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Constantine and the captive Christians of Persia : martyrdom and religious identity in Late Antiquity
\"This book demonstrates that the history of Christianity in the fourth century has been written mainly on the basis of Greek ecclesiastical histories and Syriac martyrdom narratives that date to decades, even centuries, after the fact. By closely analyzing these sources--which often exhibit conflicting religious, political, and hagiographical agendas--an evolving portrait of the first Christian emperor begins to emerge. This portrait of Constantine is useful not for re-constructing the events of the fourth century, but for understanding how the Syriac Christians of Roman Mesopotamia and Sasanian Persia used Constantine and the Christians of the West to fashion multiple political and religious identities over a prolonged period of change\"--Provided by publisher.
Book
Unraveling the origin of chirality from plasmonic nanoparticle-protein complexes
Plasmon-coupled circular dichroism has emerged as a promising approach for ultrasensitive detection of biomolecular conformations through coupling between molecular chirality and surface plasmons. Chiral nanoparticle assemblies without chiral molecules present also have large optical activities. We apply single-particle circular differential scattering spectroscopy coupled with electron imaging and simulations to identify both structural chirality of plasmonic aggregates and plasmon-coupled circular dichroism induced by chiral proteins. We establish that both chiral aggregates and just a few proteins in interparticle gaps of achiral assemblies are responsible for the ensemble signal, but single nanoparticles do not contribute. We furthermore find that the protein plays two roles: It transfers chirality to both chiral and achiral plasmonic substrates, and it is also responsible for the chiral three-dimensional assembly of nanorods. Understanding these underlying factors paves the way toward sensing the chirality of single biomolecules.
Journal Article
The Loud house. #1, There will be chaos
\"Learn from Lincoln Loud the ins and outs of living in a huge household with 10 sisters!\"--Back cover.
Book
Catalytic borylation of methane
Despite steady progress in catalytic methods for the borylation of hydrocarbons, methane has not yet been subject to this transformation. Here we report the iridium-catalyzed borylation of methane using bis(pinacolborane) in cyclohexane solvent. Initially, trace amounts of borylated products were detected with phenanthroline-coordinated Ir complexes. A combination of experimental high-pressure and high-throughput screening, and computational mechanism discovery techniques helped to rationalize the foundation of the catalysis and identify improved phosphine-coordinated catalytic complexes. Optimized conditions of 150°C and 3500-kilopascal pressure led to yields as high as ~52%, turnover numbers of 100, and improved chemoselectivity for monoborylated versus diborylated methane.
Journal Article
Uncapping energy transfer pathways in metal-organic frameworks through heterogeneous structures
Metal-organic frameworks (MOFs) are porous, crystalline materials known for their structural versatility and high thermal stability, making them promising candidates for light-emitting diode applications. Distinct classes of MOFs, such as multivariate (MTV)-MOFs and MOF-on-MOFs, introduce heterogeneity by incorporating multiple ligands within a single unit cell (MTV-MOFs) or by stacking different MOFs on top of each other (MOF-on-MOF). Although these strategies improve their properties, the mechanisms of energy transfer between their heterogeneous components and their effects on optical properties, such as quantum yields, remain poorly understood. In this study, we demonstrate that MOF heterostructures significantly improve quantum yield compared to single-ligand-based MOFs. Using Zr-UiO-67 as the base MOF, we generated an array of MOF-on-MOFs and analogous MTV-MOFs utilizing other Zr-MOFs constructed from 4,4’-azobenzenedicarboxylate or 4,4’-stilbenedicarboxylate linkers. Our results demonstrate that, although the emission color coordinates for the stilbene-based materials are identical, the MTV-MOFs increase the quantum yield from 8.2% to 10.2%, whereas the MOF-on-MOFs reach a quantum yield of up to 40.0%.
Distinct classes of MOFs, such as multivariate (MTV)-MOFs and MOF-on-MOFs, introduce heterogeneity by incorporating multiple ligands within a single unit cell (MTV-MOFs) or by stacking different MOFs on top of each other (MOF-on-MOF). Here authors show that MOF heterostructures significantly improve quantum yield compared to single-ligand-based MOFs.
Journal Article
Disentangling pleasure from incentive salience and learning signals in brain reward circuitry
Multiple signals for reward--hedonic impact, motivation, and learned associative prediction--are funneled through brain mesocorticolimbic circuits involving the nucleus accumbens and ventral pallidum. Here, we show how the hedonic \"liking\" and motivation \"wanting\" signals for a sweet reward are distinctly modulated and tracked in this circuit separately from signals for Pavlovian predictions (learning). Animals first learned to associate a fixed sequence of Pavlovian cues with sucrose reward. Subsequent intraaccumbens microinjections of an opioid-stimulating drug increased the hedonic liking impact of sucrose in behavior and firing signals of ventral pallidum neurons, and likewise, they increased incentive salience signals in firing to the reward-proximal incentive cue (but did not alter firing signals to the learned prediction value of a reward-distal cue). Microinjection of a dopamine-stimulating drug instead enhanced only the motivation component but did not alter hedonic impact or learned prediction signals. Different dedicated neuronal subpopulations in the ventral pallidum tracked signal enhancements for hedonic impact vs. incentive salience, and a faster firing pattern also distinguished incentive signals from slower hedonic signals, even for a third overlapping population. These results reveal separate neural representations of wanting, liking, and prediction components of the same reward within the nucleus accumbens to ventral pallidum segment of mesocorticolimbic circuitry.
