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Lifted Kramers spin degeneracy (LKSD) has been among the central topics of condensed-matter physics since the dawn of the band theory of solids1,2. It underpins established practical applications as well as current frontier research, ranging from magnetic-memory technology3-7 to topological quantum matter8-14. Traditionally, LKSD has been considered to originate from two possible internal symmetry-breaking mechanisms. The first refers to time-reversal symmetry breaking by magnetization of ferromagnets and tends to be strong because of the non-relativistic exchange origin15. The second applies to crystals with broken inversion symmetry and tends to be comparatively weaker, as it originates from the relativistic spin-orbit coupling (SOC)16-19. A recent theory work based on spin-symmetry classification has identified an unconventional magnetic phase, dubbed altermagnetic20,21, that allows for LKSD without net magnetization and inversion-symmetry breaking. Here we provide the confirmation using photoemission spectroscopy and ab initio calculations. We identify two distinct unconventional mechanisms of LKSD generated by the altermagnetic phase of centrosymmetric MnTe with vanishing net magnetization20-23. Our observation of the altermagnetic LKSD can have broad consequences in magnetism. It motivates exploration and exploitation of the unconventional nature of this magnetic phase in an extended family of materials, ranging from insulators and semiconductors to metals and superconductors20,21, that have been either identified recently or perceived for many decades as conventional antiferromagnets21,24,25.
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Nanoparticles (NPs) that can activate macrophages infected with the tuberculosis causative pathogen Mycobacterium tuberculosis, could be an effective host directed therapy for the disease. In this study, curdlan was conjugated to poly(lactic-co-glycolic acid) (PLGA) to produce immunotherapeutic NPs. Various physicochemical characterizations were used to evaluate the curdlan-PLGA copolymer and the NPs. Molecular dynamics and simulation studies were used to characterize the interaction between curdlan, on the polymer and on NPs, with the Dectin-1 macrophage receptor. NPs with varying curdlan densities were evaluated for their effects on the production of pro- and anti-inflammatory cytokines in M. tuberculosis infected RAW264.7 macrophages. The killing efficacy of the NPs against intracellular M. tuberculosis was assessed. Physicochemical characterization of the curdlan-PLGA copolymer and NPs indicated successful formation of curdlan-PLGA copolymer and NPs of varying curdlan density (0-8% w/w) had sizes between 330 and 453 nm. Modelling studies showed curdlan to have a strong affinity for Dectin-1. Cytotoxicity assays showed the NPs to be non-toxic over 72 h. The proinflammatory cytokine TNF-α was found to be significantly upregulated by the NPs. The NPs reduced intracellular M. tuberculosis burden over 72 h. These NPs are a promising host directed therapy for intracellular eradication of M. tuberculosis.
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Mycobacterium tuberculosis , Nanopartículas , Portadores de Fármacos/química , Glicoles , Ácido Láctico/química , Nanopartículas/química , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , beta-GlucanosRESUMEN
BACKGROUND: Large gaps remain in our understanding of the role of social media platforms in the dissemination of medical information. This cross-sectional study quantitatively assessed the accuracy and quality of information on YouTube regarding epidural labor analgesia. METHODS: YouTube was searched on May 23, 2020 using keywords 'epidural,' 'epidural for labor,' 'epidural for pregnancy,' 'epidural experience,' and 'epidural risks,' and the top 50 viewed videos from each search were screened. Primary outcomes included the proportion of videos containing non-factual information, and video quality analyzed using the modified DISCERN (mDISCERN) score. RESULTS: Thirteen of 60 (21.7%) videos included non-factual information about epidural analgesia; these videos were viewed more than 16.5 million times (60% of total viewership of the videos analyzed). Mean (standard deviation) mDISCERN score for all included videos was 1.9 (1.3), which is below the threshold for high video-quality. Videos from medical sources (hospitals, medical practices, physicians, other medical professionals) had a higher mDISCERN score compared with videos by non-medical sources (P <0.001). Educational videos from professional societies of obstetrics or obstetric anesthesiology were not captured. CONCLUSION: YouTube is an accessible platform for medical information on epidural labor analgesia, although a significant proportion of videos studied contained non-factual information and presented low video quality. Increased efforts by reputable sources including hospitals, physicians, other medical professionals, and professional societies, to disseminate accurate information, are warranted.
