The Assembly of Diversity in the Morphologies and Stellar Populations of High-Redshift Galaxies

We have studied the evolution in the morphologies, sizes, stellar-masses, colors, and internal color dispersion (ICD) of galaxies at z=1 and 2.3, using a near-IR, flux-limited catalog for the HDF-N. At z=1 most luminous galaxies have morphologies of early-to-mid Hubble-types, and many show transformations between their rest-frame UV-optical morphologies. Galaxies at z=2.3 have compact and irregular morphologies with no clearly evident Hubble-sequence candidates. The mean galaxy size grows from z=2.3 to 1 by 40%, and the density of galaxies larger than 3 kpc increases by 7 times. At z=1, the size-luminosity distribution is broadly consistent with that of local galaxies, with passive evolution. However, galaxies at z=2.3 are smaller than the large present-day galaxies, and must continue to grow in size and stellar mass. We have measured the galaxies' UV-optical ICD, which quantifies differences in morphology and the relative amount of on-going star-formation. The mean and scatter in galaxies' total colors and ICD increase from z=2.3 to 1. At z=1 many galaxies with large ICD are spirals, with a few irregular systems. Few z=2.3 galaxies have high ICD, and those that do are actively merging. We interpret this as evidence for the presence of older and more diverse stellar populations at z=1 that are not generally present at z>2. We conclude that the star-formation histories of galaxies at z>2 are dominated by discrete, recurrent bursts, which quickly homogenize the galaxies' stellar content, and are possibly associated with mergers. The increase in the stellar-population diversification by z<1.4 implies that merger-induced starbursts occur less frequently than at higher redshifts, and more quiescent star-forming modes dominate. This transition coincides with the emergence of Hubble-sequence galaxies. [Abridged]Comment: Accepted for publication in the Astrophysical Journal. 20 pages, in emulateapj forma

Structural and dynamical modeling of WINGS clusters. I. The distribution of cluster galaxies of different morphological classes within regular and irregular clusters

[Abridged] We use the WINGS database to select a sample of 67 nearby galaxy clusters with at least 30 spectroscopic members each. 53 of these clusters do not show evidence of substructures in phase-space, while 14 do. We estimate the virial radii and circular velocities of the 67 clusters by a variety of proxies (velocity dispersion, X-ray temperature, and richness) and use these estimates to build stack samples from these 53 and 14 clusters ('Reg' and 'Irr' stacks, respectively). We determine the number-density and velocity-dispersion profiles (VDPs) of E, S0, and Sp+Irr (S) galaxies in the Reg and Irr samples, separately, and fit models to these profiles. The number density profiles of E, S0, and S galaxies are adequately described by either a NFW or a cored King model, both for the Reg and Irr samples, with a slight preference for the NFW model. The spatial distribution concentration increases from the S to the S0 and to the E populations, both in the Reg and the Irr stacks, reflecting the well-known morphology-radius relation. Reg clusters have a more concentrated spatial distribution of E and S0 galaxies than Irr clusters, while the spatial distributions of S galaxies in Reg and Irr clusters are similar. We propose a new phenomenological model that provides acceptable fits to the VDP of all our galaxy samples. The VDPs become steeper and with a higher normalization from E to S0 to S galaxies. The S0 VDP is close to that of E galaxies in Reg clusters, and intermediate between those of E and S galaxies in Irr clusters. Our results suggest that S galaxies are a recently accreted cluster population, that take less than 3 Gyr to evolve into S0 galaxies after accretion, and in doing so modify their phase-space distribution, approaching that of cluster ellipticals. While in Reg clusters this evolutionary process is mostly completed, it is still ongoing in Irr clusters.Comment: A&A, in press - 11 pages, 9 figures, 4 table

Mitochondrial alterations in Parkinson's disease human samples and cellular models

Abstract Mitochondrial impairment is one of the most important hallmarks of Parkinson's disease (PD) pathogenesis. In this work, we wanted to verify the molecular basis of altered mitochondrial dynamics and disposal in Substantia nigra specimens of sporadic PD patients, by the comparison with two cellular models of PD. Indeed, SH-SY5Y cells were treated with either dopamine or 1-methyl-4-phenylpyridinium (MPP + ) in order to highlight the effect of altered dopamine homeostasis and of complex I inhibition, respectively. As a result, we found that fusion impairment of the inner mitochondrial membrane is a common feature of both PD human samples and cellular models. However, the effects of dopamine and MPP + treatments resulted to be different in terms of the mitochondrial damage induced. Opposite changes in the levels of two mitochondrial protein markers (voltage-dependent anion channels (VDACs) and cytochrome c oxidase subunit 5β (COX5β)) were observed. In this case, dopamine treatment better recapitulated the molecular picture of patients' samples. Moreover, the accumulation of PTEN-induced putative kinase 1 (PINK1), a mitophagy marker, was not observed in both PD patients samples and cellular models. Eventually, in transmission electron microscopy images, small electron dense deposits were observed in mitochondria of PD subjects, which are uniquely reproduced in dopamine-treated cells. In conclusion, our study suggests that the mitochondrial molecular landscape of Substantia nigra specimens of PD patients can be mirrored by the impaired dopamine homeostasis cellular model, thus supporting the hypothesis that alterations in this process could be a crucial pathogenetic event in PD

