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1.
Ecotoxicol Environ Saf ; 184: 109580, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31493585

RESUMO

Ionic Liquids (ILs) are generically regarded as environmentally "harmless" and thus, assumed as "non-toxic". However, due to the endless design possibilities, their ecotoxicological profile is still poorly known. An accurate knowledge on the toxicity of a substance is required, under the scope of environmental regulation worldwide, before their application and commercialization. Knowledge on the relationship between the chemical structure and toxic effects is essential for the future design of more biocompatible solvents. Focusing on the use of ILs as base lubricants, lubricant additives, or even as potential working fluids for absorption heat pumps, the knowledge on its environmental impact is of great importance, due to the possibility of spills. In this specific context, four analogues of glycine-betaine-based ILs (AGB-ILs) and four glycine-betaine based ILs (GB-ILs) were synthesized and characterized. Their ecotoxicity was assessed using representatives of two trophic levels in aquatic ecosystems, the bacteria Allivibrio fischeri (commonly used as a screening test organism) and the microalgae Raphidocelis subcapitata (as an alternative test organism that has been proven very sensitive to several IL families). The microalgae were more sensitive than the bacteria, hence, following a precautionary principle, we recommend considering the toxicity towards microalgae as an indicator in future studies regarding the focused ILs. Although four of the studied ILs were derived from a natural amino acid, all were considered hazardous for the aquatic environment, disproving the primary theory that all ILs derived from natural compounds are benign. Furthermore, the modification in the structure of anion and the cation can lead to the increase of toxicity.


Assuntos
Betaína/química , Glicina/química , Líquidos Iônicos/toxicidade , Poluentes Químicos da Água/toxicidade , Aliivibrio fischeri/efeitos dos fármacos , Ânions/química , Cátions/química , Clorofíceas/efeitos dos fármacos , Ecotoxicologia , Biomarcadores Ambientais/efeitos dos fármacos , Líquidos Iônicos/síntese química , Líquidos Iônicos/química , Poluentes Químicos da Água/síntese química , Poluentes Químicos da Água/química
2.
Aquat Toxicol ; 214: 105265, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31416018

RESUMO

The increasing use of nanoparticles (NPs) unavoidably enhances their unintended introduction into the aquatic systems, raising concerns about their nanosafety. This work aims to assess the toxicity of five oxide NPs (Al2O3, Mn3O4, In2O3, SiO2 and SnO2) using the freshwater alga Pseudokirchneriella subcapitata as a primary producer of ecological relevance. These NPs, in OECD medium, were poorly soluble and unstable (displayed low zeta potential values and presented the tendency to agglomerate). Using the algal growth inhibition assay and taking into account the respective 72 h-EC50 values, it was possible to categorize the NPs as: toxic (Al2O3 and SnO2); harmful (Mn3O4 and SiO2) and non-toxic/non-classified (In2O3). The toxic effects were mainly due to the NPs, except for SnO2 which toxicity can mainly be attributed to the Sn ions leached from the NPs. A mechanistic study was undertaken using different physiological endpoints (cell membrane integrity, metabolic activity, photosynthetic efficiency and intracellular ROS accumulation). It was observed that Al2O3, Mn3O4 and SiO2 induced an algistatic effect (growth inhibition without loss of membrane integrity) most likely as a consequence of the cumulative effect of adverse outcomes: i) reduction of the photosynthetic efficiency of the photosystem II (ФPSII); ii) intracellular ROS accumulation and iii) loss of metabolic activity. SnO2 NPs also provoked an algistatic effect probably as a consequence of the reduction of ФPSII since no modification of intracellular ROS levels and metabolic activity were observed. Altogether, the results here presented allowed to categorize the toxicity of the five NPs and shed light on the mechanisms behind NPs toxicity in the green alga P. subcapitata.


Assuntos
Clorofíceas/citologia , Exposição Ambiental , Água Doce , Nanopartículas/toxicidade , Óxidos/toxicidade , Morte Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Clorofíceas/efeitos dos fármacos , Clorofíceas/crescimento & desenvolvimento , Clorofíceas/metabolismo , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Dióxido de Silício/toxicidade , Poluentes Químicos da Água/toxicidade
3.
Sci Total Environ ; 687: 827-838, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31412486