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Analgesia Epidural , Dolor de Parto , Medios de Comunicación Sociales , Estudios Transversales , Femenino , Humanos , Difusión de la Información , Embarazo , Grabación en VideoRESUMEN
The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Néel vector indicating the direction of the staggered magnetization. Pulsed magnetic fields of 60 T were used to orient the sublattice magnetizations of capped epitaxial Mn2Au(001) thin films perpendicular to the applied field direction by a spin-flop transition. The electronic structure and its corresponding changes were investigated by angular-resolved photoemission spectroscopy with photon energies in the vacuum-ultraviolet, soft, and hard X-ray range. The results reveal an energetic rearrangement of conduction electrons propagating perpendicular to the Néel vector. They confirm previous predictions on the origin of the Néel spin-orbit torque and anisotropic magnetoresistance in Mn2Au and reflect the combined antiferromagnetic and spin-orbit interaction in this compound leading to inversion symmetry breaking.
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BACKGROUND: Antibiotics are the most prescribed medication in the neonatal intensive care unit (NICU) and there is marked variation in their use. While they are vital for treatment of infections, they put infants at risk for infections with drug resistant organisms, alteration in their microbiome and several other morbidities. Specific guidelines for neonates are often lacking and our NICU is not compliant with late onset sepsis (LOS) guidelines. OBJECTIVE: By January 2019, there will be >75% compliance with our LOS bundle for any infant admitted to Tampa General Hospital's (TGH) NICU undergoing a LOS evaluation at >72 h of life. The bundle includes documented reason for LOS evaluation, appropriate initial antibiotic selection, appropriate initial evaluation considered, and appropriate de-escalation of antibiotics. STUDY DESIGN: The project was implemented in the NICU at TGH, the academic medical center affiliated with the University of South Florida in Tampa, FL. The multidisciplinary antimicrobial stewardship (ASP) team responsible for the project consists of a neonatology attending, three neonatology fellows, a pediatric infectious disease attending, and two NICU pharmacists. The project was started in January 2017 and all data were collected prospectively. We implemented multiple Plan-Do-Study-Act cycles in a stepwise manner; outcome measures included compliance with the LOS bundle and ASP team recommendations. Our process measures were the documented reason for sepsis evaluation, appropriate initial evaluation considered, appropriate antibiotic selection and appropriate antibiotic de-escalation. Patient length of stay was the balancing measure studied. RESULTS: During this 20-month initiative, there were 232 infants who underwent LOS evaluation and there were 98 true positive cultures from blood (28%), urine (35%), and cerebrospinal fluid (3%). Commonly documented rationales for treatment of culture negative sepsis were clinical pneumonia (38%) and necrotizing enterocolitis (38%). Common indications for LOS evaluations were increased respiratory support (51%) and abdominal distension (17%). There was improvement in appropriate initial antibiotic selection (70% vs. 94%); appropriate consideration of initial evaluation (63% vs. 94%, respectively); appropriate de-escalation of antibiotics (86% vs. 100%, respectively) and increase in LOS bundle compliance (44% vs. 87%, respectively). The overall antibiotic utilization rate and length of treatment did not change significantly. CONCLUSIONS: Developing and engaging a NICU ASP team improves compliance with late onset sepsis guidelines through the implementation of a LOS bundle of care.
