bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing the origin of thick disks using ultra-deep images
Authors: Martínez-Lombilla Cristina , Trujillo Ignacio , Knapen Johan H.
Published: March 2017

The origin of thick disks is still a matter of debate. To explore such structures in unprecedented detail, we have developed a technique to reach a surface brightness limit of 28.5-29 mag/arcsec2 with the combined g, r, i bands images from the IAC Stripe82 Legacy Project (Fliri & Trujillo, 2016). We present the characterisation of the thick disk in the edge-on galaxy UGC 01040. We carefully analyse the background subtraction and masking process. The effects of the PSF are considered through galaxy modelling. We present the study of radial and vertical surface brightness profiles, making a comparison between our data, the convolved and deconvolved models and its galactic components. We find that PSF effects are important, but can be accounted for. Our technique will allow us to model thick disks in external galaxies and elucidate their formation and evolutionary history.
Stellar populations in the outskirts of M31: the mid-infrared view
Authors: Barmby P. , Ravandi M. Rafiei
Published: March 2017

The mid-infrared provides a unique view of galaxy stellar populations, sensitive to both the integrated light of old, low-mass stars and to individual dusty mass-losing stars. We present results from an extended Spitzer/IRAC survey of M31 with total lengths of 6.6 and 4.4 degrees along the major and minor axes, respectively. The integrated surface brightness profile proves to be surprisingly difficult to trace in the outskirts of the galaxy, but we can also investigate the disk/halo transition via a star count profile, with careful correction for foreground and background contamination. Our point-source catalog allows us to report on mid-infrared properties of individual objects in the outskirts of M31, via cross-correlation with PAndAS, WISE, and other catalogs.
Outer spiral structure in disk galaxies
Authors: Patsis P.A.
Published: March 2017

In several grand design barred-spiral galaxies it is observed a second, fainter, outer set of spiral arms. Typical examples of objects of this morphology can be considered NGC 1566 and NGC 5248. I suggest that such an overall structure can be the result of two dynamical mechanisms acting in the disc. The bar and both spiral systems rotate with the same pattern speed. The inner spiral is reinforced by regular orbits trapped around the stable, elliptical, periodic orbits of the central family, while the outer system of spiral arms is supported by chaotic orbits. Chaotic orbits are also responsible for a rhomboidal area surrounding the inner barred-spiral region. In general there is a discontinuity between the two spiral structures at the corotation region.
The Vertical Displacement of the Milky Way Disk
Authors: Newberg Heidi Jo , Xu Yan
Published: March 2017

An oscillating vertical displacement of the Milky Way, with a wavelength of about 8 kpc and and amplitude of about 100 pc (increasing with distance from the Galactic center) is observed towards the Galactic anticenter. These oscillations are thought to be the result of disk perturbations from dwarf satellites of the Milky Way. They explain the Monoceros Ring and could be related to Milky Way spiral structure.
A Spitzer Study of Pseudobulges in S0 Galaxies: Secular Evolution of Disks
Authors: Barway Sudhanshu , Vaghmare Kaustubh , Mathur Smita , Kembhavi Ajit
Published: March 2017

A comparison of pseudobulges in S0 and spiral galaxies is presented using structural parameters derived from 2-d decomposition of mid-infrared images taken at 3.6 μm by Spitzer IRAC. The position of the bulges on the Kormendy diagram has been used as an initial classification criterion for determining the nature of the bulge. To make the classification more secure, the criterion proposed by Fisher and Drory (2008) has also been used, which involves using the n = 2 division line on Sérsic index. We find that among the 185 S0 galaxies, 27 are pseudobulge hosts while 160 are classical. Of these 25 pseudobulge hosts, only two belong to the bright luminosity class (MK < 22.66, AB system) while rest belong to the faint luminosity class (MK > 22.66, AB system). We find that among spiral galaxies, 77 % (24 of 31) of the bulges are classified as pseudobulges. As pointed out by various studies, the presence of such a large fraction poses problems to our current picture of galaxy formation. How ever, our primary result is that the disk scale length of pseudobulge hosting S0s is significantly smaller on average than that of their spiral counterparts. This can be explained as a lowered disk luminosity which in turn implies that S0s have evolved from spiral progenitors. We also argue that early type spirals are more likely to be the progenitors based on bulge and total luminosity arguments. We speculate that if late type spirals hosting pseudobulges have to evolve into S0s, an additional mechanism along with gas stripping of spirals is needed. We have also investigated the effect of environment on pseudobulges in the two samples, but no significant trends were found in the properties of the pseudobulges as a function of the various structural parameters. The study is made more difficult because of the low number statistics one deals with when the sample is sub-divided based on whether it is in a field or group/cluster environment. The study of pseudobulges based on environment, however, is an interesting one and is something that can be considered for the future by carefully selecting a sample with statistically meaningful number of objects from diverse environments.
Using rotation measure to search for magnetic fields around galaxies at z ~ 0.5
Authors: Williams Anna , Lundgren Britt , Mao Sui Ann , Wilcots Eric , Zweibel Ellen
Published: March 2017

