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1.
Inorg Chem ; 63(15): 7007-7018, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38557070

RESUMEN

Double perovskite oxides, characterized by their tunable magnetic properties and robust interconnection between the lattice and magnetic degrees of freedom, present an enticing foundation for advanced magnetic refrigeration materials. Herein, we delve into the influence of rare-earth elements on RSrCoFeO6 (R = Sm, Eu) disordered double perovskites by examining their structural, electronic, magnetic, and magnetocaloric properties. Temperature-dependent synchrotron X-ray diffraction analysis confirmed the stability of the orthorhombic phase (Pnma) across a wide temperature range. X-ray photoemission spectroscopy revealed that both Sm and Eu are in the 3+ state, whereas multiple states for Co2+/3+ and Fe3+/4+ are identified. The magnetic investigation and magnetocaloric effect (MCE) analysis brought to light the presence of a long-range antiferromagnetic (AFM) order with a second-order phase transition (SOPT) in both samples. The maximum magnetic entropy change ΔSMmax was approximately 0.9 J/kg K for both samples at applied field 0-7 T, manifesting prominently above Neel temperatures TN ≈ 93 K (Sm) and 84 K (Eu). Nevertheless, different relative cooling powers (RCP) of 112.6 J/kg (Sm) and 95.5 J/kg (Eu) were observed. A detailed analysis of the temperature-dependent lattice parameters shed light on a distinct magnetocaloric effect across the magnetic transition temperature, unveiling an anisotropic thermal expansion [αV = 1.41 × 10-5 K-1 (Sm) and αV = 1.54 × 10-5 K-1 (Eu)] wherein the thermal expansion axial ratio αbSm/αbEu = 0.61 became lower with increasing temperature, which suggests that the Eu sample experiences a greater thermal expansion in the b-axis direction. At the atomic bonding level, the evidence for magnetoelastic coupling around the magnetic transition temperatures TN was found through the anomalies along the average Co/Fe-O bond distance, formal valence, octahedral distortion, as well as an anisotropic lattice expansion.

2.
Inorg Chem ; 63(27): 12641-12650, 2024 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-38920333

RESUMEN

Metal halide perovskites with a two-dimensional structure are utilized in photovoltaics and optoelectronics. High-crystallinity CsSn2Br5 specimens have been synthesized via ball milling. Differential scanning calorimetry curves show melting at 553 K (endothermic) and recrystallization at 516 K (exothermic). Structural analysis using synchrotron X-ray diffraction data, collected from 100 to 373 K, allows for the determination of Debye model parameters. This analysis provides insights into the relative Cs-Br and Sn-Br chemical bonds within the tetragonal structure (space group: I4/mcm), which remains stable throughout the temperature range studied. Combined with neutron data, X-N techniques permit the identification of the Sn2+ lone electron pair (5s2) in the two-dimensional framework, occupying empty space opposite to the four Sn-Br bonds of the pyramidal [SnBr4] coordination polyhedra. Additionally, diffuse reflectance UV-vis spectroscopy unveils an indirect optical gap of approximately ∼3.3 eV, aligning with the calculated value from the B3LYP-DFT method (∼3.2 eV). The material exhibits a positive Seebeck coefficient as high as 6.5 × 104 µV K-1 at 350 K, which evolves down to negative values of -3.0 × 103 µV K-1 at 550 K, surpassing values reported for other halide perovskites. Notably, the thermal conductivity remains exceptionally low, between 0.32 and 0.25 W m-1 K-1.

3.
Lancet Oncol ; 24(5): 496-508, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37142372

RESUMEN

BACKGROUND: HER2 is an actionable target in metastatic colorectal cancer. We assessed the activity of tucatinib plus trastuzumab in patients with chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer. METHODS: MOUNTAINEER is a global, open-label, phase 2 study that enrolled patients aged 18 years and older with chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer at 34 sites (clinics and hospitals) in five countries (Belgium, France, Italy, Spain, and the USA). Initially, the study was designed as a single-cohort study, which was expanded following an interim analysis to include more patients. Initially, patients were given tucatinib (300 mg orally twice daily) plus intravenous trastuzumab (8 mg/kg as an initial loading dose, then 6 mg/kg every 21 days; cohort A) for the duration of treatment (until progression), and after expansion, patients were randomly assigned (4:3), using an interactive web response system and stratified by primary tumour location, to either tucatinib plus trastuzumab (cohort B) or tucatinib monotherapy (cohort C). The primary endpoint was confirmed objective response rate per blinded independent central review (BICR) for cohorts A and B combined and was assessed in patients in the full analysis set (ie, patients with HER2-positive disease who received at least one dose of study treatment). Safety was assessed in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT03043313, and is ongoing. FINDINGS: Between Aug 8, 2017, and Sept 22, 2021, 117 patients were enrolled (45 in cohort A, 41 in cohort B, and 31 in cohort C), of whom 114 patients had locally assessed HER2-positive disease and received treatment (45 in cohort A, 39 in cohort B, and 30 in cohort C; full analysis set), and 116 patients received at least one dose of study treatment (45 in cohort A, 41 in cohort B, and 30 in cohort C; safety population). In the full analysis set, median age was 56·0 years (IQR 47-64), 66 (58%) were male, 48 (42%) were female, 88 (77%) were White, and six (5%) were Black or African American. As of data cutoff (March 28, 2022), in 84 patients from cohorts A and B in the full analysis set, the confirmed objective response rate per BICR was 38·1% (95% CI 27·7-49·3; three patients had a complete response and 29 had a partial response). In cohorts A and B, the most common adverse event was diarrhoea (55 [64%] of 86), the most common grade 3 or worse adverse event was hypertension (six [7%] of 86), and three (3%) patients had tucatinib-related serious adverse events (acute kidney injury, colitis, and fatigue). In cohort C, the most common adverse event was diarrhoea (ten [33%] of 30), the most common grade 3 or worse adverse events were increased alanine aminotransferase and aspartate aminotransferase (both two [7%]), and one (3%) patient had a tucatinib-related serious adverse event (overdose). No deaths were attributed to adverse events. All deaths in treated patients were due to disease progression. INTERPRETATION: Tucatinib plus trastuzumab had clinically meaningful anti-tumour activity and favourable tolerability. This treatment is the first US Food and Drug Administration-approved anti-HER2 regimen for metastatic colorectal cancer and is an important new treatment option for chemotherapy-refractory HER2-positive metastatic colorectal cancer. FUNDING: Seagen and Merck & Co.


