Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM fr...Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM from sewage sludge on TBBPA sorption by three soils were investigated using batch equilibration experiments in the study. DOM was observed to be sorbed on the soils and the isotherms could be fitted by the Langmuir model. The effects of DOM on TBBPA sorption were dependent on the characteristics of soils and the concentrations of DOM present. TBBPA sorption by Henan (HN) soil (sandy loam) and Liaoning (LN) soil (loamy clay) was promoted in the presence of DOM at low concentration ( 90 mg organic carbon (OC)/L), and the sorption was promoted by HN soil and inhibited by LN soil at DOM added concentration of 180 mg OC/L. TBBPA sorption by Guangxi (GX) soil (silt loam) was always inhibited in the presence of DOM. It was also found that the amount of TBBPA sorbed decreased with the increase in the solution pH value in the absence of DOM. The influencing mechanisms of DOM on the sorption of TBBPA by soils were also discussed.展开更多
We conducted thermal tests using the reagent tetrabromobisphenol A (TBBPA) and various Pd compounds to study the chemical forms of Pd obtained during the pyrolytic and oxidative decomposition of TBBPA. Thermal testing...We conducted thermal tests using the reagent tetrabromobisphenol A (TBBPA) and various Pd compounds to study the chemical forms of Pd obtained during the pyrolytic and oxidative decomposition of TBBPA. Thermal testing was conducted in an electric furnace at temperatures of 280°C - 800°C in an Ar or Ar-O2 (5%) atmosphere for a heating period of 40 min. Scanning electron microscopy-energy dispersive X-ray spectroscopy results revealed that Pd bromide was formed in the mixture of TBBPA and PdO after heating to 450°C in the Ar atmosphere. In addition, thermogravimetry-differential thermal analysis showed that as the heating temperature was increased from 350°C to 730°C, weight loss occurred at a nearly constant rate, indicating that Pd bromide decomposed in this temperature range.展开更多
Tetrabromobisphenol A(TBBPA)is used as a brominated flame retardant and can easily release into environment.It has been detected in a variety of environmental media and even in food,making it a new pollutant that is p...Tetrabromobisphenol A(TBBPA)is used as a brominated flame retardant and can easily release into environment.It has been detected in a variety of environmental media and even in food,making it a new pollutant that is potentially harmful to environment and human health.However,the toxicity and underlying mechanism of TBBPA remain to be explored.TBBPA is actively metabolized in the liver,so it is vital to study the hepatocellular toxicity of TBBPA.In this study,we treated hepatocellular carcinoma cells(HepG2)with TBBPA and searched the differentially expressed genes(DEGs)triggered by TBBPA exposure.RNA-seq analysis showed that the expression of genes,such as CLIC1 and GATSL1,were significantly down-regulated and PTENP1 was significantly up-regulated after TBBPA exposure,and these genes were involved in cell proliferation and metabolism.The down-regulated genes were enriched to peroxisome proliferator-activated receptor(PPAR)signaling pathway and up-regulated genes were enriched to Janus Kinase-signal transduces and activators of transcription(JAK-STAT)signaling pathway,which play a role in regulating cell growth.Overall,our transcriptome analysis obtained for TBBPA-treated HepG2 cells implies that TBBPA affects the cell proliferation and growth.展开更多
