce dormancy. This correlates well with the observed activity pattern of the AtET2 promoter, which is active in the maturing embryo. AtET2 action during seed development is dependent on a complex interaction with GA and the FUS3 gene, the latter evidenced by the phenotypes of the et2-1 fus3-T double mutant. We show that in vitro expressed AtET2 protein can bind to both linear and supercoiled DNA without any obvious sequence preference. This suggests that, within a larger protein complex, AtET2 might be required for the correct positioning upon the DNA. [Copyright &y& Elsevier]

A principal objective in life sciences is the visualization of biochemical processes. Fluorescence-based techniques are widely used to demonstrate transport of relevant substances across cellular membranes. In this paper we report a novel noninvasive, real-time fluorescence lifetime imaging microscopy method for visualizing uptake and release of divalent copper ions (Cu2+) in vivo. For this purpose, we employed a green fluorescent protein (GFP) form able to change its fluorescence lifetime upon Cu2+ binding. We demonstrate that this technique is selective for Cu2+. We show the reversible decrease of the fluorescence lifetime of GFP from 2.2 to 1.6 ns in Escherichia coli and from 1.8 to 1.3 ns in root cells of Arabidopsis after the addition of Cu2+. Cu2+ uptake of epidermal tobacco cells leads to a drop of the GFP lifetime from 2.5 to 2.2 ns. In summary, the spatially resolved visualization of Cu2+ distribution in vivo is demonstrated in prokaryote and eukaryote cells. [ABSTRACT FROM AUTHOR]

Iron is an essential element for life on Earth and its shortage, or excess, in the living organism may lead to severe health disorders. Plants serve as the primary source of dietary iron and improving crop iron content is an important step towards a better public health. Our review focuses on the control of iron acquisition in dicotyledonous plants and monocots that apply a reduction-based strategy in order to mobilize and import iron from the rhizosphere. Achieving a balance between shortage and excess of iron requires a tight regulation of the activity of the iron uptake system. A number of studies, ranging from single gene characterization to systems biology analyses, have led to the rapid expansion of our knowledge on iron uptake in recent years. Here, we summarize the novel insights into the regulation of iron acquisition and internal mobilization from intracellular stores. We present a detailed view of the main known regulatory networks defined by the Arabidopsis regulators FIT and POPEYE (PYE). Additionally, we analyze the root and leaf iron-responsive regulatory networks, revealing novel potential gene interactions and reliable iron-deficiency marker genes. We discuss perspectives and open questions with regard to iron sensing and post-translational regulation. [ABSTRACT FROM PUBLISHER]

The understanding of cellular processes and functions and the elucidation of their physiological mechanisms is an important aim in the life sciences. One important aspect is the uptake and the release of essential substances as well as their interactions with the cellular environment. As green fluorescent protein (GFP) can be genetically encoded in cells it can be used as an internal sensor giving a deeper insight into biochemical pathways. Here we report that the presence of copper(II) ions leads to a decrease of the fluorescence lifetime ( τ) of GFP and provide evidence for Förster resonance energy transfer (FRET) as the responsible quenching mechanism. We identify the His-tag as the responsible binding site for Cu with a dissociation constant K = 9 ±2 μM and a Förster radius R = 2.1 ±0.1 nm. The extent of the lifetime quenching depends on [Cu] which is comprehended by a mathematical titration model. We envision that Cu can be quantified noninvasively and in real-time by measuring τ of GFP. [ABSTRACT FROM AUTHOR]

More than half of the flowering plants have a sophisticated mechanism for self-pollen rejection, named self-incompatibility (SI). In Brassicaceae, recognition specificity is achieved by the interaction of the stigmatic S-RECEPTOR KINASE (SRK) and its ligand S-LOCUS CYSTEINE-RICH PROTEIN (SCR). Recent years have seen significant advances in understanding the SI response. Progress has been made on elucidating the regulation and function of proteins that act as either molecular partners of SRK or modulators of SI. Thus, modules controlling the specificity of the central receptor–ligand interaction have been identified on both SRK and SCR proteins. A role for intracellular protein trafficking in SI has also been demonstrated. Here, we integrate the novel findings into the existing model to present the current understanding of SI signaling. [Copyright &y& Elsevier]

