172 research outputs found
Rhizosphere Acidification as the Main Trait Characterizing the Differential In Vitro Tolerance to Iron Chlorosis in Interspecific Pyrus Hybrids
Physiological responses of different interspecific Pyrus hybrids and an open pollinated Pyrus
communis ‘Williams’ (Pcw) grown under in vitro culture conditions simulating lime induced chlorosis
were studied. The hybrids were derived from crosses between the ‘Pyriam’ pear rootstock and four
Pyrus species of the Mediterranean region, namely P. amygdaliformis Vill. (Pa), P. amygdaliformis persica
Bornme. (Pap), P. communis cordata (Desv.) Hook. (Pcc), and P. elaeagrifolia Pall (Pe), all known for their
higher field tolerance to iron-chlorosis than P. communis. Twenty hybrids and one open pollinated
Pcw were micropropagated, and plantlets were in vitro characterized for their physiological responses
to iron-deficiency conditions. Rooted plantlets were transferred to a culture medium with 2 µM Fe3+
DTPA and 10 or 20 mM NaHCO3. These physiological responses were scored at 1, 3, 7, and 28 days
from the start of the in vitro assay. Leaf total chlorophyll content, the capacity of roots to acidify the
medium, reduced iron, and exudates of phenolic acids and organic acids were analyzed in each media
and time sample. Leaf chlorophyll levels for the clones derived from Pcc were the highest, especially
under the highest bicarbonate concentration, followed by those derived from Pap and Pa. The higher
chlorophyll content of Pcc clones were related with their higher capacity to acidify the media but not
with their iron reduction capacity at the root level. On the other hand, hybrid clones derived from
Pe showed a higher Fe3+ reduction ability than clones from all the other species during the whole
assay but only when the bicarbonate concentration was lower. The exudation of phenolic acids by
the roots was higher in Pcw than in the other species, and this response might explain why the total
chlorophyll levels in Pcw clones are similar to those of Pe and Pa ones. These results with Pyrus spp.
bring more evidence in support of the idea that iron reduction capacity at the root level is not directly
related with a higher tolerance to iron deficiency caused by the high pH of calcareous soils. Instead,
the ability to acidify the rhizosphere is the trait of choice for the selection of the pear hybrid clones
better adapted to lime induced chlorosis. In addition, the in vitro assay to select the Pyrus clones for
tolerance to iron chlorosis could be shortened to one week of culture in 10 mM NaHCO3, measuring
the leaf chlorophyll level, acidification of the culture medium, and exudation of phenolic acids as the
physiological responses to predict tolerance to lime-induced chlorosisinfo:eu-repo/semantics/publishedVersio
Which DSM validated tools for diagnosing depression are usable in primary care research? A systematic literature review
IntroductionDepression occurs frequently in primary care. Its broad clinical variability makes it difficult to diagnose. This makes it essential that family practitioner (FP) researchers have validated tools to minimize bias in studies of everyday practice. Which tools validated against psychiatric examination, according to the major depression criteria of DSM-IV or 5, can be used for research purposes
Entering the men's domain? Gender and portfolio allocation in European governments
While all government portfolios used to be the purview of men exclusively, more and more women are selected to sit around the cabinet table. But under which circumstances do women get appointed to different ministerial portfolios? This article, proposes a theoretical framework to consider how party leaders’ attitudes and motivations influence the allocation of portfolios to male and female ministers. These propositions are tested empirically by bringing together data on 7,005 cabinet appointments across 29 European countries from the late 1980s until 2014. Considering the key partisan dynamics of the ministerial selection process, it is found that women are significantly less likely to be appointed to the ‘core’ offices of state, and ‘masculine’ and ‘neutral’ policy areas. However, these gender differences are moderated by the ideology of the party that allocates them. Women are more likely to be appointed to ‘masculine’ portfolios when a party's voters have more progressive gender attitudes. This theoretical framework and analysis enhances our understanding of women's access to the government, which has important implications for how ministers are selected, as well as how women are represented in the most powerful policy?making positions in Europe
Epigenetic mechanisms and metabolic reprogramming in fibrogenesis: dual targeting of G9a and DNMT1 for the inhibition of liver fibrosis
