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Nature Methods

Philip Roedig, Helen M Ginn, Tim Pakendorf, Geoff Sutton, Karl Harlos, Thomas S Walter, Jan Meyer, Pontus Fischer, Ramona Duman, Ismo Vartiainen, Bernd Reime, Martin Warmer, Aaron S Brewster, Iris D Young, Tara Michels-Clark, Nicholas K Sauter, Abhay Kotecha, James Kelly, David J Rowlands, Marcin Sikorsky, Silke Nelson, Daniel S Damiani, Roberto Alonso-Mori, Jingshan Ren, Elizabeth E Fry, Christian David, David I Stuart, Armin Wagner, Alke Meents
We report a method for serial X-ray crystallography at X-ray free-electron lasers (XFELs), which allows for full use of the current 120-Hz repetition rate of the Linear Coherent Light Source (LCLS). Using a micropatterned silicon chip in combination with the high-speed Roadrunner goniometer for sample delivery, we were able to determine the crystal structures of the picornavirus bovine enterovirus 2 (BEV2) and the cytoplasmic polyhedrosis virus type 18 polyhedrin, with total data collection times of less than 14 and 10 min, respectively...
June 19, 2017: Nature Methods
Wei Zheng, Yicong Wu, Peter Winter, Robert Fischer, Damian Dalle Nogare, Amy Hong, Chad McCormick, Ryan Christensen, William P Dempsey, Don B Arnold, Joshua Zimmerberg, Ajay Chitnis, James Sellers, Clare Waterman, Hari Shroff
We improve multiphoton structured illumination microscopy using a nonlinear guide star to determine optical aberrations and a deformable mirror to correct them. We demonstrate our method on bead phantoms, cells in collagen gels, nematode larvae and embryos, Drosophila brain, and zebrafish embryos. Peak intensity is increased (up to 40-fold) and resolution recovered (up to 176 ± 10 nm laterally, 729 ± 39 nm axially) at depths ∼250 μm from the coverslip surface.
June 19, 2017: Nature Methods
Brandon Frenz, Alexandra C Walls, Edward H Egelman, David Veesler, Frank DiMaio
Accurate atomic modeling of macromolecular structures into cryo-electron microscopy (cryo-EM) maps is a major challenge, as the moderate resolution makes accurate placement of atoms difficult. We present Rosetta enumerative sampling (RosettaES), an automated tool that uses a fragment-based sampling strategy for de novo model completion of macromolecular structures from cryo-EM density maps at 3-5-Å resolution. On a benchmark set of nine proteins, RosettaES was able to identify near-native conformations in 85% of segments...
June 19, 2017: Nature Methods
Ian A Mellis, Rohit Gupte, Arjun Raj, Sara H Rouhanifard
Conversion of adenosine to inosine is a frequent type of RNA editing, but important details about the biology of this conversion remain unknown because of a lack of imaging tools. We developed inoFISH to directly visualize and quantify adenosine-to-inosine-edited transcripts in situ. We found that editing of the GRIA2, EIF2AK2, and NUP43 transcripts is uncorrelated with nuclear localization and paraspeckle association. Further, NUP43 exhibits constant editing levels between single cells, while GRIA2 editing levels vary...
June 12, 2017: Nature Methods
Geoffrey Fudenberg, Maxim Imakaev
Chromosome conformation capture (3C) and fluorescence in situ hybridization (FISH) are two widely used technologies that provide distinct readouts of 3D chromosome organization. While both technologies can assay locus-specific organization, how to integrate views from 3C, or genome-wide Hi-C, and FISH is far from solved. Contact frequency, measured by Hi-C, and spatial distance, measured by FISH, are often assumed to quantify the same phenomena and used interchangeably. Here, however, we demonstrate that contact frequency is distinct from average spatial distance, both in polymer simulations and in experimental data...
June 12, 2017: Nature Methods
Kevin M Boergens, Manuel Berning, Tom Bocklisch, Dominic Bräunlein, Florian Drawitsch, Johannes Frohnhofen, Tom Herold, Philipp Otto, Norman Rzepka, Thomas Werkmeister, Daniel Werner, Georg Wiese, Heiko Wissler, Moritz Helmstaedter
We report webKnossos, an in-browser annotation tool for 3D electron microscopic data. webKnossos provides flight mode, a single-view egocentric reconstruction method enabling trained annotator crowds to reconstruct at a speed of 1.5 ± 0.6 mm/h for axons and 2.1 ± 0.9 mm/h for dendrites in 3D electron microscopic data from mammalian cortex. webKnossos accelerates neurite reconstruction for connectomics by 4- to 13-fold compared with current state-of-the-art tools, thus extending the range of connectomes that can realistically be mapped in the future...
