The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
William Gerson Matias - One of the best experts on this subject based on the ideXlab platform.
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crystalline phase dependent toxicity of aluminum oxide nanoparticles toward Daphnia magna and ecological risk assessment
Environmental Research, 2020Co-Authors: Diego Jose Nogueira, Oswaldo Savoldi Neto, Marlon Luiz Neves Da Silva, Carmen Simioni, Luciane C Ouriques, Denice Shulz Vicentini, William Gerson MatiasAbstract:Abstract Aluminum oxide nanoparticles (Al2O3 NPs) can be found in different crystalline phases, and with the emergence of nanotechnology there has been a rapid increase in the demand for Al2O3 NPs in different engineering areas and for consumer products. However, a careful evaluation of the potential environmental and human health risks is required to assess the implications of the release of Al2O3 NPs into the environment. Thus, the objective of this study was to investigate the toxicity of two crystalline phases of Al2O3 NPs, alpha (α-Al2O3 NPs) and eta (η-Al2O3 NPs), toward Daphnia magna and evaluate the risk to the aquatic ecology of Al2O3 NPs with different crystalline phases, based on a probabilistic approach. Different techniques were used for the characterization of the Al2O3 NPs. The toxicity toward Daphnia magna was assessed based on multiple toxicological endpoints, and the probabilistic species sensitivity distribution (PSSD) was used to estimate the risk of Al2O3 NPs to the aquatic ecology. The results obtained verify the toxic potential of the NPs toward D. magna even in sublethal concentrations, with a more pronounced effect being observed for η-Al2O3 NPs. The toxicity is associated with an increase in the reactive oxygen species (ROS) content and deregulation of antioxidant enzymatic/non-enzymatic enzymes (CAT, SOD and GSH). In addition, changes in MDA levels were observed, indicating that D. magna was under oxidative stress. The most prominent chronic toxic effects were observed in the organisms exposed to η-Al2O3 NPs, since the lowest LOEC was 3.12 mg/L for all parameters, while for α-Al2O3 NPs the lowest LOEC was 6.25 mg/L for longevity, growth and reproduction. However, the risk assessment results indicate that, based on a probabilistic approach, Al2O3 NPs (alpha, gamma, delta, eta and theta) only a very limited risk to organisms in surface waters.
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synthesis characterization and toxicological evaluation of cr2o3 nanoparticles using Daphnia magna and aliivibrio fischeri
Ecotoxicology and Environmental Safety, 2016Co-Authors: Rodrigo Costa Puerari, Silvia Pedroso Melegari, Cristina H. Da Costa, Cristiane Funghetto Fuzinatto, Eder C Schmidt, Zenilda L. Bouzon, Denice Schulz Vicentini, William Gerson MatiasAbstract:Abstract Chromium III oxide (Cr2O3) nanoparticles (NPs) are used in pigments for ceramics, dyes, paints and cosmetics. However, few studies addressing the toxic potential of these NPs have been reported in the literature. Thus, this research aimed to evaluate the acute and chronic effects of Cr2O3 NPs through acute toxicity tests with Daphnia magna and Aliivibrio fischeri and chronic toxicity tests with Daphnia magna. Cr2O3 NPs were synthesized by the sol–gel method and characterized through TEM, X-Ray diffraction (XRD), zeta potential (ZP) and surface area analysis. In the acute toxicity tests the EC50,48h value obtained with D. magna was 6.79 mg L−1 and for A. fischeri the EC50,15min value was 16.10 mg L−1 and the EC50,30min value was 12.91 mg L−1. Regarding the chronic toxicity tests with D. magna, effects on longevity (OEC=1.00 mg L−1), reproduction (OEC=1.00 mg L−1) and growth (OEC=0.50 mg L−1) were observed. On the SEM and TEM images, ultrastructural alterations in the organelles of exposed organisms were also observed. Thus, toxicological studies with NPs are of great importance in order to reduce the risk of environmental contamination.