Magnetic fields are an important component in galaxies, and yet, we still do not know how these magnetic fields were originally seeded within galaxies, nor how they have grown to the strengths we observe today. One way we can unravel this complex problem is by measuring the growth of magnetic fields over cosmic time. We present the initial results of a rotation measure study to search for the presence of coherent magnetic fields around young disk-like galaxies at z ~ 0.5. The S-band receiver at the VLA allows us to simultaneously observe Stokes I, Q, U, and V from 2-4 GHz. With these broadband polarization observations we apply multiple methods for determining the rotation measure of each source, improving the fidelity of our results. Beyond magnetogenesis, the results of this study also have implications for the life-cycle of baryons within galaxies and the composition of galactic haloes.
Large scale profiles of galaxies at z=0-2 studied by stacking the HSC SSP survey data
Authors: Kubo Mariko , Ouchi Masami , Shibuya Takatoshi
Published: March 2017

We are carrying out the study of the evolution of radial surface brightness profiles of galaxies from z = 0 to 2 by stacking analysis using data corrected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP). This will allow us to constrain the large scale average profiles of various galaxy populations at high redshift. From the stacking analysis of galaxies selected based on their photometric redshifts, we successfully detected the outer components of galaxies at z > 1 extending to at least ~80 kpc, which imply an early formation for the galaxy outskirts.
Falling outer rotation curves of star-forming galaxies at 0.7 < z < 2.6 probed with KMOS3D and SINS/zC-SINF
Authors: Lang Philipp , Schreiber Natascha M. Förster , Genzel Reinhard , Burkert Andreas , Lutz Dieter , Tacconi Linda , Wisnioski Emily , Wuyts Stijn ,   the KMOS team
Published: March 2017

We exploit the deep Hα IFU kinematic data from the KMOS3D and SINS/zC-SINF surveys to explore the so far unconstrained outer rotation curves of star-forming disk galaxies at high redshift. Through stacking the signal of ~ 100 massive disks at 0.7 < z < 2.6, we construct a representative rotation curve reaching out to several effective radii. Our stacked rotation curve exhibits a turnover with a steep falloff in the outer regions, significantly strengthening the tantalizing evidence previously hinted at in a handful only of individual disks among the sample with the deepest data.

This finding confirms the high baryon fractions found by comparing the stellar, gas and dynamical masses of high redshift galaxies independently of assumptions on the light-to-mass conversion and Initial stellar Mass Function (IMF). The rapid falloff of the stacked rotation curve is most naturally explained by the effects of pressure gradients, which are significant in the gas-rich, turbulent high-z disks and which would imply a possible pressure-driven truncation of the outer disk.
Outer Disk Star Formation in HI selected Galaxies
Authors: Meurer G. R.
Published: March 2017

The HI in galaxies often extends past their conventionally defined optical extent. I report results from our team which has been probing low intensity star formation in outer disks using imaging in Hα and ultraviolet. Using a sample of hundreds of HI selected galaxies, we confirm that outer disk HII regions and extended UV disks are common. Hence outer disks are not dormant but are dimly forming stars. Although the ultraviolet light in galaxies is more centrally concentrated than the HI, the UV/HI ratio (the Star Formation Efficiency) is nearly constant, with a slight dependency on surface brightness. This result is well accounted for in a model where disks maintain a constant stability parameter Q. This model also accounts for how the ISM and star formation are distributed in the bright parts of galaxies, and how HI appears to trace the distribution of dark matter in galaxy outskirts.
New Conversion Laws for CO Observations
Authors: Barnes Peter J. , Muller Erik , Hernandez Audra K. , Duarte-Cabral Ana , Schuller Frederic
Published: March 2017

We describe new conversion laws, from CO molecular line data to inferred mass column, based on observations of the three main CO isotopologues in several surveys of the Galactic Plane. The new conversion laws replace the use of the single “X-factor” in widespread use, with a more physically-based relationship between the CO line’s optical depth, excitation, and column density. It has the effect of increasing the inferred mass column, over the single X-factor, by typically a factor of 2–3. This means that the molecular mass of the Milky Way may have been substantially underestimated in previous studies, and suggests that scaling laws like the Kennicutt-Schmidt relations may also need to be recalibrated. Because of its statistical basis on a large fraction of our Galaxy’s ISM, this new law is also recommended for use in studies of other Milky-Way-analogue spiral galaxies.
Stellar Spirals in Triaxial Dark Matter Halos
Authors: Hu Shaoran , Sijacki Debora
Published: March 2017

Two-armed grand-design spirals may form if the shape of its dark matter halo changes abruptly enough. The feasibility of such a mechanism is tested in realistic simulations. The interplay of such externally-driven spirals and self-induced transient spirals is then studied. Subhaloes are also found to lead to transient grand-design spiral structures when they impact the disk.
A ‘Universal’ Density Profile for the Outer Stellar Halos of Galaxies
Authors: Remus Rhea-Silvia , Burkert Andreas , Dolag Klaus
Published: March 2017

The outer stellar halos of galaxies contain vital information about the formation history of galaxies, since the relaxation timescales in the outskirts are long enough to keep the memory, while the information about individual formation events in the central parts has long been lost due to mixing, star formation and relaxation. To unveil some of the information encoded in these faint outer halo regions, we study the stellar outskirts of galaxies selected from a fully hydrodynamical high-resolution cosmological simulation, called Magneticum. We find that the density profiles of the outer stellar halos of galaxies over a broad mass range can be well described by an Einasto profile. For a fixed total mass range, the free parameters of the Einasto fits are closely correlated. Galaxies which had more (dry) merger events tend to have lesser curved outer stellar halos, however, we find no indication that the amount of curvature is correlated with galaxy morphology. The Einasto-like shape of the outer stellar halo densities can also explain the observed differences between the Milky Way and Andromeda outer stellar halos.
3D-spectroscopy of SBS star-forming galaxies
Authors: Hakopian S. A. , Dodonov S. N. , Moiseev A. V. , Smirnova A. A.
Published: March 2017