Tetrabromobisphenol A-bis(2,3-dibromopropyl ether)(TBBPA-BDBPE),a widely used flame retardant,has been frequently detected in various environmental compartments,but its health hazard remains largely unknown.Here,we in...Tetrabromobisphenol A-bis(2,3-dibromopropyl ether)(TBBPA-BDBPE),a widely used flame retardant,has been frequently detected in various environmental compartments,but its health hazard remains largely unknown.Here,we investigated the adverse effects of TBBPA-BDBPE(50 and 1000μg/kg/day)on postnatal testis development in CD-1 mice and the underlying mechanism.Following the first week of maternal exposure,neonatal mice in the high-dose group exhibited reduced seminiferous tubule area,fewer Sertoli cells and germ cells,and damaged microtubules in Sertoli cells;even microtubule damage was also observed in the low-dose group.When exposure extended to adulthood,male offspring in the high-dose group presented more remarkable alterations in reproductive parameters,including reduced sperm count;in the low-dose group,microtubule damage was also observable,along with blood−testis barrier impairment.Further molecular docking analysis and tubulin polymerization assay indicated that TBBPA-BDBPE could interact with tubulin and disrupt its polymerization.Moreover,we observed attenuated microtubules in mouse Sertoli cells in vitro(TM4)following TBBPABDBPE treatment,suggesting that TBBPA-BDBPE impaired testis development possibly by interfering with tubulin dynamics.This study not only highlights the male reproductive hazard of TBBPA-BDBPE but also greatly improved the understanding of the molecular mechanism for male reproductive toxicity of chemicals.展开更多
Hexabromocyclododecane(HBCD) and tetrabromobisphenol A(TBBPA) are two kinds of brominated flame retardants and widely present in the environment and biota. The levels,spatial distributions and mass inventories of HBCD...Hexabromocyclododecane(HBCD) and tetrabromobisphenol A(TBBPA) are two kinds of brominated flame retardants and widely present in the environment and biota. The levels,spatial distributions and mass inventories of HBCD and TBBPA were investigated in sediments and paddy soils from the Liaohe River Basin in northeast China. The concentrations of ΣHBCD and TBBPA were in the range of not detected(nd) to 4.02 ng/g dry weight(dw) and 0.03 to 4.06 ng/g dw, respectively. γ-HBCD was dominated in sediments,while the abundance of α-HBCD was relatively high in paddy soils. The spatial distributions of HBCD and TBBPA in surface sediments and paddy soils indicated that the local point-input was their major source. The significant correlation between total organic carbon(TOC) contents and the HBCD levels suggested that TOC content also exerted an influence on the distribution of HBCD in sediments. Meanwhile, it was found that the irrigation with river water was not the major transportation pathway of HBCD and TBBPA in paddy soils. Based on the study, it was estimated that there were about 1.67 tons HBCD and 2.20 tons TBBPA deposited into sediments of the Liaohe River system every year. The total mass inventories of HBCD and TBBPA in sediments were far higher than that in paddy soils.展开更多
Tetrabromobisphenol A(TBBPA)is one of the most widely used brominated flame retardants and is extensively used in electronic equipment,furniture,plastics,and textiles.It is frequently detected in water,soil,air,and or...Tetrabromobisphenol A(TBBPA)is one of the most widely used brominated flame retardants and is extensively used in electronic equipment,furniture,plastics,and textiles.It is frequently detected in water,soil,air,and organisms,including humans,and has raised concerns in the scientific community regarding its potential adverse health effects.Human exposure to TBBPA is mainly via diet,respiration,and skin contact.Various in vivo and in vitro studies based on animal and cell models have demonstrated that TBBPA can induce multifaceted effects in cells and animals,and potentially exert hepatic,renal,neural,cardiac,and reproductive toxicities.Nevertheless,other reports have claimed that TBBPA might be a safe chemical.In this review,we re-evaluated most of the published TBBPA toxicological assessments with the goal of reaching a conclusion about its potential toxicity.We concluded that,although low TBBPA exposure levels and rapid metabolism in humans may signify that TBBPA is a safe chemical for the general population,particular attention should be paid to the potential effects of TBBPA on early developmental stages.展开更多