RESUMO

Microalgal toxicity tests using integrative endpoints as algal growth are regularly required to analyse the toxicity of potentially hazardous substances in the aquatic environment. However, these do not provide mechanistic information on the toxic mode of action by which contaminants may affect algae. Bottled waters can be used as a substitute for culturing media and should not impose any stress to the cultured organisms. However, certain chemical components can interfere with specific cell targets which are not revealed by general toxicity assays. The present study investigated the sensitivity of flow cytometry (FCM) to analyse sub-lethal effects of different bottled waters to the freshwater microalgae Raphidocelis subcapitata. Several endpoints were analysed including growth rate, natural pigments content, cell size, complexity, viability and cycle, Reactive Oxygen Species (ROS) formation, mitochondrial membrane potential and Lipid Peroxidation (LPO). Additionally, photosystem II (PSII) performance was analysed by PAM fluorometry, to provide further information on the absorption, distribution and use of energy in photosynthesis. Results indicated that the most sensitive endpoints were the oxidative stress related endpoints ROS formation and LPO, pigment content, morphological endpoints as cell size, complexity and cycle, with growth rate being one of the least sensitive. Although being essential macronutrients for algal growth, the chemical elements Ca, Na, Mg, and NH4 were identified as being primarily responsible for the observed toxicological effects to exposed algae. The applied methodology proved to be of high throughput, simultaneously assembling information on morphological, biochemical, and physiological status of algal cells. FCM also showed potential to reveal mechanistic information on the toxic mode of action of the bottled waters before any effects on algal growth was observed. The used approach demonstrated its potential for being integrated into future microalgal toxicity bioassays for testing chemicals to improve the hazard information obtained from currently approved internationally accepted test guidelines.


Assuntos
Clorofíceas/efeitos dos fármacos , Testes de Toxicidade/métodos , Poluentes Químicos da Água/toxicidade , Biomarcadores , Monitoramento Ambiental/métodos , Citometria de Fluxo , Microalgas
4.
Environ Sci Pollut Res Int ; 26(26): 26991-27001, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31313230

RESUMO

Commercial usage of ZnO nanoparticles has increased recently due to its versatile applications, raising serious environmental concern because of its ultimate release of nanoparticles in aquatic ecosystem. Therefore, it is important to understand the impact of ZnO nanoparticle toxicity especially on algal flora, which is the primary producer in the aquatic food chain. In the current study, algal growth kinetics was assessed after the exposure of zinc oxide nanoparticles and its bulk counterpart to Coelastrella terrestris (Chlorophyceae). Zinc oxide nanoparticles were found to be more toxic (y = 34.673x, R2 = - 0.101, 1 mg L-1 nanoparticle (NP)) than bulk (y = 50.635x, R2 = 0.173, 1 mg L-1 bulk) by entrapping the algal cell surface. Higher toxicity may be due to oxidative stress within the algal cell as confirmed through biochemical analysis. Biochemical parameters revealed stressful physiological condition in the alga under nanoparticle exposure, as lactate dehydrogenase release (18.89 ± 0.2 NP; 13.67 ± 0.2 bulk), lipid peroxidation (0.9147 ± 1.2 NP; 0.7480 ± 0.8 bulk), and catalase activity (4.77 ± 0.1 NP; 3.32 ± 0.1 bulk) were found higher at 1 mg L-1 in the case of nano-form. Surface adsorptions of nanoparticles were observed by SEM. Cell organelle damage, cell wall breakage, and cytoplasm shrinkage were found as responses under toxic condition through SEM and TEM. Toxicity was found to be influenced by dose concentration and exposure period. This study indicates that nano-form of ZnO is found to be more toxic than bulk form to freshwater alga.


Assuntos
Clorofíceas/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Óxido de Zinco/toxicidade , Catalase/metabolismo , Clorofíceas/crescimento & desenvolvimento , Clorofíceas/metabolismo , Relação Dose-Resposta a Droga , Ecossistema , Ecotoxicologia , Água Doce , L-Lactato Desidrogenase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Nanopartículas Metálicas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Microscopia Eletrônica de Varredura , Estresse Oxidativo/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Poluentes Químicos da Água/química , Óxido de Zinco/química
5.
Bioresour Technol ; 289: 121720, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31271916

RESUMO

Haematococcus pluvialis is a main biological resource for the antioxidant astaxanthin production, however, potential modulators and molecular mechanisms underpinning astaxanthin accumulation remain largely obscured. We discovered that provision of ethanol (0.4%) significantly triggered the cellular astaxanthin content up to 3.85% on the 4th day of treatment. Amongst, 95% of the accumulated astaxanthin was esterified, particularly enriched with monoesters. Ultrastructural analysis revealed that ethanol altered cell wall structure and physiological properties. Antioxidant analyses revealed that astaxanthin accumulation offset the ethanol induced oxidative stress. Ethanol treatment reduced carbohydrates while increased lipids and jasmonic acid production. Transcriptomic analysis uncovered that ethanol orchestrated the expression of crucial genes involved in carotenogenesis, e.g. PSY, BKT and CRTR-b were significantly upregulated. Moreover, methyl jasmonic acid synthesis was induced and played a major role in regulating the carotenogenic genes. The findings uncovered the novel viewpoint in the intricate transcriptional regulatory mechanisms of astaxanthin biosynthesis.