In the base of our studies of star-forming processes are the data provided by panoramic spectroscopy of galaxies composing our SBS subsample. Observations with multi-pupil spectrographs are organized in a way to obtain the spectral range centered in permitted hydrogen Hα Balmer line, by capturing at least the forbidden doublets of nitrogen [NII]6548,6583 and sulfur [SII]6716,6731. The results obtained are the spatial distributions across the targets of emission intensities and derived properties from line parameters such as radial velocities, which give us the possibility to explore gas kinematics and physical characteristics of HII regions.
Spatially-resolved SFR in nearby disk galaxies using IFS data
Authors: Catalán-Torrecilla C. , de Paz A. Gil , Castillo-Morales A. , Méndez-Abreu J. , Pascual S. , Ruiz-Lara T. , de Lorenzo-Cáceres A. , Sánchez-Menguiano L.
Published: March 2017

Exploring the spatial distribution of the star formation rate (SFR) in nearby galaxies is essential to understand their evolution through cosmic time. With this aim in mind, we use a representative sample that contains a variety of morphological types, the CALIFA Integral Field Spectroscopy (IFS) sample. Previous to this work, we have verified that our extinction-corrected Hα measurements successfully reproduce the values derived from other SFR tracers such as Hαobs + IR or UVobs + IR (Catalán-Torrecilla et al. 2015).

Now, we go one step further applying 2-dimensional photometric decompositions (Méndez-Abreu et al. (2008), Méndez-Abreu et al. (2014)) over these datacubes. This method allows us to obtain the amount of SFR in the central part (bulge or nuclear source), the bar and the disk, separately. First, we determine the light coming from each component as the ratio between the luminosity in every component (bulge, bar or disk) and the total luminosity of the galaxy. Then, for each galaxy we multiply the IFS datacubes by these previous factors to recover the luminosity in each component. Finally, we derive the spectrum associated to each galaxy component integrating the spatial information in the weighted datacube using an elliptical aperture covering the whole galaxy.

2D photometric decomposition applied over 3D datacubes will give us a more detailed understanding of the role that disks play in more massive galaxies. Knowing if the disks in more massive SF galaxies have on average a lower or higher level of star formation activity and how these results are affected by the presence of nuclear bars are still open questions that we can now solve. We describe the behavior of these components in the SFR vs. stellar mass diagram. In particular, we highlight the role of the disks and their contribution to both the integrated SFR for the whole galaxy and the SFR in the disk at different stellar masses in the SFR vs. stellar mass diagram together with their relative position to the star forming Main Sequence.
The Neutral Hydrogen Cosmological Mass Density at z = 5
Authors: Crighton Neil H. M. , Murphy Michael T. , Prochaska J. Xavier , Worseck Gábor , Rafelski Marc , Becker George D. , Ellison Sara L. , Fumagalli Michele , Lopez Sebastian , Meiksin Avery , O’Meara John M.
Published: March 2017

We present the largest homogeneous survey of redshift > 4.4 damped Lyα systems (DLAs) using the spectra of 163 quasars that comprise the Giant Gemini GMOS (GGG) survey. With this survey we make the most precise high-redshift measurement of the cosmological mass density of neutral hydrogen, ΩHI. After correcting for systematic effects using a combination of mock and higher-resolution spectra, we find ΩHI= 0.98+0.20-0.18 × 10−3 at 〈z〉 = 4.9, assuming a 20% contribution from lower column density systems below the DLA threshold. By comparing to literature measurements at lower redshifts, we show that ΩHI can be described by the functional form ΩHI(z) ∝ (1 + z)0.4. This gradual decrease from z = 5 to 0 suggests that in the galaxies which dominate the cosmic star formation rate, Hi is a transitory gas phase fuelling star formation which must be continually replenished by more highly-ionized gas from the intergalactic medium, and from recycled galactic winds.
The Circumgalactic Medium of Andromeda
Authors: Lehner Nicolas ,   the Project AMIGA team
Published: March 2017

Our view of galaxies has been transformed in recent years with diffuse halo gas surrounding galaxies that contains at least as many metals and baryons as their disks. While single sight lines through galaxy halos seen in absorption have provided key new constraints, they provide only average properties. Our massive neighbor, the Andromeda (M31) galaxy, provides an unique way to study its circumgalactic medium whereby we can study it using not one or two, but ~36 sightlines thanks to its proximity. With our Large HST program — Project AMIGA (Absorption Maps In the Gas of Andromeda), our goals are to determine the spatial distribution of the halo properties of a L* galaxy using 36 background targets at different radii and azimuths. In this brief paper, I discuss briefly the scientific rationale of Project AMIGA and some early science results. In particular, for the first time we have demonstrated that M31 has a gaseous halo that extends to Rvir with as much as metal and baryonic masses than in its disk and has substantial change in its ionization properties with more highly ionized gas found at R ~ Rvir than cooler gas found near the disk.
Outflows in low-mass galaxies at z >1
Authors: Maseda Michael V. ,   the MUSE GTO consortium
Published: March 2017

