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Horie Y, Nomura M, Ernesto UDL, Naija A, Akkajit P, Okamura H. Impact of acetyl tributyl citrate on gonadal sex differentiation and expression of biomarker genes for endocrine disruption in Japanese medaka. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 260:106553. [PMID: 37182273 DOI: 10.1016/j.aquatox.2023.106553] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 04/24/2023] [Accepted: 05/05/2023] [Indexed: 05/16/2023]
Abstract
Plasticizers are broadly classified as phthalate or nonphthalate. Recently, acetyl tributyl citrate (ATBC), an environmentally friendly nonphthalate plasticizer, was revealed to have the ability to disrupt thyroid hormone activity in fish species. Therefore, we aimed to assess whether ATBC exhibits any sex hormone (i.e., androgenic or estrogenic) activities. First, we examined the effects of ATBC on gonadal sex differentiation. Subsequently, we analyzed the different expression of biomarker genes that respond to endocrine-disrupting chemicals (EDCs) with sexual hormone activity in the liver. We observed normal testes and ovaries after both XX and XY medakas were exposed to ATBC, indicating that ATBC is not an EDCs with strong sex hormone activity and that it does not induce intersex (testis-to-ova or ovo-to-testis) or sex changes in Japanese medaka. The vitellogenin 1 (vtg1) and vitellogenin 2 (vtg2) mRNA expression levels in the liver of XX medakas were significantly reduced compared with those in the control group, whereas the expression levels of these genes in the liver of XY medakas remained unchanged. Finally, we examined the changes in the expression of biomarker genes that respond to EDCs with sex hormone activity in the gonads. The expression levels of biomarker genes did not differ significantly from that of the control group, although the expression levels of gsdf mRNA tended to increase while that of aromatase mRNA tended to decrease in the ovary of XX medakas following ATBC exposure. Conversely, the expression levels of gsdf and aromatase mRNAs in the testis of XY medakas remained unchanged. These results suggest that ATBC does not exhibit estrogenic activity, although it may have weak androgenic activity or no sexual hormone activity.
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Affiliation(s)
- Yoshifumi Horie
- Research Center for Inland Seas (KURCIS), Kobe University, Fukaeminami-machi, Higashinada-ku, Kobe 658-0022, Japan.
| | - Miho Nomura
- Graduate School of Maritime Science, Kobe University, Fukaeminami-machi, Higashinada-ku, Kobe 658-0022, Japan
| | | | - Azza Naija
- Biomedical Research Center, Qatar University, Doha, Qatar
| | - Pensiri Akkajit
- Faculty of Technology and Environment, Prince of Songkla University, Phuket Campus, Phuket, Thailand
| | - Hideo Okamura
- Research Center for Inland Seas (KURCIS), Kobe University, Fukaeminami-machi, Higashinada-ku, Kobe 658-0022, Japan
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Lim EQ, Seah MQ, Lau WJ, Hasbullah H, Goh PS, Ismail AF, Emadzadeh D. Evaluation of Surface Properties and Separation Performance of NF and RO Membranes for Phthalates Removal. MEMBRANES 2023; 13:413. [PMID: 37103840 PMCID: PMC10142473 DOI: 10.3390/membranes13040413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/30/2023] [Accepted: 04/04/2023] [Indexed: 06/19/2023]
Abstract
Many studies indicated that phthalates, a common plasticizer, lurk silently in water bodies and can potentially harm living organisms. Therefore, removing phthalates from water sources prior to consumption is crucial. This study aims to evaluate the performance of several commercial nanofiltrations (NF) (i.e., NF3 and Duracid) and reverse osmosis (RO) membranes (i.e., SW30XLE and BW30) in removing phthalates from simulated solutions and further correlate the intrinsic properties of membranes (e.g., surface chemistry, morphology, and hydrophilicity) with the phthalates removal. Two types of phthalates, i.e., dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP), were used in this work, and the effects of pH (ranging from 3 to 10) on the membrane performance were studied. The experimental findings showed that the NF3 membrane could yield the best DBP (92.5-98.8%) and BBP rejection (88.7-91.7%) regardless of pH, and these excellent results are in good agreement with the surface properties of the membrane, i.e., low water contact angle (hydrophilicity) and appropriate pore size. Moreover, the NF3 membrane with a lower polyamide cross-linking degree also exhibited significantly higher water flux compared to the RO membranes. Further investigation indicated that the surface of the NF3 membrane was severely covered by foulants after 4-h filtration of DBP solution compared to the BBP solution. This could be attributed to the high concentration of DBP presented in the feed solution owing to its high-water solubility (13 ppm) compared to BBP (2.69 ppm). Further research is still needed to study the effect of other compounds (e.g., dissolved ions and organic/inorganic matters that might be present in water) on the performance of membranes in removing phthalates.