Intracellular trafficking of plant receptor kinases (PRKs) is a key step in regulation of cellular signaling. Our current knowledge in this field is based on systems that address signaling pathways affecting the whole cell. There are, however, signaling phenomena that add a further layer of complexity. In the Brassica self-incompatibility response, a single cell can adequately respond to two opposite stimuli: accepting cross-pollen and rejecting self-pollen simultaneously. To understand how PRK signaling can influence the coexistence of two seemingly exclusive states of the cell, we investigated the subcellular localization and internalization of the S-receptor kinase (SRK) involved in the self-incompatibility response of Brassica oleracea. Here, we describe the unusual subcellular distribution of SRK3, which localizes predominantly to intracellular compartments and to a much lesser extent to the plasma membrane. Using an anti-SRK antibody that fully substitutes for the natural ligand, we demonstrate that the interaction with the receptor takes place at the plasma membrane and is followed by SRK internalization in endosomes that are enriched in the SRK negative regulator Thioredoxin-h-like1. [ABSTRACT FROM AUTHOR]

Abstract: EFFECTORS OF TRANSCRIPTION2 (ET) are plant-specific regulatory proteins characterized by the presence of two to five C-terminal DNA- and Zn-binding repeats, and a highly conserved cysteine pattern. We describe the structural characterization of the three member Arabidopsis thaliana ET gene family and reveal some allelic sequence polymorphisms. A mutation analysis showed that AtET2 affects the expression of various KNAT genes involved in the maintenance of the undifferentiated state of cambial meristem cells. It also plays a role in the regulation of GA5 (gibberellin 3-beta-dioxygenase) and the cell-cycle-related GASA4. A correlation was established between AtET2 expression and the cellular differentiation state. AtET–GFP fusion proteins shuttle between the cytoplasm and nucleus, with the AtET2 product prevented from entering the nucleus in non-differentiating cells. Within the nucleus, AtET2 probably acts via a single strand cutting domain. A more general regulatory role for ET factors is proposed, governing cell differentiation in cambial meristems, a crucial process for the development of plant vascular tissues. [Copyright &y& Elsevier]

We have determined and compared nucleotide excision repair capability of several rat tissues by a method based on restoration of the transformation activity of UV-irradiated pBlueScript by incubation in repair-competent protein extracts. After 3 h of incubation, plasmid DNA was isolated and used to transform competent Escherichia coli cells. Damaged plasmids showed low transformation efficiency prior to incubation in repair-competent extracts. After incubation the transformation efficiency was restored to different extents permitting calculation of the repair capacity of the extracts. Our results showed that rapidly proliferating tissues such as liver, kidney and testis showed higher nucleotide excision repair capacity than slowly proliferating tissues such as heart, muscle, lung and spleen. When liver and splenocytes were stimulated to proliferation by partial hepatectomy and mitogen stimulation, their repair capability increased in parallel with the respective proliferative rates. [ABSTRACT FROM AUTHOR]

