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GATA2 Promotes Hematopoietic Development and Represses Cardiac Differentiation of Human Mesoderm.
In vertebrates, GATA2 is a master regulator of hematopoiesis and is expressed throughout embryo development and in adult life. Although the essential role of GATA2 in mouse hematopoiesis is well established, its involvement during early human hematopoietic development is not clear. By combining time-controlled overexpression of GATA2 with genetic knockout experiments, we found that GATA2, at the mesoderm specification stage, promotes the generation of hemogenic endothelial progenitors and their further differentiation to hematopoietic progenitor cells, and negatively regulates cardiac differentiation. Surprisingly, genome-wide transcriptional and chromatin immunoprecipitation analysis showed that GATA2 bound to regulatory regions, and repressed the expression of cardiac development-related genes. Moreover, genes important for hematopoietic differentiation were upregulated by GATA2 in a mostly indirect manner. Collectively, our data reveal a hitherto unrecognized role of GATA2 as a repressor of cardiac fates, and highlight the importance of coordinating the specification and repression of alternative cell fates.Ramón y Cajal Program, Spanish Ministry of Economy, Industry, and Competitiveness, Spanish Cancer Association, FERO, Instituto de Salud Carlos III, European Social Fund, MINECO, PERIS Program of the Generalitat de Catalunya, Obra Social la Caixa-Fundacion Josep Carreras, Spanish Institute of Health Carlos III, Wellcome Trust, MRC, CRUK, NIH-NIDD
Fall, Recovery and Characterization of the Novato L6 Chondrite Breccia
The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance (CAMS) project determined the meteor's trajectory between 95 and 45 km altitude. The final fragmentation at 33 1 km altitude was exceptionally well documented by digital photographs. The first sample was recovered before rain hit the area. First results from a consortium study of the meteorite's characterization, cosmogenic and radiogenic nuclides, origin and conditions of the fall are presented. Some meteorites did not retain fusion crust and show evidence of spallation. Before entry, the meteoroid was 35+/-5 cm in diameter (mass 80+/-35 kg) with a cosmic ray exposure age of 9+/-1 Ma, if it had a one-stage exposure history. However, based on the cosmogenic nuclide inventory, a two-stage exposure history is more likely, with lower shielding in the last few Ma. Thermoluminescence data suggest a collision event within the last approx. 0.1 Ma. Novato likely belonged to the class of shocked L chondrites that have a common shock age of 470 Ma, based on the U,Th-He age of 460+/-220 Ma. The measured orbits of Novato, Jesenice and Innisfree are consistent with a proposed origin of these shocked L chondrites in the Gefion asteroid family, but leave open the possibility that they came to us directly from the 5:2 mean motion resonance with Jupiter. Novato experienced a stronger compaction than did other L6 chondrites of shock-stage S4. Despite this, a freshly broken surface shows a wide range of organic compounds
TOI-332 b: a super dense Neptune found deep within the Neptunian desert
To date, thousands of planets have been discovered, but there are regions of the orbital parameter space that are still bare. An example is the short period and intermediate mass/radius space known as the ‘Neptunian desert’, where planets should be easy to find but discoveries remain few. This suggests unusual formation and evolution processes are responsible for the planets residing here. We present the discovery of TOI-332 b, a planet with an ultra-short period of 0.78 d that sits firmly within the desert. It orbits a K0 dwarf with an effective temperature of 5251 ± 71 K. TOI-332 b has a radius of R⊕, smaller than that of Neptune, but an unusually large mass of 57.2 ± 1.6 M⊕. It has one of the highest densities of any Neptune-sized planet discovered thus far at g cm−3. A 4-layer internal structure model indicates it likely has a negligible hydrogen-helium envelope, something only found for a small handful of planets this massive, and so TOI-332 b presents an interesting challenge to planetary formation theories. We find that photoevaporation cannot account for the mass-loss required to strip this planet of the Jupiter-like envelope it would have been expected to accrete. We need to look towards other scenarios, such as high-eccentricity migration, giant impacts, or gap opening in the protoplanetary disc, to try and explain this unusual discovery
