Search

Abstract Muonic atom spectroscopy is a method that can determine absolute nuclear charge radii with typical relative precision of $$10^{-3}$$ . Recent developments have enabled to extend muonic atom spectroscopy to microscopic target quantities as low as $$5\,{\upmu }\text {g}$$ . This substantial reduction from the traditional limit of the order of $$100\,\text {mg}$$ is based on a transfer mechanism in a high-pressure hydrogen gas cell, which transports the muon to the surface of the target material rather than stopping it over a broad depth range. This approach enables the measurement of absolute nuclear charge radii of long-lived radioactive isotopes (half-life above $$\sim$$ 20 years), but the production of appropriate targets for the technique has presented some major challenges, such as the formation of organic layers on the substrate. This study presents a systematic investigation of the stopping efficiency for different target preparation methods: ion implantation, drop-on-demand printing, and molecular plating. Notable differences between the three methods were discovered in terms of their performance allowing to further fine tune the method of choice for future target preparations. Our findings show that implantation provides appropriate targets for our method with negligible losses. This achievement opens the landscape of potential measurements to isotopes where high mass separation is required not achievable with other methods. Furthermore, molecular plated targets performed substantially better than those prepared using drop-on-demand printing.

Abstract Structural variants (SVs) are important contributors to human disease. Their characterization remains however difficult due to their size and association with repetitive regions. Long-read sequencing (LRS) and optical genome mapping (OGM) can aid as their molecules span multiple kilobases and capture SVs in full. In this study, we selected six individuals who presented with unresolved SVs. We applied LRS onto all individuals and OGM to a subset of three complex cases. LRS detected and fully resolved the interrogated SV in all samples. This enabled a precise molecular diagnosis in two individuals. Overall, LRS identified 100% of the junctions at single-basepair level, providing valuable insights into their formation mechanisms without need for additional data sources. Application of OGM added straightforward variant phasing, aiding in the unravelment of complex rearrangements. These results highlight the potential of LRS and OGM as follow-up molecular tests for complete SV characterization. We show that they can assess clinically relevant structural variation at unprecedented resolution. Additionally, they detect (complex) cryptic rearrangements missed by conventional methods. This ultimately leads to an increased diagnostic yield, emphasizing their added benefit in a diagnostic setting. To aid their rapid adoption, we provide detailed laboratory and bioinformatics workflows in this manuscript.

A comparative vacuum ultraviolet spectroscopy study conducted at ISOLDE-CERN of the radiative decay of the ^{229m}Th nuclear clock isomer embedded in different host materials is reported. The ratio of the number of radiative decay photons and the number of ^{229m}Th embedded are determined for single crystalline CaF_{2}, MgF_{2}, LiSrAlF_{6}, AlN, and amorphous SiO_{2}. For the latter two materials, no radiative decay signal was observed and an upper limit of the ratio is reported. The radiative decay wavelength was determined in LiSrAlF_{6} and CaF_{2}, reducing its uncertainty by a factor of 2.5 relative to our previous measurement. This value is in agreement with the recently reported improved values from laser excitation.

IntroductionAntibody production and the generation of memory B cells are regulated by T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in germinal centers. However, the precise role of Tfr cells in controlling antibody production is still unclear. We have previously shown that both Tfh and Tfr cells express the IL-1R1 agonist receptor, whereas only Tfr cells express the IL-1R2 decoy and IL-1Ra antagonist receptors. We aimed to investigate the role of IL-1 receptors in the regulation of B cell responses by Tfh and Tfr.MethodsWe generated mice with IL-1 receptors inactivated in Tfh or Tfr and measured antibody production and cell activation after immunisation.ResultsWhile IL-1β levels are increased in the draining lymph node after immunisation, antigen-specific antibody levels and cell phenotypes indicated that IL-1β can activate both Tfh and Tfr cells through IL-1R1 stimulation. Surprisingly, expression of IL-1R2 and IL-1Ra on Tfr cells does not block IL-1 activation of Tfh cells, but rather prevents IL-1/IL-1R1-mediated early activation of Tfr cells. IL-1Rs also regulate the antibody response to autoantigens and its associated pathophysiology in an experimental lupus model.DiscussionCollectively, our results show that IL-1 inhibitory receptors expressed by Tfr cells prevent their own activation and suppressive function, thus licensing IL-1-mediated activation of Tfh cells after immunisation. Further mechanistic studies should unravel these complex interactions between IL-1β and follicular helper and regulatory T cells and provide new avenues for therapeutic intervention.

