Plants and sodium ions: keeping company with the enemy

Plants face a dilemma about sodium metabolism. Uptake of ubiquitous sodium ions is desirable as a way to build osmotic potential, absorb water and sustain turgor, but excess sodium ions may be toxic. Information from a number of plant species about the proteins involved in sodium-ion uptake helps to explain how plants manage to take in just the right amount

Overexpression of the sodium ATPase of Saccharomyces cerevisiae: conditions for phosphorylation from ATP and Pi

AbstractThe ENA1 gene of Saccharomyces cerevisiae encodes a putative ATPase necessary for Na+ efflux. Plasma membranes and intracellular membranes of a yeast strain overexpressing the ENA1 gene contain significant amounts of ENA1 protein. Consequences of the overexpression with reference to the wild-type strain are: (1) a 5-fold higher content of the ENA1-protein in plasma membranes; (2) lower Na+ and Li+ effluxes; (3) slightly higher Na+ tolerance; and (4) much higher Li+ tolerance. The ENA1-specific ATPase activity in plasma membrane preparations of the overexpressing strain was low, but an ENA1 phosphoprotein was clearly detected when the plasma membranes were exposed to ATP in the presence of Na+ or to Pi in the absence of Na+. The characteristics of this phosphoprotein, which correspond to the acyl phosphate intermediaries of P-type ATPases, the absolute requirement of Na+ or other alkali cations for phosphorylation, and the Na+ and pH dependence of phosphorylation from ATP and Pi suggest that the product of the ENA1 gene may be a Na,H-ATPase, which can also pump other alkali cations. The role of the intracellular membranes structures produced with the overexpression of ENA1 in Na+ and Li+ tolerances and the existence of a β-subunit of the ENA1 ATPase are discussed

Regulation of durum wheat Na(+)/H (+) exchanger TdSOS1 by phosphorylation

We have identified a plasma membrane Na+/H+ exchanger from durum wheat, designated TdSOS1. Heterologous expression of TdSOS1 in a yeast strain lacking endogenous Na+ efflux proteins showed complementation of the Na+- and Li+-sensitive phenotype by a mechanism involving cation efflux. Salt tolerance conferred by TdSOS1 was maximal when co-expressed with the Arabidopsis protein kinase complex SOS2/SOS3. In vitro phosphorylation of TdSOS1 with a hyperactive form of the Arabidopsis SOS2 kinase (T/DSOS2∆308) showed the importance of two essential serine residues at the C-terminal hydrophilic tail (S1126, S1128). Mutation of these two serine residues to alanine decreased the phosphorylation of TdSOS1 by T/DSOS2∆308 and prevented the activation of TdSOS1. In addition, deletion of the C-terminal domain of TdSOS1 encompassing serine residues at position 1126 and 1128 generated a hyperactive form that had maximal sodium exclusion activity independent from the regulatory SOS2/SOS3 complex. These results are consistent with the presence of an auto-inhibitory domain at the C-terminus of TdSOS1 that mediates the activation of TdSOS1 by the protein kinase SOS2. Expression of TdSOS1 mRNA in young seedlings of the durum wheat variety Om Rabia3, using different abiotic stresses (ionic and oxidative stress) at different times of exposure, was monitored by RT–PCR.Peer Reviewe

Domain wall dynamics in expanding spaces

We study the effects on the dynamics of kinks due to expansions and contractions of the space. We show that the propagation velocity of the kink can be adiabatically tuned through slow expansions/contractions, while its width is given as a function of the velocity. We also analyze the case of fast expansions/contractions, where we are no longer on the adiabatic regime. In this case the kink moves more slowly after an expansion-contraction cycle as a consequence of loss of energy through radiation. All these effects are numerically studied in the nonlinear Klein-Gordon equations (both for the sine-Gordon and for the phi^4 potential), and they are also studied within the framework of the collective coordinate evolution equations for the width and the center of mass of the kink. These collective coordinate evolution equations are obtained with a procedure that allows us to consider even the case of large expansions/contractions.Comment: LaTeX, 18 pages, 2 figures, improved version to appear in Phys Rev

Promotion of Direct Electron Transfer to Cytochrome c by Functionalized Thiophene-based Conducting Polymers

Controlling direct electron transfer (DET) to redox proteins is of great interest for fundamental studies on biochemical processes and the development of biotechnological devices, such as biosensors or enzymatic fuel cells. Cytochrome c is a classical model protein for studying DET reactions that plays a key role in the onset of cellular apoptosis and the mitochondrial respiratory chain. In this contribution, we explored DET between cyt c and conducting polymers bearing the chemical structure of thiophene, specifically PEDOT, and its OH-containing derivative, PHMeEDOT. The combination of electrochemistry and in situ FTIR spectroscopy allowed us to gain more insight into the inner mechanism of DET at physiological pH. Hydrophilic interactions favour the correct orientation of the heme crevice of cytochrome c towards the polymer surface. When a positive charge is injected into the conducting polymer, the increasing electrostatic repulsion between protein and surface induces the desorption of lysine residues near the heme group and stimulates protein flipping. This effect was more pronounced at PEDOT- than PHMeEDOT-modified electrodes since the latter shows stronger interactions with lysine residues, partially hindering protein rotation at moderate potential. The potential-induced reorientation process was similar on both polymer surfaces, only at high positive potentials.Financial support by Spanish Ministry of Science (projects TED2021-129894B-I00 and PDC2021-120884-I00), Generalitat Valenciana (projects GVA-THINKINAZUL/2021/015, MFA/2022/058 and CIPROM/2021/62) and European Union (NextGenerationEU PRTR-C17.I1) is gratefully acknowledged. A.G.-Q. acknowledges funding received from his Marie Skłodowska-Curie Postdoctoral Fellowship (Grant Number MSCA-IF-EF-ST 2020/101018277)