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Programas de Optimización del Uso de los Antimicrobianos , Sepsis , Antibacterianos/uso terapéutico , Niño , Humanos , Lactante , Recién Nacido , Unidades de Cuidado Intensivo Neonatal , Mejoramiento de la Calidad , Sepsis/diagnóstico , Sepsis/tratamiento farmacológicoRESUMEN
Aims: The primary objective of the present study was to evaluate the economic burden of specific learning disability (SpLD) by estimating its direct, indirect, and intangible costs. A secondary objective was to assess the impact of variables on the economic burden. Settings and Design: Cross-sectional single-arm descriptive study. Setting: Learning disability clinic in a public medical college in Mumbai. Subjects and Methods: The study cases (aged ≥8 years) were recruited by non-probability sampling. A structured questionnaire was used to interview the parent/guardian to collect data related to direct and indirect costs. Intangible costs data were collected by documenting the willingness-to-pay value using the contingent valuation technique. Statistical Analysis Used: A quantile regression model was used to assess the impact of predictor variables on the costs. Results: The direct, indirect, and intangible costs due to SpLD were Indian Rupees (INR) 5,936,053, 29,261,220, and 42,295,000, respectively. Indirect costs comprised 83.1% of the total costs. Expenditure on tuitions and remedial education comprised 61.61% and 64.39% of the indirect and direct costs, respectively. The average annual learning disability clinic costs were INR 2,169,888. The average annual total costs per student were INR 90,773. Longer duration of poor school performance was predictive of higher direct, indirect, and total costs; and higher socioeconomic status was predictive of lower intangible costs. Conclusion: SpLD is a cost-intensive disability (intangible > indirect > direct costs). Tuitions, which are not the therapy for SpLD, are the most costly component of indirect costs. Remedial education is the most costly component of direct costs.
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Costo de Enfermedad , Educación Especial/economía , Costos de la Atención en Salud/estadística & datos numéricos , Discapacidades para el Aprendizaje/economía , Adolescente , Niño , Estudios Transversales , Femenino , Humanos , India/epidemiología , Discapacidades para el Aprendizaje/epidemiología , Masculino , Prevalencia , Análisis de Regresión , Educación Compensatoria/economía , Factores Socioeconómicos , Encuestas y CuestionariosRESUMEN
The premartensite phase of shape memory and magnetic shape memory alloys (MSMAs) is believed to be a precursor state of the martensite phase with preserved austenite phase symmetry. The thermodynamic stability of the premartensite phase and its relation to the martensitic phase is still an unresolved issue, even though it is critical to the understanding of the functional properties of MSMAs. We present here unambiguous evidence for macroscopic symmetry breaking leading to robust Bain distortion in the premartensite phase of 10% Pt-substituted Ni2MnGa. We show that the robust Bain-distorted premartensite (T2) phase results from another premartensite (T1) phase with preserved cubic-like symmetry through an isostructural phase transition. The T2 phase finally transforms to the martensite phase with additional Bain distortion on further cooling. Our results demonstrate that the premartensite phase should not be considered as a precursor state with the preserved symmetry of the cubic austenite phase.
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BACKGROUND: Several SNPs were identified through GWAS for their association with type 2 diabetes which has implications to pancreatic ß-cell physiology. OBJECTIVE: We aimed to study the role of risk alleles of TCF7L2, KCNJ11, CDKN2A, CDKAL1, IGF2BP2, SLC30A8 and KCNQ1 along with pharmacokinetic variants in response to sulfonylureas. METHOD: We performed a prospective study on 209 newly diagnosed subjects; treatment naive T2D subjects were recruited. Individuals were started with glibenclamide monotherapy and followed-up for 12 weeks. Genotyping was done, using PCR-RFLP and TETRA-ARMS PCR and confirmed by DNA sequencing. RESULTS: In univariate regression analysis, KCNJ11 (rs5219) was only the predictor for glibenclamide treatment failure. CONCLUSION: The present data suggests a possible role of KCNJ11 gene in altered response to glibenclamide.
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Diabetes Mellitus Tipo 2/genética , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Gliburida/farmacología , Hipoglucemiantes/farmacología , Polimorfismo de Nucleótido Simple , Canales de Potasio de Rectificación Interna/genética , Adulto , Anciano , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/patología , Femenino , Genotipo , Humanos , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patología , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Adulto JovenRESUMEN
With the advent of donation after circulatory death programs in Australia and New Zealand, greater knowledge is needed about physiologic variation in haemodynamic activity following withdrawal of cardiorespiratory support. The ANZICS Statement on Death and Organ Donation allows provision for variation in the observation times between two and five minutes after cessation of the circulation prior to declaration of death. We report our experience of two cases, the first where electrical activity and pulse returned after a 102 second pause and the second where electrical activity returned after a three minute pause; both longer than previously reported cases.
