3,285 research outputs found
Spatio-temporal expression patterns of Arabidopsis thaliana and Medicago truncatula defensin-like genes
Plant genomes contain several hundred defensin-like (DEFL) genes that encode short cysteine-rich proteins resembling defensins, which are well known antimicrobial polypeptides. Little is known about the expression patterns or functions of many DEFLs because most were discovered recently and hence are not well represented on standard microarrays. We designed a custom Affymetrix chip consisting of probe sets for 317 and 684 DEFLs from Arabidopsis thaliana and Medicago truncatula, respectively for cataloging DEFL expression in a variety of plant organs at different developmental stages and during symbiotic and pathogenic associations. The microarray analysis provided evidence for the transcription of 71% and 90% of the DEFLs identified in Arabidopsis and Medicago, respectively, including many of the recently annotated DEFL genes that previously lacked expression information. Both model plants contain a subset of DEFLs specifically expressed in seeds or fruits. A few DEFLs, including some plant defensins, were significantly up-regulated in Arabidopsis leaves inoculated with Alternaria brassicicola or Pseudomonas syringae pathogens. Among these, some were dependent on jasmonic acid signaling or were associated with specific types of immune responses. There were notable differences in DEFL gene expression patterns between Arabidopsis and Medicago, as the majority of Arabidopsis DEFLs were expressed in inflorescences, while only a few exhibited root-enhanced expression. By contrast, Medicago DEFLs were most prominently expressed in nitrogen-fixing root nodules. Thus, our data document salient differences in DEFL temporal and spatial expression between Arabidopsis and Medicago, suggesting distinct signaling routes and distinct roles for these proteins in the two plant species
The Quantity of Intracluster Light: Comparing Theoretical and Observational Measurement Techniques Using Simulated Clusters
Using a suite of N-body simulations of galaxy clusters specifically tailored
to study the intracluster light (ICL) component, we measure the quantity of ICL
using a number of different methods previously employed in the literature for
both observational and simulation data sets. By measuring the ICL of the
clusters using multiple techniques, we identify systematic differences in how
each detection method identifies the ICL. We find that techniques which define
the ICL solely based on the current position of the cluster luminosity, such as
a surface brightness or local density threshold, tend to find less ICL than
methods utilizing time or velocity information, including stellar particles'
density history or binding energy. The range of ICL fractions (the fraction of
the clusters' total luminosity found in the ICL component) we measure at z=0
across all our clusters using any definition span the range from 9-36%, and
even within a single cluster different methods can change the measured ICL
fraction by up to a factor of two. Separating the cluster's central galaxy from
the surrounding ICL component is a challenge for all ICL techniques, and
because the ICL is centrally concentrated within the cluster, the differences
in the measured ICL quantity between techniques are largely a consequence of
this central galaxy/ICL separation. We thoroughly explore the free parameters
involved with each measurement method, and find that adjusting these parameters
can change the measured ICL fraction by up to a factor of two. While for all
definitions the quantity of ICL tends to increase with time, the ICL fraction
does not grow at a uniform rate, nor even monotonically under some definitions.