Summary: The key basic helix–loop–helix (bHLH) transcription factor in iron (Fe) uptake, FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR (FIT), is controlled by multiple signaling pathways, important to adjust Fe acquisition to growth and environmental constraints. FIT protein exists in active and inactive protein pools, and phosphorylation of serine Ser272 in the C‐terminus, a regulatory domain of FIT, provides a trigger for FIT activation.Here, we use phospho‐mutant activity assays and study phospho‐mimicking and phospho‐dead mutations of three additional predicted phosphorylation sites, namely at Ser221 and at tyrosines Tyr238 and Tyr278, besides Ser 272.Phospho‐mutations at these sites affect FIT activities in yeast, plant, and mammalian cells. The diverse array of cellular phenotypes is seen at the level of cellular localization, nuclear mobility, homodimerization, and dimerization with the FIT‐activating partner bHLH039, promoter transactivation, and protein stability. Phospho‐mimicking Tyr mutations of FIT disturb fit mutant plant complementation.Taken together, we provide evidence that FIT is activated through Ser and deactivated through Tyr site phosphorylation. We therefore propose that FIT activity is regulated by alternative phosphorylation pathways. [ABSTRACT FROM AUTHOR]

Highlights • Proposal of a novel image processing algorithm for the testing of optical focusing mirrors. • Computing of accurate wavefront gradient estimations from a single defocused "bironchigram" sample. • Complete and valid indirect measurement optical technique featuring an accuracy akin to interferometry. Abstract Since its proposal the Ronchi "ruling" test has been considered as the most remarkable technique of the Schlieren family. Despite being based on fringe pattern generation and commonly interpreted in a qualitative way, it was capable of achieving outstanding results in the detection of aberrations in optical surfaces. Given its theoretical straightforwardness, experimental simplicity and economic affordability in comparison to other methodologies in the field, in the present work is addressed the lingering issue of how to extract quantitative information from digital captures of this test. Such task was accomplished taking advantage of the improved Ronchi test with a square grid, from which it was possible to develop a mathematical model with foundation in the Fourier theory to describe its observations. Thereupon, it was devised a novel iterative algorithm grounded in Fourier phase measuring able to compute fairly accurate wavefront gradient estimations from a single "bironchigram" sample with grid defocus. This procedure is complemented by a mandatory integration algorithm that is based on the regularization theory. The overall proposed methodology was put to test in a large aspherical mirror, estimating a surface aberration profile with a P–V (peak to valley) ratio of 155 nm, value well in accord with the one reported by the commercial interferometric system used for validation. [ABSTRACT FROM AUTHOR]

Organisms require micronutrients, and Arabidopsis (Arabidopsis thaliana) IRON-REGULATED TRANSPORTER1 (IRT1) is essential for iron (Fe2+) acquisition into root cells. Uptake of reactive Fe2+ exposes cells to the risk of membrane lipid peroxidation. Surprisingly little is known about how this is avoided. IRT1 activity is controlled by an intracellular variable region (IRT1vr) that acts as a regulatory protein interaction platform. Here, we describe that IRT1vr interacted with peripheral plasma membrane SEC14-Golgi dynamics (SEC14-GOLD) protein PATELLIN2 (PATL2). SEC14 proteins bind lipophilic substrates and transport or present them at the membrane. To date, no direct roles have been attributed to SEC14 proteins in Fe import. PATL2 affected root Fe acquisition responses, interacted with ROS response proteins in roots, and alleviated root lipid peroxidation. PATL2 had high affinity in vitro for the major lipophilic antioxidant vitamin E compound a-tocopherol. Molecular dynamics simulations provided insight into energetic constraints and the orientation and stability of the PATL2-ligand interaction in atomic detail. Hence, this work highlights a compelling mechanism connecting vitamin E with root metal ion transport at the plasma membrane with the participation of an IRT1-interacting and a-tocopherol-binding SEC14 protein. [ABSTRACT FROM AUTHOR]

Tooth anatomic factors like ectopic enamel pearls are often associated with localized periodontal inflammation and bone loss. There are no existing paleopathological data for such structural anomalies in ancient populations associated with periodontal pathology in the literature. A rare case of enamel pearl on the maxillary right first molar of women associated with localized periodontitis is presented and discussed. [ABSTRACT FROM AUTHOR]

