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https://www.readbyqxmd.com/read/28522692/mitotic-chromosome-assembly-despite-nucleosome-depletion-in-xenopus-egg-extracts
#1
Keishi Shintomi, Fukashi Inoue, Hiroshi Watanabe, Keita Ohsumi, Miho Ohsugi, Tatsuya Hirano
The nucleosome is the fundamental structural units of eukaryotic chromatin. During mitosis, duplicated nucleosome fibers are organized into a pair of rod-shaped structures (chromatids) within a mitotic chromosome. However, it remains unclear whether nucleosome assembly is indeed an essential prerequisite for mitotic chromosome assembly. Here, we combined mouse sperm nuclei and Xenopus cell-free egg extracts depleted of the histone chaperone Asf1 and found that chromatid-like structures could be assembled even in the near-absence of nucleosomes...
May 18, 2017: Science
https://www.readbyqxmd.com/read/28522691/mechanism-of-transmembrane-signaling-by-sensor-histidine-kinases
#2
Ivan Gushchin, Igor Melnikov, Vitaly Polovinkin, Andrii Ishchenko, Anastasia Yuzhakova, Pavel Buslaev, Gleb Bourenkov, Sergei Grudinin, Ekaterina Round, Taras Balandin, Valentin Borshchevskiy, Dieter Willbold, Gordon Leonard, Georg Büldt, Alexander Popov, Valentin Gordeliy
One of the major and essential classes of transmembrane (TM) receptors, present in all domains of life, is sensor histidine kinases (HKs), parts of two-component signaling systems (TCS). The structural mechanisms of transmembrane signaling by these sensors are poorly understood. We present here crystal structures of the periplasmic sensor domain, the TM domain and the cytoplasmic HAMP domain of the Escherichia coli nitrate/nitrite sensor HK NarQ in the ligand-bound and mutated ligand-free states. The structures reveal that the ligand binding induces significant rearrangements and piston-like shifts of TM helices...
May 18, 2017: Science
https://www.readbyqxmd.com/read/28522690/resistance-to-malaria-through-structural-variation-of-red-blood-cell-invasion-receptors
#3
Ellen M Leffler, Gavin Band, George B J Busby, Katja Kivinen, Quang Si Le, Geraldine M Clarke, Kalifa A Bojang, David J Conway, Muminatou Jallow, Fatoumatta Sisay-Joof, Edith C Bougouma, Valentina D Mangano, David Modiano, Sodiomon B Sirima, Eric Achidi, Tobias O Apinjoh, Kevin Marsh, Carolyne M Ndila, Norbert Peshu, Thomas N Williams, Chris Drakeley, Alphaxard Manjurano, Hugh Reyburn, Eleanor Riley, David Kachala, Malcolm Molyneux, Vysaul Nyirongo, Terrie Taylor, Nicole Thornton, Louise Tilley, Shane Grimsley, Eleanor Drury, Jim Stalker, Victoria Cornelius, Christina Hubbart, Anna E Jeffreys, Kate Rowlands, Kirk A Rockett, Chris C A Spencer, Dominic P Kwiatkowski
The malaria parasite Plasmodium falciparum invades human red blood cells via interactions between host and parasite surface proteins. By analyzing genome sequence data from human populations, including 1269 individuals from sub-Saharan Africa, we identify a diverse array of large copy number variants affecting the host invasion receptor genes GYPA and GYPB We find that a nearby association with severe malaria is explained by a complex structural rearrangement involving the loss of GYPB and gain of two GYPB-A hybrid genes, which encode a serologically distinct blood group antigen known as Dantu...
May 18, 2017: Science
https://www.readbyqxmd.com/read/28495879/dual-comb-spectroscopy-of-water-vapor-with-a-free-running-semiconductor-disk-laser
#4
S M Link, D J H C Maas, D Waldburger, U Keller
Dual-comb spectroscopy offers the potential for high accuracy combined with fast data acquisition. Applications are often limited, however, by the complexity of optical comb systems. Here we present dual-comb spectroscopy of water vapor using a substantially simplified single-laser system. Very good spectroscopy measurements with fast sampling rates are achieved with a free-running dual-comb mode-locked semiconductor disk laser. The absolute stability of the optical comb modes is characterized both for free-running operation and with simple microwave stabilization...