Assuntos
Clorofíceas/metabolismo , Ciclopentanos/metabolismo , Etanol/farmacologia , Oxilipinas/metabolismo , Clorofíceas/efeitos dos fármacos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Xantofilas/biossíntese
6.
Sci Total Environ ; 689: 133-140, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31271982

RESUMO

Some metal-based engineered nanoparticles (ENPs) undergo fast dissolution and/or aggregation when they are released in the environment. The underlying processes are controlled by psychochemical/biological parameters of the environment and the properties of the particles. In this study, we investigated the interaction between algal cells and zero valent copper nanoparticles (Cu0-ENPs) to elucidate how the cells influence the dissolution and aggregation kinetics of the particles and how these kinetics influence the cellular uptake of Cu. Our finding showed that the concentration of dissolved Cu ([Cu]dissolved) in the supernatant of the culture media without algal cells was higher than the [Cu]dissolved in the media with algal cells. In the absence of the cells, dissolved organic matter (DOC) increased the dissolution of the particle due to increasing the stability of the particles against aggregation, thus increasing the available surface area. In the presence of algae, Cu0-ENPs heteroaggregated with the cells. Thus, the available surface area decreased over time and this resulted in a low dissolution rate of the particles. The DOC corona on the surface of the particles increased the heteroaggregation of the particles with the cells and decreases the uptake of the particles. Our findings showed that microorganisms influence the fate of ENPs in the environment, and they do so by modifying the dissolution and aggregation kinetics of the Cu0-ENPs.


Assuntos
Clorofíceas/metabolismo , Cobre/metabolismo , Nanopartículas Metálicas , Clorofíceas/efeitos dos fármacos , Liberação Controlada de Fármacos , Substâncias Húmicas/análise , Cinética , Solubilidade
7.
Bioresour Technol ; 287: 121419, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31078811

RESUMO

Microalgae are a promising biofuel resource, but their high cost and low productivity hinder their commercial applications. In the present study, Monoraphidium sp. QLZ-3 was cultivated in walnut shell extracts (WSE) supplemented with carbon dioxide (CO2). Biomass was enhanced from 0.40 g L-1 to 1.18 g L-1, and lipid content reached 49.54% in WSE-12% CO2 media. Biomass and lipid productivity reached 196.88 and 97.52 mg L-1 d-1, which were 1.33- and 1.57-fold higher than those of the control, respectively. The amount of carbohydrates increased, but the protein contents decreased. Furthermore, the application of CO2 promoted nutrient and polyphenol absorption and upregulated the expression levels of lipid biosynthetic genes of this WSE-cultivated alga. These results indicated that coupling WSE and CO2 could be an efficient strategy to enhance biofuel production by microalgae.


Assuntos
Biomassa , Dióxido de Carbono/farmacologia , Clorofíceas/metabolismo , Juglans/química , Lipídeos/biossíntese , Microalgas/metabolismo , Nutrientes , Biocombustíveis , Metabolismo dos Carboidratos , Carboidratos , Clorofíceas/efeitos dos fármacos , Microalgas/efeitos dos fármacos
8.
Sci Total Environ ; 682: 70-79, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31108270

RESUMO

Gold nanorods have shown to pose adverse effects to biota. Whether these effects may be potentiated through prolonged exposure has been rarely studied. Therefore, this work aimed at evaluating the effects of long-term exposure to sublethal levels of cetyltrimethylammonium bromide (CTAB) coated gold nanorods (Au-NR) on two freshwater microalgae: Chlorella vulgaris and Raphidocelis subcapitata. These algae were exposed to several concentrations of Au-NR for 72 h and, afterwards, to the corresponding EC5,72h, for growth, during 16 days. The sensitivity of the two algae to Au-NR was assessed at days 0, 4, 8, 12 and 16 (D0, D4, D8, D12 and D16, respectively) after a 72-h exposure to several concentrations of Au-NR. At the end of the assays, effects on yield and population growth rate were evaluated. Raphidocelis subcapitata was slightly more sensitive to Au-NR than C. vulgaris: EC50,72h,D0 for yield were 48.1 (35.3-60.9) and 70.5 (52.4-88.6) µg/L Au-NR, respectively while for population growth rate were above the highest tested concentrations (53 and 90 µg/L, respectively). For R. subcapitata the long-term exposure to Au-NR increased its sensitivity to this type of nanostructures. For C. vulgaris, a decrease on the effects caused by Au-NR occurred over time, with no significant effects being observed for yield or population growth rate at D12 and D16. The capping agent CTAB caused reductions in yield above 30% (D0) for both algae at the concentration matching the one at the highest Au-NR tested concentration. When exposed to CTAB, the highest inhibition values were 69% (D4) and 21.3% (D8) for R. subcapitata, and 64% (D12) and 21% (D16) to C. vulgaris, for yield and population growth rate, respectively. These results suggested long-term exposures should be included in ecological risk assessments since short-term standard toxicity may either under- or overestimate the risk posed by Au-NR.


