The SAMI Galaxy Survey: Spatially resolving the environmental quenching of star formation in GAMA galaxies

We use data from the Sydney-AAO Multi-Object Integral Field Spectrograph (SAMI) Galaxy Survey and the Galaxy And Mass Assembly (GAMA) survey to investigate the spatially-resolved signatures of the environmental quenching of star formation in galaxies. Using dust-corrected measurements of the distribution of Hα emission we measure the radial profiles of star formation in a sample of 201 star-forming galaxies covering three orders of magnitude in stellar mass (M∗M∗; 108.1-1010.95 M⊙) and in 5th nearest neighbour local environment density (Σ5; 10−1.3- 102.1 Mpc−2). We show that star formation rate gradients in galaxies are steeper in dense (log10(Σ5/Mpc2) > 0.5) environments by 0.58 ± 0.29 dex re−1 in galaxies with stellar masses in the range 1010 1.0). These lines of evidence strongly suggest that with increasing local environment density the star formation in galaxies is suppressed, and that this starts in their outskirts such that quenching occurs in an outside-in fashion in dense environments and is not instantaneous

The SAMI Galaxy Survey: Data Release One with emission-line physics value-added products

We present the first major release of data from the SAMI Galaxy Survey. This data release focuses on the emission-line physics of galaxies. Data Release One includes data for 772 galaxies, about 20 per cent of the full survey. Galaxies included have the redshift range 0.004 < z < 0.092, a large mass range (7.6 < logM*/M⊙ < 11.6), and star formation rates of ~10-4 to ~101M⊙ yr-1. For each galaxy, we include two spectral cubes and a set of spatially resolved 2D maps: single- and multi-component emission-line fits (with dust-extinction corrections for strong lines), local dust extinction, and star formation rate. Calibration of the fibre throughputs, fluxes, and differential atmospheric refraction has been improved over the Early Data Release. The data have average spatial resolution of 2.16 arcsec (full width at half-maximum) over the 15 arcsec diameter field of view and spectral (kinematic) resolution of R = 4263 (σ = 30 km s-1) around Ha. The relative flux calibration is better than 5 per cent, and absolute flux calibration has an rms of 10 per cent. The data are presented online through the Australian Astronomical Observatory's Data Central

Exploitation of Drosophila Choriogenesis Process as a Model Cellular System for Assessment of Compound Toxicity: the Phloroglucinol Paradigm

Phloroglucinol (1,3,5 tri-hydroxy-benzene) (PGL), a natural phenolic substance, is a peroxidase inhibitor and has anti-oxidant, anti-diabetic, anti-inflammatory, anti-thrombotic, radio-protective, spasmolytic and anti-cancer activities. PGL, as a medicine, is administered to patients to control the symptoms of irritable bowel syndrome and acute renal colic, in clinical trials. PGL, as a phenolic substance, can cause cytotoxic effects. Administration of PGL up to 300 mg/kg (bw) is well tolerated by animals, while in cell lines its toxicity is developed at concentrations above the dose of 10 μg/ml. Furthermore, it seems that tumor or immortalized cells are more susceptible to the toxic power of PGL, than normal cells. However, studies of its cytotoxic potency, at the cellular level, in complex, differentiated and meta-mitotic biological systems, are still missing. In the present work, we have investigated the toxic activity of PGL in somatic epithelial cells, constituting the follicular compartment of a developing egg-chamber (or, follicle), which directs the choriogenesis (i.e. chorion assembly) process, during late oogenesis of Drosophila melanogaster. Our results reveal that treatment of in vitro growing Drosophila follicles with PGL, at a concentration of 0.2 mM (or, 25.2 μg/ml), does not lead to follicle-cell toxicity, since the protein-synthesis program and developmental pattern of choriogenesis are normally completed. Likewise, the 1 mM dose of PGL was also characterized by lack of toxicity, since the chorionic proteins were physiologically synthesized and the chorion structure appeared unaffected, except for a short developmental delay, being observed. In contrast, concentrations of 10, 20 or 40 mM of PGL unveiled a dose-dependent, increasing, toxic effect, being initiated by interruption of protein synthesis and disassembly of cell-secretory machinery, and, next, followed by fragmentation of the granular endoplasmic reticulum (ER) into vesicles, and formation of autophagic vacuoles. Follicle cells enter into an apoptotic process, with autophagosomes and large vacuoles being formed in the cytoplasm, and nucleus showing protrusions, granular nucleolus and condensed chromatin. PGL, also, proved able to induce disruption of nuclear envelope, activation of nucleus autophagy (nucleophagy) and formation of a syncytium-like pattern being produced by fusion of plasma membranes of two or more individual follicle cells. Altogether, follicle cell-dependent choriogenesis in Drosophila has been herein presented as an excellent, powerful and reliable multi-cellular, differentiated, model biological (animal) system for drug-cytotoxicity assessment, with the versatile compound PGL serving as a characteristic paradigm. In conclusion, PGL is a substance that may act beneficially for a variety of pathological conditions and can be safely used for differentiated somatic -epithelial- cells at clinically low concentrations. At relatively high doses, it could potentially induce apoptotic and autophagic cell death, thus being likely exploited as a therapeutic agent against a number of pathologies, including human malignancies. © 2020, The Author(s)

The Snapshot Hubble U-band Cluster Survey (SHUCS). I. Survey Description and First Application to the Mixed Star Cluster Population of NGC 4041

