Plutella xylostella is a recurring pest on cruciferous crops around the world. In Brazil, it typically requires large number of insecticide sprays, which may lead to fast evolution of resistance. The aim of this study was to assess the susceptibility of Brazilian diamondback moth populations to the insecticides abamectin, deltamethrin, and spinosad. Leaf dip bioassays were used to determine mortality data obtained after 48 h of exposure to insecticides and subjected to Probit analysis. The population from Bonito, state of Pernambuco, Brazil, had the highest toxicity ratio (20.2 -fold) to abamectin compared to the reference population. The LC 50 values for deltamethrin ranged from 85.2 to 360.1 mg L -1 , demonstrating a high survival of populations in relation to this insecticide field dose rate (7.5 mg L -1). The toxicity ratios of the estimated LC 50 s, however, were very low (varying from 2.2 -to 4.2 -fold). Most populations exhibited toxicity ratios for spinosad, ranging from 2.3 -to 5.1 -fold, while both the LC 50 and LC 95 values reflected a high susceptibility to the spinosad field dosage (120 mg L -1).Only the Bonito -PE population resisted to abamectin, while all P. xylostella populations were resistant to deltamethrin, but particularly susceptible to spinosad because of the absence of selection pressure with it in these areas.

The correct parametrization of lanthanide complexes is of the utmost importance for their characterization using computational tools such as molecular dynamics simulations. This allows the optimization of their properties for a wide range of applications, including medical imaging. Here we present a systematic study to establish the best strategies for the correct parametrization of lanthanide complexes using [Gd­(DOTA)]− as a reference, which is used as a contrast agent in MRI. We chose the bonded model to parametrize the lanthanide complexes, which is especially important when considering the study of the complex as a whole (e.g., for the study of the dynamics of its interaction with proteins or membranes). We followed two strategies: a so-called heuristic approach employing strategies already published by other authors and another based on the more recent MCPB.py tool. Adjustment of the Lennard-Jones parameters of the metal was required. The final topologies obtained with both strategies were able to reproduce the experimental ion to oxygen distance, vibrational frequencies, and other structural properties. We report a new strategy to adjust the Lennard-Jones parameters of the metal ion in order to capture dynamic properties such as the residence time of the capping water (τm). For the first time, the correct assessment of the τm value for Gd-based complexes was possible by recording the dissociative events over up to 10 μs all-atom simulations. The MCPB.py tool allowed the accurate parametrization of [Gd­(DOTA)]− in a simpler procedure, and in this case, the dynamics of the water molecules in the outer hydration sphere was also characterized. This sphere was divided into the first hydration layer, an intermediate region, and an outer hydration layer, with a residence time of 18, 10 and 19 ps, respectively, independent of the nonbonded parameters chosen for Gd3+. The Lennard-Jones parameters of Gd3+ obtained here for [Gd­(DOTA)]− may be used with similarly structured gadolinium MRI contrast agents. This allows the use of molecular dynamics simulations to characterize and optimize the contrast agent properties. The characterization of their interaction with membranes and proteins will permit the design of new targeted contrast agents with improved pharmacokinetics.

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RES UMOO gesso é obtido do mineral gipsita, sulfato de cálcio que ocorre na forma dihidratada. Tanto as formas minerais quanto as formas residuais de gesso, têm mostrado eficácia quando aplicadas em solos para fins diversos como, por exemplo, na redução da saturação por alumínio e na recuperação de solos sódicos. O objetivo deste trabalho foi avaliar o potencial do gesso do Araripe na melhoria do ambiente radicular da cana-de-açúcar. Assim, foi conduzido um experimento em uma área agrí-cola do município de Sirinhaém, Pernambuco. Os tratamentos foram compostos por uma testemunha, pelo uso isolado de calcário, uso isolado do gesso e pela combinação de calcário e gesso mineral. A aplicação de gesso do Araripe proporcionou maior distribuição percentual de raízes de cana-de-açúcar. A movimentação do cálcio em profundidade, na forma de CaSO 4 0 , foi determinante para a melhoria do ambiente radicular em profundidade. Aos 30 dias após a aplicação os teores de cálcio foram elevados em profundidade, mesmo sendo o gesso aplicado a lanço e sem incorporação, sobrepujando os teores de alumínio trocáveis originalmente elevados. Palavras-chave: gipsita, sulfato de cálcio, raízes, cana-de-açúcarUse of Araripe gypsum to improve sugarcane root environment AB S TR ACTGypsum is obtained from the mineral gypsite, calcium sulphate in the dihidrated form. Both mineral and residual gypsum forms have shown efficacy when applied in soils for several uses, as for example, reduction of aluminum saturation and reclamation of sodic soils. The objective of this work was to evaluate the potential of the Araripe gypsum to improve of sugarcane root environment. An experiment was carried out in an agricultural field of Sirinhaém municipality, Pernambuco State, Brazil. The treatments were composed of a control, lime used without gypsum, gypsum without lime, and the combination of lime and gypsum. The application of Araripe gypsum allowed an increase in the percentage of sugarcane root distribution. The downward movement of calcium as CaSO 4 0 was determinant for the root environment improvement in depth. Calcium contents were found to increase in depth 30 days after application, even with the gypsum being applied on surface without incorporation, reducing the aluminum content.

Background: rhodamines are dyes widely used as fluorescent tags in cell imaging, probing of mitochondrial membrane potential, and as P-glycoprotein model substrates. In all these applications, detailed understanding of the interaction between rhodamines and biomembranes is fundamental. Methods: we combined atomistic molecular dynamics (MD) simulations and fluorescence spectroscopy to characterize the interaction between rhodamines 123 and B (Rh123 and RhB, respectively) and POPC bilayers. Results: while the xanthene moiety orients roughly parallel to the membrane plane in unrestrained MD simulations, variations on the relative position of the benzoic ring (below the xanthene for Rh123, above it for RhB) were observed, and related to the structure of the two dyes and their interactions with water and lipids. Subtle distinctions were found among different ionization forms of the probes. Experimentally, RhB displayed a lipid/water partition coefficient more than two orders of magnitude higher than Rh123, in agreement with free energy profiles obtained from umbrella sampling MD. Conclusions: this work provided detailed insights on the similarities and differences in the behavior of bilayer-inserted Rh123 and RhB, related to the structure of the probes. The much higher affinity of RhB for the membranes increases the local concentration and explains its higher apparent affinity for P-glycoprotein reconstituted in model membranes.