Assuntos
Clorofíceas/efeitos dos fármacos , Coloide de Ouro/toxicidade , Microalgas/efeitos dos fármacos , Nanotubos/toxicidade , Poluentes Químicos da Água/toxicidade , Chlorella vulgaris/efeitos dos fármacos , Água Doce , Fatores de Tempo
9.
Enzyme Microb Technol ; 127: 1-5, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31088611

RESUMO

A two-step strategy was employed to culture Dunaliella tertiolecta, an oleaginous unicellular green alga, combined by the salt stress and sodium azide intervention, to observe their effects on its lipid accumulation. When the algae cultured at different salt concentrations reached the logarithmic growth phase, sodium azide was added. The results showed that the addition of sodium azide significantly increased the lipid content and had no significant effect on cell biomass. The lipid yield and single cell lipid content under 50 µM sodium azide increased by 10.4% and 21.7%. Under the two-step culture condition, combining of the treatment of 50 µM sodium azide and 2.5 M salt stress, the total lipid productivity and single-cell lipid content were 10% and 70.5% higher than that of the control. It seemed that sodium azide and salinity might have a synergistic effect on the lipid accumulation of D. tertiolecta. It can be concluded that sodium azide is an effective inducer of lipid accumulation in D. tertiolecta, and two-stage cultivation is a feasible way to improve lipid accumulation in microalgae.


Assuntos
Clorofíceas/efeitos dos fármacos , Clorofíceas/metabolismo , Inibidores Enzimáticos/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Estresse Salino , Azida Sódica/metabolismo , Biotecnologia/métodos , Clorofíceas/crescimento & desenvolvimento , Lipídeos/análise
10.
Enzyme Microb Technol ; 127: 17-21, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31088612

RESUMO

Glycerol-3-phosphate (G3P) is the important precursors for triacylglycerol synthesis, while glycerol-3-phosphate dehydrogenase (GPDH) determines the formation of G3P. In this study, two GDPH genes, Dtgdp1 and Dtgdp2 were isolated and identified from Dunaliella tertiolecta. The full-length Dtgdp1 and Dtgdp2 CDS were 2016 bp and 2094 bp, which encoded two putative protein sequences of 671 and 697 amino acids with predicted molecular weights of 73.64 kDa and 76.73 kDa, respectively. DtGDP1 and DtGDP2 both had a close relationship with those of algal and higher plants. DtGDP1 shared two conserved superfamily (A1 and A2) and four signature motifs (I-IV), and the DtGDP2 showed six signature domains (from motif I to VI) and DAO_C conserved family. Our previous work showed that the triethylamine intervention could greatly increase the triacylglycerol content (up to 80%) of D. tertiolecta. This study aims to investigate the effect of triethylamine on GPDH expression. Results showed that, when treated by triethylamine at 100 ppm and 150 ppm, the expression levels of Dtgdp1 and Dtgpd2 were increased to 5.121- and 56.964-fold compared with the control, respectively. Triethylamine seemed to enhance lipid metabolic flow by inducing the expressions of Dtgdp1 and Dtgdp2 to increase the lipid content, which provides a new insight into the desired pathway of lipid synthesis in algae through genetic engineering.


Assuntos
Clorofíceas/efeitos dos fármacos , Clorofíceas/metabolismo , Etilaminas/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glicerolfosfato Desidrogenase/biossíntese , Metabolismo dos Lipídeos/efeitos dos fármacos , Motivos de Aminoácidos , Clorofíceas/enzimologia , Clorofíceas/genética , Glicerolfosfato Desidrogenase/química , Glicerolfosfato Desidrogenase/genética , Peso Molecular
11.
PLoS One ; 14(4): e0214398, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30943225