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Affiliation(s)
- En Qi Lim
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
- Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Mei Qun Seah
- Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Woei Jye Lau
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
- Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Hasrinah Hasbullah
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
- Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Pei Sean Goh
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
- Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Ahmad Fauzi Ismail
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
- Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, Skudai 81310, Johor, Malaysia
| | - Daryoush Emadzadeh
- Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, ON K1N 6N5, Canada
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Struzina L, Pineda Castro MA, Kubwabo C, Siddique S, Zhang G, Fan X, Tian L, Bayen S, Aneck-Hahn N, Bornman R, Chevrier J, Misunis M, Yargeau V. Occurrence of legacy and replacement plasticizers, bisphenols, and flame retardants in potable water in Montreal and South Africa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 840:156581. [PMID: 35697219 DOI: 10.1016/j.scitotenv.2022.156581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/05/2022] [Accepted: 06/05/2022] [Indexed: 06/15/2023]
Abstract
The occurrence of thirty-nine contaminants including plasticizers, bisphenols, and flame retardants in potable water from Montreal and South Africa was analyzed to determine their presence and concentrations in different water sources. In Montreal, five bottled water (BW) brands and three drinking water treatment plants (DWTP) were included. In South Africa, water was sampled from one urban DWTP located in Pretoria, Gauteng, and one rural DWTP located in Vhembe, along with water from the same rural DWTP which had been stored in small and large plastic containers. A combination of legacy compounds, typically with proven toxic effects, and replacement compounds was investigated. Bisphenols, Dechlorane-602, Dechlorane-603, and s-dechlorane plus (s-DP) were not detected in any water samples, and a-dechlorane plus (a-DP) was only detected in one sample from Pretoria at a concentration of 1.09 ng/L. Lower brominated polybrominated diphenyl ethers (PBDE)s were detected more frequently than higher brominated PBDEs, always at low concentrations of <2 ng/L, and total PBDE levels were statistically higher in South Africa than in Montreal. Replacement flame retardants, organophosphate esters (OPEs), were detected at statistically higher concentrations in Montreal's BW (68.56 ng/L), drinking water (DW) (421.45 ng/L) and Vhembe (198.33 ng/L) than legacy PBDEs. Total OPE concentrations did not demonstrate any geographical trend; however, levels were statistically higher in Montreal's DW than Montreal's BW. Plasticizers were frequently detected in all samples, with legacy compounds DEHP, DBP, and replacement DINCH being detected in 100 % of samples with average concentrations ranging from 6.89 ng/L for DEHP in Pretoria to 175.04 ng/L for DINCH in Montreal's DW. Total plasticizer concentrations were higher in Montreal than in South Africa. The replacement plasticizers (DINCH, DINP, DIDA, and DEHA) were detected at similar frequencies and concentrations as legacy plasticizers (DEHP, DEP, DBP, MEHP). For the compounds reported in earlier studies, the concentrations detected in the present study were similar to other locations. These compounds are not currently regulated in drinking water but their frequent detection, especially OPEs and plasticizers, and the presence of replacement compounds at similar or higher levels than their legacy compounds demonstrate the importance of further investigating the prevalence and the ecological or human health effects of these compounds.
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Affiliation(s)
- Leena Struzina
- Department of Chemical Engineering, McGill University, Quebec, Canada
| | | | - Cariton Kubwabo
- Exposure and Biomonitoring Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Shabana Siddique
- Exposure and Biomonitoring Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Gong Zhang
- Exposure and Biomonitoring Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Xinghua Fan
- Exposure and Biomonitoring Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, Canada
| | - Lei Tian
- Department of Food Science and Agricultural Chemistry, McGill University, Quebec, Canada
| | - Stephane Bayen
- Department of Food Science and Agricultural Chemistry, McGill University, Quebec, Canada
| | - Natalie Aneck-Hahn
- School of Health Systems and Public Health, University of Pretoria, Private Bag X323, Arcadia, 0007 Pretoria, South Africa
| | - Riana Bornman
- School of Health Systems and Public Health, University of Pretoria, Private Bag X323, Arcadia, 0007 Pretoria, South Africa
| | - Jonathan Chevrier
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Quebec, Canada
| | | | - Viviane Yargeau
- Department of Chemical Engineering, McGill University, Quebec, Canada.