Star formation histories of local dwarf galaxies, derived through resolved stellar populations, appear complex and varied. The general picture derived from hydrodynamical simulations is one of cold gas accretion and bursty star formation, followed by feedback from supernovae and winds that heat and eject the central gas reservoirs. This ejection halts star formation until the material cools and re-accretes, resulting in an episodic SFH, particularly at stellar masses below ~ 109 M⊙. Such feedback has often been cited as the driving force behind the observed slowly-rising rotation curves in local dwarfs, due to an under-density of dark matter compared to theoretical models, which is one of the primary challenges to LCDM cosmology. However, these events have not yet been directly observed at high-redshift. Recently, using HST imaging and grism spectroscopy, we have uncovered an abundant population of low-mass galaxies (M* < 109 M⊙) at z = 1 - 2 that are undergoing strong bursts of star formation, in agreement with the theoretical predictions. These Extreme Emission Line Galaxies, with high specific SFRs and shallow gravitational potential wells, are ideal places to test the theoretical prediction of strong feedback-driven outflows. Here we use deep MUSE spectroscopy to search these galaxies for signatures of outflowing material, namely kinematic offsets between absorption lines (in the restframe optical and UV), which trace cool gas, and the nebular emission lines, which define the systemic redshift of the galaxy. Although the EELGs are intrinsically very faint, stacked spectra reveal blueshifted velocity centroids for Fe II absorption, which is indicative of outflowing cold gas. This represents the first constraint on outflows in M* < 109 M⊙ galaxies at z = 1 - 2. These outflows should regulate the star formation histories of low-mass galaxies at early cosmic times and thus play a crucial role in galaxy growth and evolution.
Results from the EDGES Survey
Authors: van Zee Liese ,   the EDGES Team
Published: March 2017

Results are presented from a deep imaging survey with the Spitzer Space Telescope which was designed to identify and measure the faint stellar populations around nearby galaxies. The Extended Disk Galaxy Exploration Science (EDGES) Survey includes a sample of 92 nearby galaxies with a range of morphological types and environments. The observations include a field-of-view of at least 5 times the optical size and are deep enough to detect stellar mass surface densities of several hundredths of a solar mass per square parsec. The observations reveal extended stellar features, such as stellar disks and stellar streams, around many of the target galaxies, as expected from hierarchical galaxy formation scenarios.
The build-up of the outskirts of distant star-forming galaxies at z ~ 2
Authors: Tacchella Sandro , Carollo C. Marcella , Dekel Avishai , Schreiber Natascha Förster , Renzini Alvio ,   zC-SINF Team
Published: March 2017

In order to constrain – and understand – the growth of galaxies, we present a sample of ~ 30 galaxies at z ~ 2 with resolved distribution of stellar mass, star-formation rate, and dust attenuation on scales of ~ 1 kpc. We find that low- and intermediate-mass galaxies grow self-similarly, doubling their stellar mass in the centers and outskirts with the same pace. More massive galaxies (~ 1011 M⊙) have a reduced star-formation activity in their center: they grow mostly in the outskirts (inside-out quenching / formation). Similar trends are find in cosmological zoom-in simulations, highlighting that high stellar mass densities are formed in a gas-rich compaction phase. This nuclear ‘starburst’ phase is followed by a suppressed star-formation activity in the center, resulting in growth of the outskirts. All in all, we put forward that we witness at z ~ 2 the dissipative formation of z = 0 M* early-type galaxies.
Faint extended structures near galaxies: preliminary results from the Wise Observatory
Authors: Brosch Noah , Mosenkov Aleksandr , Rich R. Michael
Published: March 2017

We present the first results from a survey of deep imaging of edge-on galaxies, with the goal of testing the growth-by-accretion of galaxies proposed by ΛCDM. The data were obtained with a new telescope at the Wise Observatory. Our images show previously unreported extensions of the disk, tidal distortions, and streams at the level of 27-28 mag arcsec−2.
Probing Galactic Outskirts with Dragonfly
Authors: Abraham Roberto , Merritt Allison , Zhang Jielai , van Dokkum Pieter , Conroy Charlie , Danieli Shany , Mowla Lamiya
Published: March 2017

We describe the challenges inherent to low surface brightness imaging and present some early results from the Dragonfly Nearby Galaxies survey. Wide field, ultra-low surface brightness imaging (μg > 31 mag arcsec−2) of the first eight galaxies in the survey reveals a rich variety in the distribution of stars in the outskirts of luminous nearby galaxies. The mean stellar halo mass fraction is 0.009 ± 0.005 with a peak-to-peak scatter of a factor of > 100. Some galaxies in the sample feature strongly structured halos resembling that of M31, but three of the eight galaxies have halos that are completely undetected in our data. We conclude that spiral galaxies as a class exhibit a rich variety in stellar halo properties, implying that their assembly histories have been highly non-uniform. While the outskirts of some galaxies are dominated by halos with the rich substructures predicted by numerical simulations, in other cases the outermost parts of galaxies are simply the extrapolated smooth starlight from enormous stellar disks that closely trace neutral gas morphology out to around 20 scale lengths.
The Norwegian National Council for Priority Setting in Health Care: decisions and justifications
Authors: Wester Gry , Bringedal Berit
Published: March 2017

