Creating metamaterial building blocks with directed photochemical metallization of silver onto DNA origami templates

DNA origami can be used to create a variety of complex and geometrically unique nanostructures that can be further modified to produce building blocks for applications such as in optical metamaterials. We describe a method for creating metal-coated nanostructures using DNA origami templates and a photochemical metallization technique. Triangular DNA origami forms were fabricated and coated with a thin metal layer by photochemical silver reduction while in solution or supported on a surface. The DNA origami template serves as a localized photosensitizer to facilitate reduction of silver ions directly from solution onto the DNA surface. The metallizing process is shown to result in a conformal metal coating, which grows in height to a self-limiting value with increasing photoreduction steps. Although this coating process results in a slight decrease in the triangle dimensions, the overall template shape is retained. Notably, this coating method exhibits characteristics of self-limiting and defect-filling growth, which results in a metal nanostructure that maps the shape of the original DNA template with a continuous and uniform metal layer and stops growing once all available DNA sites are exhausted

Innate lymphoid cell characterization in the rat and their correlation to gut commensal microbes.

Innate lymphoid cells (ILCs) are important for tissue immune homeostasis, and are thoroughly characterized in mice and humans. Here, we have performed in-depth characterization of rat ILCs. Rat ILCs were identified based on differential expression of transcription factors and lack of lineage markers. ILC3s represented the major ILC population of the small intestine, while ILC2s were infrequent but most prominent in liver and adipose tissue. Two major subsets of group 1 ILCs were defined. Lineage- T-bet+ Eomes+ cells were identified as conventional NK cells, while lineage- T-bet+ Eomes- cells were identified as the probable rat counterpart of ILC1s based on their selective expression of the ILC marker CD200R. Rat ILC1s were particularly abundant in liver and intestinal tissues, and were functionally similar to NK cells. Single-cell transcriptomics of spleen and liver cells confirmed the main division of NK cells and ILC1-like cells, and demonstrated Granzyme A as an additional ILC1 marker. We further report differential distributions of NK cells and ILCs along the small and large intestines, and the association of certain bacterial taxa to frequencies of ILCs. In conclusion, we provide a framework for future studies of ILCs in diverse rat experimental models, and novel data on the potential interplay between commensals and intestinal ILCs

Lymphatic vasculature mediates macrophage reverse cholesterol transport in mice

Reverse cholesterol transport (RCT) refers to the mobilization of cholesterol on HDL particles (HDL-C) from extravascular tissues to plasma, ultimately for fecal excretion. Little is known about how HDL-C leaves peripheral tissues to reach plasma. We first used 2 models of disrupted lymphatic drainage from skin — 1 surgical and the other genetic — to quantitatively track RCT following injection of [3H]-cholesterol–loaded macrophages upstream of blocked or absent lymphatic vessels. Macrophage RCT was markedly impaired in both models, even at sites with a leaky vasculature. Inhibited RCT was downstream of cholesterol efflux from macrophages, since macrophage efflux of a fluorescent cholesterol analog (BODIPY-cholesterol) was not altered by impaired lymphatic drainage. We next addressed whether RCT was mediated by lymphatic vessels from the aortic wall by loading the aortae of donor atherosclerotic Apoe-deficient mice with [2H]6-labeled cholesterol and surgically transplanting these aortae into recipient Apoe-deficient mice that were treated with anti-VEGFR3 antibody to block lymphatic regrowth or with control antibody to allow such regrowth. [2H]-Cholesterol was retained in aortae of anti–VEGFR3-treated mice. Thus, the lymphatic vessel route is critical for RCT from multiple tissues, including the aortic wall. These results suggest that supporting lymphatic transport function may facilitate cholesterol clearance in therapies aimed at reversing atherosclerosis

Imaging of Unstained DNA Origami Triangles with Electron Microscopy

Imaging of scaffolded DNA and DNA origami nanostructures has been dominated by atomic force microscopy of samples immobilized on bulk substrates. Less commonly used are electron microscopy techniques, typically carried out after negative staining of DNA structures or by using cryo‐transmission electron microscopy (TEM). Here, direct imaging of unstained DNA origami on common electron‐transparent substrates with utilizing high angular annular dark field scanning transmission electron microscopy (HAADF‐STEM) is reported. This approach establishes a method for depositing and imaging intact DNA triangles with mass‐thickness contrast sufficient to measure the scaffold‐to‐scaffold distances and the length of the triangle\u27s seam. The signal‐to‐noise ratio (SNR) of the DNA supported on amorphous carbon as a function of the carbon thickness is measured on three types of commercially available TEM grids. This allows for edge detection of ≈1 nm height DNA triangles on carbon substrates as thick as ≈25 nm. Observations on the effect on SNR with the imaging modes are discussed. The effect of cation concentration used for pretreating the grid on the image resolution is also explored. This work presents proof‐of‐concept results demonstrating that electron microscopy can be used to resolve key elements of the DNA origami triangle without the use of staining protocols

