The Experts below are selected from a list of 624 Experts worldwide ranked by ideXlab platform
Jiahua Guo - One of the best experts on this subject based on the ideXlab platform.
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transcriptional response of a green alga Raphidocelis subcapitata exposed to triclosan photosynthetic systems and dna repair
Journal of Environmental Sciences-china, 2022Co-Authors: Yongrong Hao, Yuan Lei, Jiahua GuoAbstract:Abstract Recent studies show that triclosan (TCS) exposure causes reduction in pigments, suppression of photosynthesis, and induction of oxidative stress at the physiological level, resulting in morphological alteration and growth inhibition in algae including Raphidocelis subcapitata (R. subcapitata, a freshwater model green alga). However, the underlying molecular mechanisms remain to be elucidated, especially at environmentally relevant concentrations. The present study uncovered the transcriptional profiles and molecular mechanisms of TCS toxicity in R. subcapitata using next-generation sequencing. The algal growth was drastically inhibited following a 7-day exposure at both 75 and 100 μg/L TCS, but not at 5 μg/L (environmentally realistic level). The transcriptomic analysis shows that molecular signaling pathways including porphyrin and chlorophyll metabolism, photosynthesis – antenna proteins, and photosynthesis were suppressed in all three TCS treatments, and the perturbations of these signaling pathways were exacerbated with increased TCS exposure concentrations. Additionally, signaling of replication-coupled DNA repair was only activated in 100 μg/L TCS treatment. These results indicate that photosynthesis systems were sensitive targets of TCS toxicity in R. subcapitata, which is distinct from the inhibition of lipid synthesis by TCS in bacteria. This study provides novel knowledge on molecular mechanisms of TCS toxicity in R. subcapitata.
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tylosin toxicity in the alga Raphidocelis subcapitata revealed by integrated analyses of transcriptome and metabolome photosynthesis and dna replication coupled repair
Aquatic Toxicology, 2021Co-Authors: Haotian Sun, Jiahua GuoAbstract:Abstract Tylosin (TYN) is widely used in veterinary prophylactic as a macrolide and frequently detected in the surface water. Previous studies showed that exposure to TYN caused suppression of chlorophyll biosynthesis and inhibition of photosynthesis at the physiological level, associated with reduced growth performances in algae, but the molecular mechanisms remain unknown, especially at environmental exposure levels. The present study elucidated the underlying molecular mechanism(s) of TYN toxicity in a model green alga Raphidocelis subcapitata using approaches of transcriptomics and metabolomics. Following a 7-day exposure, algal growth performances were reduced by 26.3% and 58.3% in the 3 (an environmentally realistic level) and 400 μg L−1 TYN treatment group, respectively. A total of 577 (99) and 5438 (180) differentially expressed genes (differentially accumulated metabolites) were identified in algae treated with 3 and 400 μg L−1 TYN, respectively. Signaling pathways including photosynthesis – antenna protein, porphyrin and chlorophyll metabolism, carbon fixation in photosynthetic organisms, and DNA replication were altered in the 400 μg L−1 TYN treatment, while photosynthesis and DNA replication were the shared pathways in both TYN treatments. The metabolomic data further suggest that molecular pathways related to photosynthesis, DNA replication-coupled repair and energy metabolism were impaired. Photosynthesis was identified as the most sensitive target of TYN toxicity in R. subcapitata, in contrast to protein synthesis inhibition caused by TYN in bacteria. This study provides novel mechanistic information of TYN toxicity in R. subcapitata.
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sulfamethoxazole altered transcriptomein green alga Raphidocelis subcapitata suggests inhibition of translation and dna damage repair
Frontiers in Microbiology, 2021Co-Authors: Jiahua Guo, Yibo Zhang, Haotian SunAbstract:Occurrence of sulfonamide antibiotics has been reported in surface waters with the exposures ranging from 1 as a cutoff, we identified 1 (0 up- and 1 downregulated) and 1,103 (696 up- and 407 downregulated) differentially expressed genes (DEGs) in the 5 and 300 μg L-1 treatment groups, respectively. This result suggested that SMX at an environmentally relevant exposure may not damage algal health. In the 300 μg L-1 group, DEGs were primarily enriched in the DNA replication and repair, photosynthesis, and translation pathways. Particularly, the downregulation of base and nucleotide excision repair pathways suggested that SMX may be genotoxic and cause DNA damage in alga. However, the folate biosynthesis pathway was not enriched, suggesting that SMX does not necessarily inhibit the algal growth via its mode of action in bacteria. Taken together, this study revealed the molecular mechanism of action of SMX in algal growth inhibition.
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integrative analyses of transcriptomics and metabolomics in Raphidocelis subcapitata treated with clarithromycin
Chemosphere, 2021Co-Authors: Jianglin Peng, Jiahua Guo, Yuan Lei, Haotian Sun, Jinxi SongAbstract:Abstract As a macrolide antibiotic, clarithromycin (CLA) has a high detection rate in surface water and sewage treatment plant effluents worldwide, posing a considerably high ecological risk to aquatic ecosystem. However, algal transcriptome and metabolome in response to CLA remains largely unknown. In this study, a model alga Raphidocelis subcapitata (R. subcapitata), was exposed to CLA at the concentrations of 0, 3, 10, and 15 μg L−1. Transcriptomic analysis was performed for all the treatment groups, whereas metabolomics was merely applied to 0, 3, and 10 μg L−1 groups because of the limited amount of algal biomass. After 7 d cultivation, the growth of R. subcapitata was significantly hindered at the concentrations above 10 μg L−1. A total of 115, 1833, 2911 genes were differentially expressed in 3, 10, and 15 μg L−1 groups, respectively; meanwhile, 134 and 84 differentially accumulated metabolites (DAMs) were found in the 3 and 10 μg L−1 groups. Specifically, expression levels of DEGs and DAMs related to xenobiotic metabolism, electron transport and energy synthesis were dysregulated, leading to the produced reactive oxygen species (ROS). To confront the CLA-induced injury, the biosynthesis of unsaturated fatty acids and carotenoids of R. subcapitata in 3 μg L−1 were up-regulated; although the photosynthesis was up-regulated in both 10 μg L−1 and 15 μg L−1 groups, the energy synthesis and the ability to resist ROS in these two groups were down-regulated. Overall, this study shed light on the mechanism underlying the inhibitory effects of macrolide antibiotics in algae.
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transcriptomic analysis of Raphidocelis subcapitata exposed to erythromycin the role of dna replication in hormesis and growth inhibition
Journal of Hazardous Materials, 2021Co-Authors: Jiahua Guo, Jianglin Peng, Jipu Guo, Fangshe YangAbstract:The occurrence of hormesis in the algal growth inhibition test is a major challenge in the dose-response characterization, whereas the molecular mechanism remains unraveled. The aim of this study is therefore to investigate the changes in the molecular pathways in a model green alga Raphidocelis subcapitata treated with erythromycin (ERY; 4, 80, 120 μg L-1) by transcriptomic analysis. After 7 day exposure, ERY at 4 μg L-1 caused hormetic effects (21.9 %) on cell density, whereas 52.0 % and 65.4 % were inhibited in two higher exposures. By using adj p 1 as a cutoff, we identified 218, 950, and 2896 differentially expressed genes in 4, 80, 120 μg L-1 treatment groups, respectively. In two higher ERY treated groups, genes involved in phases I, II & III metabolism processes and porphyrin and chlorophyll metabolism pathway were consistently suppressed. Interestingly, genes (e.g., pri2, mcm2, and mcm6) enriched in DNA replication process were up-regulated in 4 μg L-1 group, whereas these genes were all repressed in 120 μg L-1 group. Alteration trend in gene expression was consistent with algal growth. Taken together, our results unveiled the molecular mechanism of action in ERY- stimulated/ inhibited growth in green alga.
Vladislav Cepak - One of the best experts on this subject based on the ideXlab platform.
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toxicity of metals al cd co cr cu fe ni pb and zn on microalgae using microplate bioassay 1 chlorella kessleri scenedesmus quadricauda sc subspicatus and Raphidocelis subcapitata selenastrum capricornutum
Algological Studies, 2003Co-Authors: J Lukavsky, Sevdalina Furnadjieva, Vladislav CepakAbstract:Toxicities of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were tested using growth miniaturized algal bioassay with Chlorella kessleri, Raphidocelis subcapitata (= Selenastrum capricornutum), Scenedesmus quadricauda and Scenedesmus subspicatus. Toxicity hierarchy for all organisms, according to their mean values is: Cd> Co> Cr> Cu> Pb> Ni> Zn> Al> Fe. The sensitivity hierarchy is: Raphidocelis >Scenedesmus subspicatus > Chlorella > Scenedesmus quadricauda. The most toxic element was Cd, which was the first in toxicity hierarchy for all tested organisms. Cd has a gradual toxic curve, and has showed no stimulation, similar to Pb. Scenedesmus quadricauda showed a peak shape of growth curve with stationary phase about 300 h. Another algae showed prolonged and approximately stabile stationary phase in the period of 300-700 h, under PhAR 180 μE.m -2 . s -1 , (40 W.m -2 ) 30°C, and CO 2 supply ca 2% (v/v).
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toxicity of metals al cd cr cu fe ni pb and zn onmicroalgae 1 chlorella kessleri scenedesmus quadricauda sc subspicatus and Raphidocelis subcapitata selenastrumcapricornutum
Arch. Hydrobiol. Suppl. Algolog. Stud., 2003Co-Authors: J Lukavsky, Sevdalina Furnandjieva, Vladislav CepakAbstract:Toxicities of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were tested using growth miniaturized algal bioassay with Chlorella kessleri, Raphidocelis subcapitata (=Selenastrum capricornutum), Scenedesmus quadricauda and Scenedesmus subspicatus. Toxicity hierarchy for all organisms, according to their mean values is: Cd > Co > Cr > Cu > Pb > Ni > Zn > Al > Fe. The sensitivity hierarchy is: Raphidocelis > Scenedesmus subspicata > Chlorella > Scenedesmus quadricauda. The most toxic element was Cd, which was the first in toxicity hierarchy for all tested organisms. Cd has a gradual toxic curve, and has showed no stimulation, similar to Pb. Scenedesmus quadricauda showed a peak shape of growth curve with stationary phase about 300 h. Another algae showed prolonged and approximately stabile stationary phase in the period of 300-700 h, under PhAR 180 ľE.m-2 . s-1, (40 W.m-2) 30 oC, and CO2 supply ca 2% (v/v).
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toxicity of metals al cd cr cu fe ni pb and zn on microalgae 1 chlorella kessleri scenedesmus quadricauda sc subspicatus and Raphidocelis subcapitata selenastrum capricornutum
2003Co-Authors: J Lukavsky, Vladislav CepakAbstract:Toxicities of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were tested using growth miniaturized algal bioassay with Chlorella kessleri, Raphidocelis subcapitata (=Selenastrum capricornutum), Scenedesmus quadricauda and Scenedesmus subspicatus. Toxicity hierarchy for all organisms, according to their mean values is: Cd > Co > Cr > Cu > Pb > Ni > Zn > Al > Fe. The sensitivity hierarchy is: Raphidocelis > Scenedesmus subspicata > Chlorella > Scenedesmus quadricauda. The most toxic element was Cd, which was the first in toxicity hierarchy for all tested organisms. Cd has a gradual toxic curve, and has showed no stimulation, similar to Pb. Scenedesmus quadricauda showed a peak shape of growth curve with stationary phase about 300 h. Another algae showed prolonged and approximately stabile stationary phase in the period of 300-700 h, under PhAR 180 ľE.m-2 . s-1, (40 W.m-2) 30 oC, and CO2 supply ca 2% (v/v).
Haotian Sun - One of the best experts on this subject based on the ideXlab platform.
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tylosin toxicity in the alga Raphidocelis subcapitata revealed by integrated analyses of transcriptome and metabolome photosynthesis and dna replication coupled repair
Aquatic Toxicology, 2021Co-Authors: Haotian Sun, Jiahua GuoAbstract:Abstract Tylosin (TYN) is widely used in veterinary prophylactic as a macrolide and frequently detected in the surface water. Previous studies showed that exposure to TYN caused suppression of chlorophyll biosynthesis and inhibition of photosynthesis at the physiological level, associated with reduced growth performances in algae, but the molecular mechanisms remain unknown, especially at environmental exposure levels. The present study elucidated the underlying molecular mechanism(s) of TYN toxicity in a model green alga Raphidocelis subcapitata using approaches of transcriptomics and metabolomics. Following a 7-day exposure, algal growth performances were reduced by 26.3% and 58.3% in the 3 (an environmentally realistic level) and 400 μg L−1 TYN treatment group, respectively. A total of 577 (99) and 5438 (180) differentially expressed genes (differentially accumulated metabolites) were identified in algae treated with 3 and 400 μg L−1 TYN, respectively. Signaling pathways including photosynthesis – antenna protein, porphyrin and chlorophyll metabolism, carbon fixation in photosynthetic organisms, and DNA replication were altered in the 400 μg L−1 TYN treatment, while photosynthesis and DNA replication were the shared pathways in both TYN treatments. The metabolomic data further suggest that molecular pathways related to photosynthesis, DNA replication-coupled repair and energy metabolism were impaired. Photosynthesis was identified as the most sensitive target of TYN toxicity in R. subcapitata, in contrast to protein synthesis inhibition caused by TYN in bacteria. This study provides novel mechanistic information of TYN toxicity in R. subcapitata.
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sulfamethoxazole altered transcriptomein green alga Raphidocelis subcapitata suggests inhibition of translation and dna damage repair
Frontiers in Microbiology, 2021Co-Authors: Jiahua Guo, Yibo Zhang, Haotian SunAbstract:Occurrence of sulfonamide antibiotics has been reported in surface waters with the exposures ranging from 1 as a cutoff, we identified 1 (0 up- and 1 downregulated) and 1,103 (696 up- and 407 downregulated) differentially expressed genes (DEGs) in the 5 and 300 μg L-1 treatment groups, respectively. This result suggested that SMX at an environmentally relevant exposure may not damage algal health. In the 300 μg L-1 group, DEGs were primarily enriched in the DNA replication and repair, photosynthesis, and translation pathways. Particularly, the downregulation of base and nucleotide excision repair pathways suggested that SMX may be genotoxic and cause DNA damage in alga. However, the folate biosynthesis pathway was not enriched, suggesting that SMX does not necessarily inhibit the algal growth via its mode of action in bacteria. Taken together, this study revealed the molecular mechanism of action of SMX in algal growth inhibition.
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integrative analyses of transcriptomics and metabolomics in Raphidocelis subcapitata treated with clarithromycin
Chemosphere, 2021Co-Authors: Jianglin Peng, Jiahua Guo, Yuan Lei, Haotian Sun, Jinxi SongAbstract:Abstract As a macrolide antibiotic, clarithromycin (CLA) has a high detection rate in surface water and sewage treatment plant effluents worldwide, posing a considerably high ecological risk to aquatic ecosystem. However, algal transcriptome and metabolome in response to CLA remains largely unknown. In this study, a model alga Raphidocelis subcapitata (R. subcapitata), was exposed to CLA at the concentrations of 0, 3, 10, and 15 μg L−1. Transcriptomic analysis was performed for all the treatment groups, whereas metabolomics was merely applied to 0, 3, and 10 μg L−1 groups because of the limited amount of algal biomass. After 7 d cultivation, the growth of R. subcapitata was significantly hindered at the concentrations above 10 μg L−1. A total of 115, 1833, 2911 genes were differentially expressed in 3, 10, and 15 μg L−1 groups, respectively; meanwhile, 134 and 84 differentially accumulated metabolites (DAMs) were found in the 3 and 10 μg L−1 groups. Specifically, expression levels of DEGs and DAMs related to xenobiotic metabolism, electron transport and energy synthesis were dysregulated, leading to the produced reactive oxygen species (ROS). To confront the CLA-induced injury, the biosynthesis of unsaturated fatty acids and carotenoids of R. subcapitata in 3 μg L−1 were up-regulated; although the photosynthesis was up-regulated in both 10 μg L−1 and 15 μg L−1 groups, the energy synthesis and the ability to resist ROS in these two groups were down-regulated. Overall, this study shed light on the mechanism underlying the inhibitory effects of macrolide antibiotics in algae.
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Sulfamethoxazole-Altered Transcriptomein Green Alga Raphidocelis subcapitata Suggests Inhibition of Translation and DNA Damage Repair
'Frontiers Media SA', 2021Co-Authors: Jiahua Guo, Yibo Zhang, Haotian SunAbstract:Occurrence of sulfonamide antibiotics has been reported in surface waters with the exposures ranging from < 1 ng L–1 to approximately 11 μg L–1, which may exert adverse effects on non-target algal species, inhibiting algal growth and further hindering the delivery of several ecosystem services. Yet the molecular mechanisms of sulfonamide in algae remain undetermined. The aims of the present work are: (1) to test the hypothesis whether sulfamethoxazole (SMX) inhibits the folate biosynthesis in a model green alga Raphidocelis subcapitata; and (2) to explore the effects of SMX at an environmentally relevant concentration on algal health. Here, transcriptomic analysis was applied to investigate the changes at the molecular levels in R. subcapitata treated with SMX at the concentrations of 5 and 300 μg L–1. After 7-day exposure, the algal density in the 5 μg L–1 group was not different from that in the controls, whereas a marked reduction of 63% in the high SMX group was identified. Using the adj p < 0.05 and absolute log2 fold change > 1 as a cutoff, we identified 1 (0 up- and 1 downregulated) and 1,103 (696 up- and 407 downregulated) differentially expressed genes (DEGs) in the 5 and 300 μg L–1 treatment groups, respectively. This result suggested that SMX at an environmentally relevant exposure may not damage algal health. In the 300 μg L–1 group, DEGs were primarily enriched in the DNA replication and repair, photosynthesis, and translation pathways. Particularly, the downregulation of base and nucleotide excision repair pathways suggested that SMX may be genotoxic and cause DNA damage in alga. However, the folate biosynthesis pathway was not enriched, suggesting that SMX does not necessarily inhibit the algal growth via its mode of action in bacteria. Taken together, this study revealed the molecular mechanism of action of SMX in algal growth inhibition
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transcriptomic analysis suggests the inhibition of dna damage repair in green alga Raphidocelis subcapitata exposed to roxithromycin
Ecotoxicology and Environmental Safety, 2020Co-Authors: Jiahua Guo, Haotian Sun, Yi Bai, Zhi Chen, Qiang ZhangAbstract:Abstract 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.
Maria Da Graca Gama Melao - One of the best experts on this subject based on the ideXlab platform.
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using multiple endpoints to assess the toxicity of cadmium and cobalt for chlorophycean Raphidocelis subcapitata
Ecotoxicology and Environmental Safety, 2021Co-Authors: Larissa Luiza Dos Reis, Lays De Oliveira Goncalves Alho, Cinthia Bruno De Abreu, Maria Da Graca Gama MelaoAbstract:Abstract 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.
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exposure to environmental concentrations of fipronil and 2 4 d mixtures causes physiological morphological and biochemical changes in Raphidocelis subcapitata
Ecotoxicology and Environmental Safety, 2020Co-Authors: Raquel Aparecida Moreira, Cassiana Carolina Montagner, Giseli Swerts Rocha, Maria Da Graca Gama Melao, Lais Conceicao Menezes Da Silva, Bianca Veloso Goulart, Evaldo Luiz Gaeta EspindolaAbstract:The occurrence of pesticides and their mixtures in the environment can alter the ecological relationships between aquatic food chains. Since fipronil and 2,4-dichlorophenoxyacetic acid (2,4-D) are commonly found together in Brazilian water bodies, the present study aimed to investigate through an integrative approach the toxicity mechanisms of environmentally relevant concentrations of pesticides Regent® 800 WG (active ingredient - a.i. fipronil), DMA® 806 BR (a.i. 2,4-D) isolated and in mixtures on the green alga Raphidocelis subcapitata using multiple parameters: physiological (growth rate and chlorophyll a fluorescence), morphological (cell complexity and size), biochemical (composition of lipid classes) and related to the photosynthetic activity (variable fluorescence, the maximum quantum yield of the photosystem II - PSII - and the efficiency of the oxygen evolving complex - OEC - of PSII). The results indicated that fipronil significantly inhibited algal population growth, increased the chlorophyll a content (observed by fluorescence), cell size and lipid class content of triacylglycerol (TAG), free fatty acid (FFA) and acetone mobile polar lipid (AMPL) and, on the other hand, decreased variable fluorescence of algae. The tested concentrations of 2,4-D increased the chlorophyll a fluorescence, the cell size and the lipid classes TAG and FFA. The pesticide mixtures have had more effects on algae than isolated compounds, causing alterations in all parameters analyzed, including photosynthetic activity (maximum quantum yield and efficiency of the oxygen evolving complex of the PSII), in which no alterations were observed for the toxicity of the single pesticides. The results suggest that these analyses are important to evaluate pesticide toxicity mechanisms in ecological risk assessments of tropical regions. Thus, here we demonstrate the importance of using multiple parameters in ecotoxicological studies to obtain a better understanding of the toxicity of these compounds for phytoplankton.
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zinc and aluminum mixtures have synergic effects to the algae Raphidocelis subcapitata at environmental concentrations
Chemosphere, 2020Co-Authors: Renan Castelhano Gebara, Giseli Swerts Rocha, Lays De Oliveira Goncalves Alho, Adrislaine Da Silva Mansano, Maria Da Graca Gama MelaoAbstract:Abstract A large number of metals is present in aquatic ecosystems, often occurring simultaneously, however, the isolated toxicity of them are better well known than their mixtures. Based on that, for the first time we aimed to test the effects of zinc (Zn) and aluminum (Al) mixtures to the microalgae Raphidocelis subcapitata. Regarding isolated toxicity, the 96 h IC50 of Zn and Al based on specific growth rates occurred, respectively, at 0.40 and 27.40 μM, thus Zn was ≈70-fold more toxic than Al. Both Zn and Al altered the cell size and complexity of R. subcapitata at the highest concentrations, although only during Zn exposure was the chlorophyll a fluorescence significantly diminished. Microalgae exposed to Al produced more ROS than during Zn exposure. Moreover, algae produced less ROS at the highest Zn concentration than in the lower concentrations. According to species sensitivity curves (SSD), R. subcapitata was the most sensitive organism to Zn and one of the most sensitive to Al. With respect to mixture toxicity tests, there were significant deviations for both CA (concentration addition) and IA (independent action) models, although data best fitted the CA model and DL (dose level-dependence) deviation, in which metals showed synergic effects at low concentrations and antagonist effects at higher concentrations.
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responses of Raphidocelis subcapitata exposed to cd and pb mechanisms of toxicity assessed by multiple endpoints
Ecotoxicology and Environmental Safety, 2019Co-Authors: Lays De Oliveira Goncalves Alho, Renan Castelhano Gebara, Hugo Sarmento, Karime De Araujo Paina, Maria Da Graca Gama MelaoAbstract:Abstract Microalgae have been widely used in ecotoxicological studies in order to evaluate the impacts of heavy metals in aquatic ecosystems. However, there are few studies that analyze the effects of metals in an integrative way on photosynthetic apparatus of freshwater microalgae in the generation of reactive oxygen species (ROS) and biochemical composition. Therefore, this study aimed to assess cadmium (Cd) and lead (Pb) toxicity using synchronously physiological and biochemical endpoints, specially detecting lipidic classes for the very first time during Cd and Pb-exposure to Raphidocelis subcapitata. Here we show that analyzing the algae growth, the IC50–72 h for Cd was 0.04 µM and for Pb was 0.78 µM. In general, the Cd affected the biochemical parameters more, leading to an increase in total lipid content (7.2-fold), total carbohydrates (3.5-fold) and ROS production (3.7-fold). The higher production of lipids and carbohydrates during Cd-exposure probably acted as a defense mechanism, helping to reduce the extent of damage caused by the metal in the photosynthetic apparatus. For Pb, the physiological parameters were more sensitive, which resulted in changes of chlorophyll a synthesis and a reduction of both efficiency of oxygen-evolving complex and quantum yields. Besides that, we observed changes in the lipid class composition during Cd and Pb-exposure, suggesting these analyses as great biomarkers to assess metal toxicity mechanisms in ecological risk assessments. Thereby, here we demonstrate the importance of using multiple endpoints in ecotoxicological studies in order to obtain a better understanding of the mechanisms of metal toxicity to R. subcapitata.
Antonietta Siciliano - One of the best experts on this subject based on the ideXlab platform.
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long term multi endpoint exposure of the microalga Raphidocelis subcapitata to lanthanum and cerium
Science of The Total Environment, 2021Co-Authors: Antonietta Siciliano, Emilia Galdiero, Marco Guida, Sara Serafini, Maria Micillo, Simona Carfagna, Giovanna Salbitani, Franca Tommasi, Giusy Lofrano, Edith Guadalupe Padilla SuarezAbstract:Significant release of rare earth elements (REEs) into the environment is mainly due to active or abandoned mining sites, but their presence is globally increasing due to their use in several industrial sectors. The effects on primary producers as Raphidocelis subcapitata are still limited. This research focused on La and Ce as the two most widespread REEs that can be currently found up to hundreds of μg/L in water and wastewater. Microalgae were exposed to La and Ce for 3 days (pH = 7.8) (short-term exposure) to derive the effective concentrations inhibiting the growth on 10% (EC10) of the exposed population. EC10 values (0.5 mg/L of La and 0.4 mg/L of Ce) were used for the 28 days long-term exposure (renewal test) to observe after 7, 14, 21, and 28 days on a multi-endpoint basis microalgae growth inhibition (GI), biomarkers of stress (reactive oxygen species (ROS), superoxide dismutase (SOD), and catalase (CAT)), and bioconcentration. Results evidenced that La and Ce EC10 increased GI (day 28) up to 38% and 28%, respectively. ROS, CAT, and SOD activities showed differential responses from day 7 to day 14, 21, and 28, suggesting, in most of the cases, that La and Ce effects were counteracted (i.e., being the values at day 28 not significantly different, p > 0.05, from the relative negative controls), except for La-related ROS activities. La and Ce significantly bioconcentrated in microalgae populations up to 2- and 5-fold (i.e., at day 28 compared to day 7), in that order. Bioconcentrated La and Ce were up to 3157 and 1232 μg/g dry weight (day 28), respectively. These results suggested that low La and Ce concentrations can be slightly toxic to R. subcapitata having the potential to be bioaccumulated and potentially transferred along the food web.
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secondary effects of hypochlorite treatment on the emerging pollutant candesartan the formation of degradation byproducts and their toxicological profiles
Molecules, 2021Co-Authors: Giovanni Luongo, Antonietta Siciliano, Lucio Previtera, Giovanni Di Fabio, Marco Guida, Lorenzo Saviano, Giovanni Libralato, Armando ZarrelliAbstract:In recent years, many studies have reported the frequent detection of antihypertensive agents such as sartans (olmesartan, valsartan, irbesartan and candesartan) in the influents and effluents of wastewater treatment plants (WWTPs) and in the superficial waters of rivers and lakes in both Europe and North America. In this paper, the degradation pathway for candesartan (CAN) was investigated by simulating the chlorination process that is normally used to reduce microbial contamination in a WWTP. Twelve isolated degradation byproducts (DPs), four of which were isolated for the first time, were separated on a C-18 column by employing a gradient HPLC method, and their structures were identified by combining nuclear magnetic resonance and mass spectrometry and comparing the results with commercial standards. On the basis of these results, a mechanism of formation starting from the parent drug is proposed. The ecotoxicity of CAN and its DPs was studied by conducting a battery of ecotoxicity tests; bioassays were performed using Aliivibrio fischeri (bacterium), Daphnia magna (planktonic crustacean) and Raphidocelis subcapitata (alga). The ecotoxicity results shed new light on the increased toxicity of DPs compared with the parent compound.
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cerium gadolinium lanthanum and neodymium effects in simplified acid mine discharges to Raphidocelis subcapitata lepidium sativum and vicia faba
Science of The Total Environment, 2021Co-Authors: Antonietta Siciliano, Marco Guida, Franca Tommasi, Giusy Lofrano, Edith Guadalupe Padilla Suarez, Giovanni Pagano, Marco Trifuoggi, Isidora Gjata, Antonios Apostolos Brouziotis, Renato LiguoriAbstract:Abstract The alteration of rare earth elements (REEs) biogeochemical cycles has increased the potential effects related to their environmental exposure in a one-health perspective. Cerium (Ce), gadolinium (Gd), lanthanum (La), and neodymium (Nd) are frequently related to technological applications and their environmental concentrations are already in the μg/kg – mg/kg (i.e., or L) range depending on the considered matrices. The effect of Ce, Gd, La, and Nd was investigated in a simulated AMD (0.01–10.22 mg/L) at pH 4 and 6 considering a battery of photosynthetic organisms (Raphidocelis subcapitata, Lepidium sativum, and Vicia faba) according to a multiple-endpoint approach (growth inhibition, germination index, and mutagenicity). According to modelled chemical speciation, the considered elements were mostly in the trivalent free form (86–88%) at pH 4. Gd, La, and Nd exerted the most relevant toxic effect at pH 4. The pH 6 scenario evidenced a reduction in REEs toxicity level. Mutagenicity was detected only at pH 4 by Gd (up to 3-fold compared to negative controls), La and Nd, while Ce did not show any adverse effect. Toxic effects due to Ce, Gd, La, and Nd can be reduced by controlling the pH, but several gaps of knowledge still remain about their uptake and trophic transfer, and long-term effects on targeted species.
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photocatalytic zno assisted degradation of spiramycin in urban wastewater degradation kinetics and toxicity
Water, 2021Co-Authors: Davide Vignati, Antonietta Siciliano, Marco Guida, Giovanni Libralato, Giusy Lofrano, Federica Carraturo, Maurizio CarotenutoAbstract:The removal of contaminants of emerging concern from urban wastewater treatment plants (WWTPs) remains a challenge to promote safe wastewater reuse practices. Macrolides are the most abundant antibiotics detected in untreated wastewater and their concentration in WWTPs effluents is only partially reduced by conventional treatments. Among several advanced oxidation processes (AOPs), photocatalysis has demonstrated the capability to effectively remove pharmaceuticals from different aqueous matrices. Recently, ZnO has emerged as an efficient, promising, and less expensive alternative to TiO2, due to its photocatalytic capability and attitude to exploit better the solar spectrum than TiO2. In this study, the behaviors of ZnO photocatalysis were evaluated using a representative macrolide antibiotic, spiramycin (SPY), in aqueous solutions and urban wastewater. After 80 min of photocatalysis, 95–99% removal of SPY was achieved at 1 g L−1 ZnO concentrations in aqueous solutions and wastewater, respectively. After treatment, the effluent toxicity, evaluated using the bacterium Aliivibrio fischeri, the green alga Raphidocelis subcapitata, and the crustacean Daphnia magna ranged between slight acute and high acute hazard. Filterable and ultrafilterable Zn concentrations were quantified in treated effluents and shown to be high enough to contribute to the observed toxicity.
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Complete Characterization of Degradation Byproducts of Olmesartan Acid, Degradation Pathway, and Ecotoxicity Assessment
'MDPI AG', 2021Co-Authors: Giovanni Luongo, Antonietta Siciliano, Lucio Previtera, Giovanni Di Fabio, Marco Guida, Lorenzo Saviano, Giovanni Libralato, Armando ZarrelliAbstract:Antihypertensive drugs are among the most prescribed drugs. Olmesartan acid, of the sartan class, belongs to a relatively new generation of antihypertensive drugs called angiotensin II receptor blockers. There are very few studies on the presence and fate of sartans in the environment, despite them being marketed in huge quantities, metabolized in low percentages, and detected in wastewater and water bodies. This paper presents a study on the less abundant and more polar fractions that have been neglected in previous studies, which led to the isolation by chromatographic methods of thirteen degradation byproducts (DPs), six of which are new, identified by nuclear magnetic resonance and mass spectrometry. A mechanism of degradation from the parent drug was proposed. The ecotoxicity of olmesartan acid and identified compounds was evaluated in Aliivibrio fischeri bacteria and Raphidocelis subcapitata algae to assess acute and chronic toxicity. For 75% of the DPs, acute and chronic exposure to the compounds, at concentrations of 5 mg/L, inhibited population growth in the algae and decreased bioluminescence in the bacteria