Release of SOS2 kinase from sequestration with GIGANTEA determines salt tolerance in Arabidopsis

Kim, Woe-Yeon et al.--Environmental challenges to plants typically entail retardation of vegetative growth and delay or cessation of flowering. Here we report a link between the flowering time regulator, GIGANTEA (GI), and adaptation to salt stress that is mechanistically based on GI degradation under saline conditions, thus retarding flowering. GI, a switch in photoperiodicity and circadian clock control, and the SNF1-related protein kinase SOS2 functionally interact. In the absence of stress, the GI:SOS2 complex prevents SOS2- based activation of SOS1, the major plant Na+/H+-antiporter mediating adaptation to salinity. GI over-expressing, rapidly flowering, plants show enhanced salt sensitivity, whereas gi mutants exhibit enhanced salt tolerance and delayed flowering. Salt-induced degradation of GI confers salt tolerance by the release of the SOS2 kinase. The GISOS2 interaction introduces a higher order regulatory circuit that can explain in molecular terms, the long observed connection between floral transition and adaptive environmental stress tolerance in Arabidopsis.This research was supported by the Next-Generation BioGreen 21 Program (Systems and Synthetic Agrobiotech Center, no. PJ008025), a Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ007850), and the Ministry of Education, Science and Technology for the World Class University (WCU) program (R32-10148) from the Rural Development Administration, Republic of Korea, and by grant BIO2009-08641 financed by the Spanish Ministry of Science and Innovation and the FEDER program.Peer reviewe

Role of SOS1 in potassium nutrition

Comunicación oral presentada al FESPB celebrado del 4-9 de julio, 2010, en Valencia, España.Peer reviewe

Building capacity for dementia care in Latin America and the Caribbean

Latin America and the Caribbean (LAC) have limited facilities and professionals trained to diagnose, treat, and support people with dementia and other forms of cognitive impairment. The situation for people with dementia is poor, and worsening as the proportion of elderly in the general population is rapidly expanding. We reviewed existing initiatives and provided examples of actions taken to build capacity and improve the effectiveness of individuals, organizations, and national systems that provide treatment and support for people with dementia and their caregivers. Regional barriers to capacity building and the importance of public engagement are highlighted. Existing programs need to disseminate their objectives, accomplishments, limitations, and overall lessons learned in order to gain greater recognition of the need for capacity-building programs

Valores éticos y desempeño laboral de los empleados universitarios de sector público

The purpose of this research was to determine the relationship between ethical values and job performance on the part of administrative employees in the humanistic nucleus of the University of Zulia. The results indicate that: a) the instrumental means that characterize the ethical values of the employees are honesty, loyalty and solidarity, while democracy, sincerity, trust and respect were moderately effective; b) the parameters considered in performance were disposition, responsibility and work load, but cooperation, initiative and quality turned out to be insignificant; c) ethical values related with employee performance were honesty, democracy, loyalty, solidarity, trust and respect with a positive correlational value of 0.517.La investigación, tuvo como propósito determinar la relación entre los valores éticos y desempeño laboral de los empleados administrativos del núcleo humanístico de la Universidad del Zulia. Los resultados indican: a) los medios instrumentales que caracterizan los valores éticos de los empleados son honestidad, lealtad y solidaridad, mientras la democracia, sinceridad, confianza y respeto resultaron medianamente efectivos; b) los parámetros considerados en el desempeño son disposición, responsabilidad y cantidad, pero el cooperativismo, iniciativa y calidad resultaron insignificativos; c) los valores éticos relacionados con el desempeño son honestidad, democracia, lealtad, solidaridad, confianza y respeto obteniendo una correlación positiva media (0.517)

¿Contribuyen los talleres en el Museo de Ciencias a fomentar actitudes hacia la conservación del ambiente?

Esta investigación se centró en evaluar el impacto de seis talleres sobre la adopción de actitudes deseables respecto a la conservación del ambiente y la sostenibilidad, por parte de distintos públicos visitantes de un Museo Interactivo. La metodología incluyó: a) el diseño de escalas con cuatro opciones de respuesta que se aplicaron antes y después del taller b) entrevistas telefónicas o visita a instituciones educativas, dos meses después de la visita al Museo. El análisis cuantitativo mostró que las actitudes de los participantes mejoraron en todos los talleres aunque no siempre fue estadísticamente significativo. El análisis cualitativo reveló que los participantes mostraron actitudes de compromiso y cuidado hacia el ambiente. Algunas estuvieron asociadas a los talleres y otras a actitudes desarrolladas con anterioridad al taller.This research focused on assessing the impact of six workshops on the adoption of desirable attitudes about environmental conservation and sustainability, of different group visitors of an interactive museum. The methodology included: a) the design of four-option scales that were applied before and after the workshop b) either telephone interviews or visits to schools, two months after the visit to the museum. The quantitative analysis showed that the attitudes of the participants improved in all the workshops but not all of them were statistically significant. The qualitative analysis revealed that participants demonstrated attitudes of commitment and care towards the environment. Some of these attitudes were associated with the workshops and other associated with attitudes developed prior to the workshop