Ethylene and Nitric Oxide Involvement in the Regulation of Fe and P Deficiency Responses in Dicotyledonous Plants

Iron (Fe) and phosphorus (P) are two essential elements for plant growth. Both elements are abundant in soils but with poor availability for plants, which favor their acquisition by developing morphological and physiological responses in their roots. Although the regulation of the genes related to these responses is not totally known, ethylene (ET) and nitric oxide (NO) have been involved in the activation of both Fe-related and P-related genes. The common involvement of ET and NO suggests that they must act in conjunction with other specific signals, more closely related to each deficiency. Among the specific signals involved in the regulation of Fe- or P-related genes have been proposed Fe-peptides (or Fe ion itself) and microRNAs, like miR399 (P), moving through the phloem. These Fe- or P-related phloem signals could interact with ET/NO and confer specificity to the responses to each deficiency, avoiding the induction of the specific responses when ET/NO increase due to other nutrient deficiencies or stresses. Besides the specificity conferred by these signals, ET itself could confer specificity to the responses to Fe- or P-deficiency by acting through different signaling pathways in each case. Given the above considerations, there are preliminary results suggesting that ET could regulate different nutrient responses by acting both in conjunction with other signals and through different signaling pathways. Because of the close relationship among these two elements, a better knowledge of the physiological and molecular basis of their interaction is necessary to improve their nutrition and to avoid the problems associated with their misuse. As examples of this interaction, it is known that Fe chlorosis can be induced, under certain circumstances, by a P over- fertilization. On the other hand, Fe oxides can have a role in the immobilization of P in soils. Qualitative and quantitative assessment of the dynamic of known Fe- and P-related genes expression, selected ad hoc and involved in each of these deficiencies, would allow us to get a profound knowledge of the processes that regulate the responses to both deficiencies. The better knowledge of the regulation by ET of the responses to these deficiencies is necessary to properly understand the interactions between Fe and P. This will allow the obtention of more efficient varieties in the absorption of P and Fe, and the use of more rational management techniques for P and Fe fertilization. This will contribute to minimize the environmental impacts caused by the use of P and Fe fertilizers (Fe chelates) in agriculture and to adjust the costs for farmers, due to the high prices and/or scarcity of Fe and P fertilizers. This review aims to summarize the latest advances in the knowledge about Fe and P deficiency responses, analyzing the similarities and differences among them and considering the interactions among their main regulators, including some hormones (ethylene) and signaling substances (NO and GSNO) as well as other P- and Fe-related signals

An IoT reader for wireless passive electromagnetic sensors

This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016.In the last years, many passive electromagnetic sensors have been reported. Some of these sensors are used for measuring harmful substances. Moreover, the response of these sensors is usually obtained with laboratory equipment. This approach highly increases the total cost and complexity of the sensing system. In this work, a novel low-cost and portable Internet-of-Things (IoT) reader for passive wireless electromagnetic sensors is proposed. The reader is used to interrogate the sensors within a short-range wireless link avoiding the direct contact with the substances under test. The IoT functionalities of the reader allows remote sensing from computers and handheld devices. For that purpose, the proposed design is based on four functional layers: the radiating layer, the RF interface, the IoT mini-computer and the power unit. In this paper a demonstrator of the proposed reader is designed and manufactured. The demonstrator shows, through the remote measurement of different substances, that the proposed system can estimate the dielectric permittivity. It has been demonstrated that a linear approximation with a small error can be extracted from the reader measurements. It is remarkable that the proposed reader can be used with other type of electromagnetic sensors, which transduce the magnitude variations in the frequency domain

Several Yeast Species Induce Iron Deficiency Responses in Cucumber Plants (Cucumis sativus L.)