June 12, 2017: Nature Methods
Mattia Forcato, Chiara Nicoletti, Koustav Pal, Carmen Maria Livi, Francesco Ferrari, Silvio Bicciato
Hi-C is a genome-wide sequencing technique used to investigate 3D chromatin conformation inside the nucleus. Computational methods are required to analyze Hi-C data and identify chromatin interactions and topologically associating domains (TADs) from genome-wide contact probability maps. We quantitatively compared the performance of 13 algorithms in their analyses of Hi-C data from six landmark studies and simulations. This comparison revealed differences in the performance of methods for chromatin interaction identification, but more comparable results for TAD detection between algorithms...
June 12, 2017: Nature Methods
Harold Pimentel, Nicolas L Bray, Suzette Puente, Páll Melsted, Lior Pachter
We describe sleuth (, a method for the differential analysis of gene expression data that utilizes bootstrapping in conjunction with response error linear modeling to decouple biological variance from inferential variance. sleuth is implemented in an interactive shiny app that utilizes kallisto quantifications and bootstraps for fast and accurate analysis of data from RNA-seq experiments.
June 5, 2017: Nature Methods
Xi Long, Jennifer Colonell, Allan M Wong, Robert H Singer, Timothée Lionnet
We describe a fluorescence in situ hybridization method that permits detection of the localization and abundance of single mRNAs (smFISH) in cleared whole-mount adult Drosophila brains. The approach is rapid and multiplexable and does not require molecular amplification; it allows facile quantification of mRNA expression with subcellular resolution on a standard confocal microscope. We further demonstrate single-mRNA detection across the entire brain using a custom Bessel beam structured illumination microscope (BB-SIM)...
June 5, 2017: Nature Methods
Rongkun Tao, Yuzheng Zhao, Huanyu Chu, Aoxue Wang, Jiahuan Zhu, Xianjun Chen, Yejun Zou, Mei Shi, Renmei Liu, Ni Su, Jiulin Du, Hai-Meng Zhou, Linyong Zhu, Xuhong Qian, Haiyan Liu, Joseph Loscalzo, Yi Yang
Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is essential for biosynthetic reactions and antioxidant functions; however, detection of NADPH metabolism in living cells remains technically challenging. We develop and characterize ratiometric, pH-resistant, genetically encoded fluorescent indicators for NADPH (iNap sensors) with various affinities and wide dynamic range. iNap sensors enabled quantification of cytosolic and mitochondrial NADPH pools that are controlled by cytosolic NAD(+) kinase levels and revealed cellular NADPH dynamics under oxidative stress depending on glucose availability...
June 5, 2017: Nature Methods
Cem Kuscu, Mahmut Parlak, Turan Tufan, Jiekun Yang, Karol Szlachta, Xiaolong Wei, Rashad Mammadov, Mazhar Adli
CRISPR-Cas9-induced DNA damage may have deleterious effects at high-copy-number genomic regions. Here, we use CRISPR base editors to knock out genes by changing single nucleotides to create stop codons. We show that the CRISPR-STOP method is an efficient and less deleterious alternative to wild-type Cas9 for gene-knockout studies. Early stop codons can be introduced in ∼17,000 human genes. CRISPR-STOP-mediated targeted screening demonstrates comparable efficiency to WT Cas9, which indicates the suitability of our approach for genome-wide functional screenings...
June 5, 2017: Nature Methods
Michael Shaofei Zhang, Simon F Brunner, Nicolas Huguenin-Dezot, Alexandria Deliz Liang, Wolfgang H Schmied, Daniel T Rogerson, Jason W Chin
The phosphorylation of threonine residues in proteins regulates diverse processes in eukaryotic cells, and thousands of threonine phosphorylations have been identified. An understanding of how threonine phosphorylation regulates biological function will be accelerated by general methods to biosynthesize defined phosphoproteins. Here we describe a rapid approach for directly discovering aminoacyl-tRNA synthetase-tRNA pairs that selectively incorporate non-natural amino acids into proteins; our method uses parallel positive selections combined with deep sequencing and statistical analysis and enables the direct, scalable discovery of aminoacyl-tRNA synthetase-tRNA pairs with mutually orthogonal substrate specificity...
May 29, 2017: Nature Methods
Weijian Zong, Runlong Wu, Mingli Li, Yanhui Hu, Yijun Li, Jinghang Li, Hao Rong, Haitao Wu, Yangyang Xu, Yang Lu, Hongbo Jia, Ming Fan, Zhuan Zhou, Yunfeng Zhang, Aimin Wang, Liangyi Chen, Heping Cheng
Developments in miniaturized microscopes have enabled visualization of brain activities and structural dynamics in animals engaging in self-determined behaviors. However, it remains a challenge to resolve activity at single dendritic spines in freely behaving animals. Here, we report the design and application of a fast high-resolution, miniaturized two-photon microscope (FHIRM-TPM) that accomplishes this goal. With a headpiece weighing 2.15 g and a hollow-core photonic crystal fiber delivering 920-nm femtosecond laser pulses, the FHIRM-TPM is capable of imaging commonly used biosensors (GFP and GCaMP6) at high spatiotemporal resolution (0...
