Predation is an important interaction that can change the structure of arthropod communities across both temporal and spatial scales. In agricultural systems predation can reduce the population ...levels of several arthropod pest species of a community. This predator–prey interaction involves the predator searching and handling behaviors. Several factors can affect this interaction, such as pesticide exposure, which is a frequent feature in agroecosystems. Thus, the hypothesis of our study is that the predatory behavior of the phytoseiid mite Neoseiulus idaeus Denmark & Muma, an important natural enemy of spider mites, is affected by acaricide exposure. To test that hypothesis, the predatory mite was exposed to the acaricides abamectin, fenpyroximate, and azadirachtin in 4 exposure scenarios. The predatory behavior of N. idaeus was negatively affected by acaricide exposure when the leaf surface containing both prey and predator was sprayed leading to a reduction in the frequency of transitions between predator walking and meeting preys. Prey handling and consumption were also compromised by acaricide exposure through contaminated leaf surface and prey, and contaminated leaf surface, prey, and predator. Abamectin compromised predation regardless of the exposure scenario. Acaricide-exposure reduced the number of prey found, number of attacks, and number prey killed by N. idaeus. Moreover, partial prey consumption was observed with acaricide-exposed mites. Thus, caution is necessary while attempting to integrate acaricide applications and mass release of N. idaeus for spider mite management. Graphical Abstract
Abstract
C
-glycosides are natural products with important biological activities but are recalcitrant to degradation. Glycoside 3-oxidases (G3Oxs) are recently identified bacterial flavo-oxidases ...from the glucose-methanol-coline (GMC) superfamily that catalyze the oxidation of
C
-glycosides with the concomitant reduction of O
2
to H
2
O
2
. This oxidation is followed by C-C acid/base-assisted bond cleavage in two-step
C
-deglycosylation pathways. Soil and gut microorganisms have different oxidative enzymes, but the details of their catalytic mechanisms are largely unknown. Here, we report that
Ps
G3Ox oxidizes at 50,000-fold higher specificity (
k
cat
/K
m
) the glucose moiety of mangiferin to 3-keto-mangiferin than free D-glucose to 2-keto-glucose. Analysis of
Ps
G3Ox X-ray crystal structures and
Ps
G3Ox in complex with glucose and mangiferin, combined with mutagenesis and molecular dynamics simulations, reveal distinctive features in the topology surrounding the active site that favor catalytically competent conformational states suitable for recognition, stabilization, and oxidation of the glucose moiety of mangiferin. Furthermore, their distinction to pyranose 2-oxidases (P2Oxs) involved in wood decay and recycling is discussed from an evolutionary, structural, and functional viewpoint.
Protein stability arises from a combination of factors which are often difficult to rationalise. Therefore its improvement is better addressed through directed evolution than by rational design ...approaches. In this study, five rounds of mutagenesis/recombination followed by high-throughput screening (≈10,000 clones) yielded the hit 1B6 showing a 300-fold higher half life at 50°C than that exhibited by the homodimeric wild type PpAzoR azoreductase from Pseudomonas putida MET94. The characterization using fluorescence, calorimetry and light scattering shows that 1B6 has a folded state slightly less stable than the wild type (with lower melting and optimal temperatures) but in contrast is more resistant to irreversible denaturation. The superior kinetic stability of 1B6 variant was therefore related to an increased resistance of the unfolded monomers to aggregation through the introduction of mutations that disturbed hydrophobic patches and increased the surface net charge of the protein. Variants 2A1 and 2A1-Y179H with increased thermodynamic stability (10 to 20°C higher melting temperature than wild type) were also examined showing the distinctive nature of mutations that lead to improved structural robustness: these occur in residues that are mostly involved in strengthening the solvent-exposed loops or the inter-dimer interactions of the folded state.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The conjugation of dye-labelled DNA oligonucleotides with gold nanorods has been widely explored for the development of multifunctional fluorescent nanoprobes. Here, we show that the ...functionalization route is crucial to achieve enhanced emission in dye nano-assemblies based on gold nanorods. By using a tip-selective approach for thiol attachment of dye molecules onto gold nanorods, it was possible to effectively increase the emission by more than 10-fold relatively to that of a free dye. On the other hand, a non-selective approach revealed that indiscriminate surface functionalization has a detrimental effect on the enhancement. Simulations of discrete dipole approximation gave further insight into the surface distribution of plasmon-enhanced emission by confirming that tip regions afford an effective enhancement, while side regions exhibit a negligible effect or even emission quenching. The contrast between dye nano-assemblies obtained from tip- and non-selective functionalization was further characterized by single-particle fluorescence emission. These studies showed that tip-functionalized gold nanorods with an average of only 30 dye molecules have a comparable to or even stronger emission than non-selectively functionalized particles with approximately 10 times more dye molecules. The results herein reported could significantly improve the performance of dye nano-assemblies for imaging or sensing applications.
Conjugation of fluorescently-labelled DNA onto gold nanorods produces strongly emitting nano-assemblies, but only tip-selective functionalization affords an effective emission enhancement.