A Model for the Roll-Out of Comprehensive Adult Male Circumcision Services in African Low-Income Settings of High HIV Incidence: The ANRS 12126 Bophelo Pele Project
Bertrand Auvert and colleagues describe the large-scale roll-out of adult male circumcision through a program in South Africa
Affectus Hispaniae en la historiografía del Alto Imperio
This paper analyses texts written by Greek and Latin High Empire historians dealing with Hispania. Some of the authors have a very positive view (Florus, Iustinus, Appian) while others are clearly negative (Veleius Paterculus, Valerius Maximus) though most of them show little interest, indifference or variety of opinions. When there is interest in the region or praise, it is because the author comes from Hispania or he is trying to please an emperor born in Hispania, but it could also be due to a universal conception of history revealing a critical attitude towards Roman imperialism, as in Appian. The praise found in Iustinus’s epitome should be attributed to the author of the epitome rather than to Pompeius Trogus. This can be taken as evidence for situating Iustinus’s life and work in the 2nd century A.D. Loathing of Hispania seems to have its origins in conservative, ‘optimate’ nationalist circles, who perceive the province as the ‘popular’ region that acclaimed and welcomed ‘seditious’ individuals such as Tiberius Gracchus and Sertorius.Se estudian en este trabajo los textos de historiadores del Alto Imperio, latinos y griegos, que tratan sobre Hispania. En algunos autores encontramos una visión muy positiva (Floro, Justino, Apiano) y en otros claramente negativa (Veleyo Patérculo, Valerio Máximo), aunque en la mayoría de los casos hay escasa atención, indiferencia o diversidad de opiniones. El interés por la región y los elogios pueden estar motivados por el origen hispánico del autor o su voluntad de agradar a algún emperador oriundo de Hispania, pero también por una concepción universal de la historia que denota en ocasiones una posición crítica con el imperialismo romano, como es el caso de Apiano. La alabanza que hallamos en el epítome de Justino creemos que debe atribuirse más al epitomador que a Pompeyo Trogo, lo que apoyaría una datación temprana de la vida y la obra de Justino (s. II d.C.). La aversión hacia Hispania parece haber surgido en medios conservadores, “optimates” nacionalistas, que ven la provincia como el territorio “popular”, que encumbró y acogió a “sediciosos” como Tiberio Graco y Sertorio
Luminescent Ruthenium(II) Polypyridyl Functionalized Gold Nanoparticles; Their DNA Binding Abilities and Application As Cellular Imaging Agents
The synthesis and photophysical and biological
investigation of Ru(II)-polypyridyl stabilized watersoluble,
luminescent gold nanoparticles (AuNPs) are described.
These structures bind to DNA and undergo rapid
cellular uptake, being localized within the cell cytoplasm and
nucleus within 4 h
High major histocompatibility complex class I polymorphism despite bottlenecks in wild and domesticated populations of the zebra finch ()
Background
Two subspecies of zebra finch, Taeniopygia guttata castanotis and T. g. guttata are native to Australia and the Lesser Sunda Islands, respectively. The Australian subspecies has been domesticated and is now an important model system for research. Both the Lesser Sundan subspecies and domesticated Australian zebra finches have undergone population bottlenecks in their history, and previous analyses using neutral markers have reported reduced neutral genetic diversity in these populations. Here we characterize patterns of variation in the third exon of the highly variable major histocompatibility complex (MHC) class I α chain. As a benchmark for neutral divergence, we also report the first mitochondrial NADH dehydrogenase 2 (ND2) sequences in this important model system.
Results
Despite natural and human-mediated population bottlenecks, we find that high MHC class I polymorphism persists across all populations. As expected, we find higher levels of nucleotide diversity in the MHC locus relative to neutral loci, and strong evidence of positive selection acting on important residues forming the peptide-binding region (PBR). Clear population differentiation of MHC allele frequencies is also evident, and this may be due to adaptation to new habitats and associated pathogens and/or genetic drift. Whereas the MHC Class I locus shows broad haplotype sharing across populations, ND2 is the first locus surveyed to date to show reciprocal monophyly of the two subspecies.