Iron (Fe) deficiency is a first-order agronomic problem that causes a significant decrease in crop yield and quality. Paradoxically, Fe is very abundant in most soils, mainly in its oxidized form, but is poorly soluble and with low availability for plants. In order to alleviate this situation, plants develop different morphological and physiological Fe-deficiency responses, mainly in their roots, to facilitate Fe mobilization and acquisition. Even so, Fe fertilizers, mainly Fe chelates, are widely used in modern agriculture, causing environmental problems and increasing the costs of production, due to the high prices of these products. One of the most sustainable and promising alternatives to the use of agrochemicals is the better management of the rhizosphere and the beneficial microbial communities presented there. The main objective of this research has been to evaluate the ability of several yeast species, such as Debaryomyces hansenii, Saccharomyces cerevisiae and Hansenula polymorpha, to induce Fe-deficiency responses in cucumber plants. To date, there are no studies on the roles played by yeasts on the Fe nutrition of plants. Experiments were carried out with cucumber plants grown in a hydroponic growth system. The effects of the three yeast species on some of the most important Fe-deficiency responses developed by dicot (Strategy I) plants, such as enhanced ferric reductase activity and Fe2+ transport, acidification of the rhizosphere, and proliferation of subapical root hairs, were evaluated. The results obtained show the inductive character of the three yeast species, mainly of Debaryomyces hansenii and Hansenula polymorpha, on the Fe-deficiency responses evaluated in this study. This opens a promising line of study on the use of these microorganisms as Fe biofertilizers in a more sustainable and environmentally friendly agriculture

Following the results of the EMPA-REG OUTCOME trial with Empagliflozin, is it possible to speak of a class effect?

The recently published cardiovascular outcomes data for the first sodium-glucose cotransporter 2 (SGLT2) inhibitor, empagliflozin, have shown cardiovascular safety and additional benefits in patients with type 2 diabetes and established cardiovascular disease. Empagliflozin showed lower rates of death from cardiovascular causes or from any causes and lower hospitalization rates from heart failure compared with placebo, both in addition to standard care. This commentary discusses the existence of a possible class effect considering the available evidence described for other SGLT2 inhibitors

Valoración de la evaluación del espesor de la capa de fibras nerviosas de la retina y de las células ganglionares tras una neuritis óptica isquémica anterior

La neuropatía óptica isquémica anterior (NOIA) es una enfermedad oftalmológica caracterizada por un infarto del disco óptico que lleva a la pérdida de visión.Existen dos tipos: la forma no arterítica (NOIA NA) y la forma arterítica, esta última asociada a la arteritis de células gigantes.En ambas, es constante la rápida pérdida de visión sin dolor. Señales y síntomas como malestar general, dolores musculares, cefalea temporal, dolor al peinarse el cabello, dolor en la mandíbula después de masticar, y sensibilidad a los lados de la cabeza sobre la arteria temporal pueden estar presentes con la arteritis de células gigantes. La agudeza visual está disminuida y el disco óptico aparecehinchado. El campo visual suele presentar un defecto altitudinal inferior o superior, aunque puede estar completamente abolido.La pérdida visual suele ser permanente, con cierta recuperación dentro de las primeras semanas o meses.La forma arterítica se trata con corticoides, pero ningún tratamiento ha demostrado ser efectivo en la forma no arterítica.Se han recogido datos de 15 pacientes con NOIA NA. Para ello se han medido el espesor de la capa de fibras nerviosas de la retina (CFNR) en 4 sectores y de lacapa de células ganglionares (CGL) en 6 sectores con ayuda de la tomografía de coherencia óptica (OCT), en el instante en el que el paciente acudió a urgencias, al mes de padecer el episodio, y a los 6 meses.La primera medición muestra un aumento de espesor de la CFNR, mientras que al mes y 6 meses del episodio se observa una disminución del espesor, quedando más delgado que en el ojo contralateral. En cambio, la capa de CGL disminuye desde el primer día y sigue disminuyendo el próximo mes y manteniéndose a los 6.Con estos datos, se puede concluir que la medida del espesor de la capa de CGL unmes después de la neuritis puede predecir la disfunción visual final.<br /

Exploring the Diversity of the Thioredoxin Systems in Cyanobacteria

Cyanobacteria evolved the ability to perform oxygenic photosynthesis using light energy to reduce CO2 from electrons extracted from water and form nutrients. These organisms also devel-oped light-dependent redox regulation through the Trx system, formed by thioredoxins (Trxs) and thioredoxin reductases (TRs). Trxs are thiol-disulfide oxidoreductases that serve as reducing sub-strates for target enzymes involved in numerous processes such as photosynthetic CO2 fixation and stress responses. We focus on the evolutionary diversity of Trx systems in cyanobacteria and discuss their phylogenetic relationships. The study shows that most cyanobacteria contain at least one copy of each identified Trx, and TrxA is the only one present in all genomes analyzed. Ferredoxin thiore-doxin reductase (FTR) is present in all groups except Gloeobacter and Prochlorococcus, where there is a ferredoxin flavin-thioredoxin reductase (FFTR). Our data suggest that both TRs may have coex-isted in ancestral cyanobacteria together with other evolutionarily related proteins such as NTRC or DDOR, probably used against oxidative stress. Phylogenetic studies indicate that they have different evolutionary histories. As cyanobacteria diversified to occupy new habitats, some of these proteins were gradually lost in some groups. Finally, we also review the physiological relevance of redox regulation in cyanobacteria through the study of target enzymes.Junta de Andalucía BIO-28

