Different domains cooperate to target the human ribosomal L7a protein to the nucleus and to the nucleoli.

The human ribosomal protein L7a is a component of the major ribosomal subunit. We transiently expressed in HeLa cells L7a-β-galactosidase fusion proteins and studied their subcellular localization by indirect immunofluorescence staining with anti-β-galactosidase antibodies. We have identified three distinct domains responsible for the nuclear targeting of the protein: domain I, amino acids 23-51; domain II, amino acids 52-100; domain III, amino acids 101-220, each of which contains at least one nuclear localization signal (NLS). Through subcellular localization analysis of deletion mutants of L7a-β-galactosidase chimeras, we demonstrate that domain II plays a special role because it is necessary, although not sufficient, to target the chimeric β-galactosidase to the nucleoli. In fact, we demonstrate that the nucleolar targeting process requires the presence of domain II plus an additional basic domain that can be represented by an NLS or a basic stretch of amino acids without NLS activity. Thus, when multiple NLS are present, each NLS exerts distinct functions. Domain II drives nucleolar accumulation of a reporter protein with the cooperative action of a short basic amino acid sequence, suggesting a mechanism requiring protein-protein or protein-nucleic acid interactions

Is ram-pressure stripping an efficient mechanism to remove gas in galaxies?

We study how the gas in a sample of galaxies (M* > 10e9 Msun) in clusters, obtained in a cosmological simulation, is affected by the interaction with the intra-cluster medium (ICM). The dynamical state of each elemental parcel of gas is studied using the total energy. At z ~ 2, the galaxies in the simulation are evenly distributed within clusters, moving later on towards more central locations. In this process, gas from the ICM is accreted and mixed with the gas in the galactic halo. Simultaneously, the interaction with the environment removes part of the gas. A characteristic stellar mass around M* ~ 10e10 Msun appears as a threshold marking two differentiated behaviours. Below this mass, galaxies are located at the external part of clusters and have eccentric orbits. The effect of the interaction with the environment is marginal. Above, galaxies are mainly located at the inner part of clusters with mostly radial orbits with low velocities. In these massive systems, part of the gas, strongly correlated with the stellar mass of the galaxy, is removed. The amount of removed gas is sub-dominant compared with the quantity of retained gas which is continuously influenced by the hot gas coming from the ICM. The analysis of individual galaxies reveals the existence of a complex pattern of flows, turbulence and a constant fuelling of gas to the hot corona from the ICM that could make the global effect of the interaction of galaxies with their environment to be substantially less dramatic than previously expected.Comment: 17 pages, 12 figures, accepted for publication in MNRA

Translation and Translanguaging Pedagogies in Intercomprehension and Multilingual Teaching

Since 2007, California State University, Long Beach has developed and offered courses that highlight students’ pre-existing linguistic repertoires in English and in the Romance languages. These courses are unique in that they build upon a multilingual base for the acquisition of new languages through the method of intercomprehension. As an approach that moves among languages, Intercomprehension places learners in conditions that are conducive to translanguaging and translation. This paper discusses the role of translation and translanguaging in Intercomprehension as a pedagogical approach in these courses. Since our students are constantly moving between English and one or more Romance language(s), they actively bring the other Romance languages they are learning into the translingual repertoire they already practice through the multilingual learning strategies deployed in intercomprehension. Depuis 2007, California State University, Long Beach développe et offre des cours qui mettent en avant le répertoire linguistique préexistant des étudiants en anglais et en langues romanes. Ces cours sont uniques, car ils s’appuient sur un répertoire multilingue pour permettre l’acquisition de nouvelles langues à travers la méthode d’intercompréhension. L’intercompréhension, approche transcendant les barrières entre les langues, offre aux apprenants un contexte propice au translanguaging et à la traduction. Cet article discute du rôle de la traduction et du translanguaging dans l’intercompréhension. Étant donné que nos étudiants naviguent constamment entre l’anglais et une (ou, des) langue(s) romanes(s), ils font ainsi entrer de manière active les tierces langues romanes en cours d’apprentissage dans le répertoire translangagier qu’ils utilisent déjà par le biais des stratégies intercompréhensives

