Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.882
Filtrar
1.
Cell ; 184(14): 3829-3841.e21, 2021 07 08.
Artículo en Inglés | MEDLINE | ID: mdl-34171307

RESUMEN

Past human genetic diversity and migration between southern China and Southeast Asia have not been well characterized, in part due to poor preservation of ancient DNA in hot and humid regions. We sequenced 31 ancient genomes from southern China (Guangxi and Fujian), including two ∼12,000- to 10,000-year-old individuals representing the oldest humans sequenced from southern China. We discovered a deeply diverged East Asian ancestry in the Guangxi region that persisted until at least 6,000 years ago. We found that ∼9,000- to 6,000-year-old Guangxi populations were a mixture of local ancestry, southern ancestry previously sampled in Fujian, and deep Asian ancestry related to Southeast Asian Hòabìnhian hunter-gatherers, showing broad admixture in the region predating the appearance of farming. Historical Guangxi populations dating to ∼1,500 to 500 years ago are closely related to Tai-Kadai and Hmong-Mien speakers. Our results show heavy interactions among three distinct ancestries at the crossroads of East and Southeast Asia.


Asunto(s)
Genética de Población , Asia Sudoriental , Asia Oriental , Geografía , Humanos
2.
Nature ; 632(8024): 313-319, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38885695

RESUMEN

Oligosaccharides have myriad functions throughout biological processes1,2. Chemical synthesis of these structurally complex molecules facilitates investigation of their functions. With a dense concentration of stereocentres and hydroxyl groups, oligosaccharide assembly through O-glycosylation requires simultaneous control of site, stereo- and chemoselectivities3,4. Chemists have traditionally relied on protecting group manipulations for this purpose5-8, adding considerable synthetic work. Here we report a glycosylation platform that enables selective coupling between unprotected or minimally protected donor and acceptor sugars, producing 1,2-cis-O-glycosides in a catalyst-controlled, site-selective manner. Radical-based activation9 of allyl glycosyl sulfones forms glycosyl bromides. A designed aminoboronic acid catalyst brings this reactive intermediate close to an acceptor through a network of non-covalent hydrogen bonding and reversible covalent B-O bonding interactions, allowing precise glycosyl transfer. The site of glycosylation can be switched with different aminoboronic acid catalysts by affecting their interaction modes with substrates. The method accommodates a wide range of sugar types, amenable to the preparation of naturally occurring sugar chains and pentasaccharides containing 11 free hydroxyls. Experimental and computational studies provide insights into the origin of selectivity outcomes.


Asunto(s)
Glicósidos , Oligosacáridos , Ácidos Borónicos/química , Bromuros/química , Catálisis , Glicósidos/química , Glicósidos/síntesis química , Glicosilación , Enlace de Hidrógeno , Oligosacáridos/química , Oligosacáridos/síntesis química , Sulfonas/química
3.
Nature ; 613(7942): 53-59, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36600061

RESUMEN

Interlayer electronic coupling in two-dimensional materials enables tunable and emergent properties by stacking engineering. However, it also results in significant evolution of electronic structures and attenuation of excitonic effects in two-dimensional semiconductors as exemplified by quickly degrading excitonic photoluminescence and optical nonlinearities in transition metal dichalcogenides when monolayers are stacked into van der Waals structures. Here we report a van der Waals crystal, niobium oxide dichloride (NbOCl2), featuring vanishing interlayer electronic coupling and monolayer-like excitonic behaviour in the bulk form, along with a scalable second-harmonic generation intensity of up to three orders higher than that in monolayer WS2. Notably, the strong second-order nonlinearity enables correlated parametric photon pair generation, through a spontaneous parametric down-conversion (SPDC) process, in flakes as thin as about 46 nm. To our knowledge, this is the first SPDC source unambiguously demonstrated in two-dimensional layered materials, and the thinnest SPDC source ever reported. Our work opens an avenue towards developing van der Waals material-based ultracompact on-chip SPDC sources as well as high-performance photon modulators in both classical and quantum optical technologies1-4.

