231 research outputs found
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Industrial Freeform Generation of Microtools by Laser Micro Sintering
Precision tools with structural resolution reaching the 20 micrometer range can be generated
on an industrial scale by “laser micro sintering”. Components featuring aspect ratios above 12
and a roughness Ra down to 1.5 micrometers have already been produced from sub micrometer
grained metal powders. The components can be generated either firmly attached to a substrate or
fixed in an easily separable mode. If supporting structures are employed, undercuts up to 90° are
feasible, without, a process parameter dependent maximum angles of undercut below 90° are
obtained.
The process has been introduced into the market, labeled microSINTERING by
3D-Micromac AG.Mechanical Engineerin
Efficient CRISPR/Cas9-mediated gene knockin in mouse hematopoietic stem and progenitor cells
Mutations accumulating in hematopoietic stem and progenitor cells (HSPCs) during development can cause severe hematological disorders. Modeling these mutations in mice is essential for understanding their functional consequences. Here, we describe an efficient CRISPR/Cas9-based system to knock in and repair genes in mouse HSPCs. CRISPR/Cas9 ribonucleoproteins, in combination with recombinant adeno-associated virus (rAAV)-DJ donor templates, led to gene knockin efficiencies of up to 30% in the Lmnb1 and Actb loci of mouse HSPCs in vitro. The targeted HSPCs engraft and reconstitute all immune cell lineages in the recipient mice. Using this approach, we corrected a neomycin-disrupted Rag2 gene. The Rag2-corrected HSPCs restore B and T cell development in vivo, confirming the functionality of the approach. Our method provides an efficient strategy to study gene function in the hematopoietic system and model hematological disorders in vivo, without the need for germline mutagenesis
Efficient generation of Rosa26 knock-in mice using CRISPR/Cas9 in C57BL/6 zygotes
BACKGROUND: The CRISPR/Cas9 system is increasingly used for gene inactivation in mouse zygotes, but homology-directed mutagenesis and use of inbred embryos are less established. In particular, Rosa26 knock-in alleles for the insertion of transgenes in a genomic 'safe harbor' site, have not been produced. Here we applied CRISPR/Cas9 for the knock-in of 8-11 kb inserts into Rosa26 of C57BL/6 zygotes. RESULTS: We found that 10-20 % of live pups derived from microinjected zygotes were founder mutants, without apparent off-target effects, and up to 50 % knock-in embryos were recovered upon coinjection of Cas9 mRNA and protein. Using this approach, we established a new mouse line for the Cre/loxP-dependent expression of Cas9. CONCLUSIONS: Altogether, our protocols and resources support the fast and direct generation of new Rosa26 knock-in alleles and of Cas9-mediated in vivo gene editing in the widely used C57BL/6 inbred strain
Distribuição longitudinal de Chironomidae (Diptera) abaixo de uma barragem em um rio neotropical
The damming of a river causes dangerous consequences on structure of the environment downstream of the dam, modifying the sediment composition, which impose major adjustments in longitudinal distribution of benthic community. The construction of Engenheiro SĂ©rgio Motta Dam in the Upper Paraná River has caused impacts on the aquatic communities, which are not yet fully known. This work aimed to provide more information about the effects of this impoundment on the structure of Chironomidae larvae assemblage. The analysis of data of physical and chemical variables in relation to biological data of 8 longitudinal sections in the Upper Paraná River showed that composition of Chironomidae larvae of stations near Engenheiro SĂ©rgio Motta Dam differed of the other stations (farther of the Dam) The predominance of coarse sediments at stations upstream and finer sediments further downstream affected the choice of habitat by different morphotypes of Chironomidae and it caused a change in the structure of this assemblage in the longitudinal stretch.O barramento de um rio pode causar graves consequĂŞncias sobre a natureza do ambiente, abaixo da barragem, modificando a composição do sedimento, as quais impõem importantes ajustes da distribuição longitudinal das comunidades bentĂ´nicas. A construção da Usina HidrelĂ©trica Engenheiro SĂ©rgio Motta no alto rio Paraná, tem causado impactos em várias comunidades aquáticas, que ainda nĂŁo sĂŁo totalmente conhecidos. Este trabalho objetivou fornecer mais informações sobre os efeitos desse represamento na assembleia de Chironomidae. A análise das variáveis fĂsicas e quĂmicas em relação aos dados biolĂłgicos de oito transectos longitudinais no alto rio Paraná revelou que a composição das larvas de Chironomidae das estações mais prĂłximas Ă barragem da Usina Engenheiro SĂ©rgio Motta diferiu das demais (estações mais distantes). A predominância de sedimentos mais grosseiros nas estações a montante e sedimentos mais finos mais a jusante afetou a escolha de habitat pelos diferentes morfotipos de Chironomidae, que levou a alteração na estrutura desta assembleia ao longo do trecho amostrado.Fil: Pinha, G. D.. Universidade Estadual de Maringá. Programa de PĂłs-Graduação em Ecologia de Ambientes Aquáticos Continentais; Brasil.;Fil: Aviz, D.. Universidade Federal Do Pará; Brasil.;Fil: Lopes Filho, D. R.. Universidade Estadual de Maringá. Programa de PĂłs-Graduação em Ecologia de Ambientes Aquáticos Continentais; Brasil.;Fil: Petsch, D. K.. Universidade Estadual de Maringá. Programa de PĂłs-Graduação em Ecologia de Ambientes Aquáticos Continentais; Brasil.;Fil: Marchese Garello, Mercedes Rosa. Consejo Nacional de Investigaciones cientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico CONICET- Santa Fe. Instituto Nacional de Limnologia (i); Argentina;Fil: Takeda, A. M.. Universidade Estadual de Maringá; Brasil.