Superdense galaxies and the mass-size relation at low redshift

We search for massive and compact galaxies (superdense galaxies, hereafter SDGs) at z=0.03-0.11 in the Padova-Millennium Galaxy and Group Catalogue, a spectroscopically complete sample representative of the local Universe general field population. We find that compact galaxies with radii and mass densities comparable to high-z massive and passive galaxies represent 4.4% of all galaxies with stellar masses above 3 X 10^10 M_sun, yielding a number density of 4.3 X 10^-4 h^3 Mpc^-3. Most of them are S0s (70%) or ellipticals (23%), are red and have intermediate-to-old stellar populations, with a median luminosity-weighted age of 5.4 Gyr and a median mass-weighted age of 9.2 Gyr. Their velocity dispersions and dynamical masses are consistent with the small radii and high stellar mass estimates. Comparing with the WINGS sample of cluster galaxies at similar redshifts, the fraction of superdense galaxies is three times smaller in the field than in clusters, and cluster SDGs are on average 4 Gyr older than field SDGs. We confirm the existence of a universal trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass. On top of the well known dependence of stellar age on galaxy mass, the luminosity-weighted age of galaxies depends on galaxy compactness at fixed mass, and, for a fixed mass and radius, on environment. This effect needs to be taken into account in order not to overestimate the evolution of galaxy sizes from high- to low-z. Our results and hierarchical simulations suggest that a significant fraction of the massive compact galaxies at high-z have evolved into compact galaxies in galaxy clusters today. When stellar age and environmental effects are taken into account, the average amount of size evolution of individual galaxies between high- and low-z is mild, a factor ~1.6. (abridged)Comment: ApJ, in pres

The evolution of galaxy sizes

We present a study of galaxy sizes in the local Universe as a function of galaxy environment, comparing clusters and the general field. Galaxies with radii and masses comparable to high-z massive and compact galaxies represent 4.4% of all galaxies more massive than 3 X 10^{10} M_sun in the field. Such galaxies are 3 times more frequent in clusters than in the field. Most of them are early-type galaxies with intermediate to old stellar populations. There is a trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass. We show the relation between size and luminosity-weighted age for galaxies of different stellar masses and in different environments. We compare with high-z data to quantify the evolution of galaxy sizes. We find that, once the progenitor bias due to the relation between galaxy size and stellar age is removed, the average amount of size evolution of individual galaxies between high- and low-z is mild, of the order of a factor 1.6.Comment: to appear in the proceedings of the IAU S295: The intriguing life of massive galaxies, editors D. Thomas, A. Pasquali & I. Ferrera

GASP IV: A muse view of extreme ram-pressure stripping in the plane of the sky: the case of jellyfish galaxy JO204

In the context of the GAs Stripping Phenomena in galaxies with Muse (GASP) survey, we present the characterization of JO204, a jellyfish galaxy in A957, a relatively low-mass cluster with $M=4.4 \times10^{14}M_\odot$. This galaxy shows a tail of ionized gas that extends up to 30 kpc from the main body in the opposite direction of the cluster center. No gas emission is detected in the galaxy outer disk, suggesting that gas stripping is proceeding outside-in. The stellar component is distributed as a regular disk galaxy; the stellar kinematics shows a symmetric rotation curve with a maximum radial velocity of 200km/s out to 20 kpc from the galaxy center. The radial velocity of the gas component in the central part of the disk follows the distribution of the stellar component; the gas kinematics in the tail retains the rotation of the galaxy disk, indicating that JO204 is moving at high speed in the intracluster medium. Both the emission and radial velocity maps of the gas and stellar components indicate ram-pressure as the most likely primary mechanism for gas stripping, as expected given that JO204 is close to the cluster center and it is likely at the first infall in the cluster. The spatially resolved star formation history of JO204 provides evidence that the onset of ram-pressure stripping occurred in the last 500 Myr, quenching the star formation activity in the outer disk, where the gas has been already completely stripped. Our conclusions are supported by a set of hydrodynamic simulations.Comment: accepted for publication in Ap

