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1.
Ecotoxicol Environ Saf ; 208: 111628, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396148

RESUMO

Metals may cause damage to the biota of contaminated environments. Moreover, using multiple endpoints in ecotoxicological studies is useful to better elucidate the mechanisms of toxicity of these compounds. Therefore, this study aimed to evaluate the effects of cadmium (Cd) and cobalt (Co) on growth, biochemical and photosynthetic parameters of the microalgae Raphidocelis subcapitata, through quantification of lipid classes composition, chlorophyll a (Chl a) content, maximum (ΦM) and effective (Φ'M) quantum yields and efficiency of the oxygen-evolving complex (OEC). Both metals affected the algal population growth, with an IC50-96h of 0.67 and 1.53 µM of Cd and Co, respectively. Moreover, the metals led to an increase in the total lipid content and reduced efficiency of OEC and ΦM. Cell density was the most sensitive endpoint to detect Cd toxicity after 96 h of treatment. Regarding Co, the photosynthetic parameters were the most affected and the total lipid content was the most sensitive endpoint as it was altered by the exposure to this metal in all concentrations. Cd led to increased contents of the lipid class wax esters (0.89 µM) and phospholipids (PL - at 0.89 and 1.11 µM) and decreased values of triglycerides (at 0.22 µM) and acetone-mobile polar lipids (AMPL - at 0.44 and 1.11 µM). The percentage of free fatty acids (FFA) and PL of microalgae exposed to Co increased, whereas AMPL decreased in all concentrations tested. We were able to detect differences between the toxicity mechanisms of each metal, especially how Co interferes in the microalgae at a biochemical level. Furthermore, to the best of our knowledge, this is the first study reporting Co effects in lipid classes of a freshwater Chlorophyceae. The damage caused by Cd and Co may reach higher trophic levels, causing potential damage to the aquatic communities as microalgae are primary producers and the base of the food chain.


Assuntos
Cádmio/toxicidade , Clorofíceas/fisiologia , Cobalto/toxicidade , Poluentes Químicos da Água/toxicidade , Clorofíceas/efeitos dos fármacos , Clorofila A , Ecotoxicologia , Água Doce/química , Metais/farmacologia , Microalgas/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II
2.
Ecotoxicol Environ Saf ; 207: 111264, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32911184

RESUMO

This study investigated the effect of the herbicide metolachlor (MET) on the redox homeostasis of the freshwater green alga Pseudokirchneriella subcapitata. At low MET concentrations (≤40 µg L-1), no effects on algal cells were detected. The exposure of P. subcapitata to 45-235 µg L-1 MET induced a significant increase of reactive oxygen species (ROS). The intracellular levels of ROS were particularly increased at high (115 and 235 µg L-1) but environmentally relevant MET concentrations. The exposure of algal cells to 115 and 235 µg L-1 MET originated a decrease in the levels of antioxidants molecules (reduced glutathione and carotenoids) as well as a reduction of the activity of scavenging enzymes (superoxide dismutase and catalase). These results suggest that antioxidant (non-enzymatic and enzymatic) defenses were affected by the excess of MET. As consequence of this imbalance (ROS overproduction and decline of the antioxidant system), ROS inflicted oxidative injury with lipid peroxidation and damage of cell membrane integrity. The results provide further insights about the toxic modes of action of MET on a non-target organism and emphasize the relevance of toxicological studies in the assessment of the impact of herbicides in freshwater environments.


Assuntos
Acetamidas/toxicidade , Clorofíceas/efeitos dos fármacos , Herbicidas/toxicidade , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Catalase/metabolismo , Clorofíceas/fisiologia , Água Doce , Glutationa/metabolismo , Homeostase/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo
3.
Aquat Toxicol ; 228: 105646, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33011648

RESUMO

2,4-dinitrophenol (2,4-DNP) is a phenolic compound used as a wood preservative or pesticide. The chemical is hazardous to freshwater organisms. Although 2,4-DNP poses ecological risks, only a few of its aquatic environmental risks have been investigated and very limited guidelines for freshwater aquatic ecosystems have been established by governments. This study addresses the paucity of 2,4-DNP toxicity data for freshwater ecosystems and the current lack of highly reliable trigger values for this highly toxic compound. We conducted acute bioassays using 12 species from nine taxonomic groups and chronic assays using five species from four taxonomic groups to improve the quality of the dataset and enable the estimation of protective concentrations based on species sensitivity distributions. The acute and hazardous concentrations of 2,4-DNP in 5% of freshwater aquatic species (HC5) were determined to be 0.91 (0.32-2.65) mg/L and 0.22 (0.11-0.42) mg/L, respectively. To the best of our knowledge, this is the first report of a suggested chronic HC5 for 2,4-DNP and it provides the much-needed fundamental data for the risk assessment and management of freshwater ecosystems.