May 11, 2017: Science
https://www.readbyqxmd.com/read/28495878/local-amplifiers-of-il-4r%C3%AE-mediated-macrophage-activation-promote-repair-in-lung-and-liver
#5
Carlos M Minutti, Lucy H Jackson-Jones, Belén García-Fojeda, Johanna A Knipper, Tara E Sutherland, Nicola Logan, Emma Rinqvist, Raquel Guillamat-Prats, David A Ferenbach, Antonio Artigas, Cordula Stamme, Zissis C Chroneos, Dietmar M Zaiss, Cristina Casals, Judith E Allen
The type 2 immune response controls helminth infection and maintains tissue homeostasis but can lead to allergy and fibrosis if not adequately regulated. We have discovered local tissue-specific amplifiers of type-2 mediated-macrophage activation. In the lung, surfactant protein A (SP-A) enhanced IL-4-dependent macrophage proliferation and activation, accelerating parasite clearance and reducing pulmonary injury following infection with a lung-migrating helminth. In the peritoneal cavity and liver, C1q enhancement of type 2 macrophage activation was required for liver repair following bacterial infection, but resulted in fibrosis following peritoneal dialysis...
May 11, 2017: Science
https://www.readbyqxmd.com/read/28495877/a-maternal-effect-selfish-genetic-element-in-caenorhabditis-elegans
#6
Eyal Ben-David, Alejandro Burga, Leonid Kruglyak
Selfish genetic elements spread in natural populations and have an important role in genome evolution. We discovered a selfish element causing embryonic lethality in crosses between wild strains of the nematode Caenorhabditis elegans The element is made up of sup-35, a maternal-effect toxin that kills developing embryos, and pha-1, its zygotically expressed antidote. pha-1 has long been considered essential for pharynx development on the basis of its mutant phenotype, but this phenotype arises from a loss of suppression of sup-35 toxicity...
May 11, 2017: Science
https://www.readbyqxmd.com/read/28495876/a-subcellular-map-of-the-human-proteome
#7
Peter J Thul, Lovisa Åkesson, Mikaela Wiking, Diana Mahdessian, Aikaterini Geladaki, Hammou Ait Blal, Tove Alm, Anna Asplund, Lars Björk, Lisa M Breckels, Anna Bäckström, Frida Danielsson, Linn Fagerberg, Jenny Fall, Laurent Gatto, Christian Gnann, Sophia Hober, Martin Hjelmare, Fredric Johansson, Sunjae Lee, Cecilia Lindskog, Jan Mulder, Claire M Mulvey, Peter Nilsson, Per Oksvold, Johan Rockberg, Rutger Schutten, Jochen M Schwenk, Åsa Sivertsson, Evelina Sjöstedt, Marie Skogs, Charlotte Stadler, Devin P Sullivan, Hanna Tegel, Casper Winsnes, Cheng Zhang, Martin Zwahlen, Adil Mardinoglu, Fredrik Pontén, Kalle von Feilitzen, Kathryn S Lilley, Mathias Uhlén, Emma Lundberg
Resolving the spatial distribution of the human proteome at a subcellular level greatly increases our understanding of human biology and disease. Here, we present a comprehensive image-based map of the subcellular protein distribution, the Cell Atlas, built by integrating transcriptomics and antibody-based immunofluorescence microscopy with validation by mass spectrometry. Mapping the in situ localization of 12,003 human proteins at a single-cell level to 30 subcellular structures enabled the definition of 13 major organelle proteomes...