Abstract We present a site-specific elemental analysis of nano-scale patterns whereby the data acquisition is based on Rutherford backscattering spectrometry (RBS). The analysis builds on probing a large ensemble of identical nanostructures. This ensures that a very good limit of detection can be achieved. In addition, the analysis exploits the energy loss effects of the backscattered ions within the nanostructures to distinguish signals coming from different locations of the nanostructures. The spectrum deconvolution is based on ion-trajectory calculations. With this approach, we analyse the Ru area-selective deposition on SiO2-TiN line-space patterns with a linewidth of 35 nm and a pitch of 90 nm. We quantify the selectivity and the Ru local areal density on the top versus on the sidewall of the SiO2 lines. The sensitivity to probe ruthenium deposited on the various surfaces is as low as 1013 atoms/cm2. The analysis is quantitative, traceable, and highly accurate thanks to the intrinsic capabilities of RBS.

In order to study the structural formation yield of germanium-vacancy (GeV) centers from implanted Ge in diamond, we have investigated its lattice location by using the β ^− emission channeling technique from the radioactive isotope ^75 Ge ( t _1/2 = 83 min) produced at the ISOLDE/CERN facility. ^75 Ge was introduced via recoil implantation following 30 keV ion implantation of the precursor isotope ^75 Ga (126 s) with fluences around 2 × 10 ^12 –5 × 10 ^13 cm ^−2 . While for room temperature implantation fractions around 20% were observed in split-vacancy configuration and 45% substitutional Ge, following implantation or annealing up to 900 °C, the split-vacancy fraction dropped to 6%–9% and the substitutional fraction reached 85%–96%. GeV complexes thus show a lower structural formation yield than other impurities, with substitutional Ge being the dominant configuration. Moreover, annealing or high-temperature implantation seem to favor the formation of substitutional Ge over GeV. Our results strongly suggest that GeV complexes are thermally unstable and transformed to substitutional Ge by capture of mobile carbon interstitials, which is likely to contribute to the difficulties in achieving high formation yields of these optically active centers.

Controlling multicomponent systems is difficult due to convoluted behavior, pathway complexity, and coupled equilibria. Here the authors showed modulation of aggregate morphology in a zinc porphyrin-based supramolecular system via judicious capping with a manganese porphyrin monomer, in which the monomer’s chirality can influence the supramolecular behavior.

T-cell receptors (TCRs) are formed by stochastic gene rearrangements, theoretically generating >1019 sequences. They are selected during thymopoiesis, which releases a repertoire of about 108 unique TCRs per individual. How evolution shaped a process that produces TCRs that can effectively handle a countless and evolving set of infectious agents is a central question of immunology. The paradigm is that a diverse enough repertoire of TCRs should always provide a proper, though rare, specificity for any given need. Expansion of such rare T cells would provide enough fighters for an effective immune response and enough antigen-experienced cells for memory. We show here that human thymopoiesis releases a large population of clustered CD8+ T cells harboring α/β paired TCRs that (i) have high generation probabilities and (ii) a preferential usage of some V and J genes, (iii) which CDR3 are shared between individuals, and (iv) can each bind and be activated by multiple unrelated viral peptides, notably from EBV, CMV, and influenza. These polyspecific T cells may represent a first line of defense that is mobilized in response to infections before a more specific response subsequently ensures viral elimination. Our results support an evolutionary selection of polyspecific α/β TCRs for broad antiviral responses and heterologous immunity.

Sea stars are a diverse and important component of the Southern Ocean benthos. However, scarce information is available regarding their diversity, distribution, evolution, and taxonomic uncertainties persist for multiple taxa. The Magellanic Region (south of Chile) remains under-sampled despite its pivotal location for species distribution and diversity, being located at the crossroad of three ocean basins. In this study, we assessed the biodiversity of coastal Magellanic sea stars and their affinities with other oceanic bioregions. An integrative approach combining morphological identification with DNA barcoding was implemented to highlight taxonomic discrepancies such as suspected synonymy and unrecognised diversity. Firstly, we identified a total of 15 species from the coastal Magellanic Region and reported the occurrence of Cycethra frigida Koehler, 1917 for the first time in this region. The distribution of these 15 species ranged from only in South America to circumpolar, bipolar, or possibly cosmopolitan. Secondly, we highlighted possible synonymy in two species pairs within the genera Anasterias and Odontaster. This preliminary biodiversity assessment forms an important baseline for monitoring and conservation purposes, especially in the face of distribution shifts as a response to climate change and the increased presence of invasive species. Developmental mode has previously been suggested to be important in shaping biogeographical patterns. However, developmental mode was insufficient to explain the observed patterns, and other factors (e.g., physiological constraints, competition, bathymetrical range, and the possibility of passively rafting on kelp) are suggested to be at least equally important. Finally, an increase in barcoding effort is needed to better capture phylogeographic patterns for each species, both by increasing the number of specimens investigated and by covering a broader geographical range.