Assuntos
2,4-Dinitrofenol/análise , Ecossistema , Monitoramento Ambiental , Água Doce/química , Praguicidas/toxicidade , Poluentes Químicos da Água/análise , Animais , Organismos Aquáticos/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Chlamydomonas/efeitos dos fármacos , Clorofíceas/efeitos dos fármacos , Embrião não Mamífero/efeitos dos fármacos , Euglena/efeitos dos fármacos , Oryzias , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Especificidade da Espécie , Testes de Toxicidade Aguda , Testes de Toxicidade Crônica , Qualidade da Água
4.
Ecotoxicol Environ Saf ; 205: 111291, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32956865

RESUMO

The purpose of this study was to determine the acute toxicity in aquatic organisms of one biocidal active substance and six metabolites derived from biocidal active substances and to assess the suitability of available QSAR models to predict the obtained values. We have reported the acute toxicity in sewage treatment plant (STP) microorganisms, in the freshwater microalgae Pseudokirchneriella subcapitata and in Daphnia magna following OECD test methods. We have also identified in silico models for acute toxicity of these trophic levels currently available in widely recognized platforms such as VEGA and the OECD QSAR ToolBox. A total of six, four and two models have been selected for Daphnia, algae and microorganisms, respectively. Finally, we have compared the in silico and in vivo data for the seven compounds plus two previously assayed biocidal substances. None of the compounds tested were toxic for Daphnia and STP microorganisms. For microalgae, CGA71019 (1,2,4 triazole) presented an ErC50 value of 38.3 mg/L. The selected in silico models have provided lower EC50 values and are therefore more conservative. Models from the OECD QSAR ToolBox predicted values for 7 out of 9 and for 4 out of 9 chemicals for Daphnia and P. subcapitata, respectively. No predictive models were identified in such platform for STP microorganism's acute effects. In terms of models's specificity, biocide-specific models, developed from curated datasets integrated by biocidal active substances and implemented in VEGA, perform better in the case of microalgae but for Daphnia an alternative, non biocide-specific has revealed a better performance. For STP microorganisms only biocide-specific models have been identified.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Desinfetantes/toxicidade , Modelos Biológicos , Poluentes Químicos da Água/toxicidade , Animais , Clorofíceas/efeitos dos fármacos , Simulação por Computador , Daphnia/efeitos dos fármacos , Desinfetantes/química , Desinfetantes/metabolismo , Água Doce/química , Microalgas/efeitos dos fármacos , Relação Quantitativa Estrutura-Atividade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo
5.
Ecotoxicol Environ Saf ; 201: 110737, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32505758

RESUMO

Macrolide antibiotics are common contaminants in the aquatic environment. They are toxic to a wide range of primary producers, inhibiting the algal growth and further hindering the delivery of several ecosystem services. Yet the molecular mechanisms of macrolides in algae remain undetermined. The objectives of this study were therefore to: 1. evaluate whether macrolides at the environmentally relevant level inhibit the growth of algae; and 2. test the hypothesis that macrolides bind to ribosome and inhibit protein translocation in algae, as it does in bacteria. In this study, transcriptomic analysis was applied to elucidate the toxicological mechanism in a model green alga Raphidocelis subcapitata treated with 5 and 90 µg L-1 of a typical macrolide roxithromycin (ROX). While exposure to ROX at 5 µg L-1 for 7 days did not affect algal growth and the transciptome, ROX at 90 µg L-1 resulted in 45% growth inhibition and 2306 (983 up- and 1323 down-regulated) DEGs, which were primarily enriched in the metabolism of energy, lipid, vitamins, and DNA replication and repair pathways. Nevertheless, genes involved in pathways in relation to translation and protein translocation and processing were dysregulated. Surprisingly, we found that genes involved in the base excision repair process were mostly repressed, suggesting that ROX may be genotoxic and cause DNA damage in R. subcapitata. Taken together, ROX was unlikely to pose a threat to green algae in the environment and the mode of action of macrolides in bacteria may not be directly extrapolated to green algae.