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Barbagallo S, Baldauf C, Orosco E, Roy NM. Di-butyl phthalate (DBP) induces defects during embryonic eye development in zebrafish. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:178-185. [PMID: 34773557 DOI: 10.1007/s10646-021-02468-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Di-butyl phthalate (DBP) is a phthalate ester (PAEs) added during the manufacturing of plastics to make them stronger, yet more pliable. DBP is noncovalently bound to plastics resulting in leaching into the environment. Concerning concentrations of DBP have been noted in surface and groundwater, aquatic ecosystems, soil and atmospheric environments globally. Global production of phthalates and thus concomitant exposure has increased over the years making studies on the ecological and environmental safety needed. Most of the literature on DBP focuses on the endocrine disrupting properties of phthalate esters, but the developmental toxicity of DBP is an understudied area. Here, we treat gastrula staged zebrafish embryos with environmentally relevant concentrations of DBP (2.5 µM). We find defects in eye development at 96 h post fertilization including a decrease in the size of the lens and retina in DBP-treated embryos. Defects in eye vascularization as well as loss of the optic nerve and optic tectum were also noted. Here we conclude that exposure to environmentally relevant doses of DBP during early embryonic development is toxic to eye development.
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Affiliation(s)
| | - Cassidy Baldauf
- Department of Biology, Sacred Heart University, Fairfield, CT, USA
| | - Emily Orosco
- Department of Biology, Sacred Heart University, Fairfield, CT, USA
| | - Nicole M Roy
- Department of Biology, Sacred Heart University, Fairfield, CT, USA.
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Tokarz J, Schmitt SM, Möller G, Brändli AW, Adamski J. Functional characterization of two 20β-hydroxysteroid dehydrogenase type 2 homeologs from Xenopus laevis reveals multispecificity. J Steroid Biochem Mol Biol 2021; 210:105874. [PMID: 33722706 DOI: 10.1016/j.jsbmb.2021.105874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/25/2021] [Accepted: 03/09/2021] [Indexed: 11/23/2022]
Abstract
The African clawed frog, Xenopus laevis, is a versatile model for biomedical research and is largely similar to mammals in terms of organ development, anatomy, physiology, and hormonal signaling mechanisms. Steroid hormones control a variety of processes and their levels are regulated by hydroxysteroid dehydrogenases (HSDs). The subfamily of 20β-HSD type 2 enzymes currently comprises eight members from teleost fish and mammals. Here, we report the identification of three 20β-HSD type 2 genes in X. tropicalis and X. laevis and the functional characterization of the two homeologs from X. laevis. X. laevis Hsd20b2.L and Hsd20b2.S showed high sequence identity with known 20β-HSD type 2 enzymes and mapped to the two subgenomes of the allotetraploid frog genome. Both homeologs are expressed during embryonic development and in adult tissues, with strongest signals in liver, kidney, intestine, and skin. After recombinant expression in human cell lines, both enzymes co-localized with the endoplasmic reticulum and catalyzed the conversion of cortisone to 20β-dihydrocortisone. Both Hsd20b2.L and Hsd20b2.S catalyzed the 20β-reduction of further C21 steroids (17α-hydroxyprogesterone, progesterone, 11-deoxycortisol, 11-deoxycorticosterone), while only Hsd20b2.S was able to convert corticosterone and cortisol to their 20β-reduced metabolites. Estrone was only a poor and androstenedione no substrate for both enzymes. Our results demonstrate multispecificity of 20β-HSD type 2 enzymes from X. laevis similar to other teleost 20β-HSD type 2 enzymes. X. laevis 20β-HSD type 2 enzymes are probably involved in steroid catabolism and in the generation of pheromones for intraspecies communication. A role in oocyte maturation is unlikely.
