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)

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    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

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    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

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    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

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    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

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    We present the observed HI size-mass relation of 204204 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 0<z<0.0840 < z < 0.084, 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 (DHID_{\rm HI}) and the mass (MHIM_{\rm HI}) of HI discs. We measure a slope of 0.501±0.0080.501\pm 0.008, an intercept of 3.2520.074+0.073-3.252^{+0.073}_{-0.074}, and an observed scatter of 0.0570.057 dex. For the first time, we quantify the intrinsic scatter of 0.054±0.0030.054 \pm 0.003 dex (10%{\sim} 10 \%), 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 DHIMHID_{\rm HI} - M_{\rm HI} 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

    MIGHTEE-HI: The first MeerKAT HI mass function from an untargeted interferometric survey

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    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 (0z0.0840 \leq z \leq 0.084 ). 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: 1/Vmax1/\rm V_{\rm max} and Modified Maximum Likelihood (MML). We find a low-mass slope α=1.290.26+0.37\alpha=-1.29^{+0.37}_{-0.26}, `knee' mass log10(M/M)=10.070.24+0.24\log_{10}(M_{*}/{\rm M_{\odot}}) = 10.07^{+0.24}_{-0.24} and normalisation log10(ϕ/Mpc3)=2.340.36+0.32\log_{10}(\phi_{*}/\rm Mpc^{-3})=-2.34^{+0.32}_{-0.36} (H0=67.4H_0 = 67.4 kms1^{-1} Mpc1^{-1}) for 1/Vmax1/\rm V_{\rm max} and α=1.440.10+0.13\alpha=-1.44^{+0.13}_{-0.10}, `knee' mass log10(M/M)=10.220.13+0.10\log_{10}(M_{*}/{\rm M_{\odot}}) = 10.22^{+0.10}_{-0.13} and normalisation log10(ϕ/Mpc3)=2.520.14+0.19\log_{10}(\phi_{*}/\rm Mpc^{-3})=-2.52^{+0.19}_{-0.14} for MML. When using 1/Vmax1/\rm V_{\rm max} we find both the low-mass slope and `knee' mass to be consistent within 1σ1\sigma with previous studies based on single-dish surveys. The cosmological mass density of HI is found to be slightly larger than previously reported: ΩHI=5.460.99+0.94×104h67.41\Omega_{\rm HI}=5.46^{+0.94}_{-0.99} \times 10^{-4}h^{-1}_{67.4} from 1/Vmax1/\rm V_{\rm max} and ΩHI=6.310.31+0.31×104h67.41\Omega_{\rm HI}=6.31^{+0.31}_{-0.31} \times 10^{-4}h^{-1}_{67.4} 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 &lt; 0.5*

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    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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