May 11, 2017: Science
https://www.readbyqxmd.com/read/28495875/macrophage-function-in-tissue-repair-and-remodeling-requires-il-4-or-il-13-with-apoptotic-cells
#8
Lidia Bosurgi, Y Grace Cao, Mar Cabeza-Cabrerizo, Andrea Tucci, Lindsey D Hughes, Yong Kong, Jason S Weinstein, Paula Licona-Limon, Edward T Schmid, Facundo Pelorosso, Nicola Gagliani, Joseph E Craft, Richard A Flavell, Sourav Ghosh, Carla V Rothlin
Tissue repair is a subset of a broad repertoire of IL-4/IL-13-dependent host responses during helminth infection. Here, we show that IL-4/IL-13 alone were not sufficient, but IL-4/IL-13 together with apoptotic cells induced the tissue repair program in macrophages. Genetic ablation of sensors of apoptotic cells impaired the proliferation of tissue-resident macrophages and the induction of anti-inflammatory/tissue repair genes in the lung following helminth infection or in the gut following induction of colitis...
May 11, 2017: Science
https://www.readbyqxmd.com/read/28473639/ring-attractor-dynamics-in-the-drosophila-central-brain
#9
Sung Soo Kim, Hervé Rouault, Shaul Druckmann, Vivek Jayaraman
Ring attractors are a class of recurrent networks hypothesized to underlie the representation of heading direction. Such network structures, schematized as a ring of neurons whose connectivity depends on their heading preferences, can sustain a bump-like activity pattern whose location can be updated by continuous shifts along either turn direction. We recently reported that a population of fly neurons represents the animal's heading via bump-like activity dynamics. We combined two-photon calcium imaging in head-fixed flying flies with optogenetics to overwrite the existing population representation with an artificial one, which was then maintained by the circuit with naturalistic dynamics...
May 4, 2017: Science
https://www.readbyqxmd.com/read/28473638/mapping-the-human-dc-lineage-through-the-integration-of-high-dimensional-techniques
#10
Peter See, Charles-Antoine Dutertre, Jinmiao Chen, Patrick Günther, Naomi McGovern, Sergio Erdal Irac, Merry Gunawan, Marc Beyer, Kristian Händler, Kaibo Duan, Hermi Rizal Bin Sumatoh, Nicolas Ruffin, Mabel Jouve, Ester Gea-Mallorquí, Raoul C M Hennekam, Tony Lim, Chan Chung Yip, Ming Wen, Benoit Malleret, Ivy Low, Nurhidaya Binte Shadan, Charlene Foong Shu Fen, Alicia Tay, Josephine Lum, Francesca Zolezzi, Anis Larbi, Michael Poidinger, Jerry K Y Chan, Qingfeng Chen, Laurent Renia, Muzlifah Haniffa, Philippe Benaroch, Andreas Schlitzer, Joachim L Schultze, Evan W Newell, Florent Ginhoux
Dendritic cells (DC) are professional antigen-presenting cells that orchestrate immune responses. The human DC population comprises two main functionally specialized lineages, whose origins and differentiation pathways remain incompletely defined. Here, we combine two high-dimensional technologies-single-cell mRNA sequencing and cytometry by time-of-flight (CyTOF), to identify human blood CD123(+)CD33(+)CD45RA(+) DC precursors (pre-DC). Pre-DC share surface markers with plasmacytoid DC (pDC) but have distinct functional properties that were previously attributed to pDC...
May 4, 2017: Science
https://www.readbyqxmd.com/read/28469005/editorial-retraction
#11
Jeremy Berg
No abstract text is available yet for this article.
May 3, 2017: Science
https://www.readbyqxmd.com/read/28408722/ephrin-b1-mediated-repulsion-and-signaling-control-germinal-center-t-cell-territoriality-and-function
#12
Peiwen Lu, Changming Shih, Hai Qi
Follicular T-helper (TFH) cells orchestrate the germinal center (GC) reaction locally. Local mechanisms regulating their dynamics and helper functions are not well defined. Here we found that GC-expressed Ephrin B1 (EFNB1) repulsively inhibited T cell to B cell adhesion and GC TFH retention by signaling through TFH-expressed EPHB6 receptor. At the same time, EFNB1 promoted IL-21 production from GC TFH cells by signaling predominantly through EPHB4. Consequently, EFNB1-null GCs were associated with defective production of plasma cells despite harboring excessive TFH cells...