Prevention and modulation of aminoglycoside ototoxicity (Review)

More than 60 years after their isolation and characterization, aminoglycoside (AG) antibiotics remain powerful agents in the treatment of severe gram-negative, enterococcal or mycobacterial infections. However, the clinical use of AGs is hampered by nephrotoxicity and ototoxicity, which often develop as a consequence of prolonged courses of therapy, or of administration of increased doses of these drugs. The discovery of non-ototoxic antibacterial agents, showing a wider spectrum of activity, has gradually decreased the use of AGs as first line antibiotics for many systemic infections. However, AGs are now undergoing an unexpected revival, being increasingly indicated for the treatment of severe emerging infections caused by organisms showing resistance to most first-line agents (e.g., multidrug-resistant tuberculosis, complicated nosocomially-acquired acute urinary tract infections). Increasing adoption of aminoglycosides poses again to scientists and physicians the problem of toxicity directed to the kidneys and to the inner ear. In particular, aminoglycoside-induced deafness can be profound and irreversible, especially in genetically predisposed patients. For this reason, an impressive amount of molecular strategies have been developed in the last decade to counteract the ototoxic effect of aminoglycosides. The present article overviews: i) the molecular mechanisms by which aminoglycosides exert their bactericidal activity, ii) the mechanisms whereby AGs exert their ototoxic activity in genetically-predisposed patients, iii) the drugs and compounds that have so far proven to prevent or modulate AG ototoxicity at the preclinical and/or clinical level, and iv) the dosage regimens that have so far been suggested to decrease the incidence of episodes of AG-induced ototoxicity

The endogenous HBZ interactome in ATL leukemic cells reveals an unprecedented complexity of host interacting partners involved in RNA splicing

Adult T-cell leukemia/lymphoma (ATL) is a T-cell lymphoproliferative neoplasm caused by the human T-cell leukemia virus type 1 (HTLV-1). Two viral proteins, Tax-1 and HBZ play important roles in HTLV-1 infectivity and in HTLV-1-associated pathologies by altering key pathways of cell homeostasis. However, the molecular mechanisms through which the two viral proteins, particularly HBZ, induce and/or sustain the oncogenic process are still largely elusive. Previous results suggested that HBZ interaction with nuclear factors may alter cell cycle and cell proliferation. To have a more complete picture of the HBZ interactions, we investigated in detail the endogenous HBZ interactome in leukemic cells by immunoprecipitating the HBZ-interacting complexes of ATL-2 leukemic cells, followed by tandem mass spectrometry analyses. RNA seq analysis was performed to decipher the differential gene expression and splicing modifications related to HTLV-1. Here we compared ATL-2 with MOLT-4, a non HTLV-1 derived leukemic T cell line and further compared with HBZ-induced modifications in an isogenic system composed by Jurkat T cells and stably HBZ transfected Jurkat derivatives. The endogenous HBZ interactome of ATL-2 cells identified 249 interactors covering three main clusters corresponding to protein families mainly involved in mRNA splicing, nonsense-mediated RNA decay (NMD) and JAK-STAT signaling pathway. Here we analyzed in detail the cluster involved in RNA splicing. RNAseq analysis showed that HBZ specifically altered the transcription of many genes, including crucial oncogenes, by affecting different splicing events. Consistently, the two RNA helicases, members of the RNA splicing family, DDX5 and its paralog DDX17, recently shown to be involved in alternative splicing of cellular genes after NF-κB activation by HTLV-1 Tax-1, interacted and partially co-localized with HBZ. For the first time, a complete picture of the endogenous HBZ interactome was elucidated. The wide interaction of HBZ with molecules involved in RNA splicing and the subsequent transcriptome alteration strongly suggests an unprecedented complex role of the viral oncogene in the establishment of the leukemic state

verification of a parkinson s disease protein signature in t lymphocytes by multiple reaction monitoring

Diagnosis of Parkinson's disease, the second most common neurodegenerative disease, is based on the appearance of motor symptoms. A panel of protein biomarkers in the T-lymphocyte proteome was previously proposed as a Parkinson's disease signature. Here, we designed an LC–MS based method to quantitatively evaluate this protein signature by multiple reaction monitoring (MRM) in T-lymphocytes and peripheral blood mononuclear cells from a new cohort of nine patients with Parkinson's disease and nine unaffected subjects. Patients were classified using the discriminant function obtained from two-dimensional electrophoresis and protein amounts measured by MRM, thus assigning seven controls out of nine as true negatives and nine patients out of nine as true positives. A good discriminant power was obtained by selecting a subset of peptides from the protein signature, with an area under the receiver operating characteristic curve of 0.877. A similar result is achieved by evaluating all peptides of a selected pane..