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1.
Mol Cell ; 80(6): 980-995.e13, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33202249

RESUMO

Ribosomes have been suggested to directly control gene regulation, but regulatory roles for ribosomal RNA (rRNA) remain largely unexplored. Expansion segments (ESs) consist of multitudes of tentacle-like rRNA structures extending from the core ribosome in eukaryotes. ESs are remarkably variable in sequence and size across eukaryotic evolution with largely unknown functions. In characterizing ribosome binding to a regulatory element within a Homeobox (Hox) 5' UTR, we identify a modular stem-loop within this element that binds to a single ES, ES9S. Engineering chimeric, "humanized" yeast ribosomes for ES9S reveals that an evolutionary change in the sequence of ES9S endows species-specific binding of Hoxa9 mRNA to the ribosome. Genome editing to site-specifically disrupt the Hoxa9-ES9S interaction demonstrates the functional importance for such selective mRNA-rRNA binding in translation control. Together, these studies unravel unexpected gene regulation directly mediated by rRNA and how ribosome evolution drives translation of critical developmental regulators.


Assuntos
Proteínas de Homeodomínio/genética , Biossíntese de Proteínas/genética , RNA Ribossômico/ultraestrutura , Ribossomos/genética , Regiões 5' não Traduzidas/genética , Regulação da Expressão Gênica/genética , Genes Homeobox/genética , Proteínas de Homeodomínio/ultraestrutura , Conformação de Ácido Nucleico , RNA Mensageiro/genética , RNA Ribossômico/genética , Ribossomos/ultraestrutura , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/ultraestrutura , Especificidade da Espécie
2.
Mol Cell ; 72(6): 1013-1020.e6, 2018 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-30576652

RESUMO

Expansion segments (ESs) are enigmatic insertions within the eukaryotic ribosome, the longest of which resemble tentacle-like extensions that vary in length and sequence across evolution, with a largely unknown function. By selectively engineering rRNA in yeast, we find that one of the largest ESs, ES27L, has an unexpected function in translation fidelity. Ribosomes harboring a deletion in the distal portion of ES27L have increased amino acid misincorporation, as well as readthrough and frameshifting errors. By employing quantitative mass spectrometry, we further find that ES27L acts as an RNA scaffold to facilitate binding of a conserved enzyme, methionine amino peptidase (MetAP). We show that MetAP unexpectedly controls the accuracy of ribosome decoding, which is coupled to an increase in its enzymatic function through its interaction with ES27L. These findings reveal that variable ESs of the ribosome serve important functional roles and act as platforms for the binding of proteins that modulate translation across evolution.


Assuntos
Caulobacter crescentus/metabolismo , Células-Tronco Embrionárias Murinas/metabolismo , RNA Bacteriano/metabolismo , RNA Fúngico/metabolismo , RNA Ribossômico/metabolismo , Ribossomos/metabolismo , Saccharomyces cerevisiae/metabolismo , Aminopeptidases/metabolismo , Animais , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Sítios de Ligação , Caulobacter crescentus/genética , Linhagem Celular , Proteínas Fúngicas/biossíntese , Proteínas Fúngicas/genética , Camundongos , Conformação de Ácido Nucleico , Ligação Proteica , RNA Bacteriano/química , RNA Bacteriano/genética , RNA Fúngico/química , RNA Fúngico/genética , RNA Ribossômico/química , RNA Ribossômico/genética , Ribossomos/química , Ribossomos/genética , Saccharomyces cerevisiae/genética , Relação Estrutura-Atividade
3.
Mol Cell ; 67(1): 71-83.e7, 2017 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-28625553

RESUMO

Emerging studies have linked the ribosome to more selective control of gene regulation. However, an outstanding question is whether ribosome heterogeneity at the level of core ribosomal proteins (RPs) exists and enables ribosomes to preferentially translate specific mRNAs genome-wide. Here, we measured the absolute abundance of RPs in translating ribosomes and profiled transcripts that are enriched or depleted from select subsets of ribosomes within embryonic stem cells. We find that heterogeneity in RP composition endows ribosomes with differential selectivity for translating subpools of transcripts, including those controlling metabolism, cell cycle, and development. As an example, mRNAs enriched in binding to RPL10A/uL1-containing ribosomes are shown to require RPL10A/uL1 for their efficient translation. Within several of these transcripts, this level of regulation is mediated, at least in part, by internal ribosome entry sites. Together, these results reveal a critical functional link between ribosome heterogeneity and the post-transcriptional circuitry of gene expression.