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Electrocardiografía , Paro Cardíaco , Obtención de Tejidos y Órganos , Femenino , Hospitales , Humanos , Persona de Mediana EdadRESUMEN
Antiferromagnetic spintronics is a rapidly growing field, which actively introduces new principles of magnetic storage. Despite that, most applications have been suggested for collinear antiferromagnets. In this study, we consider an alternative mechanism based on long-range helical order, which allows for direct manipulation of the helicity vector. As the helicity of long-range homogeneous spirals is typically fixed by the Dzyaloshinskii-Moriya interactions, bi-stable spirals (left- and right-handed) are rare. Here, we report a non-collinear room-temperature antiferromagnet in the tetragonal Heusler group. Neutron diffraction reveals a long-period helix propagating along its tetragonal axis. Ab-initio analysis suggests its pure exchange origin and explains its helical character resulting from a large basal plane magnetocrystalline anisotropy. The actual energy barrier between the left- and right-handed spirals is relatively small and might be easily overcome by magnetic pulse, suggesting Pt2MnGa as a potential candidate for non-volatile magnetic memory.
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A descriptive case report of a 22-year-old woman, scheduled for elective laparotomy who had a respiratory arrest after premedication with inj glycopyrrolate and ondansetron. Respiratory arrest is an uncommon side effect of glycopyrrolate with very few published reports. Ondansteron can also cause respiratory arrest, however is most often associated with bradycardia. This patient had tachycardia and respiratory arrest and is suggestive of glycopyrrolate-induced respiratory arrest. This case report highlights the importance of strict vigilance by the anaesthesiologist even during premedication.
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Adyuvantes Anestésicos/efectos adversos , Glicopirrolato/efectos adversos , Premedicación/efectos adversos , Insuficiencia Respiratoria/inducido químicamente , Adulto , Femenino , Humanos , Taquicardia/inducido químicamente , Adulto JovenRESUMEN
Arsenic (As) is a ubiquitously present environmental carcinogen that enters into the human food chain through rice grains. In our previous research, the application of thiourea (TU; a non-physiological thiol based ROS scavenger) has been demonstrated to enhance salt and UV stress tolerance as well as the crop yield under field conditions. These effects were associated with the ability of TU to maintain plant redox homeostasis. Since As stress also induces redox imbalance, the present research was initiated to evaluate the efficiency of TU in regulating As tolerance/accumulation in rice. The supplementation of TU (75 µM) to As(V) (25 µM) improved the root growth and also reduced the As concentration by 56% in the aerial parts, which could be attributed to significant downregulation of the Lsi2 transporter responsible for the translocation of As from root to shoot. The fact that these effects were not due to direct interaction between As and TU was confirmed from complexation studies using HPLC-(ICP-MS)-(ESI-MS). Short-term kinetic studies of GSH levels and the GSH/GSSG ratio confirmed the establishment of differential redox states in As and As + TU treated seedlings. The real-time RT-PCR based comparative expression profiling under As with/without TU treatment identified Sultr1;1 and Sultr1;2 as major redox-regulated sulfate transporters. Their specific induction in shoots coupled with enhanced root-to-shoot sulfate translocation (analyzed using (35)S-sulfate as a radiotracer) was observed under TU supplementation. Furthermore, the level of thiolic metabolites (PC2 in roots and GSH and PC3 in shoots) and activities of sulfur metabolism enzymes (ATP sulfurylase and cysteine synthase in roots and 5'-adenylylsulfate reductase in shoot) were also increased with As + TU as compared to As treatment. Thus, this study utilizes the interaction between As and TU to identify the critical redox regulated components of As tolerance in rice.