4.
Proc Natl Acad Sci U S A ; 121(20): e2320674121, 2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38684007

RESUMEN

Identifying and protecting hotspots of endemism and species richness is crucial for mitigating the global biodiversity crisis. However, our understanding of spatial diversity patterns is far from complete, which severely limits our ability to conserve biodiversity hotspots. Here, we report a comprehensive analysis of amphibian species diversity in China, one of the most species-rich countries on Earth. Our study combines 20 y of field surveys with new molecular analyses of 521 described species and also identifies 100 potential cryptic species. We identify 10 hotspots of amphibian diversity in China, each with exceptional species richness and endemism and with exceptional phylogenetic diversity and phylogenetic endemism (based on a new time-calibrated, species-level phylogeny for Chinese amphibians). These 10 hotspots encompass 59.6% of China's described amphibian species, 49.0% of cryptic species, and 55.6% of species endemic to China. Only four of these 10 hotspots correspond to previously recognized biodiversity hotspots. The six new hotspots include the Nanling Mountains and other mountain ranges in South China. Among the 186 species in the six new hotspots, only 9.7% are well covered by protected areas and most (88.2%) are exposed to high human impacts. Five of the six new hotspots are under very high human pressure and are in urgent need of protection. We also find that patterns of richness in cryptic species are significantly related to those in described species but are not identical.


Asunto(s)
Anfibios , Biodiversidad , Filogenia , Animales , Anfibios/clasificación , China , Conservación de los Recursos Naturales
5.
Nature ; 584(7821): 393-397, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32814886

RESUMEN

The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood1. Previous assessments found that the summed contributions of ice-mass loss, terrestrial water storage and thermal expansion of the ocean could not be reconciled with observed changes in global-mean sea level, implying that changes in sea level or some contributions to those changes were poorly constrained2,3. Recent improvements to observational data, our understanding of the main contributing processes to sea-level change and methods for estimating the individual contributions, mean another attempt at reconciliation is warranted. Here we present a probabilistic framework to reconstruct sea level since 1900 using independent observations and their inherent uncertainties. The sum of the contributions to sea-level change from thermal expansion of the ocean, ice-mass loss and changes in terrestrial water storage is consistent with the trends and multidecadal variability in observed sea level on both global and basin scales, which we reconstruct from tide-gauge records. Ice-mass loss-predominantly from glaciers-has caused twice as much sea-level rise since 1900 as has thermal expansion. Mass loss from glaciers and the Greenland Ice Sheet explains the high rates of global sea-level rise during the 1940s, while a sharp increase in water impoundment by artificial reservoirs is the main cause of the lower-than-average rates during the 1970s. The acceleration in sea-level rise since the 1970s is caused by the combination of thermal expansion of the ocean and increased ice-mass loss from Greenland. Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900.


Asunto(s)
Calor , Cubierta de Hielo/química , Agua de Mar/análisis , Agua de Mar/química , Monitoreo del Ambiente , Calentamiento Global/estadística & datos numéricos , Groenlandia , Historia del Siglo XX , Historia del Siglo XXI , Probabilidad , Incertidumbre
6.
Mol Cell ; 69(2): 279-291.e5, 2018 01 18.
Artículo en Inglés | MEDLINE | ID: mdl-29351847