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Affiliation(s)
- Janina Tokarz
- Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Molecular Endocrinology and Metabolism, Neuherberg, Germany.
| | - Stefan M Schmitt
- Walter Brendel Centre of Experimental Medicine, University Hospital and Ludwig-Maximilians-University Munich, Munich, Germany
| | - Gabriele Möller
- Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Molecular Endocrinology and Metabolism, Neuherberg, Germany
| | - André W Brändli
- Walter Brendel Centre of Experimental Medicine, University Hospital and Ludwig-Maximilians-University Munich, Munich, Germany
| | - Jerzy Adamski
- Helmholtz Zentrum München, German Research Center for Environmental Health, Research Unit Molecular Endocrinology and Metabolism, Neuherberg, Germany; German Center for Diabetes Research, Neuherberg, Germany; Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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6
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Luo X, Shu S, Feng H, Zou H, Zhang Y. Seasonal distribution and ecological risks of phthalic acid esters in surface water of Taihu Lake, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 768:144517. [PMID: 33454488 DOI: 10.1016/j.scitotenv.2020.144517] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 12/10/2020] [Accepted: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Phthalic acid esters (PAEs) are endocrine-disrupting compounds that are ubiquitous in surface water. However, early studies on PAEs only focused on six species on the priority contaminant list, and the seasonal variation in the PAE distribution in Taihu Lake, China is unclear. The present study investigated the occurrence, spatial distribution, and ecological risks of 16 PAEs in Taihu Lake during the dry, normal, and wet seasons. The results showed that dibutyl phthalate, diethylhexyl phthalate (DEHP), and diisobutyl phthalate (DIBP) were the major species detected in the surface water of Taihu Lake. The summed concentration of the six priority PAEs accounted for less than 50% of the total, indicating that the contamination of the other PAE congeners was non-negligible. Significant seasonal effects were observed that the total PAE concentration was higher in the wet season than in the dry season, and there were significant positive correlations between the total PAE concentration and rainfall, the water reserve, and the water level. In the dry season, a relatively high PAE level was detected in the area close to the inflow river estuary and the tourist island in the lake. The concentrations of PAEs in the lakeshore area were higher than those in the lake center in the normal season, and were generally high in the wet season. DEHP posed high risks for fish regardless of the season, while butyl benzyl phthalate, DIBP, dihexyl phthalate, and diphenyl phthalate also showed high risks in the normal and wet seasons. These results suggest that the contamination and risks of congeners other than the priority PAEs are also of necessary concern, and seasonal variation should be considered for a comprehensive understanding of PAE contamination in surface water.
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Affiliation(s)
- Xin Luo
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Shu Shu
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Hui Feng
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Hua Zou
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou 215009, China.
| | - Yun Zhang
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China.
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Henderson AL, Colaiácovo MP. Exposure to phthalates: germline dysfunction and aneuploidy. Prenat Diagn 2021; 41:610-619. [PMID: 33583068 DOI: 10.1002/pd.5921] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/15/2021] [Accepted: 02/10/2021] [Indexed: 01/07/2023]
Abstract
Epidemiological studies continue to reveal the enduring impact of exposures to environmental chemicals on human physiology, including our reproductive health. Phthalates, a well characterized class of endocrine disrupting chemicals and commonly utilized plasticizers, are among one of the many toxicants ubiquitously present in our environment. Phthalate exposure has been linked to increases in the rate of human aneuploidy, a phenomenon that is detected in 0.3% of livebirths resulting in genetic disorders including trisomy 21, approximately 4% of stillbirths, and over 35% of miscarriages. Here we review recent epidemiological and experimental studies that have examined the role that phthalates play in germline dysfunction, including increases in apoptosis, oxidative stress, DNA damage, and impaired genomic integrity, resulting in aneuploidy. We will further discuss subject variability, as it relates to diet and polymorphisms, and the sexual dimorphic effects of phthalate exposure, as it relates to sex-specific targets. Lastly, we discuss some of the conserved effects of phthalate exposure across humans, mammalian models and nonmammalian model organisms, highlighting the importance of using model organisms to our advantage for chemical risk assessment and unveiling potential mechanisms that underlie phthalate-induced reproductive health issues across species.