Different countries have adopted different strategies for tackling the challenge of allocating scarce health care resources fairly. Norway is one of the countries that has pioneered the effort to resolve priority setting by using a core set of priority-setting criteria. While the criteria themselves have been subject to extensive debate and numerous revisions, the question of how the criteria have been applied in practice has received less attention. In this paper, we examine how the criteria feature in the decisions and justifications of the Norwegian National Council for Priority Setting in Health Care, which has played an active role in deliberating about health care provision and coverage in Norway. We conducted a comprehensive document analysis, looking at the Council’s decisions about health care allocation as well as the reasons they had provided to justify their decisions. We found that although the Council often made use of the official priority-setting criteria, they did so in an unsystematic and inconsistent manner.
Animal-Assisted Intervention in Dementia
Authors: Tournier Isabelle , Vives Marie-Frédérique , Postal Virginie
Published: March 2017

Abstract. The present work assesses the efficacy of an animal-assisted therapy (AAT) program in the reduction of neuropsychiatric symptoms in older adults with medium to severe dementia. Performed in an Alzheimer’s disease/dementia care unit, the intervention included 11 elderly residents aged 71 to 93 years (mean age = 82.91 years; mean Mini-Mental State Examination score = 7.8/30). Behaviors during the AAT sessions as well as pre/post intervention neuropsychiatric symptoms were examined during this 5-month weekly intervention conducted by an AAT-certified psychologist along with her dog. AAT had a positive effect on total score and caregiver distress score for several neuropsychiatric symptoms (i.e., delusion, depression, disinhibition, euphoria, and aberrant motor activity). Moreover, the ratings of the various behaviors during each session suggest that the beneficial effects of AAT appear during the first few sessions. These results support the notion that regular and long-term AAT sessions are an effective alternative to pharmacological interventions for the reduction of neuropsychiatric symptoms.
Effect of Emotions in a Lexical Decision Task
Authors: Maire Hélène , Brochard Renaud , Kop Jean-Luc , Dioux Vivien , Zagar Daniel
Published: March 2017

Abstract. This study measured the effect of emotional states on lexical decision task performance and investigated which underlying components (physiological, attentional orienting, executive, lexical, and/or strategic) are affected. We did this by assessing participants’ performance on a lexical decision task, which they completed before and after an emotional state induction task. The sequence effect, usually produced when participants repeat a task, was significantly smaller in participants who had received one of the three emotion inductions (happiness, sadness, embarrassment) than in control group participants (neutral induction). Using the diffusion model ( Ratcliff, 1978 ) to resolve the data into meaningful parameters that correspond to specific psychological components, we found that emotion induction only modulated the parameter reflecting the physiological and/or attentional orienting components, whereas the executive, lexical, and strategic components were not altered. These results suggest that emotional states have an impact on the low-level mechanisms underlying mental chronometric tasks.
Mars Polar Intrigue Spurs Multidisciplinary Collaboration
Authors: Smith Isaac , Beaty David , Thorsteinsson Thorsteinn
Published: March 2017

Sixth International Conference on Mars Polar Science and Exploration; Reykjavík, Iceland; 5–9 September 2016
Zika virus evades interferon-mediated antiviral response through the co-operation of multiple nonstructural proteins in vitro
Authors: Wu Yaoxing , Liu Qingxiang , Zhou Jie , Xie Weihong , Chen Cheng , Wang Zefang , Yang Haitao , Cui Jun
Published: March 2017

Type I interferon (IFN) serves as the first line of defense against invading pathogens. Inhibition of IFN-triggered signaling cascade by Zika virus (ZIKV) plays a critical role for ZIKV to evade antiviral responses from host cells. Here we demonstrate that ZIKV nonstructural proteins NS1, NS4B and NS2B3 inhibit the induction of IFN and downstream IFN-stimulated genes through diverse strategies. NS1 and NS4B of ZIKV inhibit IFNβ signaling at TANK-binding kinase 1 level, whereas NS2B-NS3 of ZIKV impairs JAK–STAT signaling pathway by degrading Jak1 and reduces virus-induced apoptotic cell death. Furthermore, co-operation of NS1, NS4B and NS2B3 further enhances viral infection by blocking IFN-induced autophagic degradation of NS2B3. Hence, our study reveals a novel antagonistic system employing multiple ZIKV nonstructural proteins in restricting the innate antiviral responses.
Acceptable symbiont cell size differs among cnidarian species and may limit symbiont diversity
Authors: Biquand Elise , Okubo Nami , Aihara Yusuke , Rolland Vivien , Hayward David C , Hatta Masayuki , Minagawa Jun , Maruyama Tadashi , Takahashi Shunichi
Published: March 2017

Reef-building corals form symbiotic relationships with dinoflagellates of the genus Symbiodinium. Symbiodinium are genetically and physiologically diverse, and corals may be able to adapt to different environments by altering their dominant Symbiodinium phylotype. Notably, each coral species associates only with specific Symbiodinium phylotypes, and consequently the diversity of symbionts available to the host is limited by the species specificity. Currently, it is widely presumed that species specificity is determined by the combination of cell-surface molecules on the host and symbiont. Here we show experimental evidence supporting a new model to explain at least part of the specificity in coral–Symbiodinium symbiosis. Using the laboratory model Aiptasia–Symbiodinium system, we found that symbiont infectivity is related to cell size; larger Symbiodinium phylotypes are less likely to establish a symbiotic relationship with the host Aiptasia. This size dependency is further supported by experiments where symbionts were replaced by artificial fluorescent microspheres. Finally, experiments using two different coral species demonstrate that our size-dependent-infection model can be expanded to coral–Symbiodinium symbiosis, with the acceptability of large-sized Symbiodinium phylotypes differing between two coral species. Thus the selectivity of the host for symbiont cell size can affect the diversity of symbionts in corals.
Chance and necessity in the genome evolution of endosymbiotic bacteria of insects
Authors: Sabater-Muñoz Beatriz , Toft Christina , Alvarez-Ponce David , Fares Mario A
Published: March 2017