RESUMO

Nanoparticles (NPs) are causing threats to the environment. Silver NPs (AgNPs) are increasingly used in commercial products and may end up in freshwater ecosystems. The freshwater organisms are vulnerable due to water-borne and dietary exposure to AgNPs. Surface properties play an important role in the fate and behavior of AgNPs in the aquatic environment and their effects on organisms. However, effects of surface properties of AgNPs on organisms are poorly understood. In this study, we explored the effects of AgNPs coated with three different ligands; Tyrosine (T-AgNP), Epigallocatechin gallate (E-AgNP) and Curcumin (C-AgNP) in relation to the toxicity to a key aquatic organism; Daphnia carinata. The study focused on how coatings determine fate of NPs in the medium, mortality, feeding behaviour, bioaccumulation and trophic transfer from the freshwater alga, Raphidocelis subcapitata to daphnids. NP stability tests indicated that T-AgNPs were least stable in the ASTM daphnia medium while C-AgNPs were most stable. 48 h EC50 values of AgNPs to D. carinata were in the order of E-AgNP (19.37 µg L-1) > C-AgNP (21.37 µg L-1) > T-AgNP (49.74 µg L-1) while the 48 h EC50 value of Ag+ ions was 1.21 µg L-1. AgNP contaminated algae significantly decreased the feeding rates of daphnids. However, no significant differences were observed in feeding rates between algae contaminated with differently coated AgNPs. Trophic transfer studies showed that AgNPs were transferred from algae to daphnids. The bioacumulation of AgNPs in algae and the diet-borne bioaccumulation of AgNPs in daphnids varied for differently coated AgNPs. Bioaccumulation of C-AgNPs in algae was 1.5 time higher than T-AgNPs. However, the accumulation of T-AgNPs in daphnids via trophic transfer was 2.6 times higher than T-AgNPs. The knowledge generated from this study enhances the understanding of surface property dependent toxicity, bioaccumulation and trophic transfer of AgNPs in aquatic environments.


Assuntos
Clorofíceas/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Ecossistema , Poluentes Químicos da Água/toxicidade , Animais , Organismos Aquáticos/efeitos dos fármacos , Catequina/análogos & derivados , Catequina/química , Curcumina/química , Água Doce , Humanos , Ligantes , Nanopartículas Metálicas/química , Nanopartículas Metálicas/toxicidade , Prata/química , Prata/toxicidade , Nitrato de Prata/química , Propriedades de Superfície , Tirosina/química , Poluentes Químicos da Água/química
12.
Mar Drugs ; 17(3)2019 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-30909380

RESUMO

Carotenoids are lipophilic pigments found in plants and algae, as well as some bacteria, archaea, and fungi that serve two functions-(1) as light harvesting molecules-primary carotenoids, and (2) as antioxidants, acting against reactive oxygen species⁻secondary carotenoids. Because of their strong antioxidant properties, they are also valuable for the development of anti-aging and photo-protective cosmetic applications. Of particular interest is the carotenoid phytoene, for its colorless and UV absorption characteristics. In this study, we targeted a reduction of phytoene desaturase (PDS) activity with the pigment-inhibiting herbicide 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]pyridin-4-one (fluridone), which leads to the over-accumulation of phytoene in the recently characterized microalgal strain Chlorococcum sp. (UTEX B 3056). After post-incubation with fluridone, phytoene levels were measured at ~33 ug/mg cell tissue, as opposed to non-detectable levels in control cultures. Hence, the novel microalga Chlorococcum sp. is a viable candidate for the production of the high-value carotenoid phytoene and subsequent applications in cosmeceuticals, as well as more obvious nutraceutical and pharmaceutical applications.


Assuntos
Carotenoides/metabolismo , Clorofíceas/efeitos dos fármacos , Clorofíceas/metabolismo , Piridonas/farmacologia , Carotenoides/biossíntese , Ácidos Graxos/metabolismo , Oxirredutases/antagonistas & inibidores , Oxirredutases/metabolismo
13.
J Photochem Photobiol B ; 194: 21-31, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30897400

RESUMO

Aedes aegypti mosquitos are widespread vectors of several diseases and their control is of primary importance for biological and environmental reasons, and novel safe insecticides are highly desirable. An eco-friendly photosensitizing magnetic nanocarrier with larvicidal effects on Aedes aegypti was proposed. The innovative core-shell hybrid nanomaterial was synthesized by combining peculiar magnetic nanoparticles (called Surface Active Maghemite Nanoparticles - SAMNs, the core) and chlorin-e6 as photosensitizer (constituting the shell) via self-assembly in water. The hybrid nanomaterial (SAMN@chlorin) was extensively characterized and tested for the photocidal activity on larvae of Aedes aegypti. The SAMN@chlorin core-shell nanohybrid did not present any toxic effect in the dark, but, upon light exposure, showed a higher photocidal activity than free chlorin-e6. Moreover, the eco-toxicity of SAMN@chlorin was determined in adults and neonates of Daphnia magna, where delayed toxicity was observed only after prolonged (≥4 h) exposure to intense light, on the green alga Pseudokirchneriella subcapitata and on the duckweed Lemna minor on which no adverse effects were observed. The high colloidal stability, the physico-chemical robustness and the magnetic drivability of the core-shell SAMN@chlorin nanohybrid, accompanied by the high photocidal activity on Aedes aegypti larvae and reduced environmental concerns, can be proposed as a safe alternative to conventional insecticides.


Assuntos
Aedes , Compostos Férricos/química , Inseticidas/química , Larva , Nanopartículas/química , Porfirinas/química , Animais , Clorofíceas/efeitos dos fármacos , Clorofíceas/efeitos da radiação , Daphnia/efeitos dos fármacos , Daphnia/efeitos da radiação , Inseticidas/toxicidade , Luz , Porfirinas/toxicidade , Propriedades de Superfície , Água/química
14.
Eur Biophys J ; 48(3): 231-248, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30806730

RESUMO

We examined the response of algal cells to laboratory-induced cadmium stress in terms of physiological activity, autonomous features (motility and fluorescence), adhesion dynamics, nanomechanical properties, and protein expression by employing a multimethod approach. We develop a methodology based on the generalized mathematical model to predict free cadmium concentrations in culture. We used algal cells of Dunaliella tertiolecta, which are widespread in marine and freshwater systems, as a model organism. Cell adaptation to cadmium stress is manifested through cell shape deterioration, slower motility, and an increase of physiological activity. No significant change in growth dynamics showed how cells adapt to stress by increasing active surface area against toxic cadmium in the culture. It was accompanied by an increase in green fluorescence (most likely associated with cadmium vesicular transport and/or beta-carotene production), while no change was observed in the red endogenous fluorescence (associated with chlorophyll). To maintain the same rate of chlorophyll emission, the cell adaptation response was manifested through increased expression of the identified chlorophyll-binding protein(s) that are important for photosynthesis. Since production of these proteins represents cell defence mechanisms, they may also signal the presence of toxic metal in seawater. Protein expression affects the cell surface properties and, therefore, the dynamics of the adhesion process. Cells behave stiffer under stress with cadmium, and thus, the initial attachment and deformation are slower. Physicochemical and structural characterizations of algal cell surfaces are of key importance to interpret, rationalize, and predict the behaviour and fate of the cell under stress in vivo.


Assuntos
Cádmio/farmacologia , Clorofíceas/citologia , Clorofíceas/fisiologia , Laboratórios , Estresse Fisiológico/efeitos dos fármacos , Disponibilidade Biológica , Cádmio/metabolismo , Adesão Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Clorofíceas/efeitos dos fármacos , Clorofíceas/metabolismo , Eletroquímica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Cinética , Modelos Biológicos
15.
Toxins (Basel) ; 11(1)2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30650515

RESUMO

Globally, eutrophication and warming of aquatic ecosystems has increased the frequency and intensity of cyanobacterial blooms and their associated toxins, with the simultaneous detection of multiple cyanotoxins often occurring. Despite the co-occurrence of cyanotoxins such as microcystins and anatoxin-a (ATX) in water bodies, their effects on phytoplankton communities are poorly understood. The individual and combined effects of microcystin-LR (MC-LR) and ATX on the cyanobacteria Microcystis spp., and Anabaena variabilis (a.k.a. Trichormus variabilis), and the chlorophyte, Selenastrum capricornutum were investigated in the present study. Cell density, chlorophyll-a content, and the maximum quantum efficiency of photosystem II (Fv/Fm) of Microcystis cells were generally lowered after exposure to ATX or MC-LR, while the combined treatment with MC-LR and ATX synergistically reduced the chlorophyll-a concentration of Microcystis strain LE-3. Intracellular levels of microcystin in Microcystis LE-3 significantly increased following exposure to MC-LR + ATX. The maximum quantum efficiency of photosystem II of Anabaena strain UTEX B377 declined during exposure to the cyanotoxins. Nitrogen fixation by Anabaena UTEX B377 was significantly inhibited by exposure to ATX, but was unaffected by MC-LR. In contrast, the combination of both cyanotoxins (MC-LR + ATX) caused a synergistic increase in the growth of S. capricornutum. While the toxins caused an increase in the activity of enzymes that scavenge reactive oxygen species in cyanobacteria, enzyme activity was unchanged or decreased in S. capricornutum. Collectively this study demonstrates that MC-LR and ATX can selectively promote and inhibit the growth and performance of green algae and cyanobacteria, respectively, and that the combined effect of these cyanotoxins was often more intense than their individual effects on some strains. This suggests that the release of multiple cyanotoxins in aquatic ecosystems, following the collapse of blooms, may influence the succession of plankton communities.


Assuntos
Anabaena/efeitos dos fármacos , Clorofíceas/efeitos dos fármacos , Microcistinas/toxicidade , Microcystis/efeitos dos fármacos , Tropanos/toxicidade , Anabaena/crescimento & desenvolvimento , Anabaena/metabolismo , Clorofíceas/crescimento & desenvolvimento , Clorofíceas/metabolismo , Sinergismo Farmacológico , Glutationa Transferase/metabolismo , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Fixação de Nitrogênio/efeitos dos fármacos , Peroxidase/metabolismo , Superóxido Dismutase/metabolismo
16.
Ecotoxicol Environ Saf ; 171: 84-91, 2019 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-30597320

RESUMO

In this study, we estimated the toxicity risks from river sediments that were affected by multiple pollutants in the Haihe River Basin. We used a range of methods to determine the concentrations, bioavailability, and toxicity of a range of metals and contaminants in sediments and sediment porewater and then assessed the ecological risks and toxicity using various multivariate statistical approaches. We found that more than 70% of the samples were toxic. The concentrations of non-ionic ammonia (0.168-9.295 mg L-1) were generally high in the sediment porewater, while the concentrations of bioavailable chromium (Cr) and polycyclic aromatic hydrocarbons (PAHs) were also high in the porewater samples from NW01 and NW02, respectively. We used the toxic unit (TU) approach, based on the bioavailable pollutant concentrations, to determine the toxicity of PAHs, heavy metals, and non-ionic ammonia in river sediments and sediment porewater. We found that non-ionic ammonia was the main source of toxicity for Daphnia magna, and that Cr and zinc were toxic for Pseudokirchneriella subcapitata and Chironomus dilutus. By combining various indexes, we identified the main contributors to the toxicity in sediments collected from rivers affected by multiple pollutants.


Assuntos
Amônia/toxicidade , Cromo/toxicidade , Sedimentos Geológicos/química , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Poluentes Químicos da Água/toxicidade , Amônia/análise , Amônia/farmacocinética , Animais , Disponibilidade Biológica , China , Chironomidae/efeitos dos fármacos , Clorofíceas/efeitos dos fármacos , Cromo/análise , Cromo/farmacocinética , Daphnia/efeitos dos fármacos , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/farmacocinética , Medição de Risco , Rios/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/farmacocinética , Zinco/análise , Zinco/farmacocinética , Zinco/toxicidade
17.
Environ Sci Pollut Res Int ; 26(3): 2409-2420, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30467754

RESUMO

Microalgae are key test organisms to assess the effects of chemicals on aquatic ecosystems. Zinc oxide nanoparticles (ZnO NPs) as a widely used metal oxide is considered a potential threat to these primary producers at the base of the food chain. This study investigates the toxicity of ZnO NPs, bulk ZnO, and Zn2+ to the representative of freshwater microalgae, Raphidocelis subcapitata. To examine the effect of shape and size of nanoparticles, two types of spherical ZnO NPs with different sizes (20 and 40 nm) and two types of rod-shaped ZnO NPs with different lengths (100 and 500 nm) were synthesized. Microalgal cells were exposed to eight concentrations of each ZnO NP type from 0.01 to 0.7 mg/L for 96 h. The results showed that 0.7 mg/L of ZnO NP could completely inhibit algal growth. Size did not interfere with toxicity in spherical ZnO NPs, but the toxicity decreased by increasing the size of rod-shaped ZnO NPs. Spherical ZnO NPs acted more destructive to microalgal cells than nanorod shape. The addition of 0.7 mg/L of ZnO nanorods to samples caused 30% cell death, while 50% cell death was observed by adding the same concentration of nanospherical ZnO. Nano ZnO revealed to be more toxic than bulk ZnO and Zn2+. The Zn2+ released from dissolution of ZnO NPs was one of the sources of toxicity, but the ZnO nanostructures were also an important factor in the toxicity.


Assuntos
Clorofíceas/efeitos dos fármacos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/toxicidade , Microalgas/efeitos dos fármacos , Óxido de Zinco/toxicidade , Relação Dose-Resposta a Droga , Ecotoxicologia , Água Doce , Nanopartículas Metálicas/administração & dosagem , Óxido de Zinco/administração & dosagem , Óxido de Zinco/química
18.
SAR QSAR Environ Res ; 30(1): 39-50, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30477347

RESUMO

Both the acute toxicity and chronic toxicity data on aquatic organisms are indispensable parameters in the ecological risk assessment priority chemical screening process (e.g. persistent, bioaccumulative and toxic chemicals). However, most of the present modelling actions are focused on developing predictive models for the acute toxicity of chemicals to aquatic organisms. As regards chronic aquatic toxicity, considerable work is needed. The major objective of the present study was to construct in silico models for predicting chronic toxicity data for Daphnia magna and Pseudokirchneriella subcapitata. In the modelling, a set of chronic toxicity data was collected for D. magna (21 days no observed effect concentration (NOEC)) and P. subcapitata (72 h NOEC), respectively. Then, binary classification models were developed for D. magna and P. subcapitata by employing the k-nearest neighbour method (k-NN). The model assessment results indicated that the obtained optimum models had high accuracy, sensitivity and specificity. The model application domain was characterized by the Euclidean distance-based method. In the future, the data gap for other chemicals within the application domain on their chronic toxicity for D. magna and P. subcapitata could be filled using the models developed here.


Assuntos
Clorofíceas/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Relação Quantitativa Estrutura-Atividade , Testes de Toxicidade Crônica/métodos , Poluentes Químicos da Água/toxicidade , Animais , Análise por Conglomerados , Simulação por Computador , Medição de Risco
19.
Ecotoxicol Environ Saf ; 168: 287-297, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30390527

RESUMO

In the present work, quantitative structure-activity relationship (QSAR) models have been developed for ecotoxicity of pharmaceuticals on four different aquatic species namely Pseudokirchneriella subcapitata, Daphnia magna, Oncorhynchus mykiss and Pimephales promelas using genetic algorithm (GA) for feature selection followed by Partial Least Squares regression technique according to the Organization for Economic Co-operation and Development (OECD) guidelines. Double cross-validation methodology was employed for selecting suitable models. Only 2D descriptors were used for capturing chemical information and model building, whereas validation of the models was performed by considering various stringent internal and external validation metrics. Interestingly, models could be developed even without using any LogP terms in contrary to the usual dependence of toxicity on lipophilicity. However, the current manuscript proposes highly robust and more predictive models employing computed logP descriptors. The applicability domain study was performed in order to set a predefined chemical zone of applicability for the obtained QSAR models, and the test compounds falling outside the domain were not taken for further analysis while making a prioritized list. An additional comparison was made with ECOSAR, an online expert system for toxicity prediction of organic pollutants, in order to prove predictability of the obtained models. The obtained robust consensus models were utilized to predict the toxicity of a large dataset of approximately 9300 drug-like molecules in order to prioritize the existing drug-like substances in accordance to their acute predicted aquatic toxicities following a scaling technique. Finally, prioritized lists of 500 most toxic chemicals obtained by respective consensus models and those predicted from ECOSAR tool have been reported.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Consenso , Ecotoxicologia , Compostos Orgânicos/toxicidade , Relação Quantitativa Estrutura-Atividade , Poluentes Químicos da Água/toxicidade , Animais , Clorofíceas/efeitos dos fármacos , Cyprinidae , Daphnia/efeitos dos fármacos , Bases de Dados Factuais , Oncorhynchus mykiss , Preparações Farmacêuticas/análise , Testes de Toxicidade
20.
Ecotoxicol Environ Saf ; 168: 388-393, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30396135

RESUMO

Silver nanomaterials (AgNMs) of different shapes and sizes are potentially toxic to aquatic organisms. However, studies on the toxicity of AgNMs and on their shape-dependent effects on algae are scarce. The present study evaluated the effects of three AgNMs (silver nanospheres, AgNPs; silver nanowires, AgNWs; silver nanoplates, AgPLs) with different shapes coated with polyvinylpyrrolidone on the growth and photosynthetic performance of an alga, Chlorococcum infusionum. We used growth measurements and determined the photosynthetic parameters based on chlorophyll fluorescence transients in the algal cells exposed to different concentrations of the three AgNMs. The effective concentrations at 50% (EC50) of AgNPs, AgNWs, and AgPLs were calculated to be 0.1, 0.045, and 0.021 mg/L, respectively. The results showed that the toxicity of AgNMs in C. infusionum was in the order, AgPLs (40 nm diameter) > AgNWs (21,000 nm length × 42 nm diameter) > AgNPs (57 nm diameter), based on the decrease in growth and three photosynthetic activities. We propose that the toxic potential of AgNMs is primarily dependent on their diameter and secondarily on their shape. Overall, this study provides, for the first time, a comparison of the growth and photosynthetic activities of C. infusionum exposed to AgNMs of three different shapes.


Assuntos
Clorofíceas/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Clorofíceas/metabolismo , Nanopartículas Metálicas/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Fotossíntese/efeitos dos fármacos , Povidona/química , Povidona/toxicidade
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