2,307 research outputs found
Dominant negative phenotype of Bacillus thuringiensis Cry1Ab, Cry11Aa and Cry4Ba mutants suggest hetero-oligomer formation among different Cry toxins.
Background - Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix a-4 mutants had a dominant negative (DN) phenotype inhibiting the toxicity of wildtype Cry1Ab when used in equimolar or sub-stoichiometric ratios (1:1, 0.5:1, mutant:wt) indicating that oligomer formation is a key step in toxicity of Cry toxins. Methodology/Principal Findings - The DN Cry1Ab-D136N/T143D mutant that is able to block toxicity of Cry1Ab toxin, was used to analyze its capacity to block the activity against Manduca sexta larvae of other Cry1 toxins, such as Cry1Aa, Cry1Ac, Cry1Ca, Cry1Da, Cry1Ea and Cry1Fa. Cry1Ab-DN mutant inhibited toxicity of Cry1Aa, Cry1Ac and Cry1Fa. In addition, we isolated mutants in helix a-4 of Cry4Ba and Cry11Aa, and demonstrate that Cry4Ba-E159K and Cry11Aa-V142D are inactive and completely block the toxicity against Aedes aegypti of both wildtype toxins, when used at sub-stoichiometric ratios, confirming a DN phenotype. As controls we analyzed Cry1Ab-R99A or Cry11Aa-E97A mutants that are located in helix a-3 and are affected in toxin oligomerization. These mutants do not show a DN phenotype but were able to block toxicity when used in 10:1 or 100:1 ratios (mutant:wt) probably by competition of binding with toxin receptors. Conclusions/Significance - We show that DN phenotype can be observed among different Cry toxins suggesting that may interact in vivo forming hetero-oligomers. The DN phenotype cannot be observed in mutants affected in oligomerization, suggesting that this step is important to inhibit toxicity of other toxin
New Perspectives for Electrodialytic Remediation
Electrodialytic remediation has been widely used for the recovery of different contaminants from numerous matrices, such as, for example, polluted soils, wastewater sludge, fly ash, mine tailing or harbour sediments. The electrodialytic remediation is an enhancement of the electrokinetic remediation technique, and it consists of the use of ion-exchange membranes for the control of the acid and the alkaline fronts generated in the electrochemical processes. While the standard electrodialytic cell is usually built with three-compartment configuration, it has been shown that for the remediation of matrices that require acid environment, a two-compartment cell has given satisfactory removal efficiencies with reduced energy costs.
Recycling secondary batteries, with growing demand, has an increasing economic and environmental interest. This work focusses on the proposal of the electrodialytic remediation technique as a possible application for the recycling of lithium-ion cells and other secondary batteries. The recovery of valuable components, such as lithium, manganese, cobalt of phosphorous, based on current recycling processes and the characterization of solid waste is addressed.This work has received funding from the European Unionâs Horizon 2020 research and innovation programme under the Marie SkĹodowska-Curie grant agreement No. 778045. Paz-Garcia acknowledges the financial support from the University of Malaga, project: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the funding from the University of Malaga for the postdoctoral fellowship PPIT.UMA.A.3.2.2018.
Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tec
Electrodialytic Recovery of Cobalt from Spent Lithium-Ion Batteries
ContribuciĂłn en congreso cientĂficoRecycling lithium-ion batteries has an increasing interest for economic and environmental reasons. Disposal of lithium-ion batteries imposes high risk to the environment due to the toxicity of some of their essential components. In addition to this, some of these components, such as cobalt, natural graphite and phosphorus, are included in the list of critical raw materials for the European Union due to their strategic importance in the manufacturing industry. Therefore, in the recent years, numerous research studies have been focused on the development of efficient processes for battery recycling and the selective recuperation of these key components.