Comparative Study of Several Fe Deficiency Responses in the Arabidopsis thaliana Ethylene Insensitive Mutants ein2-1 and ein2-5

Iron (Fe) is an essential micronutrient for plants since it participates in essential processes such as photosynthesis, respiration and nitrogen assimilation. Fe is an abundant element in most soils, but its availability for plants is low, especially in calcareous soils. Fe deficiency causes Fe chlorosis, which can affect the productivity of the affected crops. Plants favor Fe acquisition by developing morphological and physiological responses in their roots. Ethylene (ET) and nitric oxide (NO) have been involved in the induction of Fe deficiency responses in dicot (Strategy I) plants, such as Arabidopsis. In this work, we have conducted a comparative study on the development of subapical root hairs, of the expression of the main Fe acquisition genes FRO2 and IRT1, and of the master transcription factor FIT, in two Arabidopsis thaliana ET insensitive mutants, ein2-1 and ein2-5, affected in EIN2, a critical component of the ET transduction pathway. The results obtained show that both mutants do not induce subapical root hairs either under Fe deficiency or upon treatments with the ET precursor 1-aminocyclopropane-1-carboxylate (ACC) and the NO donor S-nitrosoglutathione (GSNO). By contrast, both of them upregulate the Fe acquisition genes FRO2 and IRT1 (and FIT) under Fe deficiency. However, the upregulation was different when the mutants were exposed to ET [ACC and cobalt (Co), an ET synthesis inhibitor] and GSNO treatments. All these results clearly support the participation of ET and NO, through EIN2, in the regulation of subapical root hairs and Fe acquisition genes. The results will be discussed, taking into account the role of both ET and NO in the regulation of Fe deficiency responses

Submersible Printed Split-Ring Resonator-Based Sensor for Thin-Film Detection and Permittivity Characterization

A split-ring resonator (SRR)-based sensor for the detection of solid thickness and relative permittivity characterization of solid and liquid materials is proposed. The structure is composed of two SRRs hosted in a microstrip transmission line. The sensing principle is based on the detection of the notch introduced by the resonators in the transmission coefficient. Hence, a frequency shift of the notch is related to a change in the effective permittivity of the structure when the sensor is covered with any solid or liquid material. A complete characterization of the sensor, for the three proposed applications, is performed through simulations. Finally, all simulated results are corroborated with measurements. The proposed sensor is implemented in single-layer printed technology, resulting in a low-cost and low-complexity solution. It presents real-time response and high sensitivity. Moreover, it is fully submersible and reusable

Ethylene could influence ferric reductase, iron transporter, and H\u3csup\u3e+\u3c/sup\u3e-ATPase gene expression by affecting FER (or FER-like) gene activity

In previous works, it has been shown, by using ethylene inhibitors and precursors, that ethylene could participate in the regulation of the enhanced ferric reductase activity of Fe-deficient Strategy I plants. However, it was not known whether ethylene regulates the ferric reductase gene expression or other aspects related to this activity. This paper is a study of the effects of ethylene inhibitors and precursors on the expression of the genes encoding the ferric reductases and iron transporters of Arabidopsis thaliana (FRO2 and IRT1) and Lycopersicon esculentum (= Solanum lycopersicum) (FRO1 and IRT1) plants. The effects of ethylene inhibitors and precursors on the activity of the iron reductase and the iron transporter have been examined in parallel. Also studied were the effects of ethylene inhibitors and precursors on the expression of the H+-ATPase genes of cucumber (CsHA1 and CsHA2) and the transcription factor genes of tomato (LeFER) and Arabidopsis (AtFRU or AtFIT1, an LeFER homologue) that regulate ferric reductase, iron transporter, and H+-ATPse activity. The results obtained suggest that ethylene participates in the regulation of ferric reductase, the iron transporter, and H+-ATPase gene expression by affecting the FER (or FER-like) levels