RESUMEN

Sustained energy starvation leads to activation of AMP-activated protein kinase (AMPK), which coordinates energy status with numerous cellular processes including metabolism, protein synthesis, and autophagy. Here, we report that AMPK phosphorylates the histone methyltransferase EZH2 at T311 to disrupt the interaction between EZH2 and SUZ12, another core component of the polycomb repressive complex 2 (PRC2), leading to attenuated PRC2-dependent methylation of histone H3 at Lys27. As such, PRC2 target genes, many of which are known tumor suppressors, were upregulated upon T311-EZH2 phosphorylation, which suppressed tumor cell growth both in cell culture and mouse xenografts. Pathologically, immunohistochemical analyses uncovered a positive correlation between AMPK activity and pT311-EZH2, and higher pT311-EZH2 correlates with better survival in both ovarian and breast cancer patients. Our finding suggests that AMPK agonists might be promising sensitizers for EZH2-targeting cancer therapies.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Proteína Potenciadora del Homólogo Zeste 2/metabolismo , Animales , Carcinogénesis/genética , Ciclo Celular , Línea Celular Tumoral , Proliferación Celular , Metilación de ADN , Proteínas de Unión al ADN/metabolismo , Proteína Potenciadora del Homólogo Zeste 2/genética , Proteína Potenciadora del Homólogo Zeste 2/fisiología , Epigénesis Genética , Femenino , Histonas/metabolismo , Humanos , Ratones , Proteínas de Neoplasias , Proteínas Nucleares/metabolismo , Oncogenes , Neoplasias Ováricas/metabolismo , Fosforilación , Complejo Represivo Polycomb 2/metabolismo , Complejo Represivo Polycomb 2/fisiología , Factores de Transcripción , Regulación hacia Arriba
7.
Nucleic Acids Res ; 2024 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-39271125

RESUMEN

The efficient refactoring of natural product biosynthetic gene clusters (BGCs) for activating silent BGCs is a central challenge for the discovery of new bioactive natural products. Herein, we have developed a simple and robust CRISETR (CRISPR/Cas9 and RecET-mediated Refactoring) technique, combining clustered regulatory interspaced short palindromic repeats (CRISPR)/Cas9 and RecET, for the multiplexed refactoring of natural product BGCs. By this approach, natural product BGCs can be refactored through the synergistic interaction between RecET-mediated efficient homologous recombination and the CRISPR/Cas9 system. We first performed a proof-of-concept validation of the ability of CRISETR, and CRISETR can achieve simultaneous replacement of four promoter sites and marker-free replacement of single promoter site in natural product BGCs. Subsequently, we applied CRISETR to the promoter engineering of the 74-kb daptomycin BGC containing a large number of direct repeat sequences for enhancing the heterologous production of daptomycin. We used combinatorial design to build multiple refactored daptomycin BGCs with diverse combinations of promoters different in transcriptional strengths, and the yield of daptomycin was improved 20.4-fold in heterologous host Streptomyces coelicolor A3(2). In general, CRISETR exhibits enhanced tolerance to repetitive sequences within gene clusters, enabling efficient refactoring of diverse and complex BGCs, which would greatly accelerate discovery of novel bioactive metabolites present in microorganism.

8.
Development ; 149(19)2022 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-36178098

RESUMEN

Recent large-scale mRNA sequencing has shown that introns are retained in 5-10% of mRNA, and these events are named intron retention (IR). IR has been recognized as a key mechanism in the regulation of gene expression. However, the role of this mechanism in female reproduction in mammals remains unclear. RNA terminal phosphate cyclase B (RTCB) is a RNA ligase; we found that RTCB conditional knockout mice have premature ovarian failure and that RTCB plays a crucial role in follicular development. RTCB regulated the splicing of transcripts related to DNA methylation and DNA damage repair. In addition, it regulated the resumption of oocyte meiosis by affecting CDK1 activation. Moreover, the loss of RTCB suppressed zygotic genome activation (ZGA) and decreased translation at the global level. In addition, Rtcb deletion resulted in the accumulation of maternal mRNAs containing unspliced introns and in a decline in the overall level of transcripts. As a result, the Rtcb-/- females were sterile. Our study highlights the important role of RTCB-regulated noncanonical alternative splicing in female reproduction.


