Contribution of microscopy for understanding the mechanism of action against trypanosomatids

Transmission electron microscopy (TEM) has proved to be a useful tool to study the ultrastructural alterations and the target organelles of new antitrypanosomatid drugs. Thus, it has been observed that sesquiterpene lactones induce diverse ultrastructural alterations in both T. cruzi and Leishmania spp., such as cytoplasmic vacuolization, appearance of multilamellar structures, condensation of nuclear DNA, and, in some cases, an important accumulation of lipid vacuoles. This accumulation could be related to apoptotic events. Some of the sesquiterpene lactones (e.g., psilostachyin) have also been demonstrated to cause an intense mitochondrial swelling accompanied by a visible kinetoplast deformation as well as the appearance of multivesicular bodies. This mitochondrial swelling could be related to the generation of oxidative stress and associated to alterations in the ergosterol metabolism. The appearance of multilamellar structures and multiple kinetoplasts and flagella induced by the sesquiterpene lactone psilostachyin C indicates that this compound would act at the parasite cell cycle level, in an intermediate stage between kinetoplast segregation and nuclear division. In turn, the diterpene lactone icetexane has proved to induce the external membrane budding on T. cruzi together with an apparent disorganization of the pericellar cytoskeleton. Thus, ultrastructural TEM studies allow elucidating the possible mechanisms and the subsequent identification of molecular targets for the action of natural compounds on trypanosomatids.Fil: Lozano, Esteban Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Spina Zapata, Renata María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Barrera, Patricia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: Tonn, Carlos Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; ArgentinaFil: Sosa Escudero, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentin

CUTTING PREFERENCE OF Acromyrmex crassispinus (FOREL, 1909) AND Acromyrmex ambiguus (EMERY, 1887) (HYMENOPTERA: FORMICIDAE) BY DIFFERENT EUCALYPT SPECIES IN LABORATORY

A busca por novos m\ue9todos de manejo e controle de formigas-cortadeiras vem sendo enfoque de in\ufameros estudos pelo pa\ueds, impulsionada por aspectos econ\uf4micos e ambientais. O estabelecimento de esp\ue9cies resistentes ou menos preferidas ao corte pode contribuir substancialmente neste sentido. Logo, o objetivo deste estudo foi avaliar a prefer\ueancia de corte entre as esp\ue9cies Corymbia citriodora , Eucalyptus benthamii , Eucalyptus camaldulensis , Eucalyptus dunnii , Eucalyptus globulus e h\uedbrido de Eucalyptus urophylla X Eucalyptus grandis por Acromyrmex ambiguus e Acromyrmex crassispinus em laborat\uf3rio. Para isso, folhas foram ofertadas, simultaneamente, para seis col\uf4nias de cada esp\ue9cie em bioensaios com chance de escolha. No entanto, nos testes sem chance de escolha, apenas as esp\ue9cies menos preferidas pelo teste anterior foram utilizadas. Para Acromyrmex crassispinus, as esp\ue9cies Eucalyptus camaldulensis e h\uedbrido de Eucalyptus urophylla X Eucalyptus grandis foram mais cortadas, enquanto que as esp\ue9cies Corymbia citriodora, Eucalyptus dunnii e Eucalyptus globulus foram menos preferidas ao corte. Acromyrmex ambiguus apresentou padr\ue3o similar de prefer\ueancia, adicionando-se Eucalyptus benthamii entre as mais preferidas e excluindo-se Eucalyptus dunnii das menos preferidas.The search for new leafcutter ant management and control methods have been the aim of several studies over the country, propelled by economic and environmental aspects. The establishment of resistant or less preferred species for the cut can contribute substantially in this subject. This way, the objective of this study was to evaluate the cutting preference between the species Corymbia citriodora , Eucalyptus benthamii , Eucalyptus camaldulensis , Eucalyptus dunnii , Eucalyptus globulus and h\uedbrido de Eucalyptus urophylla X Eucalyptus grandis by Acromyrmex ambiguus and Acromyrmex crassispinus in laboratory. Therefore, leafs were offered simultaneously to six colonies of each species in bioassays with chance to choose. However, in the tests without chance to choose, only the least preferred species in the previous test were utilized. For Acromyrmex crassispinus, the species Eucalyptus camaldulensis and h\uedbrido de Eucalyptus urophylla X Eucalyptus grandis were the most cutted, besides Corymbia citriodora, Eucalyptus dunni and Eucalyptus globules were less preferred. Acromyrmex ambiguus showed similar preference pattern, adding Eucalyptus benthamii among the most preferred one and excluding Eucalyptus dunnii from the least preferred