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Affiliation(s)
- Ayana L Henderson
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
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Comparative Analysis of Neurotoxicity of Six Phthalates in Zebrafish Embryos. TOXICS 2021; 9:toxics9010005. [PMID: 33430197 PMCID: PMC7825694 DOI: 10.3390/toxics9010005] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 12/11/2022]
Abstract
The effects and underlying mechanisms of phthalates on neurotoxicity remain unclear as compared with the potentials of these substances as endocrine disruptors. The locomotor activities of zebrafish embryos were investigated upon exposure to six phthalates: dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBzP), di-2-ethylhexyl phthalate (DEHP), di-n-octyl phthalate (DnOP), and diisononyl phthalate (DiNP). Moreover, changes in fluorescence intensity in the green fluorescent protein (GFP) transgenic (Tg) lines Tg(HuC:eGFP), Tg(sox10:eGFP), and Tg(mbp:GFP) were measured after exposure to six phthalates, and changes in the expression profiles of genes involved in the cholinergic (ache) and dopaminergic systems (dat, th, and drd1b) were assessed. Exposure to BBzP, DEHP, and DiNP affected larval behaviors, whereas exposure to DMP, DEP, and DnOP revealed no alterations. A reduced expression of Tg(HuC:eGFP) was observed upon exposure to BBzP, DEHP, and DiNP. The expression of Tg(sox10:eGFP) and Tg(mbp:GFP) was reduced only in response to BBzP and DiNP, respectively. Further, exposure to DiNP upregulated ache and drd1b. The upregulation of ache and downregulation of drd1b was observed in DEHP-exposed groups. Exposure to BBzP suppressed th expression. These observations indicate that exposure to phthalates impaired embryogenesis of the neurological system and neurochemicals in zebrafish embryos, although the detailed mechanisms varied among the individual phthalates. Further mechanistic studies are needed to better understand the causality between phthalate exposure and neurotoxicity.
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Lara-Jacobo LR, Willard B, Wallace SJ, Langlois VS. Cytochrome P450 1A transcript is a suitable biomarker of both exposure and response to diluted bitumen in developing frog embryos. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 246:501-508. [PMID: 30583158 DOI: 10.1016/j.envpol.2018.12.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/12/2018] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
In order for Alberta's thick bitumen to be transported through pipelines, condensates are added creating a diluted bitumen (dilbit) mixture. Recent pipeline expansion projects have generated concern about potential dilbit spills on aquatic wildlife health. Studies have suggested that polycyclic aromatic compounds (PACs) are toxic to aquatic vertebrates and could potentially also interfere with their endocrine system. The research objectives of this study were to investigate the toxicity of dilbit to developing frog embryos and to identify the molecular mechanisms of action involved. Fertilized embryos of Western clawed frog (Silurana tropicalis) were exposed for 72 h to water accommodated fractions (WAF; 0.7-8.9 μg/L TPACs) and chemically-enhanced WAFs (CEWAF; 0.09-56.7 μg/L TPACs) of Access Western Blend (AWB) and Cold Lake Blend (CLB) dilbits. Both dilbit's CEWAFs significantly increased embryonic mortality and malformation incidence in the highest treatments tested, while WAF treatments led to no visible toxic effects. Increases of the cytochrome P450 1A (cyp1a) mRNA levels were observed for all WAF and CEWAF dilbit treatments suggesting that phase I detoxification is activated in the dilbit-exposed larvae. When exposed to PAC concentrations ranging from 0.09 to 8.9 μg/L, the frogs displayed no observable malformations, but expressed significant increases of cyp1a mRNA levels (2- to 25-fold; indicating a suitable biomarker of exposure); however, when concentrations were of 46.6 μg/L or higher, both malformed frog phenotype and induction of cyp1a mRNA level (>250-fold) were measured (indicating a suitable biomarker of response). The expression of several genes related to cellular detoxification and endocrine disruption were also measured, but were not significantly altered by the treatments. In sum, cyp1a mRNA level is a highly sensitive endpoint to measure subtle molecular changes induced by PAC exposure in the frog embryos and larvae, and data suggest that PAC concentration higher than 46 μg/L would be toxic to the developing S. tropicalis.
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Affiliation(s)
- Linda R Lara-Jacobo
- Centre Eau Terre Environnment, Institut national de la recherche scientifique (INRS), Quebec City, QC, Canada
| | - Brianna Willard
- Department of Biology, Queen's University, Kingston, ON, Canada
| | - Sarah J Wallace
- Centre Eau Terre Environnment, Institut national de la recherche scientifique (INRS), Quebec City, QC, Canada; Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada
| | - Valerie S Langlois
- Centre Eau Terre Environnment, Institut national de la recherche scientifique (INRS), Quebec City, QC, Canada; Department of Biology, Queen's University, Kingston, ON, Canada; Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada.
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