Plants grown under iron (Fe)-deficient conditions induce a set of genes that enhance the efficiency of Fe uptake by the roots. In Arabidopsis (Arabidopsis thaliana), the central regulator of this response is the basic helix-loop-helix transcription factor FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT). FIT activity is regulated by protein-protein interactions, which also serve to integrate external signals that stimulate and possibly inhibit Fe uptake. In the search of signaling components regulating FIT function, we identified ZINC FINGER OF ARABIDOPSIS THALIANA12 (ZAT12), an abiotic stress-induced transcription factor. ZAT12 interacted with FIT, dependent on the presence of the ethylene-responsive element-binding factor-associated amphiphilic repression motif. ZAT12 protein was found expressed in the root early differentiation zone, where its abundance was modulated in a root layer-specific manner. In the absence of ZAT12, FIT expression was upregulated, suggesting a negative effect of ZAT12 on Fe uptake. Consistently, zat12 loss-of-function mutants had higher Fe content than the wild type at sufficient Fe. We found that under Fe deficiency, hydrogen peroxide (H2O2) levels were enhanced in a FIT-dependent manner. FIT protein, in turn, was stabilized by H2O2 but only in the presence of ZAT12, showing that H2O2 serves as a signal for Fe deficiency responses. We propose that oxidative stress-induced ZAT12 functions as a negative regulator of Fe acquisition. A model where H2O2 mediates the negative regulation of plant responses to prolonged stress might be applicable to a variety of stress conditions. [ABSTRACT FROM AUTHOR]

In this paper, we present an alternative technique for the demodulation of single interferograms using a sliding 2-D continuous wavelet transform (2-D CWT) method. The sliding strategy proposed in this work is used with two purposes: to reduce the processing time when the 2-D CWT is applied, and to solve the problem of the phase ambiguity when closed fringes are present. Experimental results with real and simulated interferograms show that the proposed multiresolution method is a proper alternative for many applications of interferogram demodulation with closed fringes. [ABSTRACT FROM AUTHOR]

Plants are the principal source of dietary iron (Fe) for most of Earth's population and Fe deficiency can lead to major health problems. Developing strategies to improve plant Fe content is a challenge because Fe is essential and toxic and therefore regulating Fe uptake is crucial for plant survival. Acquiring soil Fe relies on complex regulatory events that occur in root epidermal cells. We review recent advances in elucidating many aspects of the regulation of Fe acquisition. These include the expanding protein network involved in FER-LIKE IRON DEFICIENCY INDUCED TRANSCRIPTION FACTOR (FIT)-dependent gene regulation and novel findings on the intracellular trafficking of the Fe transporter IRON-REGULATED TRANSPORTER 1 (IRT1). We outline future challenges and propose strategies, such as exploiting natural variation, to further expand our knowledge. [ABSTRACT FROM AUTHOR]

Due to its redox properties, iron is both essential and toxic. Therefore, soil iron availability variations pose a significant problem for plants. Recent evidence suggests that calcium and reactive oxygen species coordinate signaling events related to soil iron acquisition. Calcium was found to affect directly IRT1-mediated iron import through the lipid-binding protein EHB1 and to trigger a CBL-CIPK-mediated signaling influencing the activity of the key iron-acquisition transcription factor FIT. In parallel, under prolonged iron deficiency, reactive oxygen species both inhibit FIT function and depend on FIT through the function of the catalase CAT2. We discuss the role of calcium and reactive oxygen species signaling in iron acquisition, with post-translational mechanisms influencing the localization and activity of iron-acquisition regulators and effectors. • Ca signaling targets both Fe transporter IRT1 and transcription factor FIT. • Additional Ca-dependent kinases might fine-tune plant Fe responses. • Reactive oxygen species (ROS) and Fe balance their mutual influence through FIT and CAT2 activities. • Root ROS landscape depends on Fe acquisition capacity. • RBOH may be a crossing point of ROS and Ca signaling in Fe responses. [ABSTRACT FROM AUTHOR]