LiCoO2 is the most common material use in current lithium-ion batteries cathodes. In the current work, an electrodialytic method is proposed for the recovery of cobalt from this kind of electrode. In a standard electrodialytic cell, the treated matrix is separated from the anode and the cathode compartments by means of ion-exchange membranes. A cation-exchange membrane (CEM) allows the passage of cations and hinders the passage of anions, while the behaviour of anion-exchange membrane (AEM) does the opposite. A three-compartment electrodialytic cell has been designed and assembled, as depicted in the figure. In the central compartment, a suspension of LiCoO2 is added.
Different extracting agents, such as EDTA, HCl and HNO3, are tested to enhanced the dissolution and the selective extraction of the target metal. Dissolved cobalt-containing complexes migrate towards the cathode or the anode compartments depending on the ionic charge of the complexes. While cobalt extraction via extracting agents is an expensive treatment, as it requires the constant addition of chemicals, an efficient electrodialytic cell could allow the recirculation of the extracting agents and the economical optimization of the process.This work has received funding from the European Unionâs Horizon 2020 research and innovation programme under the Marie SkĹodowska-Curie grant agreement No. 778045. Paz-Garcia acknowledges the financial support from the University of Malaga, project: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the funding from the University of Malaga for the postdoctoral fellowship PPIT.UMA.A.3.2.2018.
Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tec
Exploring the transcriptomic data of the Australian paralysis tick, Ixodes holocyclus
Ixodes holocyclus is the paralysis tick commonly found in Australia. I. holocyclus does not cause paralysis in the primary host â bandicoots, but markedly affects secondary hosts such as companion animals, livestock and humans. Holocyclotoxins are the neurotoxin molecules in I. holocyclus responsible for paralysis symptoms. There is a limited understanding of holocyclotoxins due to the difficulties in purifying and expressing these toxins in vitro. Next-generation sequencing technologies were utilised for the first time to generate transcriptome data from two cDNA samples âsalivary glands samples collected from female adult ticks engorged on paralysed companion animals and on bandicoots. Contigencoded proteins in each library were annotated according to their best BLAST match against several databases and functionally assigned into six protein categories: housekeeping, transposable elements, pathogen-related, hypothetical, secreted and novel. The âsecreted proteinâ category is comprised of ten protein families: enzymes, protease inhibitors, antigens, mucins, immunity-related, lipocalins, glycinerich, putative secreted, salivary and toxin-like. Comparisons of contig representation between the two libraries reveal the differential expression of tick proteins collected from different hosts. This study provides a preliminary description of the I. holocyclus tick salivary gland transcriptome
Why Power Matters in Payments for Environmental Services (PES)
Payments for environmental services (PES) are payments to land owners whose land management practices help to provide environmental services (ES). In the context of watershed environmental services, the most important services are the supply, purification and regulation of water. PES was conceived as an instrument for facilitating the transition to a green economy. From this perspective, PES is a win-win solution to environmental degradation and poverty. Today, PES is a widely used policy tool for conservation. Having begun life as scattered, privately funded projects, PES has made its way into many national and internationÂŹal conservation policies around the world. The value of PES watershed transactions in 2011 was USD 8-10 billion; and the figure is still growing fast. This briefing paper challenges the notion of PES as a panacea for environmental degradation and poverty. While PES is a rapidly proliferating mechanism for natural resource management and conservation, its use is sometimes coupled with a lack of understanding of its social and econoÂŹmic impacts. To this end, we identify a number of critical issues that have received marginal policy attention in the context of the developing world, but which have a great deal of social relevance and impact. Understanding the critical issues surrounding PES can help to overcome and reduce the following drawbacks: ⢠Power asymmetries in PES negotiations. PES often involves governments and private enterprises negotiating with marginalised communities. These actorsâ differing resources and capabilities are likely to influence both the outcomes of negotiations and the operation of PES. Ensuring that the interests of marginalised communities