Brominated flame retardants(BFRs)compounds have been widely added in a number of products to reduce their flammability.In the present study,the concentrations and distribution of tetrabromobisphenol A(TBBPA)and its de...Brominated flame retardants(BFRs)compounds have been widely added in a number of products to reduce their flammability.In the present study,the concentrations and distribution of tetrabromobisphenol A(TBBPA)and its derivatives,i.e.tribromophenol dibromopropyl ether(TBPDBPE),tetrabromobisphenol A bis-dibromopropyl ether(TBBPA BDBPE),tetrabromobisphenol A bis-allyl ether(TBBPA BAE)were investigated in sediment samples collected from the Vaal River catchment,South Africa.The results showed that all these pollutants were detected in sediments with TBBPA BAE being the most abundant contaminant.The TBBPA BAE concentrations ranged from 3.5 to 44.4 ng/g(mean 16 ng/g)while the concentration ranged from not detected(nd)to 2.4 ng/g(mean 0.6 ng/g),nd-21.0 ng/g(mean 6 ng/g)and nd-2.0 ng/g(mean 0.2 ng/g)for TBPDBPE,TBBPA and TBBPA BDBPE;respectively.Higher concentrations of these pollutants were found in sampling sites receiving effluents of wastewater treatment works(WWTWs)treating some industrial wastewater suggesting effluents might play an important role in the contamination of BFRs in the environment.Negative correlation between TBBPA and TBBPA BAE was observed implying different sources or environmental fates between these pollutants.Overall,the results showed a need for further studies to be undertaken in investigating the presence,fate and sources of alternative halogenated flame retardants in the environment.展开更多
Anaerobic sewage sludge capable of rapidly degrading tetrabromobisphenol A(TBBPA) was successfully acclimated in an anaerobic reactor over 280 days. During the period from 0 to 280 days, the TBBPA degradation rate(DR)...Anaerobic sewage sludge capable of rapidly degrading tetrabromobisphenol A(TBBPA) was successfully acclimated in an anaerobic reactor over 280 days. During the period from 0 to 280 days, the TBBPA degradation rate(DR), utilization of glucose, and VSS were monitored continuously. After 280 days of acclimation, the TBBPA DR of active sludge reached 96.0% after 20 days of treatment in batch experiments. Based on scanning electron microscopy(SEM) observations and denaturing gradient gel electrophoresis(DGGE) determinations,the diversity of the microorganisms after 0 and 280 days in the acclimated anaerobic sewage sludge was compared. Furthermore, eleven metabolites, including 2-bromophenol,3-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, tribromophenol and bisphenol A,were identified by gas chromatography–mass spectrometry(GC–MS). Moreover, the six primary intermediary metabolites were also well-degraded by the acclimated anaerobic sewage sludge to varying degrees. Among the six target metabolites, tribromophenol was the most preferred substrate for biodegradation via debromination. These metabolites degraded more rapidly than monobromide and bisphenol A. The biodegradation data of the intermediary metabolites exhibited a good fit to a pseudo-first-order model.Finally, based on the metabolites, metabolic pathways were proposed. In conclusion, the acclimated microbial consortia degraded TBBPA and its metabolites well under anaerobic conditions.展开更多
A method for the selective separation of polychlorinated naphthalene (PCNs), hexabromocyclododecanes (HBCDs) and tetrabro-mobisphenol A (TBBPA) in complex matrices was developed. In the present study, the type of sorb...A method for the selective separation of polychlorinated naphthalene (PCNs), hexabromocyclododecanes (HBCDs) and tetrabro-mobisphenol A (TBBPA) in complex matrices was developed. In the present study, the type of sorbents and the volume and composition of eluting solvents were investigated in detail. Under the optimal conditions, the recoveries of PCNs, HBCDs and TBBPA in different fractions were determined with liquid/gas chromatography tandem mass spectrometry (LC or GC-MS/MS), which was nearly close to 100%. To investigate the feasibility of the developed method, it was applied to isolate target compounds from spiked soil extracts. PCNs, HBCDs and TBBPA could be subsequently eluted with hexane, hexane/dichloromethane (1:1), and hexane/dichloromethane (1:3), and the recoveries of the analysts from three fractions were satisfactory (70.9%-107%) with the exception of -HBCD at low levels. The results indicated that the method exhibited good performance for the selective separation of PCNs, HBCDs and TBBPA and showed great potential in sample pretreatment in terms of alleviating influence from different class of impurities to some extent.展开更多