Asunto(s)
Neoplasias del Colon , Neoplasias del Recto , Humanos , Masculino , Femenino , Persona de Mediana Edad , Trastuzumab/efectos adversos , Receptor ErbB-2/genética , Estudios de Cohortes , Anticuerpos Monoclonales Humanizados/efectos adversos , Neoplasias del Colon/tratamiento farmacológico , Diarrea/inducido químicamente , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos
4.
Inorg Chem ; 60(10): 7413-7421, 2021 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-33900757

RESUMEN

Skutterudite-type compounds based on □Co4Sb12 pnictide are promising for thermoelectric application due to their good Seebeck values and high carrier mobility. Filling the 8a voids (in the cubic space group Im3̅) with different elements (alkali, alkali earth, and rare earth) helps to reduce the thermal conductivity and thus increases the thermoelectric performance. A systematic characterization by synchrotron X-ray powder diffraction of different M-filled Co4Sb12 (M = K, Sr, La, Ce, and Yb) skutterudites was carried out under high pressure in the range ∼0-12 GPa. The isothermal equations of state (EOS) were obtained in this pressure range and the Bulk moduli (B0) were calculated for all the filled skutterudites, yielding unexpected results. A lattice expansion due to the filler elements fails in the description of the Bulk moduli. Topochemical studies of the filler site environment exhibited a slight disturbance and an increased ionic character when the filler is incorporated. The mechanical properties by means of Bulk moduli resulted in being sensitive to the presence of filler atoms inside the skutterudite voids, being affected by the covalent/ionic exchange of the Co-Sb and Sb-Sb bonds.

5.
BMC Cardiovasc Disord ; 21(1): 144, 2021 03 18.
Artículo en Inglés | MEDLINE | ID: mdl-33736607

RESUMEN

BACKGROUND: The PEGASUS-TIMI 54 trial inclusion criteria effectively identified high-risk patients with recent myocardial infarction (MI) who would benefit from continuing dual antiplatelet therapy (DAPT) with ticagrelor for more than 12 months. It is unknown how many real-world patients meet these criteria during the acute phase of ST-elevation MI (STEMI), or the extent to which these criteria predict a patient's risk and prognosis. Study objectives were: (1) determine the proportion of PEGASUS-TIMI 54-like patients (PG-l) in a real-world cohort of patients hospitalized with STEMI and to assess their ischemic and hemorrhagic risk; (2) examine their ischemic and hemorrhagic in-hospital events (major adverse cardiovascular and cerebrovascular events [MACCE] and clinically relevant bleeding); (3) evaluate their long-term outcomes and the impact on the long-term prognosis of the type of DAPT prescribed at discharge. METHODS: This observational study was conducted in 1086 patients admitted to hospital with a diagnosis of STEMI between February 2011 and March 2018 and enrolled in the CARDIO-STEMI Sanremo registry. Patients' demographic and clinical characteristics, procedural variables, and individual ischemic and hemorrhagic risk scores were assessed in-hospital. Four-year survival was also analyzed. RESULTS: The proportion of PG-I patients was 69.2%. Compared with non-PG-l patients, PG-l patients were older, had more multivessel disease and comorbidities, and experienced more frequent MACCE (8.3% vs. 3.6%, p = 0.005) and clinically significant bleeding events (6.7% vs. 2.7%, p = 0.008), a higher rate of in-hospital death (6.5% vs. 1.5%, p < 0.001), and higher follow-up mortality rate (14.8% vs. 7.7%; p = 0.002). Four-year survival was significantly lower in the PG-l group (83.9% vs. 91.8%; Log-rank = 0.001) and was related to the cumulative number of concurrent risk factors. In the unadjusted analysis, survival was greater in patients discharged on ticagrelor than on another P2Y12 inhibitor (90.2% vs. 76.7%, Log-rank = 0.001), and the difference was particularly evident in PG-l patients. CONCLUSIONS: The risk of MACCE for PG-l patients increased with the number of concurrent PEGASUS-TIMI 54 risk features. Treatment with ticagrelor on discharge was associated with improved survival rates during 4 years of follow-up.


