277 research outputs found
Effect of thyroid hormone concentration on the transcriptional response underlying induced metamorphosis in the Mexican axolotl (\u3ci\u3eAmbystoma\u3c/i\u3e)
Background
Thyroid hormones (TH) induce gene expression programs that orchestrate amphibian metamorphosis. In contrast to anurans, many salamanders do not undergo metamorphosis in nature. However, they can be induced to undergo metamorphosis via exposure to thyroxine (T4). We induced metamorphosis in juvenile Mexican axolotls (Ambystoma mexicanum) using 5 and 50 nM T4, collected epidermal tissue from the head at four time points (Days 0, 2, 12, 28), and used microarray analysis to quantify mRNA abundances.
Results
Individuals reared in the higher T4 concentration initiated morphological and transcriptional changes earlier and completed metamorphosis by Day 28. In contrast, initiation of metamorphosis was delayed in the lower T4 concentration and none of the individuals completed metamorphosis by Day 28. We identified 402 genes that were statistically differentially expressed by ≥ two-fold between T4 treatments at one or more non-Day 0 sampling times. To complement this analysis, we used linear and quadratic regression to identify 542 and 709 genes that were differentially expressed by ≥ two-fold in the 5 and 50 nM T4 treatments, respectively.
Conclusion
We found that T4 concentration affected the timing of gene expression and the shape of temporal gene expression profiles. However, essentially all of the identified genes were similarly affected by 5 and 50 nM T4. We discuss genes and biological processes that appear to be common to salamander and anuran metamorphosis, and also highlight clear transcriptional differences. Our results show that gene expression in axolotls is diverse and precise, and that axolotls provide new insights about amphibian metamorphosis
Iterative Multi-granular Image Editing using Diffusion Models
Recent advances in text-guided image synthesis has dramatically changed how
creative professionals generate artistic and aesthetically pleasing visual
assets. To fully support such creative endeavors, the process should possess
the ability to: 1) iteratively edit the generations and 2) control the spatial
reach of desired changes (global, local or anything in between). We formalize
this pragmatic problem setting as Iterative Multi-granular Editing. While there
has been substantial progress with diffusion-based models for image synthesis
and editing, they are all one shot (i.e., no iterative editing capabilities)
and do not naturally yield multi-granular control (i.e., covering the full
spectrum of local-to-global edits). To overcome these drawbacks, we propose
EMILIE: Iterative Multi-granular Image Editor. EMILIE introduces a novel latent
iteration strategy, which re-purposes a pre-trained diffusion model to
facilitate iterative editing. This is complemented by a gradient control
operation for multi-granular control. We introduce a new benchmark dataset to
evaluate our newly proposed setting. We conduct exhaustive quantitatively and
qualitatively evaluation against recent state-of-the-art approaches adapted to
our task, to being out the mettle of EMILIE. We hope our work would attract
attention to this newly identified, pragmatic problem setting.Comment: Pre-prin
2,4,6,8-Tetrakis(4-ethylphenyl)-3,7-diazabicyclo[3.3.1]nonan-9-one
The bicyclo[3.3.1]nonane ring in the title compound, C39H44N2O, adopts a chair–boat conformation with the four benzene rings being directed away from the carbonyl group. The presence of C—H⋯O contacts leads to helical supramolecular chains along the b axis
Sal-Site: Integrating new and existing ambystomatid salamander research and informational resources
Salamanders of the genus Ambystoma are a unique model organism system because they enable natural history and biomedical research in the laboratory or field. We developed Sal-Site to integrate new and existing ambystomatid salamander research resources in support of this model system. Sal-Site hosts six important resources: 1) Salamander Genome Project: an information-based web-site describing progress in genome resource development, 2) Ambystoma EST Database: a database of manually edited and analyzed contigs assembled from ESTs that were collected from A. tigrinum tigrinum and A. mexicanum, 3) Ambystoma Gene Collection: a database containing full-length protein-coding sequences, 4) Ambystoma Map and Marker Collection: an image and database resource that shows the location of mapped markers on linkage groups, provides information about markers, and provides integrating links to Ambystoma EST Database and Ambystoma Gene Collection databases, 5) Ambystoma Genetic Stock Center: a website and collection of databases that describe an NSF funded salamander rearing facility that generates and distributes biological materials to researchers and educators throughout the world, and 6) Ambystoma Research Coordination Network: a web-site detailing current research projects and activities involving an international group of researchers. Sal-Site is accessible at
MIGHTEE-HI: the HI Size-Mass relation over the last billion years
We present the observed HI size-mass relation of galaxies from the
MIGHTEE Survey Early Science data. The high sensitivity of MeerKAT allows us to
detect galaxies spanning more than 4 orders of magnitude in HI mass, ranging
from dwarf galaxies to massive spirals, and including all morphological types.
