Influence of Al2O3 Particle Size on Microstructure, Mechanical Properties and Abrasive Wear Behavior of Flame-Sprayed and Remelted NiCrBSi Coatings

The influence of micrometric alumina (low surface area-to-volume ratio) and nanometric alumina (high surface area-to-volume ratio) on microstructure, hardness and abrasive wear of a NiCrBSi hardfacing alloy coating applied to an AISI 304 substrate using flame spraying (FS) combined with surface flame melting (SFM) is studied. Remelting after spraying improved the mechanical and tribological properties of the coatings. Microstructural characterization using XRD, SEM and EDS indicated that alumina additions produced similar phases (NiSi, Ni3B, CrC and Ni31Si12) regardless of the alumina size, but the phases differed in morphology, size distribution and relative proportions from one coating to another. The addition of 12 wt.% nanometric Al2O3 increased the phases concentration more than five- to sixfold and reduced the hard phases size about four-to threefold compared with NiCrBSi + 12 wt.% micrometric Al2O3. Nanoalumina led to reduced mass loss during abrasive wear compared to micrometric alumina and greater improvement in hardness

The senescence-associated secretory phenotype induces cellular plasticity and tissue regeneration

Senescence is a form of cell cycle arrest induced by stress such as DNA damage and oncogenes. However, while arrested, senescent cells secrete a variety of proteins collectively known as the senescence-associated secretory phenotype (SASP), which can reinforce the arrest and induce senescence in a paracrine manner. However, the SASP has also been shown to favor embryonic development, wound healing, and even tumor growth, suggesting more complex physiological roles than currently understood. Here we uncover timely new functions of the SASP in promoting a proregenerative response through the induction of cell plasticity and stemness. We show that primary mouse keratinocytes transiently exposed to the SASP exhibit increased expression of stem cell markers and regenerative capacity in vivo. However, prolonged exposure to the SASP causes a subsequent cell-intrinsic senescence arrest to counter the continued regenerative stimuli. Finally, by inducing senescence in single cells in vivo in the liver, we demonstrate that this activates tissue-specific expression of stem cell markers. Together, this work uncovers a primary and beneficial role for the SASP in promoting cell plasticity and tissue regeneration and introduces the concept that transient therapeutic delivery of senescent cells could be harnessed to drive tissue regeneration

Puesta en marcha y coordinación del Máster en Optometría Avanzada y Salud Visual

Durante el curso 2015-2016 se va a implantar, en la Universidad de Alicante, el máster en Optometría Avanzada y Salud Visual, que fue aprobado por la ANECA en diciembre del 2014. Con el fin de coordinar las actividades docentes de cada una de las asignaturas del máster y dentro del Proyecto de Redes de Investigación en Docencia Universitaria 2014-2015, se ha creado una red formada por todos los profesores coordinadores de las asignaturas que constituyen el plan de estudios y que han participado en la realización de la memoria de dicho máster. En esta red se pretende la coordinación entre todas las asignaturas para organizar y desarrollar sus actividades con el fin de conseguir una buena distribución de la carga docente y un mejor aprovechamiento por parte del alumno de la docencia recibida. Por otra parte, dado que en este máster participan varias empresas del sector óptico y clínicas oftalmológicas es necesario determinar qué actividades propuestas por las empresas y clínicas se van a incluir en cada asignatura y planificarlas adecuadamente

Trabajo de coordinación para la implantación del Máster en Optometría Avanzada y Salud Visual

Durante el curso 2013-2014 la Universidad de Alicante ha propuesto la implantación del Master en Optometría Avanzada y Salud Visual, dicha solicitud está siendo actualmente evaluada por la ANECA. Con el fin de coordinar la docencia de este Máster y dentro del Proyecto de Redes de Investigación en Docencia Universitaria 2013-2014, se ha creado una red formada por todos los profesores que han participado en la elaboración del plan de estudios. En esta red esta red se pretende la coordinación entre las distintas asignaturas para elaborar las guías docentes a partir de los datos de las fichas enviadas a la ANECA. Por otra parte también se ha modificado la memoria atendiendo a las alegaciones realizadas por la ANECA. Y se han desarrollado los contenidos, la metodología de las distintas actividades propuestas con el fin de asegurar la consecución de las competencias previstas

Analysis of Expressed Sequence Tags of the Cyclically Parthenogenetic Rotifer Brachionus plicatilis