Asunto(s)
Aspirina/administración & dosificación , Terapia Antiplaquetaria Doble , Intervención Coronaria Percutánea , Inhibidores de Agregación Plaquetaria/administración & dosificación , Antagonistas del Receptor Purinérgico P2Y/administración & dosificación , Infarto del Miocardio con Elevación del ST/terapia , Ticagrelor/administración & dosificación , Anciano , Aspirina/efectos adversos , Toma de Decisiones Clínicas , Ensayos Clínicos como Asunto , Esquema de Medicación , Terapia Antiplaquetaria Doble/efectos adversos , Terapia Antiplaquetaria Doble/mortalidad , Femenino , Hemorragia/inducido químicamente , Mortalidad Hospitalaria , Humanos , Italia , Masculino , Persona de Mediana Edad , Intervención Coronaria Percutánea/efectos adversos , Intervención Coronaria Percutánea/mortalidad , Inhibidores de Agregación Plaquetaria/efectos adversos , Estudios Prospectivos , Antagonistas del Receptor Purinérgico P2Y/efectos adversos , Sistema de Registros , Medición de Riesgo , Factores de Riesgo , Infarto del Miocardio con Elevación del ST/diagnóstico , Infarto del Miocardio con Elevación del ST/mortalidad , Ticagrelor/efectos adversos , Factores de Tiempo , Resultado del Tratamiento
6.
Transfusion ; 60(8): 1666-1668, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32358818

RESUMEN

BACKGROUND: Plasma exchange with plasma replacement has been the mainstay for the treatment of thrombotic thrombocytopenic purpura (TTP) for several decades. Recently an anti-von Willebrand factor (VWF) medication, caplacizumab, has been approved for treatment of TTP when used with plasma exchange. We report a patient with immune-mediated TTP that had an anaphylactic reaction to plasma who was then given caplacizumab daily for 1 week without further plasma exchange therapy with a good clinical and laboratory response. CASE REPORT: A 63-year-old woman with acute confusion and multiple ecchymoses after tooth extraction developed TTP with a hemoglobin (Hb) of 6.3 g/dL, white blood cell count 15 × 109 /L, platelets (PLTs) 12 × 109 /L, lactate dehydrogenase (LDH) 1212 IU/mL, and creatinine 0.9 mg/dL. Her ADAMTS13 level was less than 5% and plasma exchange was started. During the first plasma exchange the patient developed anaphylaxis with hypotension, shortness of breath, angioedema, and urticaria. She recovered from this reaction with treatment and no further plasma exchanges were performed. Instead she was given methylprednisolone, caplacizumab, and later rituximab. The caplacizumab was given daily for 8 days during which her PLT counts and ADAMTS13 levels improved. Her Hb level also increased. She continued to receive oral prednisone and rituximab after discharge was doing well latest follow up (Day 114). CONCLUSION: Caplacizumab may be used safely and effectively without concomitant plasma exchange in a patient with anaphylaxis to plasma.


Asunto(s)
Anafilaxia/prevención & control , Transfusión de Componentes Sanguíneos/efectos adversos , Plasma , Púrpura Trombocitopénica Trombótica/tratamiento farmacológico , Anticuerpos de Dominio Único/administración & dosificación , Reacción a la Transfusión/prevención & control , Anafilaxia/etiología , Femenino , Humanos , Persona de Mediana Edad
7.
Inorg Chem ; 59(20): 14932-14943, 2020 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-33006896

RESUMEN

Black phosphorus (BP) allotrope has an orthorhombic crystal structure with a narrow bandgap of 0.35 eV. This material is promising for 2D technology since it can be exfoliated down to one single layer: the well-known phosphorene. In this work, bulk BP was synthesized under high-pressure conditions at high temperatures. A detailed structural investigation using neutron and synchrotron X-ray diffraction revealed the occurrence of anisotropic strain effects on the BP lattice; the combination of both sets of diffraction data allowed visualization of the lone electron pair 3s2. Temperature-dependent neutron diffraction data collected at low temperature showed that the a axis (zigzag) exhibits a quasi-temperature-independent thermal expansion in the temperature interval from 20 up to 150 K. These results may be a key to address the anomalous behavior in electrical resistivity near 150 K. Thermoelectric properties were also provided; low thermal conductivity from 14 down to 6 Wm-1K-1 in the range 323-673 K was recorded in our polycrystalline BP, which is below the reported values for single-crystals in literature.

8.
Mol Plant Microbe Interact ; 32(8): 939-948, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-30893001

RESUMEN

In the establishment of plant-rhizobial symbiosis, the plant hosts express nodulin proteins during root nodule organogenesis. A limited number of nodulins have been characterized, and these perform essential functions in root nodule development and metabolism. Most nodulins are expressed in the nodule and at lower levels in other plant tissues. Previously, we isolated Nodulin 22 (PvNod22) from a common bean (Phaseolus vulgaris L.) cDNA library derived from Rhizobium-infected roots. PvNod22 is a noncanonical, endoplasmic reticulum (ER)-localized, small heat shock protein that confers protection against oxidative stress when overexpressed in Escherichia coli. Virus-induced gene silencing of PvNod22 resulted in necrotic lesions in the aerial organs of P. vulgaris plants cultivated under optimal conditions, activation of the ER-unfolded protein response (UPR), and, finally, plant death. Here, we examined the expression of PvNod22 in common bean plants during the establishment of rhizobial endosymbiosis and its relationship with two cellular processes associated with plant immunity, the UPR and autophagy. In the RNA interference lines, numerous infection threads stopped their progression before reaching the cortex cell layer of the root, and nodules contained fewer nitrogen-fixing bacteroids. Collectively, our results suggest that PvNod22 has a nonredundant function during legume-rhizobia symbiosis associated with infection thread elongation, likely by sustaining protein homeostasis in the ER.


Asunto(s)
Interacciones Huésped-Patógeno , Proteínas de la Membrana , Phaseolus , Proteínas de Plantas , Rhizobium , Simbiosis , Regulación de la Expresión Génica de las Plantas , Proteínas de Choque Térmico , Interacciones Huésped-Patógeno/genética , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Fijación del Nitrógeno , Phaseolus/microbiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Rhizobium/fisiología , Nódulos de las Raíces de las Plantas/microbiología , Simbiosis/genética
9.
BMC Genomics ; 20(1): 800, 2019 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-31684871

RESUMEN

BACKGROUND: Reactive oxygen species (ROS) are generated by NADPH oxidases known as respiratory burst oxidase homologs (RBOHs) in plants. ROS regulate various cellular processes, including the mutualistic interactions between legumes and nitrogen-fixing bacteria or arbuscular mycorrhizal (AM) fungi. Rboh is a multigene family comprising nine members (RbohA-I) in common bean (Phaseolus vulgaris). The RNA interference-mediated silencing of RbohB (PvRbohB-RNAi) in this species diminished its ROS production and greatly impaired nodulation. By contrast, the PvRbohB-RNAi transgenic roots showed early hyphal root colonization with enlarged fungal hypopodia; therefore, we proposed that PvRbohB positively regulates rhizobial infection (Rhizobium tropici) and inhibits AM colonization by Rhizophagus irregularis in P. vulgaris. RESULTS: To corroborate this hypothesis, an RNA-Seq transcriptomic analysis was performed to identify the differentially expressed genes in the PvRbohB-RNAi roots inoculated with Rhizobium tropici or Rhizophagus irregularis. We found that, in the early stages, root nodule symbioses generated larger changes of the transcriptome than did AM symbioses in P. vulgaris. Genes related to ROS homeostasis and cell wall flexibility were markedly upregulated in the early stages of rhizobial colonization, but not during AM colonization. Compared with AM colonization, the rhizobia induced the expression of a greater number of genes encoding enzymes involved in the metabolism of auxins, cytokinins, and ethylene, which were typically repressed in the PvRbohB-RNAi roots. CONCLUSIONS: Our research provides substantial insights into the genetic interaction networks in the early stages of rhizobia and AM symbioses with P. vulgaris, as well as the differential roles that RbohB plays in processes related to ROS scavenging, cell wall remodeling, and phytohormone homeostasis during nodulation and mycorrhization in this legume.


Asunto(s)
Perfilación de la Expresión Génica , Glomeromycota/fisiología , NADPH Oxidasas/genética , Phaseolus/genética , Phaseolus/microbiología , Raíces de Plantas/genética , Rhizobium tropici/fisiología , Pared Celular/metabolismo , Phaseolus/citología , Phaseolus/enzimología , Raíces de Plantas/microbiología , Transducción de Señal/genética , Simbiosis
10.
J Exp Bot ; 70(3): 1049-1061, 2019 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-30462254

RESUMEN

Bax-inhibitor 1 (BI-1) is a cell death suppressor conserved in all eukaryotes that modulates cell death in response to abiotic stress and pathogen attack in plants. However, little is known about its role in the establishment of symbiotic interactions. Here, we demonstrate the functional relevance of an Arabidopsis thaliana BI-1 homolog (PvBI-1a) to symbiosis between the common bean (Phaseolus vulgaris) and Rhizobium tropici. We show that the changes in expression of PvBI-1a observed during early symbiosis resemble those of some defence response-related proteins. By using gain- and loss-of-function approaches, we demonstrate that the overexpression of PvBI-1a in the roots of common bean increases the number of rhizobial infection events (and therefore the final number of nodules per root), but induces the premature death of nodule cells, affecting their nitrogen fixation efficiency. Nodule morphological alterations are known to be associated with changes in the expression of genes tied to defence, autophagy, and vesicular trafficking. Results obtained in the present work suggest that BI-1 has a dual role in the regulation of programmed cell death during symbiosis, extending our understanding of its critical function in the modulation of host immunity while responding to beneficial microbes.


Asunto(s)
Proteínas de la Membrana/genética , Phaseolus/genética , Proteínas de Plantas/genética , Rhizobium tropici/fisiología , Apoptosis/genética , Regulación de la Expresión Génica de las Plantas , Proteínas de la Membrana/metabolismo , Phaseolus/microbiología , Inmunidad de la Planta/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/microbiología , Raíces de Plantas/fisiología , Simbiosis/genética
11.
Plant Cell ; 28(9): 2326-2341, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27577790

RESUMEN

Eukaryotes contain three types of lipid kinases that belong to the phosphatidylinositol 3-kinase (PI3K) family. In plants and Saccharomyces cerevisiae, only PI3K class III family members have been identified. These enzymes regulate the innate immune response, intracellular trafficking, autophagy, and senescence. Here, we report that RNAi-mediated downregulation of common bean (Phaseolus vulgaris) PI3K severely impaired symbiosis in composite P. vulgaris plants with endosymbionts such as Rhizobium tropici and Rhizophagus irregularis Downregulation of Pv-PI3K was associated with a marked decrease in root hair growth and curling. Additionally, infection thread growth, root-nodule number, and symbiosome formation in root nodule cells were severely affected. Interestingly, root colonization by AM fungi and the formation of arbuscules were also abolished in PI3K loss-of-function plants. Furthermore, the transcript accumulation of genes encoding proteins known to interact with PI3K to form protein complexes involved in autophagy was drastically reduced in these transgenic roots. RNAi-mediated downregulation of one of these genes, Beclin1/Atg6, resulted in a similar phenotype as observed for transgenic roots in which Pv-PI3K had been downregulated. Our findings show that an autophagy-related process is crucial for the mutualistic interactions of P. vulgaris with beneficial microorganisms.

12.
Inorg Chem ; 58(17): 11828-11835, 2019 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-31432670

RESUMEN

RNiO3 (R = rare-earth element) perovskite materials are well-known to exhibit characteristic metal-insulator transitions. The structural distortion increases as the R member becomes smaller along the series. For SmNiO3, a high-hydrostatic-pressure preparation procedure, yielding samples with much enhanced crystalline quality, combined with the extremely high angular resolution of synchrotron X-ray diffraction (XRD) allowed us to identify a monoclinic phase in the insulating regime (below the metal-insulator transition temperature (TMI) of 127 °C), defined in the space group P21/n. This monoclinic symmetry had not been demonstrated directly using nonresonant XRD or neutron diffraction. This has important repercussions on the electronic nature of this material since the monoclinic structure contains two inequivalent Ni positions, implying a charge disproportionation phenomenon. In the metallic regime (above TMI), the standard orthorhombic Pbnm structure is observed. Therefore, there is a coupled structural and electronic transition, as happens for the very small rare-earth compounds of the RNiO3 perovskite series. Across TMI there is a dramatic rearrangement of the lattice parameters, degree of tilting, and distortion of the NiO6 octahedra, showing the convergence of the Ni-O bond lengths upon entering the metallic phase. Brown's valence analysis of the different elements agrees with other reported values in the literature, matching with bond and charge disproportionation models. By magnetization measurements a Néel temperature (TN) corresponding to the antiferromagnetic ordering of the Ni moments is identified at TN= 220 K, whereas Sm moments experience long-range ordering below 36 K.

13.
J Exp Bot ; 69(8): 2037-2048, 2018 04 09.
Artículo en Inglés | MEDLINE | ID: mdl-29394394

RESUMEN

Root hair curling is an early and essential morphological change required for the success of the symbiotic interaction between legumes and rhizobia. At this stage rhizobia grow as an infection thread within root hairs and are internalized into the plant cells by endocytosis, where the PI3K enzyme plays important roles. Previous observations show that stress conditions affect early stages of the symbiotic interaction, from 2 to 30 min post-inoculation, which we term as very early host responses, and affect symbiosis establishment. Herein, we demonstrated the relevance of the very early host responses for the symbiotic interaction. PI3K and the NADPH oxidase complex are found to have key roles in the microsymbiont recognition response, modulating the apoplastic and intracellular/endosomal ROS induction in root hairs. Interestingly, compared with soybean mutant plants that do not perceive the symbiont, we demonstrated that the very early symbiont perception under sublethal saline stress conditions induced root hair death. Together, these results highlight not only the importance of the very early host-responses on later stages of the symbiont interaction, but also suggest that they act as a mechanism for local control of nodulation capacity, prior to the abortion of the infection thread, preventing the allocation of resources/energy for nodule formation under unfavorable environmental conditions.


Asunto(s)
Bradyrhizobium/fisiología , Glycine max/enzimología , Fosfatidilinositol 3-Quinasa/metabolismo , Proteínas de Plantas/metabolismo , Nodulación de la Raíz de la Planta , Simbiosis , Interacciones Huésped-Patógeno , NADPH Oxidasas/genética , NADPH Oxidasas/metabolismo , Fosfatidilinositol 3-Quinasa/genética , Proteínas de Plantas/genética , Raíces de Plantas/enzimología , Raíces de Plantas/genética , Raíces de Plantas/microbiología , Raíces de Plantas/fisiología , Especies Reactivas de Oxígeno/metabolismo , Glycine max/genética , Glycine max/microbiología , Glycine max/fisiología
14.
Plant Physiol ; 172(3): 2002-2020, 2016 11.
Artículo en Inglés | MEDLINE | ID: mdl-27698253

RESUMEN

The target of rapamycin (TOR) protein kinase regulates metabolism, growth, and life span in yeast, animals, and plants in coordination with nutrient status and environmental conditions. The nutrient-dependent nature of TOR functionality makes this kinase a putative regulator of symbiotic associations involving nutrient acquisition. However, TOR's role in these processes remains to be understood. Here, we uncovered the role of TOR during the bean (Phaseolus vulgaris)-Rhizobium tropici (Rhizobium) symbiotic interaction. TOR was expressed in all tested bean tissues, with higher transcript levels in the root meristems and senesced nodules. We showed TOR promoter expression along the progressing infection thread and in the infected cells of mature nodules. Posttranscriptional gene silencing of TOR using RNA interference (RNAi) showed that this gene is involved in lateral root elongation and root cell organization and also alters the density, size, and number of root hairs. The suppression of TOR transcripts also affected infection thread progression and associated cortical cell divisions, resulting in a drastic reduction of nodule numbers. TOR-RNAi resulted in reduced reactive oxygen species accumulation and altered CyclinD1 and CyclinD3 expression, which are crucial factors for infection thread progression and nodule organogenesis. Enhanced expression of TOR-regulated ATG genes in TOR-RNAi roots suggested that TOR plays a role in the recognition of Rhizobium as a symbiont. Together, these data suggest that TOR plays a vital role in the establishment of root nodule symbiosis in the common bean.


Asunto(s)
Phaseolus/enzimología , Phaseolus/microbiología , Proteínas de Plantas/metabolismo , Rhizobium/fisiología , Nódulos de las Raíces de las Plantas/microbiología , Simbiosis/genética , Serina-Treonina Quinasas TOR/metabolismo , Secuencia de Aminoácidos , Autofagia/genética , Pared Celular/genética , Regulación hacia Abajo/genética , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Fagosomas/metabolismo , Fagosomas/ultraestructura , Phaseolus/genética , Phaseolus/ultraestructura , Fenotipo , Filogenia , Proteínas de Plantas/química , Nodulación de la Raíz de la Planta/genética , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas/genética , Interferencia de ARN , Especies Reactivas de Oxígeno/metabolismo , Nódulos de las Raíces de las Plantas/genética , Nódulos de las Raíces de las Plantas/ultraestructura , Análisis de Secuencia de ADN , Serina-Treonina Quinasas TOR/química , Regulación hacia Arriba/genética
15.
BMC Cardiovasc Disord ; 17(1): 97, 2017 04 05.
Artículo en Inglés | MEDLINE | ID: mdl-28381298

RESUMEN

BACKGROUND: European guidelines recommend the use of ticagrelor versus clopidogrel in patients with ST elevation myocardial infarction (STEMI). This recommendation is based on inconclusive results and subanalyses from clinical trials. Few data are available on the effects of ticagrelor in a real-world population. METHODS: To compare the effects of ticagrelor and clopidogrel in a real-world STEMI population, we conducted a pre-post case-control study examining all patients with STEMI included in the Cardio-STEMI Sanremo registry between February 2011 and June 2013. Cases and controls were defined according to P2Y12 inhibitors, correcting the bias due to lack of randomization by propensity score analysis. Ticagrelor was introduced in 2012 in both in-hospital and pre-hospital settings independently of this study. RESULTS: Of the 416 patients enrolled in the Cardio-STEMI registry, 401 with a definite diagnosis of STEMI were included in this study. One hundred forty-two patients received ticagrelor and 259 received clopidogrel. Regarding clinical presentation and procedural data, those in the ticagrelor group had lower CRUSADE scores (23 [14-36] vs 27 [18-38]; p = 0.015] but a higher proportion of radial access (33% vs 14%; p < 0.001), percutaneous coronary intervention (PCI; 92% vs 81 %; p = 0.002) and primary PCI ≤ 12 h (82% vs 66%; p = 0.001). The patients in the ticagrelor group had a higher procedural success rate (100% vs. 96%; p = 0.044). There was no difference in Bleeding Academic Research Consortium bleeding and in unadjusted incidence of hospital major adverse cardiovascular events (MACE; cardiac death, myocardial infarction, or stroke) but there was a significant reduction in unadjusted cardiac hospital death in the ticagrelor group (0.7% vs 5.4%; p = 0.024). After correcting for propensity score, hospital death (p = 0.22) and hospital MACE (p = 0.96) did not differ in both groups. The unadjusted survival at 1 year after STEMI was higher in the ticagrelor group (97.8% vs 87.8%; p = 0.024), and this result was confirmed by propensity score analysis (hazard ratio = 0.29 [0.08-0.99]; p = 0.048). CONCLUSIONS: In this real-word propensity score analysis, ticagrelor did not affect the risk of MACE during the hospital phase, or the incidence of hospital bleeding in patients with STEMI. However, in this mono-centric experience, ticagrelor resulted in improved 1-year survival, even after correction by propensity score.


Asunto(s)
Adenosina/análogos & derivados , Puntaje de Propensión , Sistema de Registros , Infarto del Miocardio con Elevación del ST/tratamiento farmacológico , Ticlopidina/análogos & derivados , Adenosina/administración & dosificación , Anciano , Clopidogrel , Angiografía Coronaria , Relación Dosis-Respuesta a Droga , Electrocardiografía , Femenino , Estudios de Seguimiento , Mortalidad Hospitalaria/tendencias , Humanos , Italia/epidemiología , Masculino , Persona de Mediana Edad , Inhibidores de Agregación Plaquetaria/administración & dosificación , Antagonistas del Receptor Purinérgico P2Y/administración & dosificación , Estudios Retrospectivos , Infarto del Miocardio con Elevación del ST/diagnóstico , Infarto del Miocardio con Elevación del ST/mortalidad , Tasa de Supervivencia/tendencias , Ticagrelor , Ticlopidina/administración & dosificación , Factores de Tiempo
16.
BMC Genomics ; 16: 423, 2015 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-26059339

RESUMEN

BACKGROUND: MiRNAs and phasiRNAs are negative regulators of gene expression. These small RNAs have been extensively studied in plant model species but only 10 mature microRNAs are present in miRBase version 21, the most used miRNA database, and no phasiRNAs have been identified for the model legume Phaseolus vulgaris. Thanks to the recent availability of the first version of the common bean genome, degradome data and small RNA libraries, we are able to present here a catalog of the microRNAs and phasiRNAs for this organism and, particularly, we suggest new protagonists in the symbiotic nodulation events. RESULTS: We identified a set of 185 mature miRNAs, including 121 previously unpublished sequences, encoded by 307 precursors and distributed in 98 families. Degradome data allowed us to identify a total of 181 targets for these miRNAs. We reveal two regulatory networks involving conserved miRNAs: those known to play crucial roles in the establishment of nodules, and novel miRNAs present only in common bean, suggesting a specific role for these sequences. In addition, we identified 125 loci that potentially produce phased small RNAs, with 47 of them having all the characteristics of being triggered by a total of 31 miRNAs, including 14 new miRNAs identified in this study. CONCLUSIONS: We provide here a set of new small RNAs that contribute to the broader knowledge of the sRNAome of Phaseolus vulgaris. Thanks to the identification of the miRNA targets from degradome analysis and the construction of regulatory networks between the mature microRNAs, we present here the probable functional regulation associated with the sRNAome and, particularly, in N2-fixing symbiotic nodules.


Asunto(s)
Phaseolus/genética , Proteínas de Plantas/genética , ARN de Planta/análisis , Análisis de Secuencia de ARN/métodos , Secuencia Conservada , Bases de Datos Genéticas , Regulación de la Expresión Génica de las Plantas , Redes Reguladoras de Genes , MicroARNs/análisis , MicroARNs/metabolismo , Phaseolus/metabolismo , Filogenia , Proteínas de Plantas/metabolismo , ARN de Planta/metabolismo , ARN Interferente Pequeño/análisis , ARN Interferente Pequeño/metabolismo
17.
Sensors (Basel) ; 15(1): 855-67, 2015 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-25569758

RESUMEN

Emerging evidence indicates that some reactive oxygen species (ROS), such as the superoxide anion radical and hydrogen peroxide (H2O2), are central regulators of plant responses to biotic and abiotic stresses. Thus, the cellular levels of ROS are thought to be tightly regulated by an efficient and elaborate pro- and antioxidant system that modulates the production and scavenging of ROS. Until recently, studies of ROS in plant cells have been limited to biochemical assays and the use of fluorescent probes; however, the irreversible oxidation of these fluorescent probes makes it impossible to visualize dynamic changes in ROS levels. In this work, we describe the use of Hyper, a recently developed live cell probe for H2O2 measurements in living cells, to monitor oxidative stress in Arabidopsis roots subjected to aluminum treatment. Hyper consists of a circularly permuted YFP (cpYFP) inserted into the regulatory domain of the Escherichia coli hydrogen peroxide-binding protein (OxyR), and is a H2O2-specific ratiometric, and therefore quantitative, probe that can be expressed in plant and animal cells. Now we demonstrate that H2O2 levels drop sharply in the elongation zone of roots treated with aluminum. This response could contribute to root growth arrest and provides evidence that H2O2 is involved in early Al sensing.


Asunto(s)
Aluminio/toxicidad , Arabidopsis/crecimiento & desarrollo , Técnicas Biosensibles , Peróxido de Hidrógeno/análisis , Raíces de Plantas/crecimiento & desarrollo , Arabidopsis/efectos de los fármacos , Espacio Intracelular/metabolismo , Raíces de Plantas/efectos de los fármacos , Plantas Modificadas Genéticamente
18.
Mol Plant Microbe Interact ; 27(1): 18-29, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24073881

RESUMEN

The importance of plant small heat shock proteins (sHsp) in multiple cellular processes has been evidenced by their unusual abundance and diversity; however, little is known about their biological role. Here, we characterized the in vitro chaperone activity and subcellular localization of nodulin 22 of Phaseolus vulgaris (PvNod22; common bean) and explored its cellular function through a virus-induced gene silencing-based reverse genetics approach. We established that PvNod22 facilitated the refolding of a model substrate in vitro, suggesting that it acts as a molecular chaperone in the cell. Through microscopy analyses of PvNod22, we determined its localization in the endoplasmic reticulum (ER). Furthermore, we found that silencing of PvNod22 resulted in necrotic lesions in the aerial organs of P. vulgaris plants cultivated under optimal conditions and that downregulation of PvNod22 activated the ER-unfolded protein response (UPR) and cell death. We also established that PvNod22 expression in wild-type bean plants was modulated by abiotic stress but not by chemicals that trigger the UPR, indicating PvNod22 is not under UPR control. Our results suggest that the ability of PvNod22 to suppress protein aggregation contributes to the maintenance of ER homeostasis, thus preventing the induction of cell death via UPR in response to oxidative stress during plant-microbe interactions.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Proteínas de la Membrana/metabolismo , Phaseolus/genética , Proteínas de Plantas/metabolismo , Respuesta de Proteína Desplegada , Muerte Celular , Regulación hacia Abajo , Retículo Endoplásmico/metabolismo , Flores/citología , Flores/genética , Flores/metabolismo , Silenciador del Gen , Genes Reporteros , Proteínas de Choque Térmico Pequeñas/genética , Proteínas de Choque Térmico Pequeñas/metabolismo , Homeostasis , Proteínas de la Membrana/genética , Phaseolus/citología , Phaseolus/metabolismo , Fenotipo , Filogenia , Hojas de la Planta/citología , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Raíces de Plantas/citología , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Plantas Modificadas Genéticamente , Proteínas Recombinantes , Plantones/citología , Plantones/genética , Plantones/metabolismo , Transducción de Señal , Estrés Fisiológico , Nicotiana/citología , Nicotiana/genética , Nicotiana/metabolismo
19.
Plant Cell Physiol ; 55(3): 580-92, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24399235

RESUMEN

Legume plants secrete signaling molecules called flavonoids into the rhizosphere. These molecules activate the transcription of rhizobial nod genes, which encode proteins involved in the synthesis of signaling compounds named Nod factors (NFs). NFs, in turn, trigger changes in plant gene expression, cortical cell dedifferentiation and mitosis, depolarization of the root hair cell membrane potential and rearrangement of the actin cytoskeleton. Actin polymerization plays an important role in apical growth in hyphae and pollen tubes. Using sublethal concentrations of fluorescently labeled cytochalasin D (Cyt-Fl), we visualized the distribution of filamentous actin (F-actin) plus ends in living Phaseolus vulgaris and Arabidopsis root hairs during apical growth. We demonstrated that Cyt-Fl specifically labeled the newly available plus ends of actin microfilaments, which probably represent sites of polymerization. The addition of unlabeled competing cytochalasin reduced the signal, suggesting that the labeled and unlabeled forms of the drug bind to the same site on F-actin. Exposure to Rhizobium etli NFs resulted in a rapid increase in the number of F-actin plus ends in P. vulgaris root hairs and in the re-localization of F-actin plus ends to infection thread initiation sites. These data suggest that NFs promote the formation of F-actin plus ends, which results in actin cytoskeleton rearrangements that facilitate infection thread formation.


Asunto(s)
Actinas/metabolismo , Lipopolisacáridos/farmacología , Phaseolus/efectos de los fármacos , Phaseolus/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Citoesqueleto de Actina/efectos de los fármacos , Citoesqueleto de Actina/metabolismo
20.
Mol Phylogenet Evol ; 79: 1-11, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24952318

RESUMEN

Bean plants from the Phaseolus genus are widely consumed and represent a nitrogen source for human nutrition. They provide biological fertilization by establishing root nodule symbiosis with nitrogen-fixing bacteria. To establish a successful interaction, bean plants and their symbiotic bacteria need to synchronize a proper molecular crosstalk. Within the Phaseolus genus, P. vulgaris has been the prominent species to study nodulation with Rhizobium symbionts. However the Phaseolus genus comprises diverse species whose symbionts have not been analyzed. Here we identified and studied nodule bacteria from representative Phaseolus species not previously analyzed and from all the described wild species related to P. vulgaris. We found Bradyrhizobium in nodules from most species representing all Phaseolus clades except in five phylogenetically related species from the P. vulgaris clade. Therefore we propose that Bradyrhizobium nodulation is common in Phaseolus and that there was a symbiont preference shift to Rhizobium nodulation in few related species. This work sets the basis to further study the genetic basis of this symbiont substitution.


Asunto(s)
Bradyrhizobium/genética , Phaseolus/microbiología , Rhizobium/genética , Simbiosis , Bradyrhizobium/aislamiento & purificación , Bradyrhizobium/fisiología , ADN Espaciador Ribosómico/genética , Genes Bacterianos , México , Phaseolus/clasificación , Filogenia , ARN Ribosómico 16S/genética , Rhizobium/aislamiento & purificación , Rhizobium/fisiología , Nódulos de las Raíces de las Plantas/microbiología , Análisis de Secuencia de ADN
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