April 13, 2017: Science
https://www.readbyqxmd.com/read/28408721/decarboxylative-borylation
#13
Chao Li, Jie Wang, Lisa M Barton, Shan Yu, Maoqun Tian, David S Peters, Manoj Kumar, Anthony W Yu, Kristen A Johnson, Arnab K Chatterjee, Ming Yan, Phil S Baran
The widespread use of alkyl boronic acids and esters is frequently hampered by the challenges associated with their preparation. Herein we describe a simple and practical method to rapidly access densely functionalized alkyl boronate esters from abundant carboxylic substituents. This broad-scope Ni-catalyzed reaction uses the same activating principle as amide bond formation to replace a carboxylic acid with a boronate ester. Application to peptides allowed expedient preparations of α-amino boronic acids, often with high stereoselectivity, facilitating the synthesis of both FDA approved alkyl boronic acid drugs (Velcade and Ninlaro) as well as a boronic acid version of the iconic antibiotic vancomycin...
April 13, 2017: Science
https://www.readbyqxmd.com/read/28386026/coupling-between-distant-biofilms-and-emergence-of-nutrient-time-sharing
#14
Jintao Liu, Rosa Martinez-Corral, Arthur Prindle, Dong-Yeon D Lee, Joseph Larkin, Marçal Gabalda-Sagarra, Jordi Garcia-Ojalvo, Gürol M Süel
Bacteria within communities can interact to organize their behavior. It has been unclear whether such interactions can extend beyond a single community to coordinate the behavior of distant populations. We discovered that two Bacillus subtilis biofilm communities undergoing metabolic oscillations can become coupled through electrical signaling and synchronize their growth dynamics. Coupling increases competition by also synchronizing demand for limited nutrients. As predicted by mathematical modeling, we confirm that biofilms resolve this conflict by switching from in-phase to antiphase oscillations...
May 12, 2017: Science
https://www.readbyqxmd.com/read/28386025/greater-role-for-atlantic-inflows-on-sea-ice-loss-in-the-eurasian-basin-of-the-arctic-ocean
#15
Igor V Polyakov, Andrey V Pnyushkov, Matthew B Alkire, Igor M Ashik, Till M Baumann, Eddy C Carmack, Ilona Goszczko, John Guthrie, Vladimir V Ivanov, Torsten Kanzow, Richard Krishfield, Ronald Kwok, Arild Sundfjord, James Morison, Robert Rember, Alexander Yulin
Arctic sea-ice loss is a leading indicator of climate change and can be attributed, in large part, to atmospheric forcing. Here, we show that recent ice reductions, weakening of the halocline, and shoaling of intermediate-depth Atlantic Water layer in the eastern Eurasian Basin have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin. The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin...
April 6, 2017: Science
https://www.readbyqxmd.com/read/28360137/the-applied-value-of-public-investments-in-biomedical-research
#16
Danielle Li, Pierre Azoulay, Bhaven N Sampat
Scientists and policy-makers have long argued that public investments in science have practical applications. Using data on patents linked to U.S. National Institutes of Health (NIH) grants over a 27-year period, we provide a large-scale accounting of linkages between public research investments and subsequent patenting. We find that about 10% of NIH grants generate a patent directly but 30% generate articles that are subsequently cited by patents. Although policy-makers often focus on direct patenting by academic scientists, the bulk of the effect of NIH research on patenting appears to be indirect...