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Adaptación Fisiológica/efectos de los fármacos , Arsénico/toxicidad , Oryza/metabolismo , Tiourea/farmacología , Cromatografía Líquida de Alta Presión , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Glutatión/metabolismo , Humanos , Cinética , Oryza/efectos de los fármacos , Oryza/enzimología , Oryza/genética , Oxidación-Reducción/efectos de los fármacos , Fenotipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Brotes de la Planta/efectos de los fármacos , Brotes de la Planta/metabolismo , Plantones/efectos de los fármacos , Plantones/metabolismo , Espectrofotometría Atómica , Estrés Fisiológico/efectos de los fármacos , Compuestos de Sulfhidrilo/metabolismo , Azufre/metabolismo , Radioisótopos de AzufreRESUMEN
Tributyl phosphate (TBP) has enormous applications in the field of extraction, fuel reprocessing, as defoamers and/or plasticizers. Excessive usage of this organophosphorus compound, poses an environmental threat. The present study deals with microbial degradation of TBP using Klebsiella pneumoniae S3 isolated from the soil. Diauxic growth curve pattern explains a preferential utilization of TBP. The strain S3 was able to biotransform TBP (1,000 mg L⻹) to dibutyl phosphate within 48 h and showed higher tolerance towards TBP up to 17.0 g L⻹. Toxicity of the parent as well as degraded product was assessed using comet assay. Generation of reactive oxygen species elaborates the oxidative stress imposed upon the bacterial strain by TBP. The antioxidant defense mechanism was studied using various biomarkers namely catalase, glutathione-S-transferase, and superoxide dismutase. The present study describes a faster and eco-friendly alternative for disposal of TBP.
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Klebsiella pneumoniae/metabolismo , Organofosfatos/metabolismo , Biotransformación , Ensayo Cometa , Contaminantes Ambientales/metabolismo , Contaminantes Ambientales/toxicidad , Klebsiella pneumoniae/crecimiento & desarrollo , Klebsiella pneumoniae/aislamiento & purificación , Pruebas de Mutagenicidad , Organofosfatos/toxicidad , Estrés Oxidativo , Microbiología del SueloRESUMEN
The present study analyzed the expression level of aquaporins of plasma membrane intrinsic protein (PIP) class in response to arsenite (AsIII) exposure of 100 µM from 0.5 h to 8 days in Brassica juncea. The expression levels of most of the PIPs were down-regulated during the course of AsIII exposure. This led to decrease in total water content of plants, which in turn hampered seedling growth. The level of reactive oxygen species (superoxide radicals and hydrogen peroxide), lipid peroxidation and root oxidizability increased significantly upon exposure to AsIII as compared to that of control leading to an increase in cell death. The study proposes that the down-regulation of PIPs happened presumably to regulate AsIII levels, which, however, occurred at the cost of reduced growth, disturbed water balance and induced oxidative stress.
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Acuaporinas/genética , Perfilación de la Expresión Génica , Planta de la Mostaza/genética , Proteínas de Plantas/genética , Acuaporinas/metabolismo , Arsenitos/toxicidad , Muerte Celular/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas , Peróxido de Hidrógeno/metabolismo , Peroxidación de Lípido , Planta de la Mostaza/efectos de los fármacos , Planta de la Mostaza/crecimiento & desarrollo , Estrés Oxidativo , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Isoformas de Proteínas/genética , Plantones/genética , Plantones/crecimiento & desarrollo , Estrés Fisiológico/genética , Agua/químicaRESUMEN
Octapeptide (OP)/FSH-Receptor Binding Inhibitor-8 (FRBI-8), is a synthetic peptide corresponding to N-terminal sequence of purified fraction of Follicle Stimulating Hormone Binding-Inhibitor (FSHBI), isolated earlier from human ovarian follicular-fluid. In order to avoid the repeated drug-administration, OP-loaded, polymeric polylactide (PLA) nanoparticle formulation (NP-OP), was developed using multiple-emulsion technique. This yielded an average particle size of 120 nm with 70% encapsulation-efficiency. In vitro release profile of NP-OP showed sustained release of OP for 21 days. In vivo anti-fertility studies were conducted in marmosets. Results indicated that control animals conceived in the same cycle while two of three treated animals failed to conceive in treatment cycle. The in vivo studies thus corroborate with in vitro release of OP, demonstrating its anti-fertility activity in 66% of animals.