May 29, 2017: Nature Methods
Zoë N Rogers, Christopher D McFarland, Ian P Winters, Santiago Naranjo, Chen-Hua Chuang, Dmitri Petrov, Monte M Winslow
Cancer growth is a multistage, stochastic evolutionary process. While cancer genome sequencing has been instrumental in identifying the genomic alterations that occur in human tumors, the consequences of these alterations on tumor growth remain largely unexplored. Conventional genetically engineered mouse models enable the study of tumor growth in vivo, but they are neither readily scalable nor sufficiently quantitative to unravel the magnitude and mode of action of many tumor-suppressor genes. Here, we present a method that integrates tumor barcoding with ultradeep barcode sequencing (Tuba-seq) to interrogate tumor-suppressor function in mouse models of human cancer...
May 22, 2017: Nature Methods
David A Knowles, Joe R Davis, Hilary Edgington, Anil Raj, Marie-Julie Favé, Xiaowei Zhu, James B Potash, Myrna M Weissman, Jianxin Shi, Douglas F Levinson, Philip Awadalla, Sara Mostafavi, Stephen B Montgomery, Alexis Battle
Identifying interactions between genetics and the environment (GxE) remains challenging. We have developed EAGLE, a hierarchical Bayesian model for identifying GxE interactions based on associations between environmental variables and allele-specific expression. Combining whole-blood RNA-seq with extensive environmental annotations collected from 922 human individuals, we identified 35 GxE interactions, compared with only four using standard GxE interaction testing. EAGLE provides new opportunities for researchers to identify GxE interactions using functional genomic data...
May 22, 2017: Nature Methods
Aaron T L Lun, Arianne C Richard, John C Marioni
When comparing biological conditions using mass cytometry data, a key challenge is to identify cellular populations that change in abundance. Here, we present a computational strategy for detecting 'differentially abundant' populations by assigning cells to hyperspheres, testing for significant differences between conditions and controlling the spatial false discovery rate. Our method ( outperforms other approaches in simulations and finds novel patterns of differential abundance in real data...
May 15, 2017: Nature Methods
Qing Dai, Sharon Moshitch-Moshkovitz, Dali Han, Nitzan Kol, Ninette Amariglio, Gideon Rechavi, Dan Dominissini, Chuan He
The ribose of RNA nucleotides can be 2'-O-methylated (Nm). Despite advances in high-throughput detection, the inert chemical nature of Nm still limits sensitivity and precludes mapping in mRNA. We leveraged the differential reactivity of 2'-O-methylated and 2'-hydroxylated nucleosides to periodate oxidation to develop Nm-seq, a sensitive method for transcriptome-wide mapping of Nm with base precision. Nm-seq uncovered thousands of Nm sites in human mRNA with features suggesting functional roles.
May 15, 2017: Nature Methods
Joshua A Bagley, Daniel Reumann, Shan Bian, Julie Lévi-Strauss, Juergen A Knoblich
Human brain development involves complex interactions between different regions, including long-distance neuronal migration or formation of major axonal tracts. Different brain regions can be cultured in vitro within 3D cerebral organoids, but the random arrangement of regional identities limits the reliable analysis of complex phenotypes. Here, we describe a coculture method combining brain regions of choice within one organoid tissue. By fusing organoids of dorsal and ventral forebrain identities, we generate a dorsal-ventral axis...
May 10, 2017: Nature Methods
Catalina A Vallejos, Davide Risso, Antonio Scialdone, Sandrine Dudoit, John C Marioni
Single-cell transcriptomics is becoming an important component of the molecular biologist's toolkit. A critical step when analyzing data generated using this technology is normalization. However, normalization is typically performed using methods developed for bulk RNA sequencing or even microarray data, and the suitability of these methods for single-cell transcriptomics has not been assessed. We here discuss commonly used normalization approaches and illustrate how these can produce misleading results. Finally, we present alternative approaches and provide recommendations for single-cell RNA sequencing users...
June 2017: Nature Methods
Nan Yang, Soham Chanda, Samuele Marro, Yi-Han Ng, Justyna A Janas, Daniel Haag, Cheen Euong Ang, Yunshuo Tang, Quetzal Flores, Moritz Mall, Orly Wapinski, Mavis Li, Henrik Ahlenius, John L Rubenstein, Howard Y Chang, Arturo Alvarez Buylla, Thomas C Südhof, Marius Wernig
Approaches to differentiating pluripotent stem cells (PSCs) into neurons currently face two major challenges-(i) generated cells are immature, with limited functional properties; and (ii) cultures exhibit heterogeneous neuronal subtypes and maturation stages. Using lineage-determining transcription factors, we previously developed a single-step method to generate glutamatergic neurons from human PSCs. Here, we show that transient expression of the transcription factors Ascl1 and Dlx2 (AD) induces the generation of exclusively GABAergic neurons from human PSCs with a high degree of synaptic maturation...
June 2017: Nature Methods
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