The contribution of amino acids (AAs) to soil nitrogen (N) fluxes is higher than previously thought. The fact that AA uptake is pivotal for N nutrition in boreal ecosystems highlights plant AA transporters as key components of the N cycle. At the same time, very little is known about AA transport and respective transporters in trees. Tree genomes may contain 13 or more genes encoding the lysine histidine transporter (LHT) family proteins, and this complicates the study of their significance for tree N-use efficiency. With the strategy of obtaining a tool to study N-use efficiency, our aim was to identify and characterize a relevant AA transporter in hybrid aspen (Populus tremula L. x tremuloides Michx.). We identified PtrLHT1.2, the closest homolog of Arabidopsis thaliana (L.) Heynh AtLHT1, which is expressed in leaves, stems and roots. Complementation of a yeast AA uptake mutant verified the function of PtrLHT1.2 as an AA transporter. Furthermore, PtrLHT1.2 was able to fully complement the phenotypes of the Arabidopsis AA uptake mutant lht1 aap5 , including early leaf senescence-like phenotype, reduced growth, decreased plant N levels and reduced root AA uptake. Amino acid uptake studies finally showed that PtrLHT1.2 is a high affinity transporter for neutral and acidic AAs. Thus, we identified a functional AtLHT1 homolog in hybrid aspen, which harbors the potential to enhance overall plant N levels and hence increase biomass production. This finding provides a valuable tool for N nutrition studies in trees and opens new avenues to optimizing tree N-use efficiency. [ABSTRACT FROM AUTHOR]

Obtaining the precise value of the sample averaged heat loss coefficient has been a challenge that yet is not been satisfactorily resolved. This paper proposes an experimental setup and an optimized method to evaluate the averaged heat loss coefficient by the surface of the metal sample without need to know the thermal properties of the sample. A thermal camera along with the heat flow sensors was used to measure the heat loss coefficient in an absolute (non-relative) way. Also, a numerical simulation was done where minimum approximations are applied, and it is not necessary to make any adjustments with a complicated theoretical model. Then, it was experimentally demonstrated that the heat loss coefficient does not depend on the thermal properties of the metal sample. The influence in the difference of the temperature of the sample with the room temperature, on the factor h is monotonously increasing independent from heating or cooling regime. The proposed method has the advantage that the value of the heat loss coefficient is obtained experimentally, and the results are congruent with the COMSOL simulation outcomes. [ABSTRACT FROM AUTHOR]

Background and aims: Mungbean (Vigna radiata) is an important nutrient-rich crop with an increasing significance as food in Asia and other parts of the world. The conditions under which mungbean grows on the field might vary significantly and therefore understanding the behavior of plants on different soil types is crucial for obtaining optimal nutrient yields. In particular, iron availability in the soil might significantly influence plant growth and the loading of this element in the seed. The consumption of iron is one of the major problems of human nutrition worldwide. Lack of iron causes iron deficiency anemia, the most common nutrient disorder, leading to major developmental penalties or even death. Here, we aimed at understanding how iron is taken up in mungbean and how increasing its availability in the soil changes the iron distribution within three popular mungbean varieties, NM-94, CN9-5 and Harsha. Approach and results: We could show that mungbean secretes phenolic compounds to support its iron acquisition and observed significant quantitative variations in the phenolic release, and root-surface ferric reductase activity among the three varieties. We found that in terms of iron distribution between organs, plants react differently when grown on soils with significantly different Fe content. In standard soils, the CN9-5 and Harsha varieties tended to achieve better iron distribution towards the seed, and higher iron content than NM-94. On the contrary, on iron-rich soil iron distribution towards the seed in NM-94 was strongly enhanced and led to the highest content among the three varieties. The data provide important insights into the choice of mungbean varieties depending on the soil conditions. [ABSTRACT FROM AUTHOR]