Asunto(s)
Empalme Alternativo , Aminoacil-ARNt Sintetasas/metabolismo , Fosfatos , Empalme Alternativo/genética , Animales , Femenino , Ligasas/genética , Mamíferos/genética , Ratones , Oocitos , Empalme del ARN , ARN Mensajero/genética
9.
Am J Pathol ; 194(7): 1346-1373, 2024 07.
Artículo en Inglés | MEDLINE | ID: mdl-38631549

RESUMEN

Because the mechanotransduction by stromal stiffness stimulates the rupture and repair of the nuclear envelope in pancreatic progenitor cells, accumulated genomic aberrations are under selection in the tumor microenvironment. Analysis of cell growth, micronuclei, and phosphorylated Ser-139 residue of the histone variant H2AX (γH2AX) foci linked to mechanotransduction pressure in vivo during serial orthotopic passages of mouse KrasLSL-G12D/+;Trp53flox/flox;Pdx1-Cre (KPC) cancer cells in the tumor and in migrating through the size-restricted 3-µm micropores. To search for pancreatic cancer cell-of-origin, analysis of single-cell data sets revealed that the extracellular matrix shaped an alternate route of acinar-ductal transdifferentiation of acinar cells into topoisomerase II α (TOP2A)-overexpressing cancer cells and derived subclusters with copy number amplifications in MYC-PTK2 (protein tyrosine kinase 2) locus and PIK3CA. High-PTK2 expression is associated with 171 differentially methylated CpG loci, 319 differentially expressed genes, and poor overall survival in The Cancer Genome Atlas-Pancreatic Adenocarcinoma cohort. Abolished RGD-integrin signaling by disintegrin KG blocked the PTK2 phosphorylation, increased cancer apoptosis, decreased vav guanine nucleotide exchange factor 1 (VAV1) expression, and prolonged overall survival in the KPC mice. Reduction of α-smooth muscle actin deposition in the CD248 knockout KPC mice remodeled the tissue stroma and down-regulated TOP2A expression in the epithelium. In summary, stromal stiffness induced the onset of cancer cells-of-origin by ectopic TOP2A expression, and the genomic amplification of MYC-PTK2 locus via alternative transdifferentiation of pancreatic progenitor cells is the vulnerability useful for disintegrin KG treatment.


Asunto(s)
Inestabilidad Cromosómica , Progresión de la Enfermedad , Neoplasias Pancreáticas , Animales , Neoplasias Pancreáticas/patología , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Ratones , Humanos , Carcinoma in Situ/patología , Carcinoma in Situ/genética , Carcinoma in Situ/metabolismo , Células del Estroma/metabolismo , Células del Estroma/patología , Microambiente Tumoral , Mecanotransducción Celular , Quinasa 1 de Adhesión Focal
10.
Chem Rev ; 123(16): 9940-9981, 2023 08 23.
Artículo en Inglés | MEDLINE | ID: mdl-37561162

RESUMEN

A survey of protein databases indicates that the majority of enzymes exist in oligomeric forms, with about half of those found in the UniProt database being homodimeric. Understanding why many enzymes are in their dimeric form is imperative. Recent developments in experimental and computational techniques have allowed for a deeper comprehension of the cooperative interactions between the subunits of dimeric enzymes. This review aims to succinctly summarize these recent advancements by providing an overview of experimental and theoretical methods, as well as an understanding of cooperativity in substrate binding and the molecular mechanisms of cooperative catalysis within homodimeric enzymes. Focus is set upon the beneficial effects of dimerization and cooperative catalysis. These advancements not only provide essential case studies and theoretical support for comprehending dimeric enzyme catalysis but also serve as a foundation for designing highly efficient catalysts, such as dimeric organic catalysts. Moreover, these developments have significant implications for drug design, as exemplified by Paxlovid, which was designed for the homodimeric main protease of SARS-CoV-2.