Background. Rotifers are among the most common non-arthropod animals and are the most experimentally tractable members of the basal assemblage of metazoan phyla known as Gnathifera. The monogonont rotifer Brachionus plicatilis is a developing model system for ecotoxicology, aquatic ecology, cryptic speciation, and the evolution of sex, and is an important food source for finfish aquaculture. However, basic knowledge of the genome and transcriptome of any rotifer species has been lacking. Methodology/Principal Findings. We generated and partially sequenced a cDNA library from B. plicatilis and constructed a database of over 2300 expressed sequence tags corresponding to more than 450 transcripts. About 20% of the transcripts had no significant similarity to database sequences by BLAST; most of these contained open reading frames of significant length but few had recognized Pfam motifs. Sixteen transcripts accounted for 25% of the ESTs; four of these had no significant similarity to BLAST or Pfam databases. Putative up- and downstream untranslated regions are relatively short and AT rich. In contrast to bdelloid rotifers, there was no evidence of a conserved trans-spliced leader sequence among the transcripts and most genes were single-copy. Conclusions/Significance. Despite the small size of this EST project it revealed several important features of the rotifer transcriptome and of individual monogonont genes. Because there is little genomic data for Gnathifera, the transcripts we found with no known function may represent genes that are species-, class-, phylum- or even superphylum-specific; the fact that some are among the most highly expressed indicates their importance. The absence of trans-spliced leader exons in this monogonont species contrasts with their abundance in bdelloid rotifers and indicates that the presence of this phenomenon can vary at the subphylum level. Our EST database provides a relatively large quantity of transcript-level data for B. plicatilis, and more generally of rotifers and other gnathiferan phyla, and can be browsed and searched at gmod.mbl.edu

β Subunit M2–M3 Loop Conformational Changes Are Uncoupled from α1 β Glycine Receptor Channel Gating: Implications for Human Hereditary Hyperekplexia

Hereditary hyperekplexia, or startle disease, is a neuromotor disorder caused mainly by mutations that either prevent the surface expression of, or modify the function of, the human heteromeric α1 β glycine receptor (GlyR) chloride channel. There is as yet no explanation as to why hyperekplexia mutations that modify channel function are almost exclusively located in the α1 to the exclusion of β subunit. The majority of these mutations are identified in the M2–M3 loop of the α1 subunit. Here we demonstrate that α1 β GlyR channel function is less sensitive to hyperekplexia-mimicking mutations introduced into the M2–M3 loop of the β than into the α1 subunit. This suggests that the M2–M3 loop of the α subunit dominates the β subunit in gating the α1 β GlyR channel. A further attempt to determine the possible mechanism underlying this phenomenon by using the voltage-clamp fluorometry technique revealed that agonist-induced conformational changes in the β subunit M2–M3 loop were uncoupled from α1 β GlyR channel gating. This is in contrast to the α subunit, where the M2–M3 loop conformational changes were shown to be directly coupled to α1 β GlyR channel gating. Finally, based on analysis of α1 β chimeric receptors, we demonstrate that the structural components responsible for this are distributed throughout the β subunit, implying that the β subunit has evolved without the functional constraint of a normal gating pathway within it. Our study provides a possible explanation of why hereditary hyperekplexia-causing mutations that modify α1 β GlyR channel function are almost exclusively located in the α1 to the exclusion of the β subunit

Genome size evolution at the speciation level: The cryptic species complex Brachionus plicatilis (Rotifera)

<p>Abstract</p> <p>Background</p> <p>Studies on genome size variation in animals are rarely done at lower taxonomic levels, e.g., slightly above/below the species level. Yet, such variation might provide important clues on the tempo and mode of genome size evolution. In this study we used the flow-cytometry method to study the evolution of genome size in the rotifer <it>Brachionus plicatilis</it>, a cryptic species complex consisting of at least 14 closely related species.</p> <p>Results</p> <p>We found an unexpectedly high variation in this species complex, with genome sizes ranging approximately seven-fold (haploid '1C' genome sizes: 0.056-0.416 pg). Most of this variation (67%) could be ascribed to the major clades of the species complex, i.e. clades that are well separated according to most species definitions. However, we also found substantial variation (32%) at lower taxonomic levels - within and among genealogical species - and, interestingly, among species pairs that are not completely reproductively isolated. In one genealogical species, called <it>B</it>. 'Austria', we found greatly enlarged genome sizes that could roughly be approximated as multiples of the genomes of its closest relatives, which suggests that whole-genome duplications have occurred early during separation of this lineage. Overall, genome size was significantly correlated to egg size and body size, even though the latter became non-significant after controlling for phylogenetic non-independence.</p> <p>Conclusions</p> <p>Our study suggests that substantial genome size variation can build up early during speciation, potentially even among isolated populations. An alternative, but not mutually exclusive interpretation might be that reproductive isolation tends to build up unusually slow in this species complex.</p