OBJECTIVE: Hepatic stellate cells (HSC) transdifferentiation into myofibroblasts is central to fibrogenesis. Epigenetic mechanisms, including histone and DNA methylation, play a key role in this process. Concerted action between histone and DNA-mehyltransferases like G9a and DNMT1 is a common theme in gene expression regulation. We aimed to study the efficacy of CM272, a first-in-class dual and reversible G9a/DNMT1 inhibitor, in halting fibrogenesis. DESIGN: G9a and DNMT1 were analysed in cirrhotic human livers, mouse models of liver fibrosis and cultured mouse HSC. G9a and DNMT1 expression was knocked down or inhibited with CM272 in human HSC (hHSC), and transcriptomic responses to transforming growth factor-β1 (TGFβ1) were examined. Glycolytic metabolism and mitochondrial function were analysed with Seahorse-XF technology. Gene expression regulation was analysed by chromatin immunoprecipitation and methylation-specific PCR. Antifibrogenic activity and safety of CM272 were studied in mouse chronic CCl4 administration and bile duct ligation (BDL), and in human precision-cut liver slices (PCLSs) in a new bioreactor technology. RESULTS: G9a and DNMT1 were detected in stromal cells in areas of active fibrosis in human and mouse livers. G9a and DNMT1 expression was induced during mouse HSC activation, and TGFβ1 triggered their chromatin recruitment in hHSC. G9a/DNMT1 knockdown and CM272 inhibited TGFβ1 fibrogenic responses in hHSC. TGFβ1-mediated profibrogenic metabolic reprogramming was abrogated by CM272, which restored gluconeogenic gene expression and mitochondrial function through on-target epigenetic effects. CM272 inhibited fibrogenesis in mice and PCLSs without toxicity. CONCLUSIONS: Dual G9a/DNMT1 inhibition by compounds like CM272 may be a novel therapeutic strategy for treating liver fibrosis
Smart Tourism Destinations: Can the Destination Management Organizations Exploit Benefits of the ICTs? Evidences from a Multiple Case Study
Recent developments of ICTs enable new ways to experience tourism and conducted to the concept of smart tourism. The adoption of cutting-edge technologies and its combination with innovative organizational models fosters cooperation, knowledge sharing, and open innovation among service providers in tourism destination. Moreover, it offers innovative services to visitors. In few words, they become smart tourism destinations. In this paper, we report first results of the SMARTCAL project aimed at conceiving a digital platform assisting Destination Management Organizations (DMOs) in providing smart tourism services. A DMO is the organization charged with managing the tourism offer of a collaborative network, made up of service providers acting in a destination. In this paper, we adopted a multiple case studies approach to analyze five Italian DMOs. Our aims were to investigate (1) if, and how, successful DMOs were able to offer smart tourism services to visitors; (2) if the ICTs adoption level was related to the collaboration level among DMO partners. First results highlighted that use of smart technologies was still in an embryonic stage of development, and it did not depend from collaboration levels
Spatiotemporal dynamics of ultrarelativistic beam-plasma instabilities
An electron or electron-positron beam streaming through a plasma is
notoriously prone to micro-instabilities. For a dilute ultrarelativistic
infinite beam, the dominant instability is a mixed mode between longitudinal
two-stream and transverse filamentation modes, with a phase velocity oblique to
the beam velocity. A spatiotemporal theory describing the linear growth of this
oblique mixed instability is proposed, which predicts that spatiotemporal
effects generally prevail for finite-length beams, leading to a significantly
slower instability evolution than in the usually assumed purely temporal
regime. These results are accurately supported by particle-in-cell (PIC)
simulations. Furthermore, we show that the self-focusing dynamics caused by the
plasma wakefields driven by finite-width beams can compete with the oblique
instability. Analyzed through PIC simulations, the interplay of these two
processes in realistic systems bears important implications for upcoming
accelerator experiments on ultrarelativistic beam-plasma interactions
Generation of meter-scale hydrogen plasmas and efficient, pump-depletion-limited wakefield excitation using 10 GeV electron bunches
High repetition rates and efficient energy transfer to the accelerating beam
are important for a future linear collider based on the beam-driven plasma
wakefield acceleration scheme (PWFA-LC). This paper reports the first results
from the Plasma Wakefield Acceleration Collaboration (E300) that are beginning
to address both of these issues using the recently commissioned FACET-II
facility at SLAC. We have generated meter-scale hydrogen plasmas using
time-structured 10 GeV electron bunches from FACET-II, which hold the promise
of dramatically increasing the repetition rate of PWFA by rapidly replenishing
the gas between each shot compared to the hitherto used lithium plasmas that
operate at 1-10 Hz. Furthermore, we have excited wakes in such plasmas that are
suitable for high gradient particle acceleration with high drive-bunch to wake
energy transfer efficiency -- a first step in achieving a high overall energy
transfer efficiency. We have done this by using time-structured electron drive
bunches that typically have one or more ultra-high current (>30 kA) femtosecond
spike(s) superimposed on a longer (~0.4 ps) lower current (<10 kA) bunch
structure. The first spike effectively field-ionizes the gas and produces a
meter-scale (30-160 cm) plasma, whereas the subsequent beam charge creates a
wake. The length and amplitude of the wake depends on the longitudinal current
profile of the bunch and plasma density. We find that the onset of pump
depletion, when some of the drive beam electrons are nearly fully depleted of
their energy, occurs for hydrogen pressure >1.5 Torr. We also show that some
electrons in the rear of the bunch can gain several GeV energies from the wake.