Conclusions
Despite genetic bottlenecks and genetic drift, all surveyed zebra finch populations have maintained high MHC Class I diversity. The diversity at the MHC Class I locus in the Lesser Sundan subspecies contrasts sharply with the lack of diversity in previously examined neutral loci, and may thus be a result of selection acting to maintain polymorphism. Given uncertainty in historical population demography, however, it is difficult to rule out neutral processes in maintaining the observed diversity. The surveyed populations also differ in MHC Class I allele frequencies, and future studies are needed to assess whether these changes result in functional immune differences
The TESS-Keck Survey II: An Ultra-Short Period Rocky Planet and its Siblings Transiting the Galactic Thick-Disk Star TOI-561
We report the discovery of TOI-561, a multi-planet system in the galactic
thick disk that contains a rocky, ultra-short period planet (USP). This bright
() star hosts three small transiting planets identified in photometry
from the NASA TESS mission: TOI-561 b (TOI-561.02, P=0.44 days, ), c (TOI-561.01, P=10.8 days,
), and d (TOI-561.03, P=16.3 days,
). The star is chemically ([Fe/H],
[/H]) and kinematically consistent with the galactic
thick disk population, making TOI-561 one of the oldest (Gyr) and
most metal-poor planetary systems discovered yet. We dynamically confirm
planets b and c with radial velocities from the W. M. Keck Observatory High
Resolution Echelle Spectrometer. Planet b has a mass and density of
and gcm, consistent with
a rocky composition. Its lower-than-average density is consistent with an
iron-poor composition, although an Earth-like iron-to-silicates ratio is not
ruled out. Planet c is and gcm,
consistent with an interior rocky core overlaid with a low-mass volatile
envelope. Several attributes of the photometry for planet d (which we did not
detect dynamically) complicate the analysis, but we vet the planet with
high-contrast imaging, ground-based photometric follow-up and radial
velocities. TOI-561 b is the first rocky world around a galactic thick-disk
star confirmed with radial velocities and one of the best rocky planets for
thermal emission studies.Comment: Accepted at The Astronomical Journal; 25 pages, 10 figure
Long-Lived Phonon Polaritons in Hyperbolic Materials
Natural hyperbolic materials with dielectric permittivities of opposite signs along different principal axes can confine long-wavelength electromagnetic waves down to the nanoscale, well below the diffraction limit. Confined electromagnetic waves coupled to phonons in hyperbolic dielectrics including hexagonal boron nitride (hBN) and α-MoO3 are referred to as hyperbolic phonon polaritons (HPPs). HPP dissipation at ambient conditions is substantial, and its fundamental limits remain unexplored. Here, we exploit cryogenic nanoinfrared imaging to investigate propagating HPPs in isotopically pure hBN and naturally abundant α-MoO3 crystals. Close to liquid-nitrogen temperatures, losses for HPPs in isotopic hBN drop significantly, resulting in propagation lengths in excess of 8 μm, with lifetimes exceeding 5 ps, thereby surpassing prior reports on such highly confined polaritonic modes. Our nanoscale, temperature-dependent imaging reveals the relevance of acoustic phonons in HPP damping and will be instrumental in mitigating such losses for miniaturized mid-infrared technologies operating at liquid-nitrogen temperatures.Research at Columbia is supported by Vannevar Bush Faculty
Fellowship ONR-VB: N00014-19-1-2630. We thank A.
Sternbach and S. Zhang for helpful discussions. Exfoliation
and transfer of hBN onto desired substrates and electron beam
lithography of gold disks were performed by J.T.M. and
supported by the National Science Foundation
(DMR1904793). Additional structure fabrication was supported
by the Center on Precision-Assembled Quantum
Materials, funded through the U.S. National Science
Foundation (NSF) Materials Research Science and Engineering
Centers (award no. DMR-2011738). Initial simulations
and experimental design from Vanderbilt were provided by
J.D.C. in collaboration with the Columbia team (D.N.B. and
G.N.) and was supported by the Office of Naval Research
(N00014-18-1-2107). The hBN phonon band structure
calculation was performed by R.C. and L.A. and supported
by the Spanish MINECO/FEDER grant (MAT2015-71035-
R). Cryogenics nano-optics experiments at Columbia were
solely supported as part of Programmable Quantum Materials,
an Energy Frontier Research Center funded by the U.S.
Department of Energy (DOE), Office of Science, Basic Energy
Sciences (BES), under award no. DE-SC0019443. D.N.B is the
Gordon and Betty Moore Foundation’s EPiQS Initiative
Investigator no. 9455.Peer reviewe
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