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Proteínas Portadoras/química , Anticoncepción , Nanopartículas/química , Folículo Ovárico/química , Fragmentos de Péptidos/química , Animales , Callithrix/fisiología , Proteínas Portadoras/administración & dosificación , Femenino , Humanos , Nanopartículas/administración & dosificación , Tamaño de la Partícula , Fragmentos de Péptidos/administración & dosificación , Polímeros/administración & dosificación , Polímeros/químicaRESUMEN
Eggshell membrane is a natural material, essentially made up of protein fibers having flexibility in the aqueous solution and possessing gas and water permeability. It is used as a biomembrane for immobilization of urease for the development of a potentiometric urea biosensor. Eggshell membrane was treated with polyethyleneimine (PEI) to impart polycation characteristics. Urease was immobilized on the PEI treated eggshell membrane through adsorption. SEM study was carried out to observe the changes in surface morphology after immobilization. FTIR study of membrane was carried out to observe the changes in IR spectra after immobilization of enzyme. Immobilized membrane was associated with ammonium ion selective electrode. Biosensor exhibited sigmoidal responses for the urea concentration range from 0.5 to 10mM. The response time of the biosensor was 120 s. A single membrane was reused for 270 reactions without loss of activity. The urease-eggshell membranes were stable for 2 months when stored in buffer even at room temperature.
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Ureasa/metabolismo , Técnicas Biosensibles , Membrana Celular/química , Huevos , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/metabolismo , Electrodos de Iones Selectos , Microscopía Electrónica de Rastreo , Polietileneimina/química , Potenciometría , Espectroscopía Infrarroja por Transformada de Fourier , Urea/análisis , Ureasa/químicaRESUMEN
MicroRNAs (miRNAs) constitute a novel mechanism of gene regulation affecting plant development, growth, and stress response. To study the role of miRNAs in arsenic (As) stress, microarray profiling of miRNAs was performed in Brassica juncea using a custom Phalanx Plant OneArray containing 381 unique miRNA probes representing 618 miRNAs from 22 plant species. miRNA microarray hybridization of roots exposed to As for 1h and 4h revealed that a total of 69 miRNAs belonging to 18 plant miRNA families had significantly altered expression. The As-responsive miRNAs also exhibited a time- and organ-dependent change in their expression. Putative target prediction for the miRNAs suggested that they regulate various developmental processes (e.g. miR156, miR169, and miR172), sulphur uptake, transport, and assimilation (miR395, miR838, and miR854), and hormonal biosynthesis and/or function (e.g. miR319, miR167, miR164, and miR159). Notable changes were observed in the level of auxins [indole-3-acetic acid (IAA), indole-3- butyric acid, and naphthalene acetic acid], jasmonates [jasmonic acid (JA) and methyl jasmonate], and abscisic acid. The exogenous supply of JA and IAA improved growth of plants under As stress and altered expression of miR167, miR319, and miR854, suggesting interplay of hormones and miRNAs in the regulation of As response. In conclusion, the present work demonstrates the role of miRNAs and associated mechanisms in the plant's response towards As stress.