are protected in PES negotiations is not just a social imperative, but also contributes to sustainability. ⢠PES participation is not always voluntary. EnvironÂŹmental laws, strict contract clauses, unclear particiÂŹpation mechanisms and intermediary agency pressure tend to force PES on service-providers. Voluntary participation should be guaranteed by implementing organisations. In addition, PES policies should inte-grate peasantsâ perspectives (i. e. what do providers think they need?), so that PES is a tool for rather than a hurdle to rural development. ⢠PES schemes are introduced in contexts where natural resource distribution is skewed. PES could exacerbate this skewed distribution or even reduce the degree of control that the less powerful have over natural resources. In many situations, PES may result in service-providers not actually having access to the services they are helping to conserve, or losing control over their resources. PES should be tied to the fair redistribution of natural resource rights. ⢠PES may compete with communal organisations, and erode cultural and conservation practices that are not based on monetary payments
Sea level anomalies exacerbate beach erosion
Sea level anomalies are intra-seasonal increases in water level forced by meteorological and oceanographic processes unrelated to storms. The effects of sea level anomalies on beach morphology are unknown but important to constrain because these events have been recognized over large stretches of continental margins. Here, we present beach erosion measurements along Onslow Beach, a barrier island on the U.S. East Coast, in response to a year with frequent sea level anomalies and no major storms. The anomalies enabled extensive erosion, which was similar and in most places greater than the erosion that occurred during a year with a hurricane. These results highlight the importance of sea level anomalies in facilitating coastal erosion and advocate for their inclusion in beach-erosion models and management plans. Sea level anomalies amplify the erosive effects of accelerated sea level rise and changes in storminess associated with global climate change
Gender differences in human immunodeficiency virus (HIV) RNA and CD4 cell counts among new entrants to HIV care
ABSTRACTClinic database extraction identified 806 new entrants to human immunodeficiency virus (HIV) care in Cleveland, OH, USA. At entry, women had higherCD4 counts and lower HIVRNAlevels than men (mean, 388 vs. 310 cells/ÂľL, and 8.94 Ă 104 vs. 1.27 Ă 105 copies/mL, respectively), but the proportion of entrants with category C illnesses, category B conditions, sexually transmitted diseases and CD4 counts < 200 ÂľL did not differ between genders. Hepatitis B seroprevalence was higher in men (8.7% vs. 0.6%), but there was no difference in hepatitis C prevalence. Whether women in Cleveland seek HIV care earlier, or whether early markers of HIV disease differ between the genders, remains to be determined
Final state effects on superfluid He in the deep inelastic regime
A study of Final State Effects (FSE) on the dynamic structure function of
superfluid He in the Gersch--Rodriguez formalism is presented. The main
ingredients needed in the calculation are the momentum distribution and the
semidiagonal two--body density matrix. The influence of these ground state
quantities on the FSE is analyzed. A variational form of is used, even
though simpler forms turn out to give accurate results if properly chosen.
Comparison to the experimental response at high momentum transfer is performed.
The predicted response is quite sensitive to slight variations on the value of
the condensate fraction, the best agreement with experiment being obtained with
. Sum rules of the FSE broadening function are also derived and
commented. Finally, it is shown that Gersch--Rodriguez theory produces results
as accurate as those coming from other more recent FSE theories.Comment: 20 pages, RevTex 3.0, 11 figures available upon request, to be appear
in Phys. Rev.
Determination and analysis of plasma radiative properties for numerical simulations of laboratory radiative blast waves launched in xenon clusters
Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon plasmas are commonly used for the medium in which the radiative shocks propagate. The knowledge of the plasma radiative properties is crucial for the correct understanding and for the hydrodynamic simulations of radiative shocks. In this work, we perform an analysis of the radiative properties of xenon plasmas in a range of matter densities and electron temperatures typically found in laboratory experiments of radiative shocks launched in xenon plasmas. Furthermore, for a particular experiment, our analysis is applied to make a diagnostics of the electron temperatures of the radiative shocks since they could not be experimentally measure
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