We developed the T3-induced Xenopus metamorphosis assay, which is supposed to be able to sensitively detect thyroid hormone(TH) signaling disruption of chemicals. The present study aimed to validate the T3-induced Xen...We developed the T3-induced Xenopus metamorphosis assay, which is supposed to be able to sensitively detect thyroid hormone(TH) signaling disruption of chemicals. The present study aimed to validate the T3-induced Xenopus metamorphosis assay by re-evaluating the TH signaling antagonism of tetrabromobisphenol A(TBBPA), a known TH signaling disruptor. According to the assay we developed, Xenopus tadpoles at stage 52 were exposed to 10–500 nmol/L TBBPA in the presence of 1 nmol/L T3. After 96 hr of exposure, TBBPA in the range of 10–500 nmol/L was found to significantly inhibit T3-induced morphological changes of Xenopus tadpoles in a concentration-dependent manner in term of body weight and four morphological endpoints including head area(HA), mouth width(MW), unilateral brain width/brain length(ULBW/BL), and hind-limb length/snout-vent length(HLL/SVL).The results show that these endpoints we developed are sensitive for characterizing the antagonistic effects of TBBPA on T3-induced metamorphosis. Following a 24-hr exposure,we found that TBBPA antagonized expression of T3-induced TH-response genes in the tail,which is consistent with previous findings in the intestine. We propose that the tail can be used as an alternative tissue to the intestine for examining molecular endpoints for evaluating TH signaling disruption. In conclusion, our results demonstrate that the T3-induced Xenopus metamorphosis assay we developed is an ideal in vivo assay for detecting TH signaling disruption.展开更多
基金the National Natural Science Foundation of China (No. 20577020, 20737001)
文摘Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM from sewage sludge on TBBPA sorption by three soils were investigated using batch equilibration experiments in the study. DOM was observed to be sorbed on the soils and the isotherms could be fitted by the Langmuir model. The effects of DOM on TBBPA sorption were dependent on the characteristics of soils and the concentrations of DOM present. TBBPA sorption by Henan (HN) soil (sandy loam) and Liaoning (LN) soil (loamy clay) was promoted in the presence of DOM at low concentration ( 90 mg organic carbon (OC)/L), and the sorption was promoted by HN soil and inhibited by LN soil at DOM added concentration of 180 mg OC/L. TBBPA sorption by Guangxi (GX) soil (silt loam) was always inhibited in the presence of DOM. It was also found that the amount of TBBPA sorbed decreased with the increase in the solution pH value in the absence of DOM. The influencing mechanisms of DOM on the sorption of TBBPA by soils were also discussed.
文摘We conducted thermal tests using the reagent tetrabromobisphenol A (TBBPA) and various Pd compounds to study the chemical forms of Pd obtained during the pyrolytic and oxidative decomposition of TBBPA. Thermal testing was conducted in an electric furnace at temperatures of 280°C - 800°C in an Ar or Ar-O2 (5%) atmosphere for a heating period of 40 min. Scanning electron microscopy-energy dispersive X-ray spectroscopy results revealed that Pd bromide was formed in the mixture of TBBPA and PdO after heating to 450°C in the Ar atmosphere. In addition, thermogravimetry-differential thermal analysis showed that as the heating temperature was increased from 350°C to 730°C, weight loss occurred at a nearly constant rate, indicating that Pd bromide decomposed in this temperature range.
基金supported by the National Natural Science Foundation of China(Nos.22234008,21927807,22021003).