Asunto(s)
COVID-19 , Humanos , SARS-CoV-2 , Polímeros
11.
Cereb Cortex ; 34(1)2024 01 14.
Artículo en Inglés | MEDLINE | ID: mdl-38044479

RESUMEN

Accumulating evidence from functional magnetic resonance imaging studies supported brain dysfunction during emotional processing in bipolar disorder (BD) and major depressive disorder (MDD). However, child and adolescent BD and MDD could display different activation patterns, which have not been fully understood. This study aimed to investigate common and distinct activation patterns of pediatric BD (PBD) and MDD (p-MDD) during emotion processing using meta-analytic approaches. Literature search identified 25 studies, contrasting 252 PBD patients, and 253 healthy controls (HCs) as well as 311 p-MDD patients and 263 HCs. A total of nine meta-analyses were conducted pulling PBD and p-MDD experiments together and separately. The results revealed that PBD and p-MDD showed distinct patterns during negative processing. PBD patients exhibited activity changes in bilateral precuneus, left inferior parietal gyrus, left angular gyrus, and right posterior cingulate cortex while p-MDD patients showed functional disruptions in the left rectus, left triangular part of the inferior frontal gyrus, left orbital frontal cortex, left insula, and left putamen. In conclusion, the activity changes in PBD patients were mainly in regions correlated with emotion perception while the dysfunction among p-MDD patients was in the fronto-limbic circuit and reward-related regions in charge of emotion appraisal and regulation.


Asunto(s)
Trastorno Bipolar , Trastorno Depresivo Mayor , Adolescente , Niño , Humanos , Trastorno Bipolar/diagnóstico por imagen , Encéfalo , Emociones/fisiología , Giro del Cíngulo , Imagen por Resonancia Magnética/métodos , Corteza Prefrontal
12.
Cell Mol Life Sci ; 81(1): 338, 2024 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-39120703

RESUMEN

Alveolar bone loss is a main manifestation of periodontitis. Human periodontal ligament stem cells (PDLSCs) are considered as optimal seed cells for alveolar bone regeneration due to its mesenchymal stem cell like properties. Osteogenic potential is the premise for PDLSCs to repair alveolar bone loss. However, the mechanism regulating osteogenic differentiation of PDLSCs remain elusive. In this study, we identified Neuron-derived orphan receptor 1 (NOR1), was particularly expressed in PDL tissue in vivo and gradually increased during osteogenic differentiation of PDLSCs in vitro. Knockdown of NOR1 in hPDLSCs inhibited their osteogenic potential while NOR1 overexpression reversed this effect. In order to elucidate the downstream regulatory network of NOR1, RNA-sequencing was used. We found that downregulated genes were mainly enriched in TGF-ß, Hippo, Wnt signaling pathway. Further, by western blot analysis, we verified that the expression level of phosphorylated-SMAD2/3 and phosphorylated-SMAD4 were all decreased after NOR1 knockdown. Additionally, ChIP-qPCR and dual luciferase reporter assay indicated that NOR1 could bind to the promoter of TGFBR1 and regulate its activity. Moreover, overexpression of TGFBR1 in PDLSCs could rescue the damaged osteogenic potential after NOR1 knockdown. Taken together, our results demonstrated that NOR1 could activate TGF-ß/SMAD signaling pathway and positively regulates the commitment of osteoblast lineages of PDLSCs by targeting TGFBR1 directly.


Asunto(s)
Diferenciación Celular , Osteoblastos , Osteogénesis , Ligamento Periodontal , Receptor Tipo I de Factor de Crecimiento Transformador beta , Transducción de Señal , Factor de Crecimiento Transformador beta , Humanos , Diferenciación Celular/genética , Células Cultivadas , Osteoblastos/metabolismo , Osteoblastos/citología , Osteogénesis/genética , Ligamento Periodontal/citología , Ligamento Periodontal/metabolismo , Receptor Tipo I de Factor de Crecimiento Transformador beta/metabolismo , Receptor Tipo I de Factor de Crecimiento Transformador beta/genética , Células Madre/metabolismo , Células Madre/citología , Factor de Crecimiento Transformador beta/metabolismo
13.
Nucleic Acids Res ; 51(17): 8909-8924, 2023 09 22.
Artículo en Inglés | MEDLINE | ID: mdl-37604686