Thus, the ICL can be used as a rough indicator of dynamical age, where more
dynamically advanced clusters will on average have higher ICL fractions.Comment: 18 pages, 11 figues. Accepted for publication in Ap
Inhibition of αvβ5 Integrin Attenuates Vascular Permeability and Protects against Renal Ischemia-Reperfusion Injury
Ischemia-reperfusion injury (IRI) is a leading cause of AKI. This common clinical complication lacks effective therapies and can lead to the development of CKD. The αvβ5 integrin may have an important role in acute injury, including septic shock and acute lung injury. To examine its function in AKI, we utilized a specific function-blocking antibody to inhibit αvβ5 in a rat model of renal IRI. Pretreatment with this anti-αvβ5 antibody significantly reduced serum creatinine levels, diminished renal damage detected by histopathologic evaluation, and decreased levels of injury biomarkers. Notably, therapeutic treatment with the αvβ5 antibody 8 hours after IRI also provided protection from injury. Global gene expression profiling of post-ischemic kidneys showed that αvβ5 inhibition affected established injury markers and induced pathway alterations previously shown to be protective. Intravital imaging of post-ischemic kidneys revealed reduced vascular leak with αvβ5 antibody treatment. Immunostaining for αvβ5 in the kidney detected evident expression in perivascular cells, with negligible expression in the endothelium. Studies in a three-dimensional microfluidics system identified a pericyte-dependent role for αvβ5 in modulating vascular leak. Additional studies showed αvβ5 functions in the adhesion and migration of kidney pericytes in vitro Initial studies monitoring renal blood flow after IRI did not find significant effects with αvβ5 inhibition; however, future studies should explore the contribution of vasomotor effects. These studies identify a role for αvβ5 in modulating injury-induced renal vascular leak, possibly through effects on pericyte adhesion and migration, and reveal αvβ5 inhibition as a promising therapeutic strategy for AKI
Charting the future of cancer health disparities research: A position statement from the American Association for Cancer Research, the American Cancer Society, the American Society of Clinical Oncology, and the National Cancer Institute
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138314/1/caac21404_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138314/2/caac21404.pd
Observations of T-Tauri Stars using HST-GHRS: I. Far Ultraviolet Emission Lines
We have analyzed GHRS data of eight CTTS and one WTTS. The GHRS data consists
of spectral ranges 40 A wide centered on 1345, 1400, 1497, 1550, and 1900 A.
These UV spectra show strong SiIV, and CIV emission, and large quantities of
sharp (~40 km/s) H2 lines. All the H2 lines belong to the Lyman band and all
the observed lines are single peaked and optically thin. The averages of all
the H2 lines centroids for each star are negative which may indicate that they
come from an outflow. We interpret the emission in H2 as being due to
fluorescence, mostly by Ly_alpha, and identify seven excitation routes within 4
A of that line. We obtain column densities (10^12 to 10^15 cm^-2) and optical
depths (~1 or less) for each exciting transition. We conclude that the
populations are far from being in thermal equilibrium. We do not observe any
lines excited from the far blue wing of Ly_alpha, which implies that the
molecular features are excited by an absorbed profile. SiIV and CIV (corrected
for H2 emission) have widths of ~200 km/s, and an array of centroids
(blueshifted lines, centered, redshifted). These characteristics are difficult
to understand in the context of current models of the accretion shock. For DR
Tau we observe transient strong blueshifted emission, perhaps the a result of
reconnection events in the magnetosphere. We also see evidence of multiple
emission regions for the hot lines. While CIV is optically thin in most stars
in our sample, SiIV is not. However, CIV is a good predictor of SiIV and H2
emission. We conclude that most of the flux in the hot lines may be due to
accretion processes, but the line profiles can have multiple and variable
components.Comment: 67 pages, 19 figures, Accepted in Ap
Optical Colors of Intracluster Light in the Virgo Cluster Core
We continue our deep optical imaging survey of the Virgo cluster using the
CWRU Burrell Schmidt telescope by presenting B-band surface photometry of the
core of the Virgo cluster in order to study the cluster's intracluster light
(ICL). We find ICL features down to mu_b ~ 29 mag sq. arcsec, confirming the
results of Mihos et al. (2005), who saw a vast web of low-surface brightness
streams, arcs, plumes, and diffuse light in the Virgo cluster core using V-band
imaging. By combining these two data sets, we are able to measure the optical
colors of many of the cluster's low-surface brightness features. While much of
our imaging area is contaminated by galactic cirrus, the cluster core near the
cD galaxy, M87, is unobscured. We trace the color profile of M87 out to over
2000 arcsec, and find a blueing trend with radius, continuing out to the
largest radii. Moreover, we have measured the colors of several ICL features
which extend beyond M87's outermost reaches and find that they have similar
colors to the M87's halo itself, B-V ~ 0.8. The common colors of these features
suggests that the extended outer envelopes of cD galaxies, such as M87, may be
formed from similar streams, created by tidal interactions within the cluster,
that have since dissolved into a smooth background in the cluster potential.Comment: 14 pages. Published in ApJ, September 201
Revealing natural relationships among arbuscular mycorrhizal fungi: culture line BEG47 represents Diversispora epigaea, not Glomus versiforme
Background: Understanding the mechanisms underlying biological phenomena, such as evolutionarily conservative trait inheritance, is predicated on knowledge of the natural relationships among organisms. However, despite their enormous ecological significance, many of the ubiquitous soil inhabiting and plant symbiotic arbuscular mycorrhizal fungi (AMF, phylum Glomeromycota) are incorrectly classified.