文摘Tetrabromobisphenol A(TBBPA)is used as a brominated flame retardant and can easily release into environment.It has been detected in a variety of environmental media and even in food,making it a new pollutant that is potentially harmful to environment and human health.However,the toxicity and underlying mechanism of TBBPA remain to be explored.TBBPA is actively metabolized in the liver,so it is vital to study the hepatocellular toxicity of TBBPA.In this study,we treated hepatocellular carcinoma cells(HepG2)with TBBPA and searched the differentially expressed genes(DEGs)triggered by TBBPA exposure.RNA-seq analysis showed that the expression of genes,such as CLIC1 and GATSL1,were significantly down-regulated and PTENP1 was significantly up-regulated after TBBPA exposure,and these genes were involved in cell proliferation and metabolism.The down-regulated genes were enriched to peroxisome proliferator-activated receptor(PPAR)signaling pathway and up-regulated genes were enriched to Janus Kinase-signal transduces and activators of transcription(JAK-STAT)signaling pathway,which play a role in regulating cell growth.Overall,our transcriptome analysis obtained for TBBPA-treated HepG2 cells implies that TBBPA affects the cell proliferation and growth.
基金supported by the National Key Research and Development Program of China(2018YFA0901103)the National Natural Science Foundation of China(21876196).
文摘Tetrabromobisphenol A-bis(2,3-dibromopropyl ether)(TBBPA-BDBPE),a widely used flame retardant,has been frequently detected in various environmental compartments,but its health hazard remains largely unknown.Here,we investigated the adverse effects of TBBPA-BDBPE(50 and 1000μg/kg/day)on postnatal testis development in CD-1 mice and the underlying mechanism.Following the first week of maternal exposure,neonatal mice in the high-dose group exhibited reduced seminiferous tubule area,fewer Sertoli cells and germ cells,and damaged microtubules in Sertoli cells;even microtubule damage was also observed in the low-dose group.When exposure extended to adulthood,male offspring in the high-dose group presented more remarkable alterations in reproductive parameters,including reduced sperm count;in the low-dose group,microtubule damage was also observable,along with blood−testis barrier impairment.Further molecular docking analysis and tubulin polymerization assay indicated that TBBPA-BDBPE could interact with tubulin and disrupt its polymerization.Moreover,we observed attenuated microtubules in mouse Sertoli cells in vitro(TM4)following TBBPABDBPE treatment,suggesting that TBBPA-BDBPE impaired testis development possibly by interfering with tubulin dynamics.This study not only highlights the male reproductive hazard of TBBPA-BDBPE but also greatly improved the understanding of the molecular mechanism for male reproductive toxicity of chemicals.
基金supported by the National Natural Science Foundation of China (nos. 21205117, 21277139)the Special Fund for Agro-scientific Research in the Public Interest (no. 201503108)+1 种基金the Hi-Tech Research and Development Program (863) of China (no. 2013AA065203)the National Basic Research Program (973) of China (no. 2015CB453100)
文摘Hexabromocyclododecane(HBCD) and tetrabromobisphenol A(TBBPA) are two kinds of brominated flame retardants and widely present in the environment and biota. The levels,spatial distributions and mass inventories of HBCD and TBBPA were investigated in sediments and paddy soils from the Liaohe River Basin in northeast China. The concentrations of ΣHBCD and TBBPA were in the range of not detected(nd) to 4.02 ng/g dry weight(dw) and 0.03 to 4.06 ng/g dw, respectively. γ-HBCD was dominated in sediments,while the abundance of α-HBCD was relatively high in paddy soils. The spatial distributions of HBCD and TBBPA in surface sediments and paddy soils indicated that the local point-input was their major source. The significant correlation between total organic carbon(TOC) contents and the HBCD levels suggested that TOC content also exerted an influence on the distribution of HBCD in sediments. Meanwhile, it was found that the irrigation with river water was not the major transportation pathway of HBCD and TBBPA in paddy soils. Based on the study, it was estimated that there were about 1.67 tons HBCD and 2.20 tons TBBPA deposited into sediments of the Liaohe River system every year. The total mass inventories of HBCD and TBBPA in sediments were far higher than that in paddy soils.