Summary Nutrient acquisition is entangled with growth and stress in sessile organisms. The bHLH transcription factor FIT is a key regulator of Arabidopsis iron (Fe) acquisition and post-translationally activated upon low Fe. We identified CBL-INTERACTING PROTEIN KINASE CIPK11 as a FIT interactor. Cytosolic Ca2+ concentration and CIPK11 expression are induced by Fe deficiency. cipk11 mutant plants display compromised root Fe mobilization and seed Fe content. Fe uptake is dependent on CBL1/CBL9. CIPK11 phosphorylates FIT at Ser272, and mutation of this target site modulates FIT nuclear accumulation, homo-dimerization, interaction with bHLH039, and transcriptional activity and affects the plant's Fe-uptake ability. We propose that Ca2+-triggered CBL1/9-mediated activation of CIPK11 and subsequent phosphorylation of FIT shifts inactive into active FIT, allowing regulatory protein interactions in the nucleus. This biochemical link between Fe deficiency and the cellular Ca2+ decoding machinery represents an environment-sensing mechanism to adjust nutrient uptake. Graphical Abstract Highlights • Iron-regulated and calcium-dependent protein kinase CIPK11 interacts with FIT • CIPK11 and calcium sensors CBL1/9 promote FIT-dependent Fe deficiency responses • FIT is phosphorylated in plants, and CIPK11 phosphorylates FIT at Ser272 • Mutation at Ser272 modulates FIT activity, affecting seed iron content Gratz et al. uncovered a phosphorylation-based mechanism for regulation of the central Arabidopsis root iron uptake transcription factor FIT. FIT is activated at the protein level. Phosphorylation at Ser272 by the calcium-dependent kinase CIPK11 activates FIT, highlighting the role of calcium signaling and post-translational modifications in plant iron nutrition responses. [ABSTRACT FROM AUTHOR]

Iron is a key transition element in the biosphere and is crucial for living organisms, although its cellular excess can be deleterious. Maintaining the balance of optimal iron availability in the model plant Arabidopsis (Arabidopsis thaliana) requires the precise operation of iron import through the principal iron transporter IRON-REGULATED TRANSPORTER1 (IRT1). Targeted inhibition of IRT1 can prevent oxidative stress, thus promoting plant survival. Here, we report the identification of an IRT1 inhibitor, namely the C2 domain-containing peripheral membrane protein ENHANCED BENDING1 (EHB1). EHB1 interacts with the cytoplasmically exposed variable region of IRT1, and we demonstrate that this interaction is greatly promoted by the presence of calcium. We found that EHB1 binds lipids characteristic of the plasma membrane, and the interaction between EHB1 and plant membranes is calcium-dependent. Molecular simulations showed that EHB1 membrane binding is a two-step process that precedes the interaction between EHB1 and IRT1. Genetic and physiological analyses indicated that EHB1 acts as a negative regulator of iron acquisition. The presence of EHB1 prevented the IRT1-mediated complementation of iron-deficient fet3fet4 yeast (Saccharomyces cerevisiae). Our data suggest that EHB1 acts as a direct inhibitor of IRT1-mediated iron import into the cell. These findings represent a major step in understanding plant iron acquisition, a process that underlies the primary production of bioavailable iron for land ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: In this work we present a phase to (x,y,z)-coordinates transformation method for the calibration of a fringe projection profilometer. Our technique is divided in two parts: (1) phase to z transformation (for axial calibration) based on the typical polynomial fitting which uses a flat plane placed at several z positions to measure the phase of the projected fringes. (2) Phase to x and y transformation (for transverse calibration) based on the use of a crossed gratings pattern and a Fourier phase measurement method to determine x and y coordinates at several z positions. As will be shown the use of the crossed gratings pattern and the Fourier phase measurement method for transverse calibration is advantageous in several aspects: an unique image can give us x and y information at once. It provides x and y coordinates at each pixel in the image avoiding the use of interpolation methods. We present some experimental results and explain the viability of the proposed technique. [Copyright &y& Elsevier]