RESUMEN

Archaeal ribosomes have many domain-specific features; however, our understanding of these structures is limited. We present 10 cryo-electron microscopy (cryo-EM) structures of the archaeal ribosome from crenarchaeota Sulfolobus acidocaldarius (Sac) at 2.7-5.7 Å resolution. We observed unstable conformations of H68 and h44 of ribosomal RNA (rRNA) in the subunit structures, which may interfere with subunit association. These subunit structures provided models for 12 rRNA expansion segments and 3 novel r-proteins. Furthermore, the 50S-aRF1 complex structure showed the unique domain orientation of aRF1, possibly explaining P-site transfer RNA (tRNA) release after translation termination. Sac 70S complexes were captured in seven distinct steps of the tRNA translocation reaction, confirming conserved structural features during archaeal ribosome translocation. In aEF2-engaged 70S ribosome complexes, 3D classification of cryo-EM data based on 30S head domain identified two new translocation intermediates with 30S head domain tilted 5-6° enabling its disengagement from the translocated tRNA and its release post-translocation. Additionally, we observed conformational changes to aEF2 during ribosome binding and switching from three different states. Our structural and biochemical data provide new insights into archaeal translation and ribosome translocation.


Archaeal ribosomes display variations in their ribosomal proteins and ribosomal RNA (rRNA) expansion segments (ESs). Protein translation in archaea combines features in both bacterial and eukaryotic translation. In this study, we present 10 cryo-electron microscopy structures of the archaeal ribosome from crenarchaeota Sulfolobus acidocaldarius (Sac). The 50S and 30S subunit structures present 3 novel ribosomal proteins and 12 rRNA ESs. The 70S Sac ribosome structures were captured in seven distinct functional states, including pre-, intermediate- and post-translocation states. Specifically, we identified two novel translocation intermediates, in which the 30S subunit head domain tilts outward to release the translocated P-site transfer RNA. The structures of archaeal ribosomes provide insights into the archaeal translation and ribosome translocation.


Asunto(s)
Ribosomas , Sulfolobus acidocaldarius , Microscopía por Crioelectrón , Proteínas Ribosómicas/metabolismo , Ribosomas/metabolismo , ARN Ribosómico/metabolismo , ARN de Transferencia/metabolismo , Sulfolobus acidocaldarius/citología , Sulfolobus acidocaldarius/metabolismo
14.
Proc Natl Acad Sci U S A ; 119(32): e2204779119, 2022 08 09.
Artículo en Inglés | MEDLINE | ID: mdl-35914128

RESUMEN

Earlier work has shown that siRNA-mediated reduction of the SUPT4H or SUPT5H proteins, which interact to form the DSIF complex and facilitate transcript elongation by RNA polymerase II (RNAPII), can decrease expression of mutant gene alleles containing nucleotide repeat expansions differentially. Using luminescence and fluorescence assays, we identified chemical compounds that interfere with the SUPT4H-SUPT5H interaction and then investigated their effects on synthesis of mRNA and protein encoded by mutant alleles containing repeat expansions in the huntingtin gene (HTT), which causes the inherited neurodegenerative disorder, Huntington's Disease (HD). Here we report that such chemical interference can differentially affect expression of HTT mutant alleles, and that a prototypical chemical, 6-azauridine (6-AZA), that targets the SUPT4H-SUPT5H interaction can modify the biological response to mutant HTT gene expression. Selective and dose-dependent effects of 6-AZA on expression of HTT alleles containing nucleotide repeat expansions were seen in multiple types of cells cultured in vitro, and in a Drosophila melanogaster animal model for HD. Lowering of mutant HD protein and mitigation of the Drosophila "rough eye" phenotype associated with degeneration of photoreceptor neurons in vivo were observed. Our findings indicate that chemical interference with DSIF complex formation can decrease biochemical and phenotypic effects of nucleotide repeat expansions.