Assuntos
Células-Tronco Embrionárias/metabolismo , Biossíntese de Proteínas , RNA Mensageiro/metabolismo , Proteínas Ribossômicas/metabolismo , Ribossomos/metabolismo , Animais , Linhagem Celular , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes , Sítios Internos de Entrada Ribossomal , Mapas de Interação de Proteínas , Interferência de RNA , RNA Mensageiro/genética , Proteínas Ribossômicas/genética , Ribossomos/genética , Transcriptoma , Transfecção
4.
J Am Chem Soc ; 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38591952

RESUMO

Oxide ion conductors are attractive materials because of their wide range of applications, such as solid oxide fuel cells. Oxide ion conduction in oxyhalides (compounds containing both oxide ions and halide ions) is rare. In the present work, we found that Sillén oxychlorides, Bi2-xTexLuO4+x/2Cl (x = 0, 0.1, and 0.2), show high oxide ion conductivity. The bulk conductivity of Bi1.9Te0.1LuO4.05Cl reaches 10-2 S cm-1 at 431 °C, which is much lower than 644 °C of yttria-stabilized zirconia (YSZ) and 534 °C of La0.8Sr0.2Ga0.83Mg0.17O2.815 (LSGM). Thanks to the low activation energy, Bi1.9Te0.1LuO4.05Cl exhibits a high bulk conductivity of 1.5 × 10-3 S cm-1 even at a low temperature of 310 °C, which is 204 times higher than that of YSZ. The low activation energy is attributed to the interstitialcy oxide ion diffusion in the triple fluorite-like layer, as evidenced by neutron diffraction experiments (Rietveld and neutron scattering length density analyses), bond valence-based energy calculations, static DFT calculations, and ab initio molecular dynamics simulations. The electrical conductivity of Bi1.9Te0.1LuO4.05Cl is almost independent of the oxygen partial pressure from 10-18 to 10-4 atm at 431 °C, indicating the electrolyte domain. Bi1.9Te0.1LuO4.05Cl also exhibits high chemical stability under a CO2 flow and ambient air at 400 °C. The oxide ion conduction due to the two-dimensional interstitialcy diffusion is considered to be common in Sillén oxyhalides with triple fluorite-like layers, such as Bi1.9Te0.1RO4.05Cl (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu) and Bi6-2xTe2xO8+xBr2 (x = 0.1, 0.5). The present study opens a new field of materials chemistry: oxide ion-conducting Sillén oxyhalides with triple fluorite-like layers.

5.
J Am Chem Soc ; 146(2): 1476-1483, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38166110

RESUMO

Ion conductors comprising noncentrosymmetric frameworks have emerged as new functional materials. However, strongly correlated polarity functionality and ion transport have not been achieved. Herein, we report a ferroelectric proton conductor, K2MnN(CN)4·H2O (1·H2O), exhibiting the strong correlation between its polar skeleton and conductive ions that generate anomalous ferroelectricity via the proton-bias phenomenon. The application of an electric field of ±1 kV/cm (0.1 Hz) on 1·H2O at 298 K produced the ferroelectricity (polarization = 1.5 × 104 µC/cm2), which was enhanced by the ferroelectric-skeleton-trapped conductive protons. Furthermore, the strong polarity-proton transport coupling of 1·H2O induced a proton-rectification-like directional ion-conductive behavior that could be adjusted by the magnitude and direction of DC electric fields. Moreover, 1·H2O exhibited reversible polarity switching between the polar 1·H2O and its dehydrated form, 1, with a centrosymmetric structure comprising an order-disorder-type transition of the nitrido-bridged chains.