Methodology/Principal Findings:
Here, we focused on a frequently used model AMF registered as culture BEG47. This fungus is a descendent of the ex-type culture-lineage of Glomus epigaeum, which in 1983 was synonymised with Glomus versiforme. It has since then been used as ‘G. versiforme BEG47’. We show by morphological comparisons, based on type material, collected 1860–61, of G. versiforme and on type material and living ex-type cultures of G. epigaeum, that these two AMF species cannot be conspecific, and by molecular phylogenetics that BEG47 is a member of the genus Diversispora.
Conclusions: This study highlights that experimental works published during the last >25 years on an AMF named ‘G. versiforme’ or ‘BEG47’ refer to D. epigaea, a species that is actually evolutionarily separated by hundreds of millions of years from all members of the genera in the Glomerales and thus from most other commonly used AMF ‘laboratory strains’. Detailed redescriptions substantiate the renaming of G. epigaeum (BEG47) as D. epigaea, positioning it systematically in the order Diversisporales, thus enabling an evolutionary understanding of genetical, physiological, and ecological traits, relative to those of other AMF. Diversispora epigaea is widely cultured as a laboratory strain of AMF, whereas G. versiforme appears not to have been cultured nor found in the field since its original description
The Morphological Butcher-Oemler effect in the SDSS Cut&Enhance Galaxy Cluster Catalog
We investigate the evolution of the fractions of late type cluster galaxies
as a function of redshift, using one of the largest, most uniform cluster
samples available. The sample consists of 514 clusters of galaxies in the range
0.02<z<0.3 from the Sloan Digital Sky Survey Cut & Enhance galaxy cluster
catalog. This catalog was created using a single automated cluster finding
algorithm on uniform data from a single telescope, with accurate CCD
photometry, thus, minimizing selection biases. We use four independent methods
to analyze the evolution of the late type galaxy fraction. Specifically, we
select late type galaxies based on: restframe g-r color, u-r color, galaxy
profile fitting and concentration index. The first criterion corresponds to the
one used in the classical Butcher-Oemler analyses. The last three criteria are
more sensitive to the morphological type of the galaxies. In all four cases, we
find an increase in the fraction of late type galaxies with increasing
redshift, significant at the 99.9% level. The results confirm that cluster
galaxies do change colors with redshift (the Butcher-Oemler effect) and, in
addition, they change their morphology to later-type toward higher redshift --
indicating a morphological equivalent of the Butcher-Oemler effect. We also
find a tendency of richer clusters to have lower fractions of late type
galaxies. The trend is consistent with a ram pressure stripping model, where
richer clusters have more effective ram pressure due to their higher
temperature.Comment: 44 pages, 15 figures, accepted for PAS
Multi-Messenger Astronomy with Extremely Large Telescopes
The field of time-domain astrophysics has entered the era of Multi-messenger
Astronomy (MMA). One key science goal for the next decade (and beyond) will be
to characterize gravitational wave (GW) and neutrino sources using the next
generation of Extremely Large Telescopes (ELTs). These studies will have a
broad impact across astrophysics, informing our knowledge of the production and
enrichment history of the heaviest chemical elements, constrain the dense
matter equation of state, provide independent constraints on cosmology,
increase our understanding of particle acceleration in shocks and jets, and
study the lives of black holes in the universe. Future GW detectors will
greatly improve their sensitivity during the coming decade, as will
near-infrared telescopes capable of independently finding kilonovae from
neutron star mergers. However, the electromagnetic counterparts to
high-frequency (LIGO/Virgo band) GW sources will be distant and faint and thus
demand ELT capabilities for characterization. ELTs will be important and
necessary contributors to an advanced and complete multi-messenger network.Comment: White paper submitted to the Astro2020 Decadal Surve
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