Asunto(s)
Azauridina , Proteína Huntingtina , Enfermedad de Huntington , Proteínas Mutantes , Mutación , Proteínas Nucleares , Fenotipo , Proteínas Represoras , Factores de Elongación Transcripcional , Alelos , Animales , Azauridina/farmacología , Células Cultivadas , Expansión de las Repeticiones de ADN , Modelos Animales de Enfermedad , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Humanos , Proteína Huntingtina/biosíntesis , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Enfermedad de Huntington/genética , Mediciones Luminiscentes , Proteínas Mutantes/biosíntesis , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Proteínas Nucleares/metabolismo , Células Fotorreceptoras de Invertebrados/efectos de los fármacos , Proteínas Represoras/metabolismo , Factores de Elongación Transcripcional/metabolismo
15.
Nano Lett ; 24(33): 10055-10061, 2024 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-39047260

RESUMEN

Nonlocal metasurfaces, exemplified by resonant waveguide gratings (RWGs), spatially and angularly configure optical wavefronts through narrow-band resonant modes, unlike the broad-band and broad-angle responses of local metasurfaces. However, forward design techniques for RWGs remain constrained at lower efficiency. Here, we present a topology-optimized metasurface resonant waveguide grating (MRWG) composed of titanium dioxide on a glass substrate capable of operating simultaneously at red, yellow, green, and blue wavelengths. Through adjoint-based topology optimization, while considering nonlocal effects, we significantly enhance its diffraction efficiency, achieving numerical efficiencies up to 78% and Q-factors as high as 1362. Experimentally, we demonstrated efficiencies of up to 59% with a Q-factor of 93. Additionally, we applied our topology-optimized metasurface to color selectivity, producing vivid colors at 4 narrow-band wavelengths. Our investigation represents a significant advancement in metasurface technology, with potential applications in see-through optical combiners and augmented reality platforms.

16.
Nano Lett ; 24(5): 1660-1666, 2024 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-38266180

RESUMEN

Scalable and addressable integrated manipulation of qubits is crucial for practical quantum information applications. Different waveguides have been used to transport the optical and electrical driving pulses, which are usually required for qubit manipulation. However, the separated multifields may limit the compactness and efficiency of manipulation and introduce unwanted perturbation. Here, we develop a tapered fiber-nanowire-electrode hybrid structure to realize integrated optical and microwave manipulation of solid-state spins at nanoscale. Visible light and microwave driving pulses are simultaneously transported and concentrated along an Ag nanowire. Studied with spin defects in diamond, the results show that the different driving fields are aligned with high accuracy. The spatially selective spin manipulation is realized. And the frequency-scanning optically detected magnetic resonance (ODMR) of spin qubits is measured, illustrating the potential for portable quantum sensing. Our work provides a new scheme for developing compact, miniaturized quantum sensors and quantum information processing devices.

17.
J Am Chem Soc ; 146(2): 1532-1542, 2024 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-38174923

RESUMEN

Described here is a mild and stereoselective protocol for the synthesis of [3]dendralenes via the intermolecular dimerization of allenes. With the proper choice of a ruthenium catalyst, a range of unactivated 1,1-disubstituted allenes, without prefunctionalization in the allylic position, reacted efficiently to provide rapid access to densely substituted [3]dendralenes. An intermolecular C-C bond and three different types of C═C double bonds (di-, tri-, and tetrasubstituted) embedded in an acyclic structure were constructed with good to high E/Z stereocontrol. This is in contrast to the known catalytic protocols that focus on allenes with prefunctionalization at the allylic position and/or monosubstituted allenes, which would proceed by a different mechanism or require less stereocontrol. The silyl-substituted dendralene products are precursors of other useful dendralene molecules. Density functional theory (DFT) studies and control experiments supported a mechanism involving oxidative cyclometalation, ß-H elimination (the rate-determining step), and reductive elimination.

18.
J Am Chem Soc ; 146(29): 20477-20493, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-38982945

RESUMEN

Cobalt complexes with chiral quinox ligands effectively promote the enantioselective conjugate addition of enones using aryl, heteroaryl, and alkenyl halides and sulfonates. Additionally, a cobalt complex with a strongly donating diphosphine, BenzP*, successfully catalyzes the asymmetric reductive arylation and alkenylation of α,ß-unsaturated amides. Both catalytic systems show broad scopes and tolerance of sensitive functional groups. Both reactions can be scaled up with low loadings of cobalt catalysts. Experimental results and density functional theory (DFT) calculations suggest a new mechanism of elementary 1,4-addition of aryl cobalt(I) complexes.