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synthesis characterization and toxicological evaluation of cr2o3 nanoparticles using Daphnia magna and aliivibrio fischeri
Ecotoxicology and Environmental Safety, 2016Co-Authors: Rodrigo Costa Puerari, Silvia Pedroso Melegari, Cristina H. Da Costa, Cristiane Funghetto Fuzinatto, Eder C Schmidt, Zenilda L. Bouzon, Denice Schulz Vicentini, William Gerson MatiasAbstract:Abstract Chromium III oxide (Cr2O3) nanoparticles (NPs) are used in pigments for ceramics, dyes, paints and cosmetics. However, few studies addressing the toxic potential of these NPs have been reported in the literature. Thus, this research aimed to evaluate the acute and chronic effects of Cr2O3 NPs through acute toxicity tests with Daphnia magna and Aliivibrio fischeri and chronic toxicity tests with Daphnia magna. Cr2O3 NPs were synthesized by the sol–gel method and characterized through TEM, X-Ray diffraction (XRD), zeta potential (ZP) and surface area analysis. In the acute toxicity tests the EC50,48h value obtained with D. magna was 6.79 mg L−1 and for A. fischeri the EC50,15min value was 16.10 mg L−1 and the EC50,30min value was 12.91 mg L−1. Regarding the chronic toxicity tests with D. magna, effects on longevity (OEC=1.00 mg L−1), reproduction (OEC=1.00 mg L−1) and growth (OEC=0.50 mg L−1) were observed. On the SEM and TEM images, ultrastructural alterations in the organelles of exposed organisms were also observed. Thus, toxicological studies with NPs are of great importance in order to reduce the risk of environmental contamination.
Taisen Iguchi - One of the best experts on this subject based on the ideXlab platform.
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comparative ovarian microarray analysis of juvenile hormone responsive genes in water flea Daphnia magna potential targets for toxicity
Journal of Applied Toxicology, 2017Co-Authors: Norihisa Tatarazako, Taisen Iguchi, Kenji Toyota, Tim D Williams, Tomomi SatoAbstract:The freshwater zooplankton Daphnia magna has been extensively employed in chemical toxicity tests such as OECD Test Guidelines 202 and 211. Previously, it has been demonstrated that the treatment of juvenile hormones (JHs) or their analogues to female daphnids can induce male offspring production. Based on this finding, a rapid screening method for detection of chemicals with JH-activity was recently developed using adult D. magna. This screening system determines whether a chemical has JH-activity by investigating the male offspring inducibility. Although this is an efficient high-throughput short-term screening system, much remains to be discovered about JH-responsive pathways in the ovary, and whether different JH-activators act via the same mechanism. JH-responsive genes in the ovary including developing oocytes are still largely undescribed. Here, we conducted comparative microarray analyses using ovaries from Daphnia magna treated with fenoxycarb (Fx; artificial JH agonist) or methyl farnesoate (MF; a putative innate JH in daphnids) to elucidate responses to JH agonists in the ovary, including developing oocytes, at a JH-sensitive period for male sex determination. We demonstrate that induction of hemoglobin genes is a well-conserved response to JH even in the ovary, and a potential adverse effect of JH agonist is suppression of vitellogenin gene expression, that might cause reduction of offspring number. This is the first report demonstrating different transcriptomics profiles from MF and an artificial JH agonist in D. magna ovary, improving understanding the tissue-specific mode-of-action of JH. Copyright © 2016 John Wiley & Sons, Ltd.
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Analysis of expressed sequence tags of the water flea Daphnia magna
Genome, 2005Co-Authors: Hajime Watanabe, Norihisa Tatarazako, Shigeto Oda, Hiroyo Nishide, Ikuo Uchiyama, Masatoshi Morita, Taisen IguchiAbstract:To study gene expression in the water flea Daphnia magna we constructed a cDNA library and characterized the expressed sequence tags (ESTs) of 7210 clones. The EST sequences clustered into 2958 nonredundant groups. BLAST analyses of both protein and DNA databases showed that 1218 (41%) of the unique sequences shared significant similarities to known nucleotide or amino acid sequences, whereas the remaining 1740 (59%) showed no significant similarities to other genes. Clustering analysis revealed particularly high expression of genes related to ATP synthesis, structural proteins, and proteases. The cDNA clones and EST sequence information should be useful for future functional analysis of daphnid biology and investigation of the links between ecology and genomics.Key words: Daphnia magna, EST, classification, ATP synthesis.
Saba Asghari - One of the best experts on this subject based on the ideXlab platform.
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toxicity of various silver nanoparticles compared to silver ions in Daphnia magna
Journal of Nanobiotechnology, 2012Co-Authors: Saba Asghari, Seyed Ali Johari, Ji Hyun Lee, Yong Seok Kim, Yong Bae Jeon, Hyun Jung Choi, Min Chaul MoonAbstract:Background To better understand the potential ecotoxicological impacts of silver nanoparticles released into freshwater environments, the Daphnia magna 48-hour immobilization test was used.
Norihisa Tatarazako - One of the best experts on this subject based on the ideXlab platform.
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comparative ovarian microarray analysis of juvenile hormone responsive genes in water flea Daphnia magna potential targets for toxicity
Journal of Applied Toxicology, 2017Co-Authors: Norihisa Tatarazako, Taisen Iguchi, Kenji Toyota, Tim D Williams, Tomomi SatoAbstract:The freshwater zooplankton Daphnia magna has been extensively employed in chemical toxicity tests such as OECD Test Guidelines 202 and 211. Previously, it has been demonstrated that the treatment of juvenile hormones (JHs) or their analogues to female daphnids can induce male offspring production. Based on this finding, a rapid screening method for detection of chemicals with JH-activity was recently developed using adult D. magna. This screening system determines whether a chemical has JH-activity by investigating the male offspring inducibility. Although this is an efficient high-throughput short-term screening system, much remains to be discovered about JH-responsive pathways in the ovary, and whether different JH-activators act via the same mechanism. JH-responsive genes in the ovary including developing oocytes are still largely undescribed. Here, we conducted comparative microarray analyses using ovaries from Daphnia magna treated with fenoxycarb (Fx; artificial JH agonist) or methyl farnesoate (MF; a putative innate JH in daphnids) to elucidate responses to JH agonists in the ovary, including developing oocytes, at a JH-sensitive period for male sex determination. We demonstrate that induction of hemoglobin genes is a well-conserved response to JH even in the ovary, and a potential adverse effect of JH agonist is suppression of vitellogenin gene expression, that might cause reduction of offspring number. This is the first report demonstrating different transcriptomics profiles from MF and an artificial JH agonist in D. magna ovary, improving understanding the tissue-specific mode-of-action of JH. Copyright © 2016 John Wiley & Sons, Ltd.
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acute toxicity of 50 metals to Daphnia magna
Journal of Applied Toxicology, 2015Co-Authors: Akira Okamoto, Norihisa Tatarazako, Masumi YamamuroAbstract:Metals are essential for human life and physiological functions but may sometimes cause disorders. Therefore, we conducted acute toxicity testing of 50 metals in Daphnia magna: EC50s of seven elements (Be, Cu, Ag, Cd, Os, Au and Hg) were 100,000 μgl 1 ; and. 7 elements (Ti, Zr, Bi, Nb, Hf, Re and Ta) did not show EC50 at the upper limit of respective aqueous solubility, and EC50s were not obtained. Ga, Ru and Pd adhered to the body of D. magna and physically retarded the movement of D. magna. These metals formed hydroxides after adjusting the pH. Therefore, here, we distinguished this physical effect from the physiological toxic effect. The acute toxicity results of 40 elements obtained in this study were not correlated with electronegativity. Similarly, the acute toxicity results of metals including the rare metals were also not correlated with first ionization energy, atomic weight, atomic number, covalent radius, atomic radius or ionic radius. Copyright © 2014 John Wiley & Sons, Ltd.
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Analysis of expressed sequence tags of the water flea Daphnia magna
Genome, 2005Co-Authors: Hajime Watanabe, Norihisa Tatarazako, Shigeto Oda, Hiroyo Nishide, Ikuo Uchiyama, Masatoshi Morita, Taisen IguchiAbstract:To study gene expression in the water flea Daphnia magna we constructed a cDNA library and characterized the expressed sequence tags (ESTs) of 7210 clones. The EST sequences clustered into 2958 nonredundant groups. BLAST analyses of both protein and DNA databases showed that 1218 (41%) of the unique sequences shared significant similarities to known nucleotide or amino acid sequences, whereas the remaining 1740 (59%) showed no significant similarities to other genes. Clustering analysis revealed particularly high expression of genes related to ATP synthesis, structural proteins, and proteases. The cDNA clones and EST sequence information should be useful for future functional analysis of daphnid biology and investigation of the links between ecology and genomics.Key words: Daphnia magna, EST, classification, ATP synthesis.
Silvia Pedroso Melegari - One of the best experts on this subject based on the ideXlab platform.
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synthesis characterization and toxicological evaluation of cr2o3 nanoparticles using Daphnia magna and aliivibrio fischeri
Ecotoxicology and Environmental Safety, 2016Co-Authors: Rodrigo Costa Puerari, Silvia Pedroso Melegari, Cristina H. Da Costa, Cristiane Funghetto Fuzinatto, Eder C Schmidt, Zenilda L. Bouzon, Denice Schulz Vicentini, William Gerson MatiasAbstract:Abstract Chromium III oxide (Cr2O3) nanoparticles (NPs) are used in pigments for ceramics, dyes, paints and cosmetics. However, few studies addressing the toxic potential of these NPs have been reported in the literature. Thus, this research aimed to evaluate the acute and chronic effects of Cr2O3 NPs through acute toxicity tests with Daphnia magna and Aliivibrio fischeri and chronic toxicity tests with Daphnia magna. Cr2O3 NPs were synthesized by the sol–gel method and characterized through TEM, X-Ray diffraction (XRD), zeta potential (ZP) and surface area analysis. In the acute toxicity tests the EC50,48h value obtained with D. magna was 6.79 mg L−1 and for A. fischeri the EC50,15min value was 16.10 mg L−1 and the EC50,30min value was 12.91 mg L−1. Regarding the chronic toxicity tests with D. magna, effects on longevity (OEC=1.00 mg L−1), reproduction (OEC=1.00 mg L−1) and growth (OEC=0.50 mg L−1) were observed. On the SEM and TEM images, ultrastructural alterations in the organelles of exposed organisms were also observed. Thus, toxicological studies with NPs are of great importance in order to reduce the risk of environmental contamination.
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synthesis characterization and toxicological evaluation of cr2o3 nanoparticles using Daphnia magna and aliivibrio fischeri
Ecotoxicology and Environmental Safety, 2016Co-Authors: Rodrigo Costa Puerari, Silvia Pedroso Melegari, Cristina H. Da Costa, Cristiane Funghetto Fuzinatto, Eder C Schmidt, Zenilda L. Bouzon, Denice Schulz Vicentini, William Gerson MatiasAbstract:Abstract Chromium III oxide (Cr2O3) nanoparticles (NPs) are used in pigments for ceramics, dyes, paints and cosmetics. However, few studies addressing the toxic potential of these NPs have been reported in the literature. Thus, this research aimed to evaluate the acute and chronic effects of Cr2O3 NPs through acute toxicity tests with Daphnia magna and Aliivibrio fischeri and chronic toxicity tests with Daphnia magna. Cr2O3 NPs were synthesized by the sol–gel method and characterized through TEM, X-Ray diffraction (XRD), zeta potential (ZP) and surface area analysis. In the acute toxicity tests the EC50,48h value obtained with D. magna was 6.79 mg L−1 and for A. fischeri the EC50,15min value was 16.10 mg L−1 and the EC50,30min value was 12.91 mg L−1. Regarding the chronic toxicity tests with D. magna, effects on longevity (OEC=1.00 mg L−1), reproduction (OEC=1.00 mg L−1) and growth (OEC=0.50 mg L−1) were observed. On the SEM and TEM images, ultrastructural alterations in the organelles of exposed organisms were also observed. Thus, toxicological studies with NPs are of great importance in order to reduce the risk of environmental contamination.