An open question in evolutionary biology is how does the selection–drift balance determine the fates of biological interactions. We searched for signatures of selection and drift in genomes of five endosymbiotic bacterial groups known to evolve under strong genetic drift. Although most genes in endosymbiotic bacteria showed evidence of relaxed purifying selection, many genes in these bacteria exhibited stronger selective constraints than their orthologs in free-living bacterial relatives. Remarkably, most of these highly constrained genes had no role in the host–symbiont interactions but were involved in either buffering the deleterious consequences of drift or other host-unrelated functions, suggesting that they have either acquired new roles or their role became more central in endosymbiotic bacteria. Experimental evolution of Escherichia coli under strong genetic drift revealed remarkable similarities in the mutational spectrum, genome reduction patterns and gene losses to endosymbiotic bacteria of insects. Interestingly, the transcriptome of the experimentally evolved lines showed a generalized deregulation of the genome that affected genes encoding proteins involved in mutational buffering, regulation and amino acid biosynthesis, patterns identical to those found in endosymbiotic bacteria. Our results indicate that drift has shaped endosymbiotic associations through a change in the functional landscape of bacterial genes and that the host had only a small role in such a shift.
Defining the functional traits that drive bacterial decomposer community productivity
Authors: Evans Rachael , Alessi Anna M , Bird Susannah , McQueen-Mason Simon J , Bruce Neil C , Brockhurst Michael A
Published: March 2017

Microbial communities are essential to a wide range of ecologically and industrially important processes. To control or predict how these communities function, we require a better understanding of the factors which influence microbial community productivity. Here, we combine functional resource use assays with a biodiversity–ecosystem functioning (BEF) experiment to determine whether the functional traits of constituent species can be used to predict community productivity. We quantified the abilities of 12 bacterial species to metabolise components of lignocellulose and then assembled these species into communities of varying diversity and composition to measure their productivity growing on lignocellulose, a complex natural substrate. A positive relationship between diversity and community productivity was caused by a selection effect whereby more diverse communities were more likely to contain two species that significantly improved community productivity. Analysis of functional traits revealed that the observed selection effect was primarily driven by the abilities of these species to degrade β-glucan. Our results indicate that by identifying the key functional traits underlying microbial community productivity we could improve industrial bioprocessing of complex natural substrates.
An alternative polysaccharide uptake mechanism of marine bacteria
Authors: Reintjes Greta , Arnosti Carol , Fuchs Bernhard M , Amann Rudolf
Published: March 2017

Heterotrophic microbial communities process much of the carbon fixed by phytoplankton in the ocean, thus having a critical role in the global carbon cycle. A major fraction of the phytoplankton-derived substrates are high-molecular-weight (HMW) polysaccharides. For bacterial uptake, these substrates must initially be hydrolysed to smaller sizes by extracellular enzymes. We investigated polysaccharide hydrolysis by microbial communities during a transect of the Atlantic Ocean, and serendipitously discovered—using super-resolution structured illumination microscopy—that up to 26% of total cells showed uptake of fluorescently labelled polysaccharides (FLA-PS). Fluorescence in situ hybridisation identified these organisms as members of the bacterial phyla Bacteroidetes and Planctomycetes and the gammaproteobacterial genus Catenovulum. Simultaneous membrane staining with nile red indicated that the FLA-PS labelling occurred in the cell but not in the cytoplasm. The dynamics of FLA-PS staining was further investigated in pure culture experiments using Gramella forsetii, a marine member of Bacteroidetes. The staining patterns observed in environmental samples and pure culture tests are consistent with a ‘selfish’ uptake mechanisms of larger oligosaccharides (>600 Da), as demonstrated for gut Bacteroidetes. Ecologically, this alternative polysaccharide uptake mechanism secures substantial quantities of substrate in the periplasmic space, where further processing can occur without diffusive loss. Such a mechanism challenges the paradigm that hydrolysis of HMW substrates inevitably yields low-molecular-weight fragments that are available to the surrounding community and demonstrates the importance of an alternative mechanism of polysaccharide uptake in marine bacteria.
Erratum: Highly thermal-stable ferromagnetism by a natural composite
Authors: Ma Tianyu , Gou Junming , Hu Shanshan , Liu Xiaolian , Wu Chen , Ren Shuai , Zhao Hui , Xiao Andong , Jiang Chengbao , Ren Xiaobing , Yan Mi
Published: March 2017

Nature Communications 8: Article number: 13937 (2017); Published 18 January 2017; Updated 21 March 2017 The Author Mi Yan was incorrectly omitted from the list of corresponding Authors in the PDF of this Article, and the author Tianyu Ma was incorrectly listed as a corresponding author; the HTML version of the paper was correct from the time of publication.
Origins of chemoreceptor curvature sorting in Escherichia coli
Authors: Draper Will , Liphardt Jan
Published: March 2017