Continuum Molecular Simulation of Large Conformational Changes during Ion–Channel Gating

A modeling framework was developed to simulate large and gradual conformational changes within a macromolecule (protein) when its low amplitude high frequency vibrations are not concerned. Governing equations were derived as alternative to Langevin and Smoluchowski equations and used to simulate gating conformational changes of the Kv7.1 ion-channel over the time scale of its gating process (tens of milliseconds). The alternative equations predict the statistical properties of the motion trajectories with good accuracy and do not require the force field to be constant over the diffusion length, as assumed in Langevin equation. The open probability of the ion–channel was determined considering cooperativity of four subunits and solving their concerted transition to the open state analytically. The simulated open probabilities for a series of voltage clamp tests produced current traces that were similar to experimentally recorded currents

Observation of large Rashba spin–orbit coupling at room temperature in compositionally engineered perovskite single crystals and application in high performance photodetectors

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordIndirect absorption extended below the direct transition edge and increase in carrier lifetime derived from Rashba spin-orbit coupling may advance the optoelectronic applications of metal halide perovskites. Spin-orbit coupling in halide perovskites is due to the presence of heavy elements in their structure. However, when these materials lack an inversion symmetry, for example by the application of strain, spin-orbit coupling becomes odd in the electron’s momentum giving rise to a splitting in the electronic energy bands. Here we report on the observation of a large Rashba splitting of 117 meV at room temperature through a facile compositional engineering approach in halide perovskite single crystals, as predicted by relativistic first-principles calculations. Partial substitution of organic cations by rubidium ions in single crystals induces significant indirect absorption and dual emission as a result of a large Rashba splitting. We measured significant magneto-photocurrent, magneto-electroluminescence and magneto-photoluminescence responses in perovskite single crystal devices and thin films. They originate from the significant spin-momentum locking that leads to different precession frequencies of their respective spins about the applied magnetic field. A hybrid perovskite single crystal photodetector achieved record figures of merit, including detectivity of more than 1.3×1018 Jones which represents a three orders of magnitude improvement compared to the to date record. These findings show that facile compositional engineering of perovskite single crystals holds great promise for further advancing the optoelectronic properties of existing materials.European Regional Development Fund (ERDF)European Union Horizon 2020Ministero dell’Istruzione dell’Universitàe della Ricerca (MIUR)Università degli Studi di PerugiaCNPq, Brazi

An assessment of the levels of phthalate esters and metals in the Muledane open dump, Thohoyandou, Limpopo Province, South Africa

<p>Abstract</p> <p>Background</p> <p>This work reports the determination of the levels of phthalate esters (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diethyl hexyl phthalate (DEHP)) and metals (lead, cadmium, manganese, zinc, iron, calcium) in composite soil samples. The soil samples were collected randomly within the Muledane open dump, Thohoyandou, Limpopo province, South Africa. Control samples were collected about 200 m away from the open dump. The phthalate esters were separated and determined by capillary gas chromatography with a flame ionization detector, whilst the metals were determined by atomic absorption spectrophotometry.</p> <p>Results</p> <p>Open dump values for the phthalate esters and metals to be generally higher in comparison to control samples for DMP, DEP, DBP and DEHP – the mean values calculated were 0.31 ± 0.12, 0.21 ± 0.05, 0.30 ± 0.07, and 0.03 ± 0.01 mg/kg, respectively, for the open dump soil samples. Nonetheless, the mean open dump values for lead, cadmium, manganese, zinc, iron and calcium were 0.07 ± 0.04, 0.003 ± 0.001, 5.02 ± 1.92, 0.31 ± 0.02, 11.62 ± 9.48 and 0.12 ± 0.13 mg/kg, respectively. The results were compared statistically.</p> <p>Conclusion</p> <p>Our results revealed that the discarding of wastes into the open dump is a potential source of soil contamination in the immediate vicinity and beyond, <it>via </it>dispersal. Increased levels of phthalate esters and metals in the soil pose a risk to public health, plants and animals. Sustained monitoring of these contaminants is recommended, in addition to upgrading the facility to a landfill.</p