Assuntos
Antibacterianos/toxicidade , Clorofíceas/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Roxitromicina/toxicidade , Poluentes Químicos da Água/toxicidade , Clorofíceas/genética , Clorofíceas/crescimento & desenvolvimento , Dano ao DNA/genética , Reparo do DNA/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos
6.
Aquat Toxicol ; 224: 105496, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32408003

RESUMO

Predicting the toxicity of organic toxicants to aquatic life through chemometric approach is challenging area. In this paper, a six-descriptor quantitative structure-activity/toxicity relationship (QSAR/QSTR) model was successfully developed for the toxicity pEC10 of organic chemicals against Pseudokirchneriella subcapitata, by applying support vector machine (SVM) together with genetic algorithm. A sufficiently large data set consisting of 334 organic chemicals was randomly divided into a training set (167 compounds) and a test set (167 compounds) with a ratio of 1:1. The optimal SVM model possesses coefficient of determination R2 of 0.76 and mean absolute error (MAE) of 0.60 for the training set and R2 of 0.75 and MAE of 0.61 for the test set. Compared with other models reported in the literature, our SVM model for the toxicity pEC10 shows significant statistical quality and satisfactory predictive ability, although it has fewer molecular descriptors and more samples in the test set. A QSTR model for pEC50 of organic chemicals against Pseudokirchneriella subcapitata was also developed with the same subsets and molecular descriptors.


Assuntos
Clorofíceas/efeitos dos fármacos , Ecotoxicologia/métodos , Compostos Orgânicos , Poluentes Químicos da Água , Compostos Orgânicos/química , Compostos Orgânicos/toxicidade , Relação Quantitativa Estrutura-Atividade , Máquina de Vetores de Suporte , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade
7.
Aquat Toxicol ; 222: 105449, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32109756

RESUMO

Metolachlor (MET) is an herbicide widely used and frequently found (at µg L-1) in aquatic systems. This work aimed to study the modes of action of MET on the green microalga Pseudokirchneriella subcapitata. Algae exposed to 115 or 235 µg L-1 MET, for 48 or 72 h, presented a reduction of metabolic activity, chlorophyll a and b content and photosynthetic efficiency. The exposure to 115 or 235 µg L-1 MET also induced growth yield reduction, mean cell biovolume increase and alteration of the typical algae shape (cells lunate or helically twisted) to "French croissant"-type; at these MET concentrations, algal population was mainly composed by multinucleated cells (≥ 4 nuclei), which suggest that MET impairs the normal progression of the reproductive cycle but did not hinder nuclear division. The accumulation of multinucleated cells seems to be the consequence of the incapacity of the parent cell to release the autospores. In conclusion, MET disrupts the physiology of P. subcapitata cells; the disturbance of the progression of the reproductive cycle should be in the origin of growth slowdown (or even its arrest), increase of mean cell biovolume and modification of algal shape. This work contributed to elucidate, in a systematically and integrated way, the toxic mechanism of MET on the non-target organism, the alga P. subcapitata.


Assuntos
Acetamidas/toxicidade , Clorofíceas/efeitos dos fármacos , Herbicidas/toxicidade , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Clorofíceas/crescimento & desenvolvimento , Clorofíceas/fisiologia , Clorofila A/metabolismo , Relação Dose-Resposta a Droga , Microalgas/crescimento & desenvolvimento , Microalgas/fisiologia , Fotossíntese/efeitos dos fármacos , Reprodução/efeitos dos fármacos
8.
Aquat Toxicol ; 217: 105356, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31733504

RESUMO

In the present study, the biochemical responses and antioxidant enzymes activity of the Dunaliella salina, a green microalga, to the interaction of silver nanoparticles (AgNPs) and salicylic acid (SA) were investigated. Algal suspensions in the phase of logarithmic growth were subjected to the concentrations of 0, 5, 15, and 25 pM AgNPs with or without 1 mM SA. AgNPs level of 25 pM declined cell division but highly accumulated levels of chlorophyll, ß-carotene, proteins, free amino acid, carbohydrates, and hydrogen peroxide, which was associated with enhanced the activity of proteolysis, lipid peroxidation, and antioxidant enzymes. SA-treated cells at 25 pM AgNPs improved cell growth but declined the activities of antioxidant enzymes and proteolytic along with a lower accumulation of metabolites except ß-carotene relative to untreated controls. These results suggest that AgNPs treatment induce oxidative stress in D. salina cells, which tolerated by alga through the metabolic modifications and accumulating ß-carotene, while SA induces AgNPs tolerance by the mechanisms that direct carbon flux to growth and ß-carotene biosynthesis rather than the antioxidant enzymes or osmoprotectant metabolites.