This is the first time the relation has been explored on a blind homogeneous
data set which extends over a previously unexplored redshift range of , i.e. a period of around one billion years in cosmic time. The sample
follows the same tight logarithmic relation derived from previous work, between
the diameter () and the mass () of HI discs. We measure
a slope of , an intercept of , and an
observed scatter of dex. For the first time, we quantify the intrinsic
scatter of dex (), which provides a constraint
for cosmological simulations of galaxy formation and evolution. We derive the
relation as a function of galaxy type and find that their intrinsic scatters
and slopes are consistent within the errors. We also calculate the relation for two redshift bins and do not find any evidence for
evolution with redshift. These results suggest that over a period of one
billion years in lookback time, galaxy discs have not undergone significant
evolution in their gas distribution and mean surface mass density, indicating a
lack of dependence on both morphological type and redshift.Comment: 10 pages, 5 figures, accepted for publication in MNRA
Investigating the Role of Feedback and Motivation in Clinical Reaction Time Assessment
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146854/1/pmr21092.pd
MIGHTEE-HI: The first MeerKAT HI mass function from an untargeted interferometric survey
We present the first measurement of the HI mass function (HIMF) using data
from MeerKAT, based on 276 direct detections from the MIGHTEE Survey Early
Science data covering a period of approximately a billion years (). This is the first HIMF measured using interferometric data over
non-group or cluster field, i.e. a deep blank field. We constrain the
parameters of the Schechter function which describes the HIMF with two
different methods: and Modified Maximum Likelihood (MML).
We find a low-mass slope , `knee' mass
and normalisation
(
kms Mpc) for and
, `knee' mass and normalisation for MML. When using we
find both the low-mass slope and `knee' mass to be consistent within
with previous studies based on single-dish surveys. The cosmological mass
density of HI is found to be slightly larger than previously reported:
from and from MML but consistent within the uncertainties. We find
no evidence for evolution of the HIMF over the last billion years.Comment: 13 pages, 9 figures, accepted for publication in MNRA
MIGHTEE-Hi: Evolution of Hi Scaling Relations of Star-forming Galaxies at z < 0.5*
We present the first measurements of H I galaxy scaling relations from a blind survey at z > 0.15. We perform spectral stacking of 9023 spectra of star-forming galaxies undetected in H I at 0.23 < z < 0.49, extracted from MIGHTEE-H I Early Science data cubes, acquired with the MeerKAT radio telescope. We stack galaxies in bins of galaxy properties (stellar mass M *, star formation rateSFR, and specific star formation rate sSFR, with sSFR ≡ M */SFR), obtaining ≳5σ detections in most cases, the strongest H I-stacking detections to date in this redshift range. With these detections, we are able to measure scaling relations in the probed redshift interval, finding evidence for a moderate evolution from the median redshift of our sample z med ~ 0.37 to z ~ 0. In particular, low-M * galaxies ( {\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\sim 9 )experienceastrongHIdepletion( 0.5dexinlog10(MHI/M⊙)
), while massive galaxies ( {\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\sim 11$ ) keep their H I mass nearly unchanged. When looking at the star formation activity, highly star-forming galaxies evolve significantly in M H I (f H I, where f H I ≡ M H I/M *) at fixed SFR (sSFR), while at the lowest probed SFR (sSFR) the scaling relations show no evolution. These findings suggest a scenario in which low-M * galaxies have experienced a strong H I depletion during the last ~5 Gyr, while massive galaxies have undergone a significant H I replenishment through some accretion mechanism, possibly minor mergers. Interestingly, our results are in good agreement with the predictions of the SIMBA simulation. We conclude that this work sets novel important observational constraints on galaxy scaling relations
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