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- Nickel Oxide Nanoparticles Trigger Caspase- and Mitochondria-Dependent Apoptosis in the Yeast Saccharomyces cerevisiaePublication . Sousa, Cátia A.; Soares, Helena M. V. M.; Soares, Eduardo V.The expansion of the industrial use of nickel oxide (NiO) nanoparticles (NPs) raises concerns about their potential adverse effects. Our work aimed to investigate the mechanisms of toxicity induced by NiO NPs, using the yeast Saccharomyces cerevisiae as a cell model. Yeast cells exposed to NiO NPs exhibited typical hallmarks of regulated cell death (RCD) by apoptosis [loss of cell proliferation capacity (cell viability), exposure of phosphatidylserine at the outer cytoplasmic membrane leaflet, nuclear chromatin condensation, and DNA damage] in a process that required de novo protein synthesis. The execution of yeast cell death induced by NiO NPs is Yca1p metacaspase-dependent. NiO NPs also induced a decrease in the mitochondrial membrane potential and an increase in the frequency of respiratory-deficient mutants, which supports the involvement of mitochondria in the cell death process. Cells deficient in the apoptosis-inducing factor ( aif1Δ) displayed higher tolerance to NiO NPs, which reinforces the involvement of mitochondria in RCD by apoptosis. In summary, this study shows that NiO NPs induce caspase- and mitochondria-dependent apoptosis in yeast. Our results warn about the possible harmful effects associated with the use of NiO NPs.
- Carbon dots de síntese única para deteção de espécies reativas de oxigénioPublication . Almeida, Lícia; Sousa, Cátia A.; Duarte, Abel J.(Introdução) As espécies reativas de oxigénio (reactive oxygen species – ROS), são um conjunto de radicais livres que derivam do oxigénio e provêm da cadeia respiratória. São de importância vital nos organismos vivos em quantidade muito reduzidas, funcionando como neurotransmissores ou vasodilatadores, no entanto, quando em grandes quantidades provocam o stresse oxidativo causador de inúmeras patologias. A deteção ROS é de grande importância em diversos processos biológicos, diagnóstico de doenças e triagem de drogas quimioterápicas, para isso é importante construir unidades de carbon dots (Cdots) que sejam sensores químicos de ROS por mecanismo de extinção de fluorescência. Existem algumas estratégias de construção dos CDots, as mais vantajosas são as sínteses únicas em micro-ondas.
- Polluted Rivers—A Case Study in Porto, PortugalPublication . Lemos, Patrícia; Silva, Paulo; Sousa, Cátia A.; Duarte, Abel J.; A. Sousa, Cátia; Duarte, Abel J.; Sierra, José Ramón Arévalo; Karydis, Michael; Azzaro, MaurizioRiver contamination by microorganisms, or another chemical source, poses a serious threat to both the environment and public health. Taking immediate and appropriate actions is essential to mitigate the contamination and prevent further spread. As such, regular monitoring of these pollution agents is essential to act in time and control its minor extension. However, there is a lack of commitment to this emergent concern and respective actions around the world. This work aims to study the contamination of a Portuguese river (Tinto River) within Porto city (a highly populated urban area) regarding the total aerobic microorganisms, coliforms, and Enterococcus (as colony-forming units (CFUs) using specific solid culture media) and total organic matter (TOC). Different locations were considered along the Tinto River course (i.e., 14 locations within 11 km) and samples were collected on distinct days throughout September 2022. The overall results showed microbial contamination of aerobic microorganisms (up to 2 × 105 CFU/100 mL), total coliforms (up to 7 × 104 CFU/100 mL), Escherichia coli (up to 9 × 103 CFU/100 mL), and Enterococcus (up to 8 × 103 CFU/100 mL). The results also surpassed the maximum recommended values (MRVs) described in Portuguese decree-law no. 236/98 for irrigation waters. Moreover, TOC was found in a range of 4.54 mg/L to 57.2 mg/L. This work highlights the dangerous microbial contamination and higher amount of organic matter than would be expected for a surface water resource.
- Strenghten the nutrients in aquaponicsPublication . Martins, Camila O.; Sousa, Miguel; Ferreira, Paulo; Sousa, Cátia A.; Duarte, Abel J.(Objectives) This work is aimed to develop chemical detection systems for some of the ions, such as nitrate, nitrite, or iron, adapting simple, robust and inexpensive electronic circuits for their monitoring, in order to achieve concentrations in real time.
- Metal(loid) oxide (Al2O3, Mn3O4, SiO2 and SnO2) nanoparticles cause cytotoxicity in yeast via intracellular generation of reactive oxygen speciesPublication . Sousa, Cátia A.; Soares, Helena M. V. M.; Soares, EduardoIn 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 < 8%) 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.
- Comparison of five bacterial strains producing siderophores with ability to chelate iron under alkaline conditionsPublication . Ferreira, Carlos M. H.; Vilas-Boas, Ângela; Sousa, Cátia A.; Soares, Helena M. V. M.; Soares, Eduardo V.Iron deficiency is one of the main causes of chlorosis in plants, which leads to losses in field crops quality and yield. The use of synthetic chelates to prevent or correct iron-deficiency is not satisfactory mainly due to their poor biodegradability. The present work aimed to search suitable microorganisms to produce alternative, environment-friendly iron-chelating agents (siderophores). For this purpose, the performance of five bacteria (Azotobacter vinelandii, Bacillus megaterium, Bacillus subtilis, Pantoea allii and Rhizobium radiobacter) was evaluated, regarding siderophore production kinetics, level of siderophore production (determined by chrome azurol S, CAS method), type of siderophore produced (using Arnow and Csaky's tests) and iron-chelating capacity at pH 9.0. All bacteria were in stationary phase at 24 h, except A. vinelandii (at 72 h) and produced the maximum siderophore amount (80-140 µmol L-1) between 24 and 48 h, with the exception of A. vinelandii (at 72 h). The analysis of culture filtrates revealed the presence of catechol-type siderophores for B. subtilis and R. radiobacter and hydroxamate-type siderophores for B. megaterium and P. allii. In the case of A. vinelandii, both siderophore-types (catechol and hydroxamates) were detected. The highest iron-chelating capacity, at pH 9.0, was obtained by B. megaterium followed by B. subtilis and A. vinelandii. Therefore, these three bacteria strains are the most promising bacteria for siderophore production and chlorosis correction under alkaline conditions.