Fifteen species in one: deciphering the Brachionus plicatilis species complex (Rotifera, Monogononta) through DNA taxonomy

Understanding patterns and processes in biological diversity is a critical task given current and rapid environmental change. Such knowledge is even more essential when the taxa under consideration are important ecological and evolutionary models. One of these cases is the monogonont rotifer cryptic species complex Brachionus plicatilis, which is by far the most extensively studied group of rotifers, is widely used in aquaculture, and is known to host a large amount of unresolved diversity. Here we collate a dataset of previously available and newly generated sequences of COI and ITS1 for 1273 isolates of the B. plicatilis complex and apply three approaches in DNA taxonomy (i.e. ABGD, PTP, and GMYC) to identify and provide support for the existence of 15 species within the complex. We used these results to explore phylogenetic signal in morphometric and ecological traits, and to understand correlation among the traits using phylogenetic comparative models. Our results support niche conservatism for some traits (e.g. body length) and phylogenetic plasticity for others (e.g. genome size)

The Transcription Factor NFAT5 Is Required for Cyclin Expression and Cell Cycle Progression in Cells Exposed to Hypertonic Stress

Background: Hypertonicity can perturb cellular functions, induce DNA damage-like responses and inhibit proliferation. The transcription factor NFAT5 induces osmoprotective gene products that allow cells to adapt to sustained hypertonic conditions. Although it is known that NFAT5-deficient lymphocytes and renal medullary cells have reduced proliferative capacity and viability under hypertonic stress, less is understood about the contribution of this factor to DNA damage responses and cell cycle regulation. Methodology/Principal Findings: We have generated conditional knockout mice to obtain NFAT5−/− T lymphocytes, which we used as a model of proliferating cells to study NFAT5-dependent responses. We show that hypertonicity triggered an early, NFAT5-independent, genotoxic stress-like response with induction of p53, p21 and GADD45, downregulation of cyclins, and cell cycle arrest. This was followed by an NFAT5-dependent adaptive phase in wild-type cells, which induced an osmoprotective gene expression program, downregulated stress markers, resumed cyclin expression and proliferation, and displayed enhanced NFAT5 transcriptional activity in S and G2/M. In contrast, NFAT5−/− cells failed to induce osmoprotective genes and exhibited poorer viability. Although surviving NFAT5−/− cells downregulated genotoxic stress markers, they underwent cell cycle arrest in G1/S and G2/M, which was associated with reduced expression of cyclins E1, A2 and B1. We also show that pathologic hypertonicity levels, as occurring in plasma of patients and animal models of osmoregulatory disorders, inhibited the induction of cyclins and aurora B kinase in response to T cell receptor stimulation in fresh NFAT5−/− lymphocytes. Conclusions/Significance: We conclude that NFAT5 facilitates cell proliferation under hypertonic conditions by inducing an osmoadaptive response that enables cells to express fundamental regulators needed for cell cycle progression.Molecular and Cellular Biolog

Early Evolution of Ionotropic GABA Receptors and Selective Regimes Acting on the Mammalian-Specific Theta and Epsilon Subunits

BACKGROUND: The amino acid neurotransmitter GABA is abundant in the central nervous system (CNS) of both invertebrates and vertebrates. Receptors of this neurotransmitter play a key role in important processes such as learning and memory. Yet, little is known about the mode and tempo of evolution of the receptors of this neurotransmitter. Here, we investigate the phylogenetic relationships of GABA receptor subunits across the chordates and detail their mode of evolution among mammals. PRINCIPAL FINDINGS: Our analyses support two major monophyletic clades: one clade containing GABA(A) receptor alpha, gamma, and epsilon subunits, and another one containing GABA(A) receptor rho, beta, delta, theta, and pi subunits. The presence of GABA receptor subunits from each of the major clades in the Ciona intestinalis genome suggests that these ancestral duplication events occurred before the divergence of urochordates. However, while gene divergence proceeded at similar rates on most receptor subunits, we show that the mammalian-specific subunits theta and epsilon experienced an episode of positive selection and of relaxed constraints, respectively, after the duplication event. Sites putatively under positive selection are placed on a three-dimensional model obtained by homology-modeling. CONCLUSIONS: Our results suggest an early divergence of the GABA receptor subunits, before the split from urochordates. We show that functional changes occurred in the lineages leading to the mammalian-specific subunit theta, and we identify the amino acid sites putatively responsible for the functional divergence. We discuss potential consequences for the evolution of mammals and of their CNS