Assuntos
Clorofíceas/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Microalgas/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Ácido Salicílico/toxicidade , Prata/toxicidade , Poluentes Químicos da Água/toxicidade , Antioxidantes/metabolismo , Clorofíceas/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Microalgas/metabolismo , beta Caroteno/metabolismo
9.
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
10.
SAR QSAR Environ Res ; 30(9): 665-681, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31474156

RESUMO

The present study provides robust consensus quantitative structure-activity relationship (QSAR) models developed from 334 organic chemicals covering a wide chemical domain for the prediction of effective concentrations of chemicals for 50% and 10% inhibition of algal growth. Only 2D descriptors with definite physicochemical meaning were employed for QSAR model building, whereas development, validation and interpretation were achieved following the strict Organization for Economic Co-operation and Development (OECD) recommended guidelines. Genetic algorithm along with stepwise approach was used in feature selection while the final QSAR models were derived using partial least squares regression technique. The applicability domain of the developed models was also checked. The obtained consensus models were then used to predict 64 organic chemicals having no definite observed responses while the confidence of predictions was checked by the 'prediction reliability indicator' tool. The developed models should be applicable for data gap filling in case of new or untested organic chemicals provided they fall within the domain of the model and can also be implemented to design safer alternatives to the environment.


Assuntos
Clorofíceas/efeitos dos fármacos , Ecotoxicologia/métodos , Relação Quantitativa Estrutura-Atividade , Poluentes Químicos da Água/toxicidade , Análise dos Mínimos Quadrados , Reprodutibilidade dos Testes
11.
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
12.
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
13.
Ecotoxicology ; 28(8): 890-902, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31392637

RESUMO

Aquatic pollution caused by dyes has increased together with the growth of activities using colorants such as the textile, leather, food, and agrochemicals industries. Because most popular azo dyes are synthesized from benzidine, a carcinogenic compound, a threat to aquatic biota could be expected. The use of single species for toxicity assessment provides limited data, so a battery of test organisms, including representatives of different trophic levels such as algae, zooplankters, and fish, could undoubtedly provide more information. Therefore, our study was aimed at evaluating the toxic effect of the azo dye Direct blue 15 (DB15) on a battery of bioassays using a primary producer (Pseudokirchneriella subcapitata), a primary consumer (Ceriodaphnia dubia), and a secondary consumer (Danio rerio). P. subcapitata was more sensitive to DB15 (IC50 = 15.99 mg L-1) than C. dubia (LC50: 450 mg L-1). In the algae exposed to DB15, chlorophyll-a and -b were significantly increased, and carotenoids were reduced. The concentrations of protein, carbohydrates, and lipids per cell in P. subcapitata exposed to all DB15 concentrations were significantly higher than that measured in control. At 25 mg L-1 of DB15, survival, total progeny, and the number of released clutches were significantly decreased, and the start of reproduction was delayed in C. dubia. DB15 did not induce lethal or sublethal effects in D. rerio embryos at any of the tested concentrations from 24 to 72 h post-fertilization (hpf), but from 96 to 144 hpf, the larvae exposed to 100 and 500 mg L-1 developed yolk sac edema, curved tail, and skeletal deformations. After 144 hpf, DB15 produced a significant increase in embryos without a heartbeat, as the concentration of dye raised. The textile-used, azo dye DB15, caused toxic effects of different magnitude on microalgae, cladocerans, and zebrafish embryos; for this reason, the discharge of this colorant into waterbodies should be regulated to prevent environmental impacts.


Assuntos
Compostos Azo/toxicidade , Clorofíceas/efeitos dos fármacos , Cladóceros/efeitos dos fármacos , Corantes/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra , Animais , Embrião não Mamífero/efeitos dos fármacos , Microalgas/efeitos dos fármacos
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
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
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