Contains fulltext : 111270.pdf (preprint version ) (Open Access

Young Star Cluster Population of NGC 2997

Contains fulltext : 132448.pdf (preprint version ) (Open Access

Per os colchicine administration in cholesterol fed rabbits: Triglycerides lowering effects without affecting atherosclerosis progress

Background: Atherosclerosis is a chronic inflammatory disease that is promoted, among others, by pro-inflammatory cytokines such as IL-1β and IL-18 produced by NLRP 3 inflammasome. Development of atherosclerotic lesions is also affected by leptin. Furthermore, inflammasome's action is interfered with other inflammatory diseases, like diabetes. On the other hand, colchicine is reported to act as anti-inflammatory agent inhibiting inflammasome's action and stabilizing atherosclerotic lesions. The purpose of this study is to investigate the effect of per os colchicine on the de novo formation of atherosclerotic lesions and on the levels of IL-18, leptin and insulin in cholesterol-fed rabbits. Methods: Twenty-three male, 2 months old New Zealand White rabbits, were seperated in 3 groups and were fed with different types of diet for 7 weeks: standard, cholesterol 1% w/w and cholesterol 1% w/w plus colchicine 2 mg/kg body weight. Blood was collected for biochemical measurements and conduction of ELISA for leptin, IL-18 and insulin. Histologic examination of stained with eosin and hematoxylin aorta specimens was performed. Aortic intimal thickness was evaluated using image analysis. The statistical analysis included non-parametric tests: a) paired-sample Wilcoxon test, b) Spearman correlation coefficient and c) Kruscal-Wallis test. Results: Triglerycide levels were decreased in cholesterol plus colchicine group in the end of the experiment (p < 0.05), whereas the cholesterol group had increased levels. No statistical differences were observed in the levels of IL-18, leptin and insulin between groups. Likewise, there was neither any correlation between IL-18, leptin and intima thickness nor between IL-18 and glucose and between leptin and weight. In cholesterol and colchicine group there was a strong positive correlation between IL-18 and insulin levels in the 4th week (r s =.66, n = 10, p < 0.05), whereas in the 7th week this correlation became strong negative (r s = -.86, n = 10, p < 0.05). Finally, intima thickness in the ascending and thoracic aorta of the cholesterol and colchicine group was significantly greater than that of the other groups (p < 0.05). Conclusions: Per os administration of colchicine did not influence atherosclerosis progression in cholesterol-fed rabbits, levels of IL-18, insulin and leptin. We encountered the attenuating role of colchicine on TG levels. © 2017 The Author(s)

Galaxy And Mass Assembly (GAMA): mass-size relations of z < 0.1 galaxies subdivided by Sérsic index, colour and morphology

We use data from the Galaxy And Mass Assembly (GAMA) survey in the redshift range 0.01 < z < 0.1 (8399 galaxies in g to Ks bands) to derive the stellar mass–half-light radius relations for various divisions of ‘early’- and ‘late’-type samples. We find that the choice of division between early and late (i.e. colour, shape, morphology) is not particularly critical; however, the adopted mass limits and sample selections (i.e. the careful rejection of outliers and use of robust fitting methods) are important. In particular, we note that for samples extending to low stellar mass limits (<10 10 M ⊙ <1010M⊙ ) the Sérsic index bimodality, evident for high-mass systems, becomes less distinct and no-longer acts as a reliable separator of early- and late-type systems. The final set of stellar mass–half-light radius relations are reported for a variety of galaxy population subsets in 10 bands (ugrizZY JHKs) and are intended to provide a comprehensive low-z benchmark for the many ongoing high-z studies. Exploring the variation of the stellar mass–half-light radius relations with wavelength, we confirm earlier findings that galaxies appear more compact at longer wavelengths albeit at a smaller level than previously noted: at 10 10 M ⊙ 1010M⊙ both spiral systems and ellipticals show a decrease in size of 13 per cent from g to Ks (which is near linear in log wavelength). Finally, we note that the sizes used in this work are derived from 2D Sérsic light profile fitting (using galfit3), i.e. elliptical semimajor half-light radii, improving on earlier low-z benchmarks based on circular apertures

Star-forming, rotating spheroidal galaxies in the GAMA and SAMI surveys

The Galaxy And Mass Assembly (GAMA) survey has morphologically identified a class of 'Little Blue Spheroid' (LBS) galaxies whose relationship to other classes of galaxies we now examine in detail. Considering a sample of 868 LBSs, we find that such galaxies display similar but not identical colours, specific star formation rates, stellar population ages, massto- light ratios, and metallicities to Sd-Irr galaxies. We also find that LBSs typically occupy environments of even lower density than those of Sd-Irr galaxies, where ∼65 per cent of LBS galaxies live in isolation. Using deep, high-resolution imaging from VST KiDS and the new Bayesian, 2D galaxy profile modelling code PROFIT, we further examine the detailed structure of LBSs and find that their Sérsic indices, sizes, and axial ratios are compatible with those of low-mass elliptical galaxies. We then examine SAMI Galaxy survey integral field emission line kinematics for a subset of 62 LBSs and find that the majority (42) of these galaxies display ordered rotation with the remainder displaying disturbed/non-ordered dynamics. Finally, we consider potential evolutionary scenarios for a population with this unusual combination of properties, concluding that LBSs are likely formed by a mixture of merger and accretion processes still recently active in low-redshift dwarf populations.We also infer that if LBS-like galaxies were subjected to quenching in a rich environment, they would plausibly resemble cluster dwarf ellipticals