Journal Article
Chiral templating of self-assembling nanostructures by circularly polarized light
It is shown that circularly polarized light produces enantiomeric excesses, above 30%, of twisted nanoribbons self-assembled from racemic dispersions of CdTe nanoparticles.
The high optical and chemical activity of nanoparticles (NPs) signifies the possibility of converting the spin angular momenta of photons into structural changes in matter. Here, we demonstrate that illumination of dispersions of racemic CdTe NPs with right- (left-)handed circularly polarized light (CPL) induces the formation of right- (left-)handed twisted nanoribbons with an enantiomeric excess exceeding 30%, which is ∼10 times higher than that of typical CPL-induced reactions. Linearly polarized light or dark conditions led instead to straight nanoribbons. CPL ‘templating’ of NP assemblies is based on the enantio-selective photoactivation of chiral NPs and clusters, followed by their photooxidation and self-assembly into nanoribbons with specific helicity as a result of chirality-sensitive interactions between the NPs. The ability of NPs to retain the polarization information of incident photons should open pathways for the synthesis of chiral photonic materials and allow a better understanding of the origins of biomolecular homochirality.
Journal Article
Unified rhombic lip origins of group 3 and group 4 medulloblastoma
Medulloblastoma, a malignant childhood cerebellar tumour, segregates molecularly into biologically distinct subgroups, suggesting that a personalized approach to therapy would be beneficial
1
. Mouse modelling and cross-species genomics have provided increasing evidence of discrete, subgroup-specific developmental origins
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. However, the anatomical and cellular complexity of developing human tissues
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—particularly within the rhombic lip germinal zone, which produces all glutamatergic neuronal lineages before internalization into the cerebellar nodulus—makes it difficult to validate previous inferences that were derived from studies in mice. Here we use multi-omics to resolve the origins of medulloblastoma subgroups in the developing human cerebellum. Molecular signatures encoded within a human rhombic-lip-derived lineage trajectory aligned with photoreceptor and unipolar brush cell expression profiles that are maintained in group 3 and group 4 medulloblastoma, suggesting a convergent basis. A systematic diagnostic-imaging review of a prospective institutional cohort localized the putative anatomical origins of group 3 and group 4 tumours to the nodulus. Our results connect the molecular and phenotypic features of clinically challenging medulloblastoma subgroups to their unified beginnings in the rhombic lip in the early stages of human development.
Multi-omic mapping shows that group 3 and group 4 medulloblastomas have a common, human-specific developmental origin in the cerebellar rhombic lip, providing a basis for their ambiguous molecular features and overlapping anatomical location, and for the difficulty of modelling these tumours in mice.
Journal Article
Chitin Recognition via Chitotriosidase Promotes Pathologic Type-2 Helper T Cell Responses to Cryptococcal Infection
Pulmonary mycoses are often associated with type-2 helper T (Th2) cell responses. However, mechanisms of Th2 cell accumulation are multifactorial and incompletely known. To investigate Th2 cell responses to pulmonary fungal infection, we developed a peptide-MHCII tetramer to track antigen-specific CD4+ T cells produced in response to infection with the fungal pathogen Cryptococcus neoformans. We noted massive accruement of pathologic cryptococcal antigen-specific Th2 cells in the lungs following infection that was coordinated by lung-resident CD11b+ IRF4-dependent conventional dendritic cells. Other researchers have demonstrated that this dendritic cell subset is also capable of priming protective Th17 cell responses to another pulmonary fungal infection, Aspergillus fumigatus. Thus, higher order detection of specific features of fungal infection by these dendritic cells must direct Th2 cell lineage commitment. Since chitin-containing parasites commonly elicit Th2 responses, we hypothesized that recognition of fungal chitin is an important determinant of Th2 cell-mediated mycosis. Using C. neoformans mutants or purified chitin, we found that chitin abundance impacted Th2 cell accumulation and disease. Importantly, we determined Th2 cell induction depended on cleavage of chitin via the mammalian chitinase, chitotriosidase, an enzyme that was also prevalent in humans experiencing overt cryptococcosis. The data presented herein offers a new perspective on fungal disease susceptibility, whereby chitin recognition via chitotriosidase leads to the initiation of harmful Th2 cell differentiation by CD11b+ conventional dendritic cells in response to pulmonary fungal infection.
Journal Article
Pandemic-scale phylogenomics reveals the SARS-CoV-2 recombination landscape
Accurate and timely detection of recombinant lineages is crucial for interpreting genetic variation, reconstructing epidemic spread, identifying selection and variants of interest, and accurately performing phylogenetic analyses
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–
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. During the SARS-CoV-2 pandemic, genomic data generation has exceeded the capacities of existing analysis platforms, thereby crippling real-time analysis of viral evolution
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. Here, we use a new phylogenomic method to search a nearly comprehensive SARS-CoV-2 phylogeny for recombinant lineages. In a 1.6 million sample tree from May 2021, we identify 589 recombination events, which indicate that around 2.7% of sequenced SARS-CoV-2 genomes have detectable recombinant ancestry. Recombination breakpoints are inferred to occur disproportionately in the 3' portion of the genome that contains the spike protein. Our results highlight the need for timely analyses of recombination for pinpointing the emergence of recombinant lineages with the potential to increase transmissibility or virulence of the virus. We anticipate that this approach will empower comprehensive real-time tracking of viral recombination during the SARS-CoV-2 pandemic and beyond.
A new phylogenomic method is developed that can detect recombinations in virus lineages in pandemic-scale datasets.
Journal Article