6.
Angew Chem Int Ed Engl ; 63(15): e202401779, 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38363076

RESUMO

The Li3MX6 compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li3ScCl6 using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P63mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li3ScCl6 and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li3MX6 family further revealed that the cation/anion radius ratio, rM/rX, is the factor that determines which anion sublattice is formed and that in γ-Li3ScCl6, the difference in compressibility between Sc and Cl exceeds the ccp rM/rX threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li3ScCl6 demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings.

7.
Clin Infect Dis ; 76(6): 1074-1079, 2023 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-36306421

RESUMO

BACKGROUND: Due to potentially fatal consequences of missed bacteremia, blood cultures are often overused. While there are several prediction models that can be used to identify patients who truly need blood cultures, physicians often rely on their gestalt. We evaluated the diagnostic performance of physician gestalt for bacteremia in comparison with 2 existing prediction models: Takeshima and Shapiro. METHODS: The study enrolled consecutive adult patients with suspected infection who were in the process of being admitted to the general medicine department at 2 hospitals between April 2017 and January 2019. Attending physicians provided gestalt regarding risk of bacteremia (0%-100%). Patients with a <10% risk estimated via each strategy (ie, physician gestalt or 2 existing models) were categorized as bacteremia excluded (ie, blood cultures were considered unnecessary). Strategies were compared in terms of safety (proportion of patients with bacteremia among those classified as bacteremia excluded) and efficiency (proportion of patients classified as bacteremia excluded among the total cohort). RESULTS: Among 2014 patients, 292 (14.5%) were diagnosed with bacteremia. The safety of physician gestalt and the Takeshima and Shapiro models was 3.7% (95% confidence interval [CI], 2.2% to 5.7%), 6.5% (95% CI, 5.0% to 7.9%), and 10.8% (95% CI, 9.4% to 12.3%), whereas the efficiency of each strategy was 22.4% (95% CI, 22.5% to 26.3%), 52.7% (95% CI, 50.5% to 54.9%), and 87.8% (95% CI, 86.3% to 89.2%), respectively. CONCLUSIONS: Physician gestalt was safer but less efficient than existing models. Clinical prediction models could help reduce the overuse of blood cultures.


Assuntos
Bacteriemia , Médicos , Adulto , Humanos , Bacteriemia/diagnóstico , Hospitalização , Hemocultura , Hospitais
8.
J Am Chem Soc ; 145(36): 19759-19767, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37649142

RESUMO

α-FAPbI3 (FA+ = CH(NH2)2+) with a cubic perovskite structure is promising for photophysical applications. However, α-FAPbI3 is metastable at room temperature, and it transforms to the δ-phase at a certain period of time at room temperature. Herein, we report a thiocyanate-stabilized pseudo-cubic perovskite FAPbI3 with ordered columnar defects (α'-phase). This compound has a √5ap × âˆš5ap × ap tetragonal unit cell (ap: cell parameter of primitive perovskite cell) with a band gap of 1.91 eV. It is stable at room temperature in a dry atmosphere. Furthermore, the presence of the α'-phase in a mixed sample with the δ-phase drastically reduces the δ-to-α transition temperature measured on heating, suggesting the reduction of the nucleation energy of the α-phase or thermodynamic stabilization of the α-phase through epitaxy. The defect-ordered pattern in the α'-phase forms a coincidence-site lattice at the twinned boundary of the single crystals, thus hinting at an epitaxy- or strain-based mechanism of α-phase formation and/or stabilization. In this study, we developed a new strategy to control defects in halide perovskites and provided new insight into the stabilization of α-FAPbI3 by pseudo-halide and grain boundary engineering.

9.
Inorg Chem ; 62(26): 10481-10489, 2023 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-37349281

RESUMO

Band gap engineering using multiple anions is an established approach to novel photocatalysts that exhibit suitable band gap energies for water splitting and high photocorrosion resistance. However, few studies have been conducted on photocatalysts with polyanions, including polychalcogenide ions. Here, we present a new quaternary gallium oxysulfide with disulfide pairs (S2)2-, La4Ga2S8O3, grown out of a KI molten salt. Single-crystal X-ray diffraction analysis revealed that the oxysulfide crystallizes in the orthorhombic space group Pbcn with lattice constants of a = 18.3330(6) Å, b = 13.0590(5) Å, and c = 5.9022(3) Å. In the crystal structure, the GaS4-based zigzag chains and OLa4-based fluorite-like strips are independently arranged in two dimensions, which alternately stack via the disulfide pairs along the third direction. The oxysulfide is a direct-type semiconductor with a band gap of 2.45 eV. First-principles calculations combined with X-ray photoemission spectroscopy measurements show that S 3p states derived from the disulfide pairs dominate the valence band maximum and conduction band minimum, and these band-edge positions are suitable for the oxidation and reduction of water. Our comprehensive study based on the electronic structure suggests that the disulfide pairs make La4Ga2S8O3 a potential photocatalyst for water splitting under visible-light irradiation.

10.
Small ; 18(10): e2106785, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34923747

RESUMO

Solid oxide-ion conductors are crucial for enabling clean and efficient energy devices such as solid oxide fuel cells. Hexagonal perovskite-related oxides have been placed at the forefront of high-performance oxide-ion conductors, with Ba7 Nb4- x Mo1+ x O20+ x /2 (x = 0-0.1) being an archetypal example. Herein, high oxide-ion conductivity and stability under reducing conditions in Ba7 Ta3.7 Mo1.3 O20.15 are reported by investigating the solid solutions Ba7 Ta4- x Mo1+ x O20+ x /2 (x = 0.2-0.7). Neutron diffraction indicates a large number of interstitial oxide ions in Ba7 Ta3.7 Mo1.3 O20.15 , leading to a high level of oxide-ion conductivity (e.g., 1.08 × 10-3 S cm-1 at 377 °C). The conductivity of Ba7 Ta3.7 Mo1.3 O20.15 is higher than that of Ba7 Nb4 MoO20 and conventional yttria-stabilized zirconia. In contrast to Ba7 Nb4- x Mo1+ x O20+ x /2 (x = 0-0.1), the oxide-ion conduction in Ba7 Ta3.7 Mo1.3 O20.15 is dominant even in highly reducing atmospheres (e.g., oxygen partial pressure of 1.6 × 10-24 atm at 909 °C). From structural analyses of the synchrotron X-ray diffraction data for Ba7 Ta3.7 Mo1.3 O20.15 , contrasting X-ray scattering powers of Ta5+ and Mo6+ allow identification of the preferential occupation of Mo6+ adjacent to the intrinsically oxygen-deficient layers, as supported by DFT calculations. The high conductivity and chemical and electrical stability in Ba7 Ta3.7 Mo1.3 O20.15 provide a strategy for the development of solid electrolytes based on hexagonal perovskite-related oxides.

11.
Inorg Chem ; 61(31): 12327-12336, 2022 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-35895861

RESUMO

In the present work, we have discovered the first example of a CaEu2Ge3O10-type oxide-ion conductor, Ca1.05Sm1.95Ge3O9.975. The CaEu2Ge3O10-type structure was selected by screening 624 Ge-containing materials by the bond-valence-based-energy calculations. CaEu2Ge3O10-type CaEu2Ge3O10, CaGd2Ge3O10, and a new material CaSm2Ge3O10 were synthesized. CaSm2Ge3O10 showed the highest electrical conductivity among these three materials. Ca1+xSm2-xGe3O10-x/2 (x = 0.05, 0.1, and 0.2) were also synthesized, and we found that Ca1.05Sm1.95Ge3O9.975 exhibited the highest conductivity of 1.2 × 10-5 S cm-1 at 1373 K. Oxygen transport numbers in Ca1.05Sm1.95Ge3O9.975 were determined to be 0.64(5) at 1073 K and 0.65(8) at 1123 K, which indicates that the major carrier is the oxide ion. Therefore, CaEu2Ge3O10-type Ca1.05Sm1.95Ge3O9.975 is a new structure family of oxide-ion conductors. The crystal structures of the new materials CaSm2Ge3O10 and Ca1.05Sm1.95Ge3O9.975 were successfully analyzed by the CaEu2Ge3O10-type structure (space group P21/c) using the single-crystal X-ray diffraction data. The bond-valence-based-energy calculation for the refined crystal structure of Ca1.05Sm1.95Ge3O9.975 suggested that oxide ions migrate along the [2 0 1], [0 1 0], and [12.88 6.43 1] directions with energy barriers of 0.88, 0.92, and 1.1 eV, respectively, which indicates three-dimensional oxide-ion diffusion in Ca1.05Sm1.95Ge3O9.975.