Machine learning enabled experimental design and parameter estimation for ultrafast spin dynamics
Advanced experimental measurements are crucial for driving theoretical
developments and unveiling novel phenomena in condensed matter and material
physics, which often suffer from the scarcity of facility resources and
increasing complexities. To address the limitations, we introduce a methodology
that combines machine learning with Bayesian optimal experimental design
(BOED), exemplified with x-ray photon fluctuation spectroscopy (XPFS)
measurements for spin fluctuations. Our method employs a neural network model
for large-scale spin dynamics simulations for precise distribution and utility
calculations in BOED. The capability of automatic differentiation from the
neural network model is further leveraged for more robust and accurate
parameter estimation. Our numerical benchmarks demonstrate the superior
performance of our method in guiding XPFS experiments, predicting model
parameters, and yielding more informative measurements within limited
experimental time. Although focusing on XPFS and spin fluctuations, our method
can be adapted to other experiments, facilitating more efficient data
collection and accelerating scientific discoveries
Efficient CRISPR-mediated mutagenesis in primary immune cells using CrispRGold and a C57BL/6 Cas9 transgenic mouse line
Applying clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9)-mediated mutagenesis to primary mouse immune cells, we used high-fidelity single guide RNAs (sgRNAs) designed with an sgRNA design tool (CrispRGold) to target genes in primary B cells, T cells, and macrophages isolated from a Cas9 transgenic mouse line. Using this system, we achieved an average knockout efficiency of 80% in B cells. On this basis, we established a robust small-scale CRISPR-mediated screen in these cells and identified genes essential for B-cell activation and plasma cell differentiation. This screening system does not require deep sequencing and may serve as a precedent for the application of CRISPR/Cas9 to primary mouse cells
High-energy spin waves in the spin-1 square-lattice antiferromagnet LaNiO
Inelastic neutron scattering is used to study the magnetic excitations of the
square-lattice antiferromagnet LaNiO. We find that the spin waves
cannot be described by a simple classical (harmonic) Heisenberg model with only
nearest-neighbor interactions. The spin-wave dispersion measured along the
antiferromagnetic Brillouin-zone boundary shows a minimum energy at the
position as is observed in some square-lattice
antiferromagnets. Thus, our results suggest that the quantum dispersion
renormalization effects or longer-range exchange interactions observed in
cuprates and other square-lattice antiferromagnets are also present in
LaNiO. We also find that the overall intensity of the spin-wave
excitations is suppressed relative to linear spin-wave theory indicating that
covalency is important. Two-magnon scattering is also observed
Mendelian and Non-Mendelian Regulation of Gene Expression in Maize
Transcriptome variation plays an important role in affecting the phenotype of an organism. However, an understanding of the underlying mechanisms regulating transcriptome variation in segregating populations is still largely unknown. We sought to assess and map variation in transcript abundance in maize shoot apices in the intermated B73×Mo17 recombinant inbred line population. RNA-based sequencing (RNA-seq) allowed for the detection and quantification of the transcript abundance derived from 28,603 genes. For a majority of these genes, the population mean, coefficient of variation, and segregation patterns could be predicted by the parental expression levels. Expression quantitative trait loci (eQTL) mapping identified 30,774 eQTL including 96 trans-eQTL "hotspots," each of which regulates the expression of a large number of genes. Interestingly, genes regulated by a trans-eQTL hotspot tend to be enriched for a specific function or act in the same genetic pathway. Also, genomic structural variation appeared to contribute to cis-regulation of gene expression. Besides genes showing Mendelian inheritance in the RIL population, we also found genes whose expression level and variation in the progeny could not be predicted based on parental difference, indicating that non-Mendelian factors also contribute to expression variation. Specifically, we found 145 genes that show patterns of expression reminiscent of paramutation such that all the progeny had expression levels similar to one of the two parents. Furthermore, we identified another 210 genes that exhibited unexpected patterns of transcript presence/absence. Many of these genes are likely to be gene fragments resulting from transposition, and the presence/absence of their transcripts could influence expression levels of their ancestral syntenic genes. Overall, our results contribute to the identification of novel expression patterns and broaden the understanding of transcriptional variation in plants. © 2013 Lin et al
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