The successful implementation of the Convention on Biological Diversity's post‐2020 Global Biodiversity Framework will rely on effective translation of targets from global to national level and ...increased engagement across diverse sectors of society. Species conservation targets require policy support measures that can be applied to a diversity of taxonomic groups, that link action targets to outcome goals, and that can be applied to both global and national data sets to account for national context, which the species threat abatement and restoration (STAR) metric does. To test the flexibility of STAR, we applied the metric to vascular plants listed on national red lists of Brazil, Norway, and South Africa. The STAR metric uses data on species’ extinction risk, distributions, and threats, which we obtained from national red lists to quantify the contribution that threat abatement and habitat restoration activities could make to reducing species’ extinction risk. Across all 3 countries, the greatest opportunity for reducing plant species’ extinction risk was from abating threats from agricultural activities, which could reduce species’ extinction risk by 54% in Norway, 36% in South Africa, and 29% in Brazil. Species extinction risk could be reduced by a further 21% in South Africa by abating threats from invasive species and by 21% in Brazil by abating threats from urban expansion. Even with different approaches to red‐listing among countries, the STAR metric yielded informative results that identified where the greatest conservation gains could be made for species through threat‐abatement and restoration activities. Quantifiably linking local taxonomic coverage and data collection to global processes with STAR would allow national target setting to align with global targets and enable state and nonstate actors to measure and report on their potential contributions to species conservation.
The technical innovation of the fourth industrial revolution (Industry 4.0—I4.0) is based on the following respective conditions: horizontal and vertical integration of manufacturing systems, ...decentralization of computing resources and continuous digital engineering throughout the product life cycle. The reference architecture model for Industry 4.0 (RAMI 4.0) is a common model for systematizing, structuring and mapping the complex relationships and functionalities required in I4.0 applications. Despite its adoption in I4.0 projects, RAMI 4.0 is an abstract model, not an implementation guide, which hinders its current adoption and full deployment. As a result, many papers have recently studied the interactions required among the elements distributed along the three axes of RAMI 4.0 to develop a solution compatible with the model. This paper investigates RAMI 4.0 and describes our proposal for the development of an open-source control device for I4.0 applications. The control device is one of the elements in the hierarchy-level axis of RAMI 4.0. Its main contribution is the integration of open-source solutions of hardware, software, communication and programming, covering the relationships among three layers of RAMI 4.0 (assets, integration and communication). The implementation of a proof of concept of the control device is discussed. Experiments in an I4.0 scenario were used to validate the operation of the control device and demonstrated its effectiveness and robustness without interruption, failure or communication problems during the experiments.
Optimization of protein formulations at subzero temperatures is required for many applications such as storage, transport, and lyophilization. Using isochoric cooling (constant volume) is possible to ...reach subzero temperatures without freezing aqueous solutions. This accelerates protein damage as protein may unfold by cold denaturation and diffusional and conformational freedom is still present. The use of isochoric cooling to faster protein formulations was first demonstrated for the biomedical relevant protein disulfide isomerase A1. Three osmolytes, sucrose, glycerol, and l-arginine, significantly increased the stability of protein disulfide isomerase A1 at -20°C with all tested under isochoric cooling within the short time frame of 700 h. The redox green fluorescent protein 2 was used to evaluate the applicability of isochoric cooling for stability analysis of highly stable proteins. This derivative of GFP is 2.6-fold more stable than the highly stable GFP β-barrel structure. Nevertheless, it was possible to denature a fraction of roGFP2 at -20°C and to assign a stabilizing effect to sucrose. Isochoric cooling was further applied to insulin. Protein damage was evaluated through a signaling event elicited on human hepatocyte carcinoma cells. Insulin at -20°C under isochoric cooling lost 22% of its function after 15 days and 0.6M sucrose prevented insulin deactivation.
Site-directed mutagenesis has been used to replace Met502 in CotA laccase by the residues leucine and phenylalanine. X-ray structural comparison of M502L and M502F mutants with the wild-type CotA ...shows that the geometry of the T1 copper site is maintained as well as the overall fold of the proteins. The replacement of the weak so-called axial ligand of the T1 site leads to an increase in the redox potential by approximately 100 mV relative to that of the wild-type enzyme (E0 =455 mV). However the M502L mutant exhibits a twofold to fourfold decrease in the kcat values for the all substrates tested and the catalytic activity in M502F is even more severely compromised; 10% activity and 0.15-0.05% for the non-phenolic substrates and for the phenolic substrates tested when compared with the wild-type enzyme. T1 copper depletion is a key event in the inactivation and thus it is a determinant of the thermodynamic stability of wild-type and mutant proteins. Whilst the unfolding of the tertiary structure in the wild-type enzyme is a two-state process displaying a midpoint at a guanidinium hydrochloride concentration of 4.6 M and a free-energy exchange in water of 10 kcal/mol, the unfolding for both mutant enzymes is clearly not a two-state process. At 1.9 M guanidinium hydrochloride, half of the molecules are in an intermediate conformation, only slightly less stable than the native state (approximately 1.4 kcal/mol). The T1 copper centre clearly plays a key role, from the structural, catalytic and stability viewpoints, in the regulation of CotA laccase activity.
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