Morphological Segregation in the Surroundings of Cosmic Voids

We explore the morphology of galaxies living in the proximity of cosmic voids, using a sample of voids identified in the Sloan Digital Sky Survey Data Release 7. At all stellar masses, void galaxies exhibit morphologies of a later type than galaxies in a control sample, which represent galaxies in an average density environment. We interpret this trend as a pure environmental effect, independent of the mass bias, due to a slower galaxy build-up in the rarefied regions of voids. We confirm previous findings about a clear segregation in galaxy morphology, with galaxies of a later type being found at smaller void-centric distances with respect to the early-type galaxies. We also show, for the first time, that the radius of the void has an impact on the evolutionary history of the galaxies that live within it or in its surroundings. In fact, an enhanced fraction of late-type galaxies is found in the proximity of voids larger than the median void radius. Likewise, an excess of early-type galaxies is observed within or around voids of a smaller size. A significant difference in galaxy properties in voids of different sizes is observed up to 2 Rvoid, which we define as the region of influence of voids. The significance of this difference is greater than 3sigma for all the volume-complete samples considered here. The fraction of star-forming galaxies shows the same behavior as the late-type galaxies, but no significant difference in stellar mass is observed in the proximity of voids of different sizes.Comment: Published in ApJ

Body image importance and body dissatisfaction among Indigenous Australian adolescents

Despite their elevated risk of health problems and a propensity to be more overweight or underweight relative to the other members of the Australian population, there has been no previous investigation of body image concerns among Indigenous Australians. In this study we investigated the level of body image importance and body image dissatisfaction among 19 rural Indigenous adolescents (7 males, 12 females) and 28 urban Indigenous adolescents (15 males and 13 females). Our hypotheses that there would be gender differences in body image importance and body image satisfaction were not generally supported. However, males placed more importance on muscle size and strength than females, and rural participants placed more importance on weight than urban participants. Comparison to existing data obtained from Caucasian adolescents suggested that Indigenous youth may be less concerned and dissatisfied with body weight and shape. These results are discussed in relation to findings from studies of non-Indigenous adolescents, and Indigenous health issues. The limitations of the current study and the need for further studies are also discussed

Sustainable use of marine biodiversity as source of novel anti-biofilm agents in industrial and clinical settings

Amongst marine bacteria, cold-adapted microorganisms represent an untapped reservoir of biodiversity endowed with an interesting chemical repertoire able to synthesize a broad range of potentially valuable bioactive compounds, including antimicrobial activity. The rapid emergence of resistant bacteria is occurring worldwide, endangering the efficacy of antibiotics. One of the main causes of antibiotic resistance is the capability of microorganisms to associate into communities of cells called biofilms. These complex structures provide protection from potential stressors, including the lack of water, high or low pH, or the presence of substances toxic to microorganisms such as antibiotics, antimicrobials or heavy metals. Therefore, coordinated efforts to implement the arsenal of novel anti-infective treatments are greatly needed. In this contest, my PhD project aimed to the sustainable exploitation of Polar marine biodiversity in an attempt to find viable sources of novel anti-biofilm agents, in particular acting against Staphylococcus epidermidis, one of the most common causes of infections associated with medical devices. In detail, during the first part of my project, I focused on the study of the Antarctic marine bacterium Pseudoalteromonas haloplanktis TAC125 and of its ability to produce anti-biofilm molecules, then, on the purification, identification and characterization of the active molecule produced. By setting up of a strategy for the large scale biofilm cultivation of the Antarctic bacterium, the production yield of P. haloplanktis TAC125 anti-biofilm agent was improved, so as to allow the purification and the identification of the active molecule, the pentadecanal. However, as the pentadecanal is a chemically reactive agent, it could easily undergo oxidation reactions, therefore it could not be suitable for all possible anti-biofilm strategies. Therefore, some chemical analogues were synthesized and characterized for their anti-biofilm activity and their possible use in combination with antibiotics were investigated. Then, as a possible clinical application, an anti-biofilm coating system, active against S. epidermidis, was developed, by physical adsorption of pentadecanal and its analogues on polydimethylsiloxane (PDMS), a silicon-based material commonly used for the manufacturing of medical devices. Finally, some physiological studies were dedicated to P. haloplanktis TAC125 biofilm formation in relation with environmental adaptations, with the purpose to explore the potentiality of P. haloplanktis TAC125 in biotechnological field. In the second part of my PhD project, given their only partially explored potential, I have also studied other Polar bacteria belonging to different genera, looking for novel anti-biofilm agents against S. epidermidis. Through the screening of small metabolites and proteins/peptides libraries designed starting from planktonic cultures of Polar bacteria, some promising producer strains were identified and their anti-biofilm activities were characterized. Preliminary purification protocols were set up for each kind of molecules, according to their physico-chemical characteristics. Further studies are still ongoing to identify the structure of the active molecules