19.
Development ; 148(20)2021 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-34541605

RESUMEN

Programmed cell death (PCD) is a common cell fate in metazoan development. PCD effectors are extensively studied, but how they are temporally regulated is less understood. Here, we report a mechanism controlling tail-spike cell death onset during Caenorhabditis elegans development. We show that the zinc-finger transcription factor BLMP-1, which controls larval development timing, also regulates embryonic tail-spike cell death initiation. BLMP-1 functions upstream of CED-9 and in parallel to DRE-1, another CED-9 and tail-spike cell death regulator. BLMP-1 expression is detected in the tail-spike cell shortly after the cell is born, and blmp-1 mutations promote ced-9-dependent tail-spike cell survival. BLMP-1 binds ced-9 gene regulatory sequences, and inhibits ced-9 transcription just before cell-death onset. BLMP-1 and DRE-1 function together to regulate developmental timing, and their mammalian homologs regulate B-lymphocyte fate. Our results, therefore, identify roles for developmental timing genes in cell-death initiation, and suggest conservation of these functions.


Asunto(s)
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Muerte Celular/genética , Proteínas Represoras/genética , Transcripción Genética/genética , Animales , Apoptosis/genética , Diferenciación Celular/genética , Regulación del Desarrollo de la Expresión Génica/genética
20.
Breast Cancer Res Treat ; 203(1): 73-83, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37751078

RESUMEN

PURPOSE: Oncotype DX, a 21-gene expression profiling test, has become standard of care in the management of estrogen receptor (ER)-positive breast cancer. In multifocal tumors, it is unclear whether testing of the different foci is necessary. We evaluated the concordance of Oncotype DX recurrence scores (RS) between 2 tumor foci in synchronous bilateral or unilateral multifocal tumors and characterized pathological predictors of discordance. METHODS: We reviewed 713 ER+, HER2- primary invasive breast cancer patients with Oncotype RS and identified 17 bilateral synchronous patients (34 tumors) and 13 unilateral multifocal patients (26 tumors) with available Oncotype RS on all foci. Discordance in Oncotype RS between synchronous tumors was recorded and associations with clinicopathologic features including tumor size, histology, Nottingham histologic grade, progesterone receptor staining, and Ki67 index were analyzed. RESULTS: Bilateral synchronous tumors were present in older patients (median age 59 years) and had larger tumor (median size 17 mm) and more discordant histology (10/17, 59%) as compared to unilateral multifocal tumors (median age 49 years, p < 0.01; median tumor size 12 mm, p = 0.01; discordant histology 2/13, 15%, p = 0.03). Oncotype RS were discordant in 47% (8/17) of bilateral and 54% (7/13) of unilateral multifocal tumors. Concordant Oncotype RS was associated with similar histologic grade and Ki67 index in 78% (7/9) of bilateral and 100% (6/6) of multifocal tumors. In contrast, only 25% (2/8) of bilateral (p = 0.06) and 14% (1/7) of unilateral multifocal (p < 0.01) cases with discordant Oncotype RS had concordant histology grades and Ki67 levels. In synchronous tumors with discordant Oncotype RS and Ki67 index, all (4/4) foci with higher RS had higher Ki67 index. CONCLUSION: Discordance of Oncotype RS is common in both bilateral and unilateral multifocal breast cancer and is likely associated with discordant histologic grade or Ki67.


Asunto(s)
Neoplasias de la Mama , Neoplasias Primarias Múltiples , Neoplasias de Mama Unilaterales , Anciano , Femenino , Humanos , Persona de Mediana Edad , Biomarcadores de Tumor/genética , Neoplasias de la Mama/patología , Perfilación de la Expresión Génica , Antígeno Ki-67/genética , Antígeno Ki-67/metabolismo , Recurrencia Local de Neoplasia/patología , Pronóstico
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA