Np95 Is Implicated in Pericentromeric Heterochromatin Replication and in Major Satellite Silencing

Heterochromatin plays an important role in transcriptional repression, for the correct segregation of chromosomes and in the maintenance of genome stability. Pericentric heterochromatin (PH) replication and formation have been proposed to occur in the pericentric heterochromatin duplication body (pHDB). A central question is how the underacetylated state of heterochromatic histone H4 tail is established and controlled, because it is a key event during PH replication and is essential to maintain the compacted and silenced state of these regions. Np95 is a cell cycle regulated and is a nuclear histone-binding protein that also recruits HDAC-1 to target promoters. It is essential for S phase and for embryonic formation and is implicated in chromosome stability. Here we show that Np95 is part of the pHDB, and its functional ablation causes a strong reduction in PH replication. Depletion of Np95 also causes a hyperacetylation of lysines 8, 12, and 16 of heterochromatin histone H4 and an increase of pericentromeric major satellite transcription, whose RNAs are key players for heterochromatin formation. We propose that Np95 is a new relevant protein involved in heterochromatin replication and formation

Focused labeled proof systems for modal logic

International audienceFocused proofs are sequent calculus proofs that group inference rules into alternating positive and negative phases. These phases can then be used to define macro-level inference rules from Gentzen's original and tiny introduction and structural rules. We show here that the inference rules of labeled proof systems for modal logics can similarly be described as pairs of such phases within the LKF focused proof system for first-order classical logic. We consider the system G3K of Negri for the modal logic K and define a translation from labeled modal formulas into first-order polarized formulas and show a strict correspondence between derivations in the two systems, i.e., each rule application in G3K corresponds to a bipole—a pair of a positive and a negative phases—in LKF. Since geometric axioms (when properly polarized) induce bipoles, this strong correspondence holds for all modal logics whose Kripke frames are characterized by geometric properties. We extend these results to present a focused labeled proof system for this same class of modal logics and show its soundness and completeness. The resulting proof system allows one to define a rich set of normal forms of modal logic proofs

Effect of silver nanoparticles against Candida albicans and Candida glabrata biofilms

Objectives: Fungal infections in immunocompromised patients have been contributing to the increasing morbidity and mortality of these patients, especially associated to yeast resistance to antifungal therapy. The increase in antibiotic-resistant microorganisms has prompted interest in the use of silver as an antimicrobial agent. Thus, the aim of this study was to evaluate the antifungal efficacy of silver nanoparticles against Candida albicans and Candida glabrata biofilms. Methods: Spherical nano-silver (average diameter 5nm) particles were synthesized by silver nitrate reduction with sodium citrate. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n=2) and C. glabrata (n=2) grown in suspension using the microbroth dilution method. Silver nanoparticles were applied on adhered cells (2 h) or biofilms (48 h) and after 24h biofilms were characterized by colony forming units (CFUs) enumeration and total biomass quantification (using crystal violet staining). Results: Interestingly, C. glabrata MIC values were higher (0.4 – 3.3 µg/mL) than C. albicans (0.4 – 1.6 µg/mL). Furthermore, the results obtained revealed that silver nanoparticles were more effective in reducing 24h biofilms' biomass when applied onto adhered cells (2h) than on pre-formed biofilms (48h), with the exception of C. glabrata clinical isolate, which in both cases had a reduction around 90%. Regarding cell viability, silver nanoparticles were highly effective on adhered C. glabrata (reduction of around 70%) and respective biofilms (reduction of around 50%). On C. albicans the effect was not so notorious but there was also a reduction on the number of biofilm viable cells. Conclusion: Silver nanoparticles have great potential to be an effective alternative to antifungal agents for future therapies in Candida infections

Investigating the genetic basis of salt-tolerance in common bean: a genome-wide association study at the early vegetative stage

Salinity poses a significant challenge to global crop productivity, affecting approximately 20% of cultivated and 33% of irrigated farmland, and this issue is on the rise. Negative impact of salinity on plant development and metabolism leads to physiological and morphological alterations mainly due to high ion concentration in tissues and the reduced water and nutrients uptake. Common bean (Phaseolus vulgaris L.), a staple food crop accounting for a substantial portion of consumed grain legumes worldwide, is highly susceptible to salt stress resulting in noticeable reduction in dry matter gain in roots and shoots even at low salt concentrations. In this study we screened a common bean panel of diversity encompassing 192 homozygous genotypes for salt tolerance at seedling stage. Phenotypic data were leveraged to identify genomic regions involved in salt stress tolerance in the species through GWAS. We detected seven significant associations between shoot dry weight and SNP markers. The candidate genes, in linkage with the regions associated to salt tolerance or harbouring the detected SNP, showed strong homology with genes known to be involved in salt tolerance in Arabidopsis. Our findings provide valuable insights onto the genetic control of salt tolerance in common bean and represent a first contribution to address the challenge of salinity-induced yield losses in this species and poses the ground to eventually breed salt tolerant common bean varieties

Frenkel and charge transfer excitons in C60

We have studied the low energy electronic excitations of C60 using momentum dependent electron energy-loss spectroscopy in transmission. The momentum dependent intensity of the gap excitation allows the first direct experimental determination of the energy of the 1Hg excitation and thus also of the total width of the multiplet resulting from the gap transition. In addition, we could elucidate the nature of the following excitations - as either Frenkel or charge transfer excitons.Comment: RevTEX, 3 Figures, to appear in Phys. Rev.

No measure for culture? Value in the new economy

This paper explores articulations of the value of investment in culture and the arts through a critical discourse analysis of policy documents, reports and academic commentary since 1997. It argues that in this period, discourses around the value of culture have moved from a focus on the direct economic contributions of the culture industries to their indirect economic benefits. These indirect benefits are discussed here under three main headings: creativity and innovation, employability, and social inclusion. These are in turn analysed in terms of three forms of capital: human, social and cultural. The paper concludes with an analysis of this discursive shift through the lens of autonomist Marxist concerns with the labour of social reproduction. It is our argument that, in contemporary policy discourses on culture and the arts, the government in the UK is increasingly concerned with the use of culture to form the social in the image of capital. As such, we must turn our attention beyond the walls of the factory in order to understand the contemporary capitalist production of value and resistance to it. </jats:p

Virulence factors of non-Candida albicans Candida species

Infections caused by Candida species (candidosis) have greatly increased over recent years, mainly due to the escalation of the AIDS epidemic, population ageing, increasing number of immunocompromised patients and the more widespread use of indwelling medical devices. Besides Candida albicans, non-Candida albicans Candida (NCAC) species such as Candida glabrata, Candida tropicalis and Candida parapsilosis are now frequently identified as potential human pathogens. Candida species pathogenicity is facilitated by a number of virulence factors, most importantly adherence to medical devices and/or host cells, biofilm formation, and secretion of enzymes, such as proteases. Thus, we have been studying several of the most relevant virulence factors (adhesion, biofilm formation ability, tissue colonisation and invasion, expression of hydrolytic enzymes and antifungal agents susceptibility) of Candida clinical isolates recovered from different body sites (oral cavity and urinary and vaginal tracts). In summary, this presentation underlines both species and strain differences in terms of virulence factors associated with C. glabrata, C. parapsilosis and C. tropicalis. Furthermore, there is clear evidence demonstrating the importance of the use of new techniques including Confocal Laser Scanning Microscopy and molecular analysis tools enabling the elucidation of the mechanisms of virulence. By increasing our knowledge on Candida pathogenesis, new potential therapeutic targets may be identified that can be used as adjuvants for novel therapies

Asymmetrical copper root pruning may improve root traits for reforesting steep and/or windy sites

Our research demonstrates that plant material can be produced in the nursery with asymmetrical root systems, which may have utility for reforestation of difficult planting sites characterized by steep slopes and/or windy conditions. Such a root system can be generated using chemical root pruning by applying cupric carbonate (Cu) that can arrest the development of, or cause mortality to, root apical meristems resulting in the formation of new lateral roots with an overall increase in the biomass, length, and volume of the root system. Our objective was to investigate the effect of chemical root pruning on the morphological and architectural traits of adventitious roots produced by poplar cuttings (Populus nigra L.) grown in containers coated with Cu in various symmetrical (Side, Bottom, Side + Bottom) and asymmetrical (half side + half bottom) patterns. After six weeks, roots of the cuttings were extracted from different container depths (Top, Middle, and Bottom) and portions (non-coated, Cu-coated), and analyzed. The root systems reacted to all coating patterns by increasing length, biomass, volume, and average diameters, but magnitude of increase was further affected by depth. In particular, root growth was unaffected at the Top of the container, and length was the highest at the Bottom depth. The Middle depth had a significant increment in both biomass and volume. Also, the root population increased in diameter as a possible response to Cu exposure. Interestingly, in the asymmetrically coated containers this depth response in the non-coated portions was of higher magnitude than in the Cu-coated portions

Effect of pretreatment of Candida biofilm cells with silver nanoparticles on the adhesion capacity to human epithelial cells and polystyrene surface

Objectives: The pathogenicity of Candida spp. has been recognized by some factors, including adhesion to host cells or inert surfaces and biofilm formation. In addition, the dispersal of biofilm cells may act as a continuous source of infection. Thus, the aim of this study was to evaluate the adhesion capacity of Candida albicans and Candida glabrata cells recovered from Candida biofilms treated with silver nanoparticles (SN) to human epithelial cells and polystyrene surface. Methods: Candida biofilms (48 h) were formed in 6-well polystyrene microtiter plates and treated during 24 h with SN (diameter of 5 nm) at concentrations of 13.5 and 54 µg/mL. Controls devoid of SN were included in this study. After the treatment period, biofilms were scraped from the wells and resuspended in phosphate buffered saline. These Candida cell suspensions (107 viable cells/mL in RPMI medium) were added to HeLa cells monolayers or to empty wells of a 24-well microtiter plate (to study adhesion to polysterene). After 2 h of contact, the adhesion capacity of the yeasts to HeLa cells and polystyrene surfaces was determined using crystal violet staining. Results: Compared to the controls, the adhesion of Candida biofilm cells (pretreated with SN) to HeLa cells and polystyrene surfaces was significantly reduced. This reduction was higher when biofilm cells were pretreated with SN in a concentration of 54 µg/mL. Conclusion: These findings allow to conclude that SN may induce changes in viable yeasts, since they decrease their adhesion capacity, which can, consequently, cause lower dissemination of Candida infections

Nanopartículas de prata : análise dos efeitos anti-biofilme e anti-adesão sobre Candida albicans e Candida glabrata

Os objetivos deste trabalho foram: (1) avaliar o efeito sinergístico de nanopartículas de prata (NP) com Nistatina e Clorexidina contra biofilmes de Candida albicans e Candida glabrata; (2) verificar o efeito das NP na composição da matriz destes biofilmes e (3) investigar a capacidade de adesão a células epiteliais HeLa e a poliestireno de leveduras tratadas com NP. As drogas sozinhas ou em combinação com NP (5 nm) foram aplicadas sobre biofilmes maduros (48 h) e após 24 h de contato a atividade sinergística foi avaliada através da quantificação da biomassa total e por meio da contagem do número de colônias. Após o tratamento com NP, as matrizes dos biofilmes foram extraídas e analisadas em termos de proteínas, carboidratos e DNA. Ainda, leveduras viáveis foram recuperadas e adicionadas tanto às células HeLa quanto aos poços vazios de placas de poliestireno e, após 2 horas de contato, a adesão foi determinada usando violeta cristal. NP combinadas com Nistatina e Clorexidina exibiram atividade anti-biofilme sinergística dependente das espécies e concentrações de drogas usadas. Ainda, NP interferiram na composição da matriz extracelular dos biofilmes e a capacidade de adesão das leveduras viáveis foi significativamente reduzida após tratamento prévio com NP. Esses achados permitem concluir que NP podem contribuir na prevenção ou tratamento da estomatite protética associada à Candida. Entretanto, estudos adicionais são necessários para que estas NP sejam usadas com segurança