12.
Inorg Chem ; 61(19): 7537-7545, 2022 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-35504293

RESUMO

Hexagonal perovskite-related oxides have garnered a great deal of research interest because of their high oxide-ion conductivity at intermediate temperatures, with Ba7Nb4MoO20 being a notable example. However, concomitant proton conduction in Ba7Nb4MoO20 may cause a decrease in power efficiency when used as the electrolyte in conventional solid oxide fuel cells. Here, through investigations of the transport and structural properties of Ba7Nb4-xWxMoO20+x/2 (x = 0-0.25), we show that the aliovalent substitution of Nb5+ by W6+ not only increases the oxide-ion conductivity but also dramatically lowers proton conductivity. The highest conductivity is achieved for x = 0.15 composition, with 2.2 × 10-2 S cm-1 at 600 °C, 2.2 times higher than that of pristine Ba7Nb4MoO20. The proton transport number of Ba7Nb3.85W0.15MoO20.075 is smaller compared with Ba7Nb4MoO20, Ba7Nb3.9Mo1.1O20.05, and Ba7Ta3.7Mo1.3O20.15. The structure analyses of neutron diffraction data of Ba7Nb3.85W0.15MoO20.075 at 25 and 800 °C reveal that the aliovalent W6+ doping introduces interstitial oxide ions in the intrinsically oxygen-deficient c' layers, thereby simultaneously increasing the carrier concentration for oxide-ion conduction and decreasing oxygen vacancies responsible for dissociative absorption of water. Neutron scattering length density distribution was examined using the maximum-entropy method and neutron diffraction data at 800 °C, which indicates the interstitialcy oxide-ion diffusion in the c' layers of Ba7Nb3.85W0.15MoO20.075. Ba7Nb3.85W0.15MoO20.075 exhibits extremely high chemical and electrical stability in the wide oxygen partial pressure P(O2) region [ex. 10-23 ≤ P(O2) ≤ 1 atm at 903 °C]. The present results offer a strategy for developing pure oxide-ion conducting hexagonal perovskite-related oxides for possible industrial applications.

13.
Inorg Chem ; 61(17): 6584-6593, 2022 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-35430816

RESUMO

Narrow-gap semiconductors with visible light absorption capability have attracted attention as photofunctional materials. H--doped BaSn0.7Y0.3O3-δ containing Sn(II) species was recently reported to absorb visible light up to 600 nm, which represents the first demonstration of oxyhydride-based visible-light-absorbers. In the present study, a more detailed investigation was made to obtain information on the synthesis and properties of H--doped perovskite-type stannate with respect to the A-site cation of the material and the preparation conditions. H--doped ASn0.7Y0.3O3-δ (A = Ba, Ba0.5Sr0.5, and Sr) obtained by the reaction of ASn0.7Y0.3O3-δ precursors with CaH2 at 773 K under vacuum conditions was shown to have almost the same bandgap (ca. 2.1 eV), regardless of the A-site cation. Physicochemical measurements and theoretical calculations revealed that the identical bandgaps of H--doped ASn0.7Y0.3O3-δ are due to the simultaneous shift of the midgap states composed of Sn2+ with the conduction band minimum. Experimental results also indicated that the appropriate preparation conditions with respect to Y3+-substitution and the temperature for the synthesis of the ASn0.7Y0.3O3-δ precursors were essential to obtain H--doped products that have a low density of defects.

14.
Acta Radiol ; 63(2): 268-277, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33508952

RESUMO

BACKGROUND: In older adults, the diagnosis of acute pyelonephritis is challenging because of non-specific symptoms and false-positive urine test results. Few studies have investigated the diagnostic performance of computed tomography (CT) signs. PURPOSE: To evaluate the diagnostic performance of CT signs for acute pyelonephritis in older patients suspected of infection with unknown focus. MATERIAL AND METHODS: This cross-sectional study was conducted between 2015 and 2018. Patients aged ≥65 years who underwent blood cultures, urine culture, and non-contrast or contrast-enhanced CT on admission were included. Cases with clinically presumable infection focus before CT were excluded. Two radiologists blinded to clinical information independently reviewed five CT signs: perirenal fat stranding; pelvicalyceal wall thickening and enhancement; renal enlargement; thickening of Gerota's fascia; and area(s) of decreased attenuation. The final diagnoses were made by a clinical expert panel. RESULTS: Among 473 eligible patients, 61 were diagnosed with acute pyelonephritis. When the laterality of findings between the left and right kidneys were considered, the positive and negative likelihood ratios of perirenal fat stranding were 4.0 (95% confidence interval [CI] = 2.3-7.0) and 0.8 (95% CI = 0.7-0.9) in non-contrast CT, respectively. The other signs in non-contrast CT showed similar diagnostic performance with positive and negative likelihood ratios of 3.5-11.3 and 0.8-0.9, respectively. CONCLUSION: CT signs can help physicians diagnose acute pyelonephritis in older patients suspected of infection with unknown focus.


Assuntos
Pielonefrite/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Doença Aguda , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pielonefrite/etiologia , Sensibilidade e Especificidade
15.
Inorg Chem ; 60(19): 14613-14621, 2021 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-34463090

RESUMO

We report on the growth of single crystals of an electron-doped titanium oxyfluoride, Li2Ti(O,F)3, employing high-temperature electrolysis of TiO2 with a eutectic Li2MoO4-LiF melt. Greenish octahedral-shaped crystals (∼30 µm in size) with a cubic rocksalt-type structure were successfully obtained by precisely tuning the applied voltage. The temperature-dependent magnetic susceptibility data revealed a paramagnetic behavior at low temperatures, ensuring the presence of Ti3+ ions (mean valence number of +3.78; F/Ti ∼ 0.15). The crystals exhibited clear visible-light absorption and produced H2 from water in the presence of a sacrificial reagent under UV-light irradiation. Li2Ti(O,F)3 more efficiently produced H2 compared with a nondoped oxyfluoride Li5Ti2O6F, likely due to the doped electrons for the former. This work highlights a promising electrochemical approach toward growing electron-doped oxyfluoride crystals.

16.
Nature ; 517(7532): 33-8, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25409156

RESUMO

Emerging evidence suggests that the ribosome has a regulatory function in directing how the genome is translated in time and space. However, how this regulation is encoded in the messenger RNA sequence remains largely unknown. Here we uncover unique RNA regulons embedded in homeobox (Hox) 5' untranslated regions (UTRs) that confer ribosome-mediated control of gene expression. These structured RNA elements, resembling viral internal ribosome entry sites (IRESs), are found in subsets of Hox mRNAs. They facilitate ribosome recruitment and require the ribosomal protein RPL38 for their activity. Despite numerous layers of Hox gene regulation, these IRES elements are essential for converting Hox transcripts into proteins to pattern the mammalian body plan. This specialized mode of IRES-dependent translation is enabled by an additional regulatory element that we term the translation inhibitory element (TIE), which blocks cap-dependent translation of transcripts. Together, these data uncover a new paradigm for ribosome-mediated control of gene expression and organismal development.