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Arsénico/toxicidad , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , MicroARNs/genética , Planta de la Mostaza/efectos de los fármacos , Planta de la Mostaza/genética , Estrés Fisiológico/genética , Ciclopentanos/farmacología , Ácidos Indolacéticos/farmacología , MicroARNs/metabolismo , Modelos Biológicos , Planta de la Mostaza/crecimiento & desarrollo , Análisis de Secuencia por Matrices de Oligonucleótidos , Especificidad de Órganos/efectos de los fármacos , Especificidad de Órganos/genética , Oxilipinas/farmacología , Reguladores del Crecimiento de las Plantas/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Reproducibilidad de los Resultados , Estrés Fisiológico/efectos de los fármacos , Factores de TiempoRESUMEN
Phytoremediation is a viable strategy for management of toxic wastes in a large area/volume with low concentrations of toxic elemental pollutants. With increased industrial use of cobalt and its alloys, it has become a major metal contaminant in soils and water bodies surrounding these industries and mining sites with adverse effects on the biota. A bacterial Co-Ni permease was cloned from Rhodopseudomonas palustris and introduced into Nicotiana tabacum to explore its potential for phytoremediation and was found to be specific for cobalt and nickel. The transgenic plants accumulated more cobalt and nickel as compared to control, whereas no significant difference in accumulation of other divalent ions was observed. The transgenic plants were evaluated for cobalt content and showed increased acquisition of cobalt (up to 5 times) as compared to control. The plants were also assessed for accumulation of nickel and found to accumulate up to 2 times more nickel than control. At the same initial concentration of cobalt and nickel, transgenic plant preferentially accumulated cobalt as compared to nickel. The present study is perhaps the first attempt to develop transgenic plants expressing heterologous Co transporter with an improved capacity to uptake cobalt.
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Proteínas Bacterianas/genética , Cobalto/metabolismo , Proteínas de Transporte de Membrana/genética , Nicotiana/metabolismo , Proteínas Bacterianas/metabolismo , Biodegradación Ambiental , Proteínas de Transporte de Membrana/metabolismo , Níquel/metabolismo , Raíces de Plantas/metabolismo , Brotes de la Planta/metabolismo , Plantas Modificadas Genéticamente , Nicotiana/genéticaRESUMEN
Arsenic (As) contamination of the environment has emerged as a serious problem. Consequently, there is an urge to understand plants' responses to As. The analysis of various hypertolerant and hyperaccumulator plants and comparison of their responses with non-tolerant and nonaccumulators have provided valuable information about the mechanisms of As tolerance and detoxification. Therefore, we understand why most of the pteridophytes are able to hyperacumulate As, why it is difficult to find hyperaccumulators among angiosperms and why rice is able to translocate As to its grains more efficiently than any other cereal crop. This information can be employed to generate As hyperaccumulators in angiosperms and to develop safe cultivars of rice for human consumption through biotechnological approaches. Although measurable success, in terms of application in the field, has so far not been achieved, transgenic research has yielded promising results, which shed light on the approaches to be taken up in future endeavor. In this review, we discuss the mechanisms of As tolerance and detoxification in plants and transgenic research conducted.
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Arsénico/metabolismo , Magnoliopsida/fisiología , Plantas Modificadas Genéticamente/fisiología , Arsénico/toxicidad , Biodegradación Ambiental , Magnoliopsida/efectos de los fármacos , Magnoliopsida/genética , Plantas Modificadas Genéticamente/efectos de los fármacos , Plantas Modificadas Genéticamente/genéticaRESUMEN
Spin valves have revolutionized the field of magnetic recording and memory devices. Spin valves are generally realized in thin film heterostructures, where two ferromagnetic (FM) layers are separated by a nonmagnetic conducting layer. Here, we demonstrate spin-valve-like magnetoresistance at room temperature in a bulk ferrimagnetic material that exhibits a magnetic shape memory effect. The origin of this unexpected behavior in Mn(2)NiGa has been investigated by neutron diffraction, magnetization, and ab initio theoretical calculations. The refinement of the neutron diffraction pattern shows the presence of antisite disorder where about 13% of the Ga sites are occupied by Mn atoms. On the basis of the magnetic structure obtained from neutron diffraction and theoretical calculations, we establish that these antisite defects cause the formation of FM nanoclusters with parallel alignment of Mn spin moments in a Mn(2)NiGa bulk lattice that has antiparallel Mn spin moments. The direction of the Mn moments in the soft FM cluster reverses with the external magnetic field. This causes a rotation or tilt in the antiparallel Mn moments at the cluster-lattice interface resulting in the observed asymmetry in magnetoresistance.