March 30, 2017: Science
https://www.readbyqxmd.com/read/28360136/high-performance-light-emitting-diodes-based-on-carbene-metal-amides
#17
Dawei Di, Alexander S Romanov, Le Yang, Johannes M Richter, Jasmine P H Rivett, Saul Jones, Tudor H Thomas, Mojtaba Abdi Jalebi, Richard H Friend, Mikko Linnolahti, Manfred Bochmann, Dan Credgington
Organic LEDs promise highly efficient lighting and display technologies. We introduce a new class of linear donor-bridge-acceptor light-emitting molecules, which enable solution-processed LEDs with near-100% internal quantum efficiency at high brightness. Key to this performance is their rapid and efficient utilization of triplet states. Using time-resolved spectroscopy, we establish that luminescence via triplets occurs within 350 ns at ambient temperature, after reverse intersystem crossing to singlets. We find that molecular geometries exist at which the singlet-triplet energy gap (exchange energy) is close to zero, such that rapid interconversion is possible...
March 30, 2017: Science
https://www.readbyqxmd.com/read/28360134/colloidally-prepared-la-doped-basno3-electrodes-for-efficient-photostable-perovskite-solar-cells
#18
Seong Sik Shin, Eun Joo Yeom, Woon Seok Yang, Seyoon Hur, Min Gyu Kim, Jino Im, Jangwon Seo, Jun Hong Noh, Sang Il Seok
Perovskite solar cells (PSCs) exceeding a power conversion efficiency (PCE) of 20% have mainly been demonstrated by using mesoporous titanium dioxide (mp-TiO2) as an electron-transporting layer. However, TiO2 can reduce the stability of PSCs under illumination (including ultraviolet light). Lanthanum (La)-doped BaSnO3 (LBSO) perovskite would be an ideal replacement given its electron mobility and electronic structure, but LBSO cannot be synthesized as well-dispersible fine particles or crystallized below 500°C...
March 30, 2017: Science
https://www.readbyqxmd.com/read/28336563/complex-multifault-rupture-during-the-2016-mw-7-8-kaik%C3%A5-ura-earthquake-new-zealand
#19
Ian J Hamling, Sigrun Hreinsdóttir, Kate Clark, John Elliott, Cunren Liang, Eric Fielding, Nicola Litchfield, Pilar Villamor, Laura Wallace, Tim J Wright, Elisabetta D'Anastasio, Stephen Bannister, David Burbidge, Paul Denys, Paula Gentle, Jamie Howarth, Christof Mueller, Neville Palmer, Chris Pearson, William Power, Philip Barnes, David J A Barrell, Russ Van Dissen, Robert Langridge, Tim Little, Andrew Nicol, Jarg Pettinga, Julie Rowland, Mark Stirling
On 14th November 2016, the northeastern South Island of New Zealand was struck by a major Mw 7.8 earthquake. Field observations, in conjunction with InSAR, GPS, and seismology reveal this to be one of the most complex earthquakes ever recorded. The rupture propagated northward for more than 170 km along both mapped and unmapped faults, before continuing offshore at its northeastern extent. Geodetic and field observations reveal surface ruptures along at least 12 major faults, including possible slip along the southern Hikurangi subduction interface, extensive uplift along much of the coastline and widespread anelastic deformation including the ~8 m uplift of a fault-bounded block...
March 23, 2017: Science
https://www.readbyqxmd.com/read/28336562/de-novo-assembly-of-the-aedes-aegypti-genome-using-hi-c-yields-chromosome-length-scaffolds
#20
Olga Dudchenko, Sanjit S Batra, Arina D Omer, Sarah K Nyquist, Marie Hoeger, Neva C Durand, Muhammad S Shamim, Ido Machol, Eric S Lander, Aviva Presser Aiden, Erez Lieberman Aiden
The Zika outbreak, spread by the Aedes aegypti mosquito, highlights the need to create high-quality assemblies of large genomes in a rapid and cost-effective fashion. Here, we combine Hi-C data with existing draft assemblies to generate chromosome-length scaffolds. We validate this method by assembling a human genome, de novo, from short reads alone (67X coverage). We then combine our method with draft sequences to create genome assemblies of the mosquito disease vectors Aedes aegypti and Culex quinquefasciatus, each consisting of three scaffolds corresponding to the three chromosomes in each species...
March 23, 2017: Science
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