Impact of nickel oxide nanoparticles on yeast physiology

[Excerpt] In the recent years, nickel oxide (NiO) nanoparticles (NPs), have been used in different fields, such as in biosensors, catalysis, ceramics, electrochromic film, electronics, conductive and magnetic materials, energy storage devices, fuel cells, printing inks and wastewater treatment [1-2]. Due to the increasing use of these NPs, concerns about their possible toxic effects have been raised. In the present study, the yeast Saccharomyces cerevisiae was used as a cell model to evaluate the possible hazards of NiO NPs. Physicochemical characteristics of NiO in MES buffer, namely NPs agglomeration (examined by dynamic light scattering – DLS), surface charge (determination of zeta potential) and dissolution of the NPs (quantification of Ni2+ released in medium) were evaluated in order to be correlated with their toxicity. [...]info:eu-repo/semantics/publishedVersio

Nickel oxide nanoparticles induce toxicity in yeasts via oxidative stress

[Excerpt] The increasing use of nickel oxide (NiO) nanoparticles (NPs) raises concerns about their potential toxicity. In the present study, the yeast Saccharomyces cerevisiae was used, as a cell model, in order to elucidate whether the toxicity of NiO NPs is associated with the oxidative stress (OS). In abiotic conditions (cell free), NiO NPs were unable to induce the generation of reactive oxygen species (ROS), which excludes the possibility of exerting a pro-oxidant effect. However, yeast cells exposed to NiO NPs accumulated intracellularly superoxide anions (assessed with dihydroethidium) and hydrogen peroxide (evaluated with 2′,7′-dichlorodihydrofluorescein diacetate or dihydrorhodamine 123) when incubated in normal (oxygen) atmosphere. Yeast cells exposed to NiO also presented reduced cell viability (measured through a clonogenic assay). Yeasts co-exposed to NiO NPs and the antioxidants L-ascorbic acid (a scavenger of free radicals) or N-tertbutyl-α-phenylnitrone (a spin trapping agent) presented ROS quenching and increased cell viability, which suggests that NiO toxicity is linked to ROS production. [...]info:eu-repo/semantics/publishedVersio

Metal(loid) oxide (Al2O3, Mn3O4, SiO2 and SnO2) nanoparticles cause cytotoxicity in yeast via intracellular generation of reactive oxygen species

In this work, the physicochemical characterization of five (Al2O3, In2O3, Mn3O4, SiO2 and SnO2) nanoparticles (NPs) was carried out. In addition, the evaluation of the possible toxic impacts of these NPs and the respective modes of action were performed using the yeast Saccharomyces cerevisiae. In general, in aqueous suspension, metal(loid) oxide (MOx) NPs displayed an overall negative charge and agglomerated; these NPs were practically insoluble (dissolution <\thinspace8\\%) and did not generate detectable amounts of reactive oxygen species (ROS) under abiotic conditions. Except In2O3 NPs, which did not induce an obvious toxic effect on yeast cells (up to 100 mg/L), the other NPs induced a loss of cell viability in a dose-dependent manner. The comparative analysis of the loss of cell viability induced by the NPs with the ions released by NPs (NPs supernatant) suggested that SiO2 toxicity was mainly caused by the NPs themselves, Al2O3 and SnO2 toxic effects could be attributed to both the NPs and the respective released ions and Mn3O4 harmfulness could be mainly due to the released ions. Al2O3, Mn3O4, SiO2 and SnO2 NPs induced the loss of metabolic activity and the generation of intracellular ROS without permeabilization of plasma membrane. The co-incubation of yeast cells with MOx NPs and a free radical scavenger (ascorbic acid) quenched intracellular ROS and significantly restored cell viability and metabolic activity. These results evidenced that the intracellular generation of ROS constituted the main cause of the cytotoxicity exhibited by yeasts treated with the MOx NPs. This study highlights the importance of a ROS-mediated mechanism in the toxicity induced by MOx NPs.This work was performed in the framework of the financingby Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte and LAQV (UID/QUI/50006/2019)with funding from FCT/MCTES through national funds.info:eu-repo/semantics/publishedVersio

Comment on ``BCS to Bose-Einstein crossover phase diagram at zero temperature for a d_{x^2-y^2} order parameter superconductor: Dependence on the tight-binding structure''

The work by Soares et al. [Phys. Rev. B 65, 174506 (2002)] investigates the BCS-BE crossover for d-wave pairing in the 2-dimensional attractive Hubbard model. Contrary to their claims, we found that a non-pairing region does not exist in the density vs coupling phase diagram. The gap parameter at T=0, as obtained by solving analytically as well as numerically the BCS equations, is in fact finite for any non-zero density and coupling, even in the weak-coupling regime.Comment: 7 pages, 1 figur

Avaliação, seleção e recomendação de cutlivares de arroz de várzeas em Minas Gerais de 1997 a 2002.