Bacterial chemoreceptors organize into large clusters at the cell poles. Despite a wealth of structural and biochemical information on the system’s components, it is not clear how chemoreceptor clusters are reliably targeted to the cell pole. Here, we quantify the curvature-dependent localization of chemoreceptors in live cells by artificially deforming growing cells of Escherichia coli in curved agar microchambers, and find that chemoreceptor cluster localization is highly sensitive to membrane curvature. Through analysis of multiple mutants, we conclude that curvature sensitivity is intrinsic to chemoreceptor trimers-of-dimers, and results from conformational entropy within the trimer-of-dimers geometry. We use the principles of the conformational entropy model to engineer curvature sensitivity into a series of multi-component synthetic protein complexes. When expressed in E. coli, the synthetic complexes form large polar clusters, and a complex with inverted geometry avoids the cell poles. This demonstrates the successful rational design of both polar and anti-polar clustering, and provides a synthetic platform on which to build new systems.
Isolation and Characterization of Encephalomyocarditis Virus from Dogs in China
Authors: Luo Ya-Kun , Liang Lin , Tang Qing-Hai , Zhou Ling , Shi Li-Jun , Cong Ying-Ying , Lin Wen-Cheng , Cui Shang-Jin
Published: March 2017

Encephalomyocarditis virus (EMCV) is as a potential zoonotic agent with a wide host range. Here, we describe an EMC virus isolate, identified as EMCV C15, which was successfully obtained from the serum of dogs from animal hospitals. Virus production in cell culture was confirmed by EMCV-specific real-time RT-PCR, indirect immunofluorescence assays and electron microscopy. In addition, the open reading frame sequence (ORF) of the EMCV C15 virus was determined. From sequence comparison and phylogenetic analysis among 24 reference EMCV strains, it appears that the EMCV C15 strain is closely genetically related to strain BEL2887A/91 (>99.0% nucleotide identity). In artificially challenged dogs, the heart and brain were important targets of EMCV C15. This study provides genetic and pathogenic characterization of the EMCV C15 strain isolated in Beijing and calls for sustained surveillance of EMCV infection in China to support better prevention and control of the disease.
The role of rhizobial (NifV) and plant (FEN1) homocitrate synthases in Aeschynomene/photosynthetic Bradyrhizobium symbiosis
Authors: Nouwen Nico , Arrighi Jean-François , Cartieaux Fabienne , Chaintreuil Clémence , Gully Djamel , Klopp Christophe , Giraud Eric
Published: March 2017

In the most studied rhizobium-legume interactions, the host plant supplies the symbiont with homocitrate, an essential co-factor of the nitrogenase enzyme complex, via the expression of a nodule-specific homocitrate synthase FEN1. Photosynthetic bradyrhizobia interacting with Nod factor (NF) dependent and NF-independent Aeschynomene legumes are able to synthesize homocitrate themselves as they contain a nifV gene encoding a homocitrate synthase. Here, we show that in the model strain ORS285, nifV is required for free-living and symbiotic dinitrogen fixation with NF-independent Aeschynomene species. In contrast, in symbiosis with NF-dependent Aeschynomene species, the nifV requirement for efficient nitrogen fixation was found to be host plant dependent. Interestingly, orthologs of FEN1 were found in both NF-dependent and NF-independent Aeschynomene species. However, a high nodule specific induction of FEN1 expression was only observed in A. afraspera, a host plant in which nifV is not required for symbiotic dinitrogen fixation. These data indicate that efficient symbiotic nitrogen fixation in many of the tested Aeschynomene species requires rhizobial homocitrate synthesis. Considering that more than 10% of the fully sequenced rhizobium strains do contain a nifV gene, the Aeschynomene/photosynthetic Bradyrhizobium interaction is likely not the only rhizobium/legume symbiosis where rhizobial nifV expression is required.
Eμ and 3′RR IgH enhancers show hierarchic unilateral dependence in mature B-cells
Authors: Saintamand A. , Vincent-Fabert C. , Marquet M. , Ghazzaui N. , Magnone V. , Pinaud E. , Cogné M. , Denizot Y.
Published: March 2017

Enhancer and super-enhancers are master regulators of cell fate. While they act at long-distances on adjacent genes, it is unclear whether they also act on one another. The immunoglobulin heavy chain (IgH) locus is unique in carrying two super-enhancers at both ends of the constant gene cluster: the 5′Eμ super-enhancer promotes VDJ recombination during the earliest steps of B-cell ontogeny while the 3′ regulatory region (3′RR) is essential for late differentiation. Since they carry functional synergies in mature B-cells and physically interact during IgH locus DNA looping, we investigated if they were independent engines of locus remodelling or if their function was more intimately intermingled, their optimal activation then requiring physical contact with each other. Analysis of chromatin marks, enhancer RNA transcription and accessibility in Eμ- and 3′RR-deficient mice show, in mature activated B-cells, an unilateral dependence of this pair of enhancers: while the 3′RR acts in autonomy, Eμ in contrast likely falls under control of the 3′RR.
The G2A receptor (GPR132) contributes to oxaliplatin-induced mechanical pain hypersensitivity
Authors: Hohmann Stephan W. , Angioni Carlo , Tunaru Sorin , Lee Seungkyu , Woolf Clifford J. , Offermanns Stefan , Geisslinger Gerd , Scholich Klaus , Sisignano Marco
Published: March 2017