These results are reproduced by particle-in-cell simulations using the QPAD
code. At a pressure of ~2 Torr, simulations results and experimental data show
that the beam transfers about 60% of its energy to the wake
Wakefield Generation in Hydrogen and Lithium Plasmas at FACET-II: Diagnostics and First Beam-Plasma Interaction Results
Plasma Wakefield Acceleration (PWFA) provides ultrahigh acceleration
gradients of 10s of GeV/m, providing a novel path towards efficient, compact,
TeV-scale linear colliders and high brightness free electron lasers. Critical
to the success of these applications is demonstrating simultaneously high
gradient acceleration, high energy transfer efficiency, and preservation of
emittance, charge, and energy spread. Experiments at the FACET-II National User
Facility at SLAC National Accelerator Laboratory aim to achieve all of these
milestones in a single stage plasma wakefield accelerator, providing a 10 GeV
energy gain in a <1 m plasma with high energy transfer efficiency. Such a
demonstration depends critically on diagnostics able to measure emittance with
mm-mrad accuracy, energy spectra to determine both %-level energy spread and
broadband energy gain and loss, incoming longitudinal phase space, and matching
dynamics. This paper discusses the experimental setup at FACET-II, including
the incoming beam parameters from the FACET-II linac, plasma sources, and
diagnostics developed to meet this challenge. Initial progress on the
generation of beam ionized wakes in meter-scale hydrogen gas is discussed, as
well as commissioning of the plasma sources and diagnostics
Adaptation and Preadaptation of Salmonella enterica to Bile
Bile possesses antibacterial activity because bile salts disrupt membranes, denature proteins, and damage DNA. This study describes mechanisms employed by the bacterium Salmonella enterica to survive bile. Sublethal concentrations of the bile salt sodium deoxycholate (DOC) adapt Salmonella to survive lethal concentrations of bile. Adaptation seems to be associated to multiple changes in gene expression, which include upregulation of the RpoS-dependent general stress response and other stress responses. The crucial role of the general stress response in adaptation to bile is supported by the observation that RpoS− mutants are bile-sensitive. While adaptation to bile involves a response by the bacterial population, individual cells can become bile-resistant without adaptation: plating of a non-adapted S. enterica culture on medium containing a lethal concentration of bile yields bile-resistant colonies at frequencies between 10−6 and 10−7 per cell and generation. Fluctuation analysis indicates that such colonies derive from bile-resistant cells present in the previous culture. A fraction of such isolates are stable, indicating that bile resistance can be acquired by mutation. Full genome sequencing of bile-resistant mutants shows that alteration of the lipopolysaccharide transport machinery is a frequent cause of mutational bile resistance. However, selection on lethal concentrations of bile also provides bile-resistant isolates that are not mutants. We propose that such isolates derive from rare cells whose physiological state permitted survival upon encountering bile. This view is supported by single cell analysis of gene expression using a microscope fluidic system: batch cultures of Salmonella contain cells that activate stress response genes in the absence of DOC. This phenomenon underscores the existence of phenotypic heterogeneity in clonal populations of bacteria and may illustrate the adaptive value of gene expression fluctuations
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