A fim de tornar a orizicultura irrigada uma atividade mais atrativa, a EPAMIG desenvolve, em parceria com a EMBRAPA Arroz e Feijão, pesquisas de melhoramento genético de arroz de várzeas com o objetivo de obter cultivares superiores às já recomendadas, tanto em produtividade como em aceitação comercial

Rotation intrinsic spin coupling--the parallelism description

For the Dirac particle in the rotational system, the rotation induced inertia effect is analogously treated as the modification of the "spin connection" on the Dirac equation in the flat spacetime, which is determined by the equivalent tetrad. From the point of view of parallelism description of spacetime, the obtained torsion axial-vector is just the rotational angular velocity, which is included in the "spin connection". Furthermore the axial-vector spin coupling induced spin precession is just the rotation-spin(1/2) interaction predicted by Mashhoon. Our derivation treatment is straightforward and simplified in the geometrical meaning and physical conception, however the obtained conclusions are consistent with that of the other previous work.Comment: 10 pages, no figur

Uniformidade de distribuicao de agua na superficie e no perfil do solo, irrigado com o microaspersor Rain-Bird QN-14.

Foi avaliado, em condições, o Co eficiente de Uniformidade de Christiansen (CUC) das lâminas de água aplicadas na superfície e distribuídas no perfil do solo, nas profundidade de 0-0,20; 0,20-0,40 e 0,40-0,60 m tendo sido obtido, os coeficientes de 42,61; 64,90; 79,04 e 84,06 %, respectivamente. Observou-se também que o Coeficiente de Uniformidade de Christiansen (CUC) da redistribuição d a lâmina de água no perfil do solo aumentou com a profundidade d as camadas

Efeito da água residuária do café em plantas de milho.

O processamento do café por via úmida gera água residuária (ARC), contendo material orgânico, com potencial de poluir o meio aquático. Este trabalho teve como objetivo estudar o efeito da aplicação da ARC sobre o crescimento e teores de minerais em plantas de milho, na fase vegetativa. Foram estudados oito tratamentos: 0, 50, 100, 150, 200, 250, 300 e 350 mL de ARC por planta, aplicada sobre as folhas, em 3 ocasiões. A aplicação da ARC não provocou injúrias visíveis nas plantas de milho e nem alterou o peso da matéria seca das plantas. O teor de K aumentou e o teor de Mg diminuiu linearmente com o aumento das doses de ARC aplicadas, enquanto os teores de Ca e Na nas folhas de milho não foram afetados

Developmental Toxicity of Endocrine Disrupters Bisphenol A and Vinclozolin in a Terrestrial Isopod

Studies of the effects of endocrine-disrupting compounds (EDCs) on invertebrates are still largely underrepresented. This work aims to fill this gap by assessing the effects of bisphenol A (BPA) and vinclozolin (Vz) on the terrestrial isopod Porcellio scaber (common rough woodlouse). Male adult and sexually undifferentiated juvenile woodlice were exposed to the toxicants. Effects on molting regime and growth were investigated independently for males and female woodlice after sexual differentiation. Both chemicals elicited developmental toxicity to P. scaber by causing overall decreased growth. Nevertheless, BPA induced molting, whereas Vz delayed it. Although the LC50 values for juvenile and adult survival were fairly similar, juvenile woodlice showed an increased chronic sensitivity to both chemicals, and female woodlice were most the sensitive to BPA. We recommend the use of adults, juveniles, female, and male woodlice, as well as a large range of toxicant concentrations, to provide valuable information regarding differential dose responses, effects, and threshold values for EDCs

Perfil e superficie de distribuicao pluviometrica do microaspersor Rain-Bird QN-14.

Este trabalho teve como objetivo a obtenção do perfil e superfície de distribuição pluviométrica do microaspersor RAIN-BIRD QN-14. O microaspersor apresentou um perfil de precipitação em for ma d e uma exponencial cúbica, com u m coeficiente de determinação (r2) igual a 99,7 %. O mesmo apresentou uma intensidade de precipitação média de 1,64 mm/h, tendo-se constatado que nas proximidades do emissor, a intensidade de precipitação apresentou-se inferior a 10% em relação à média, fazendo com que o raio efetivo comece aproximadamente, a 1,00m do emissor, indo até o limite de 3,00 m. O Coeficiente de Uniformidade de Christiansen em ausência de vento foi d a ordem 15,43 %, sem contudo levar em consideração seu raio efetivo