Chemotherapy-induced peripheral neuropathic pain (CIPN) is a common and severe debilitating side effect of many widely used cytostatics. However, there is no approved pharmacological treatment for CIPN available. Among other substances, oxaliplatin causes CIPN in up to 80% of treated patients. Here, we report the involvement of the G-protein coupled receptor G2A (GPR132) in oxaliplatin-induced neuropathic pain in mice. We found that mice deficient in the G2A-receptor show decreased mechanical hypersensitivity after oxaliplatin treatment. Lipid ligands of G2A were found in increased concentrations in the sciatic nerve and dorsal root ganglia of oxaliplatin treated mice. Calcium imaging and patch-clamp experiments show that G2A activation sensitizes the ligand-gated ion channel TRPV1 in sensory neurons via activation of PKC. Based on these findings, we conclude that targeting G2A may be a promising approach to reduce oxaliplatin-induced TRPV1-sensitization and the hyperexcitability of sensory neurons and thereby to reduce pain in patients treated with this chemotherapeutic agent.
Elicitation of resistance and associated defense responses in Trichoderma hamatum induced protection against pearl millet downy mildew pathogen
Authors: Siddaiah Chandra Nayaka , Satyanarayana Niranjan Raj , Mudili Venkataramana , Kumar Gupta Vijai , Gurunathan Selvakumar , Rangappa Shobith , Huntrike Shekar Shetty , Srivastava Rakesh Kumar
Published: March 2017

Endophytic Trichoderma hamatum UoM 13 isolated from pearl millet roots was evaluated for its efficiency to suppress downy mildew disease. Under laboratory conditions, T. hamatum seed treatment significantly enhanced pearl millet seed germination and seedling vigor. T. hamatum seed treatment resulted in systemic and durable immunity against pearl millet downy mildew disease under greenhouse and field conditions. T. hamatum treated seedlings responded to downy mildew infection with high lignification and callose deposition. Analysis of defense enzymes showed that T. hamatum treatment significantly enhanced the activities of glucanase, peroxidase, phenylalanine ammonia-lyase, and polyphenol oxidase in comparison to untreated control. RT-PCR analysis revealed differentially expressed transcripts of the defense enzymes and PR-proteins in treated, untreated, and checks, wherein PR-1, PR-5, and cell wall defense HRGPs were significantly over expressed in treated seedlings as against their lower expression in controls. T. hamatum treatment significantly stimulated endogenous salicylic acid (SA) levels and significantly upregulated important SA biosynthesis gene isochorismate synthase. The results indicated that T. hamatum UoM13 treatment induces resistance corresponding to significant over expression of endogenous SA, important defense enzymes, PR-proteins, and HRGPs, suggesting that SA biosynthetic pathway is involved in pearl millet for mounting systemic immunity against downy mildew pathogen.
A clear bias in parental origin of de novo pathogenic CNVs related to intellectual disability, developmental delay and multiple congenital anomalies
Authors: Ma Ruiyu , Deng Linbei , Xia Yan , Wei Xianda , Cao Yingxi , Guo Ruolan , Zhang Rui , Guo Jing , Liang Desheng , Wu Lingqian
Published: March 2017

Copy number variation (CNV) is of great significance in human evolution and disorders. Through tracing the parent-of-origin of de novo pathogenic CNVs, we are expected to investigate the relative contributions of germline genomic stability on reproductive health. In our study, short tandem repeat (STR) and single nucleotide polymorphism (SNP) were used to determine the parent-of-origin of 87 de novo pathogenic CNVs found in unrelated patients with intellectual disability (ID), developmental delay (DD) and multiple congenital anomalies (MCA). The results shown that there was a significant difference on the distribution of the parent-of-origin for different CNVs types (Chi-square test, p = 4.914 × 10−3). An apparently paternal bias existed in deletion CNVs and a maternal bias in duplication CNVs, indicating that the relative contribution of paternal germline variations is greater than that of maternal to the origin of deletions, and vice versa to the origin of duplications. By analyzing the sequences flanking the breakpoints, we also confirmed that non-allelic homologous recombination (NAHR) served as the major mechanism for the formation of recurrent CNVs whereas non-SDs-based mechanisms played a part in generating rare non-recurrent CNVs and might relate to the paternal germline bias in deletion CNVs.
Chronic exposure to a neonicotinoid increases expression of antimicrobial peptide genes in the bumblebee Bombus impatiens
Authors: Simmons William R. , Angelini David R.
Published: March 2017

Bumblebees are important pollinators in wild and agricultural settings. In recent decades pollinator declines have been linked to the effects of increased pesticide use and the spread of disease. Synergy between these factors has been suggested, but no physiological mechanism has been identified. This study examines the connection between neonicotinoid exposure and innate immune function in the bumblebee Bombus impatiens, which is an important wild and commercial pollinator in eastern North America. Experimental colonies in the field were enclosed and provided pollen and sugar syrup containing an agriculturally relevant range of imidacloprid concentrations. Bumblebees were collected from colonies over four weeks, and the expression of antimicrobial peptides was measured using multiplex quantitative real time PCR. Significant increases in the expression of abaecin, apidaecin and hymenoptaecin were found over time in treatments receiving moderate to high concentrations of the pesticide. Responses were dependent on time of exposure and dose. These results indicate that immune function in bumblebees is affected by neonicotinoid exposure and suggest a physiological mechanism by which neonicotinoids may impact the innate immune function of bumblebee pollinators in wild and agricultural habitats.