Marine phytoplankton community data and corresponding environmental properties from eastern Norway, 1896–2020

Time series are essential for studying the long-term effects of human impact and climatic changes on the natural environment. Although data exist, no long-term phytoplankton dataset for the Norwegian coastal area has been compiled and made publicly available in a standardised format. Here we report on a compilation of phytoplankton data from inner Oslofjorden going back more than a century. The database contains 605 sampling events from 1896 to 2020, and environmental data has also been provided when available. Although the sampling frequency has varied over time, the high taxonomic quality and relatively similar methodology make it very useful. For the last 15 years (2006–2020), the sampling frequency has been almost monthly throughout the year. This dataset can be used for time series analysis to understand community structure and changes over time. It can also be used to study common taxa’ responses to environmental variables and changes, seasonal or annual species diversity and be useful for developing ecological indicators.publishedVersio

Identifying quasi-experimental studies to inform systematic reviews

OBJECTIVE: This paper reviews the available evidence and guidance on methods to identify reports of quasi-experimental (QE) studies to inform systematic reviews of health care, public health, international development, education, crime and justice, and social welfare. STUDY DESIGN AND SETTING: Research, guidance and examples of search strategies were identified by searching a range of databases, key guidance documents, selected reviews, conference proceedings and personal communication. Current practice and research evidence were summarised. RESULTS: 4914 records were retrieved by database searches and additional documents were obtained by other searches. QE studies are challenging to identify efficiently because they have no standardized nomenclature and may be indexed in various ways. Reliable search filters are not available. There is a lack of specific resources devoted to collecting QE studies and little evidence on where best to search. CONCLUSION: Searches to identify QE studies should search a range of resources and, until indexing improves, use strategies that focus on the topic rather than the study design. Better definitions, better indexing in databases, prospective registers and reporting guidance are required to improve the retrieval of QE studies and to promote SRs of what works based on the evidence from such studies

A comparative evaluation of PDQ-Evidence

BACKGROUND: A strategy for minimising the time and obstacles to accessing systematic reviews of health system evidence is to collect them in a freely available database and make them easy to find through a simple ‘Google-style’ search interface. PDQ-Evidence was developed in this way. The objective of this study was to compare PDQ-Evidence to six other databases, namely Cochrane Library, EVIPNet VHL, Google Scholar, Health Systems Evidence, PubMed and Trip. METHODS: We recruited healthcare policy-makers, managers and health researchers in low-, middle- and highincome countries. Participants selected one of six pre-determined questions. They searched for a systematic review that addressed the chosen question and one question of their own in PDQ-Evidence and in two of the other six databases which they would normally have searched. We randomly allocated participants to search PDQ-Evidence first or to search the two other databases first. The primary outcomes were whether a systematic review was found and the time taken to find it. Secondary outcomes were perceived ease of use and perceived time spent searching. We asked open-ended questions about PDQ-Evidence, including likes, dislikes, challenges and suggestions for improvements. RESULTS: A total of 89 people from 21 countries completed the study; 83 were included in the primary analyses and 6 were excluded because of data errors that could not be corrected. Most participants chose PubMed and Cochrane Library as the other two databases. Participants were more likely to find a systematic review using PDQ-Evidence than using Cochrane Library or PubMed for the pre-defined questions. For their own questions, this difference was not found. Overall, it took slightly less time to find a systematic review using PDQ-Evidence. Participants perceived that it took less time, and most participants perceived PDQ-Evidence to be slightly easier to use than the two other databases. However, there were conflicting views about the design of PDQ-Evidence. CONCLUSIONS: PDQ-Evidence is at least as efficient as other databases for finding health system evidence. However, using PDQ-Evidence is not intuitive for some people

Associations between the 17q21 region and allergic rhinitis in 5 birth cohorts

Non peer reviewe