Assuntos
Regiões 5' não Traduzidas/genética , Regulação da Expressão Gênica/genética , Genes Homeobox/genética , Sequências Reguladoras de Ácido Ribonucleico/genética , Ribossomos/metabolismo , Animais , Osso e Ossos/embriologia , Osso e Ossos/metabolismo , Linhagem Celular , Sequência Conservada , Evolução Molecular , Camundongos , Dados de Sequência Molecular , Biossíntese de Proteínas/genética , Capuzes de RNA/metabolismo , Proteínas Ribossômicas/metabolismo , Ribossomos/química , Especificidade por Substrato , Peixe-Zebra/genética
17.
Inorg Chem ; 59(20): 15384-15393, 2020 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-32991153

RESUMO

A series of aluminate-based oxyhydrides, Sr3-xAxAlO4H (A = Ca, Ba; x = 0, 1), has been synthesized by high-temperature reaction of oxide and hydride precursors under a H2 atmosphere. Their crystal structures determined via X-ray and neutron powder diffraction are isostructural with tetragonal Sr3AlO4F (space group I4/mcm), consisting of (Sr1-x/3Ax/3)2H layers and isolated AlO4 tetrahedra. Rietveld refinement based on the diffraction patterns and bond-valence-sum analysis show that Ba preferentially occupies the 10-coordinated Sr1 sites, while Ca strongly prefers to occupy the 8-coordinated Sr2 sites. Luminescence owing to the 4f-5d transition of Eu2+ or Ce3+ was observed from Eu- and Ce-doped samples, Sr3-x-yAxByAlO4H (A = Ca, Ba; B = Eu, Ce; x = 0, 1, y = 0.02), under excitation of near-ultraviolet light. Compared with its fluoride analogue, Sr3AlO4H:Ce3+ shows red shifts of both the excitation and emission bands, which is consistent with the reported hydride-based phosphors and can be explained by the covalency of the hydride ligands. The observed luminescence spectra can be decomposed into two sets of sub-bands corresponding to Ce3+ centers occupying Sr1 and Sr2 sites with distinctly different Stokes shifts (1.27 and 0.54 eV, respectively), as suggested by the results of constrained density functional theory (cDFT). The cDFT results also suggest that the large shift for Ce3+ at Sr1 is induced by large distortion of the coordinated structure with shortening of the H-Ce bond in the excited state. The current findings expand the class of oxyhydride materials and show the potential of hydride-based phosphors for optical applications.

18.
Inorg Chem ; 59(15): 11122-11128, 2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32683860

RESUMO

Substitution of oxide anions (O2-) in a metal oxide for nitrogen (N3-) results in reduction of the band gap, which is attractive in heterogeneous photocatalysis; however, only a handful of two-dimensional layered perovskite oxynitrides have been reported, and thus, the structural effects of layered oxynitrides on photocatalytic activity have not been sufficiently examined. This study reports the synthesis of a Ruddlesden-Popper phase three-layer oxynitride perovskite of K2Ca2Ta3O9N·2H2O, and the photocatalytic activity is compared with an analogous two-layer perovskite, K2LaTa2O6N·1.6H2O. Topochemical ammonolysis reaction of a Dion-Jacobson phase oxide KCa2Ta3O10 at 1173 K in the presence of K2CO3 resulted in a single-phase layered perovskite, K2Ca2Ta3O9N·2H2O, which belongs to the tetragonal P4/mmm space group, as demonstrated by synchrotron X-ray diffraction, scanning transmission electron microscopy measurements, and elemental analysis. The synthesized K2Ca2Ta3O9N·2H2O has an absorption edge at around 460 nm, with an estimated band gap of ca. 2.7 eV. K2Ca2Ta3O9N·2H2O modified with a Pt cocatalyst generated H2 from an aqueous solution containing a dissolved NaI as a reversible electron donor under visible light (λ > 400 nm) with no noticeable change in the crystal structure and light absorption properties. However, the H2 evolution activity of K2Ca2Ta3O9N·2H2O was an order of magnitude lower than that of K2LaTa2O6N·1.6H2O. Femtosecond transient absorption spectroscopy revealed that the lifetime of photogenerated mobile electrons in K2Ca2Ta3O9N·2H2O was shorter than that in K2LaTa2O6N·1.6H2O, which could explain the low photocatalytic activity of K2Ca2Ta3O9N·2H2O.