Abstract The introduction of a chemical additive to supramolecular polymers holds high potential in the development of new structures and functions. In this regard, various donor- and acceptor-based molecules have been applied in the design of these noncovalent polymers. However, the incorporation of boron–nitrogen frustrated Lewis pairs in such architectures is still rare despite their many intriguing properties in catalysis and materials science. The limited choices of suitable boron derivatives represent one of the main limitations for the advancement in this direction. Here, we examine the use of the commercially available tris(pentafluorophenyl)borane with various triphenylamine derivatives to create supramolecular B–N charge transfer systems. Our results highlight the importance of a proper balance between the donor/acceptor strength and the driving force for supramolecular polymerization to achieve stable, long-range ordered B–N systems. Detailed analyses using electron paramagnetic resonance and optical spectroscopy suggest that tris(pentafluorophenyl)borane displays complex behavior with the amide-based triphenylamine supramolecular polymers and may interact in dimers or larger chiral aggregates, depending on the specific structure of the triphenylamines.

Abstract In polymer chemistry, modulation of sequence and control over chain length are routinely applied to alter and fine-tune the properties of covalent (co)polymers. For supramolecular polymers, the same principles underlying this control have not been fully elucidated up to this date. Particularly, rational control over molecular weight in dynamic supramolecular polymers is not trivial, especially when a cooperative mechanism is operative. We start this review by summarizing how molecular-weight control has been achieved in seminal examples in the field of supramolecular polymerizations. Following this, we propose to classify the avenues taken to control molecular weights in supramolecular polymerizations. We focus on dynamic cooperative supramolecular polymerization as this is the most challenging in terms of molecular weight control. We use a mass-balance equilibrium model to predict how the nature of the interaction of an additive B with the monomers and supramolecular polymers of component A affects the degree of aggregation and the degree of polymerization. We put forward a classification system that distinguishes between B acting as a chain capper, a sequestrator, a comonomer, or an intercalator. We also highlight the experimental methods applied to probe supramolecular polymerization processes, the type of information they provide in relation to molecular weight and degree of aggregation, and how this can be used to classify the role of B. The guidelines and classification delineated in this review to assess and control molecular weights in supramolecular polymers can serve to reevaluate exciting systems present in current literature and contribute to broaden the understanding of multicomponent systems.

Background Cell-based therapies are emerging as a viable modality to treat challenging diseases, resulting in an increasing demand for their large-scale, high-quality production. Production facilities face the issue of batch-to-batch consistency while producing a safe and efficient cell-based product. Controlling culture conditions and particularly media composition is a key factor of success in this challenge. Serum and Xeno-Free Media (SXFM) represent an interesting option to achieve this goal. By reducing batch to batch variability, they increase Good Manufacturing Practices (GMP)-compliance and safety regarding xenogenic transmission, as compared to fetal bovine serum (FBS) supplemented-media or human platelet lysate supplemented medium. Methods In this study, the isolation, expansion and characteristics including the anti-inflammatory function of human mesenchymal stromal cells (MSC) are compared after culture in MEMα supplemented with human Concentrate Platelet Lysate (hCPL, reference medium) or in MSC-Brew GMP Medium. The latter is a GMP SXFM manufactured in bags under strictly controlled conditions in volumes suitable for expansion to a clinical scale and does not require neither pre-coating of the cell culture units nor the addition of blood derivatives at the isolation step. Results We showed that MSC derived from human bone-marrow and adipose tissue can be successfully isolated and expanded in this SXFM. Number and size of Colony-Forming Unit fibroblast (CFU-F) is increased compared to cells cultivated in hCPL medium. All cells retained a CD90+, CD73+, CD105+, HLADR−, CD34−, CD45− phenotype. Furthermore, the osteogenic and adipocyte potentials as well as the anti-inflammatory activity were comparable between culture conditions. All cells reached the release criteria established in our production facility to treat inflammatory pathologies. Conclusions The use of MSC-Brew GMP Medium can therefore be considered for clinical bioprocesses as a safe and efficient substitute for hCPL media.

Cell-penetrating peptides (CPPs) allow intracellular delivery of bioactive cargo molecules. The mechanisms allowing CPPs to enter cells are ill-defined. Using a CRISPR/Cas9-based screening, we discovered that KCNQ5, KCNN4, and KCNK5 potassium channels positively modulate cationic CPP direct translocation into cells by decreasing the transmembrane potential (Vm). These findings provide the first unbiased genetic validation of the role of Vm in CPP translocation in cells. In silico modeling and live cell experiments indicate that CPPs, by bringing positive charges on the outer surface of the plasma membrane, decrease the Vm to very low values (–150 mV or less), a situation we have coined megapolarization that then triggers formation of water pores used by CPPs to enter cells. Megapolarization lowers the free energy barrier associated with CPP membrane translocation. Using dyes of varying dimensions in CPP co-entry experiments, the diameter of the water pores in living cells was estimated to be 2 (–5) nm, in accordance with the structural characteristics of the pores predicted by in silico modeling. Pharmacological manipulation to lower transmembrane potential boosted CPP cellular internalization in zebrafish and mouse models. Besides identifying the first proteins that regulate CPP translocation, this work characterized key mechanistic steps used by CPPs to cross cellular membranes. This opens the ground for strategies aimed at improving the ability of cells to capture CPP-linked cargos in vitro and in vivo.