19.
Am J Emerg Med ; 38(7): 1389-1395, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31859198

RESUMO

OBJECTIVE: To evaluate the added value of inflammatory markers to vital signs to predict mortality in patients suspected of severe infection. METHODS: This study was conducted at an acute care hospital (471-bed capacity). Consecutive adult patients suspected of severe infection who presented to either ambulatory care or the emergency department from April 2015 to March 2017 were retrospectively evaluated. A prognostic model for predicting 30-day in-hospital mortality based on previously established vital signs (systolic blood pressure, respiratory rate, and mental status) was compared with an extended model that also included four inflammatory markers (C-reactive protein, neutrophil-lymphocyte ratio, mean platelet volume, and red cell distribution width). Measures of interest were model fit, discrimination, and the net percentage of correctly reclassified individuals at the pre-specified threshold of 10% risk. RESULTS: Of the 1015 patients included, 66 (6.5%) died. The extended model including inflammatory markers performed significantly better than the vital sign model (likelihood ratio test: p < 0.001), and the c-index increased from 0.69 (range 0.67-0.70) to 0.76 (range 0.75-0.77) (p = 0.01). All included markers except C-reactive protein showed significant contribution to the model improvement. Among those who died, 9.1% (95% CI -2.8-21.8) were correctly reclassified by the extended model at the 10% threshold. CONCLUSIONS: The inflammatory markers except C-reactive protein showed added predictive value to vital signs. Future studies should focus on developing and validating prediction models for use in individualized predictions including both vital signs and the significant markers.


Assuntos
Proteína C-Reativa/imunologia , Mortalidade Hospitalar , Infecções Intra-Abdominais/mortalidade , Neutrófilos , Infecções Respiratórias/mortalidade , Sepse/mortalidade , Dermatopatias Infecciosas/mortalidade , Infecções Urinárias/mortalidade , Idoso , Idoso de 80 Anos ou mais , Pressão Sanguínea , Tomada de Decisão Clínica , Técnicas de Apoio para a Decisão , Índices de Eritrócitos , Feminino , Humanos , Inflamação , Infecções Intra-Abdominais/sangue , Infecções Intra-Abdominais/imunologia , Contagem de Leucócitos , Contagem de Linfócitos , Masculino , Volume Plaquetário Médio , Pessoa de Meia-Idade , Escores de Disfunção Orgânica , Prognóstico , Taxa Respiratória , Infecções Respiratórias/sangue , Infecções Respiratórias/imunologia , Estudos Retrospectivos , Sepse/sangue , Sepse/imunologia , Dermatopatias Infecciosas/sangue , Dermatopatias Infecciosas/imunologia , Infecções Urinárias/sangue , Infecções Urinárias/imunologia
20.
Angew Chem Int Ed Engl ; 59(43): 19254-19259, 2020 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-32662185

RESUMO

Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal-organic frameworks with desirable properties; however, FeII ions are exclusively six-coordinated. Herein, we present a cyanide-bridged three-dimensional (3D) CP, FePd(CN)4 , bearing four-coordinate FeII ions, which is synthesized by thermal treatment of a two-dimensional (2D) six-coordinate FeII CP, Fe(H2 O)2 Pd(CN)4 ⋅4 H2 O, to remove water molecules. Atomic-resolution transmission electron microscopy and powder X-ray and neutron diffraction measurements revealed that the FePd(CN)4 structure is composed of a two-fold interpenetrated PtS topology network, where the FeII center demonstrates an intermediate geometry between tetrahedral and square-planar coordination. This four-coordinate FeII center with the distorted geometry can act as a thermo-responsive flexible node in the PtS network.

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