基金supported by the National Natural Science Foun-dation of China(Nos.21707160 and 21876197)the Chinese Academy of Sciences(No.QYZDJ-SSW-DQC017)the K.C.Wong Education Foundation。
文摘Tetrabromobisphenol A(TBBPA)is one of the most widely used brominated flame retardants and is extensively used in electronic equipment,furniture,plastics,and textiles.It is frequently detected in water,soil,air,and organisms,including humans,and has raised concerns in the scientific community regarding its potential adverse health effects.Human exposure to TBBPA is mainly via diet,respiration,and skin contact.Various in vivo and in vitro studies based on animal and cell models have demonstrated that TBBPA can induce multifaceted effects in cells and animals,and potentially exert hepatic,renal,neural,cardiac,and reproductive toxicities.Nevertheless,other reports have claimed that TBBPA might be a safe chemical.In this review,we re-evaluated most of the published TBBPA toxicological assessments with the goal of reaching a conclusion about its potential toxicity.We concluded that,although low TBBPA exposure levels and rapid metabolism in humans may signify that TBBPA is a safe chemical for the general population,particular attention should be paid to the potential effects of TBBPA on early developmental stages.
文摘Brominated flame retardants(BFRs)compounds have been widely added in a number of products to reduce their flammability.In the present study,the concentrations and distribution of tetrabromobisphenol A(TBBPA)and its derivatives,i.e.tribromophenol dibromopropyl ether(TBPDBPE),tetrabromobisphenol A bis-dibromopropyl ether(TBBPA BDBPE),tetrabromobisphenol A bis-allyl ether(TBBPA BAE)were investigated in sediment samples collected from the Vaal River catchment,South Africa.The results showed that all these pollutants were detected in sediments with TBBPA BAE being the most abundant contaminant.The TBBPA BAE concentrations ranged from 3.5 to 44.4 ng/g(mean 16 ng/g)while the concentration ranged from not detected(nd)to 2.4 ng/g(mean 0.6 ng/g),nd-21.0 ng/g(mean 6 ng/g)and nd-2.0 ng/g(mean 0.2 ng/g)for TBPDBPE,TBBPA and TBBPA BDBPE;respectively.Higher concentrations of these pollutants were found in sampling sites receiving effluents of wastewater treatment works(WWTWs)treating some industrial wastewater suggesting effluents might play an important role in the contamination of BFRs in the environment.Negative correlation between TBBPA and TBBPA BAE was observed implying different sources or environmental fates between these pollutants.Overall,the results showed a need for further studies to be undertaken in investigating the presence,fate and sources of alternative halogenated flame retardants in the environment.
基金supported in part by the Grant from Guangdong Province Scientific and Technological Project (2016A050503029)Fundamental Research Funds for the Universities (161gpy27)Research Fund Program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (2016K0008)
文摘Anaerobic sewage sludge capable of rapidly degrading tetrabromobisphenol A(TBBPA) was successfully acclimated in an anaerobic reactor over 280 days. During the period from 0 to 280 days, the TBBPA degradation rate(DR), utilization of glucose, and VSS were monitored continuously. After 280 days of acclimation, the TBBPA DR of active sludge reached 96.0% after 20 days of treatment in batch experiments. Based on scanning electron microscopy(SEM) observations and denaturing gradient gel electrophoresis(DGGE) determinations,the diversity of the microorganisms after 0 and 280 days in the acclimated anaerobic sewage sludge was compared. Furthermore, eleven metabolites, including 2-bromophenol,3-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, tribromophenol and bisphenol A,were identified by gas chromatography–mass spectrometry(GC–MS). Moreover, the six primary intermediary metabolites were also well-degraded by the acclimated anaerobic sewage sludge to varying degrees. Among the six target metabolites, tribromophenol was the most preferred substrate for biodegradation via debromination. These metabolites degraded more rapidly than monobromide and bisphenol A. The biodegradation data of the intermediary metabolites exhibited a good fit to a pseudo-first-order model.Finally, based on the metabolites, metabolic pathways were proposed. In conclusion, the acclimated microbial consortia degraded TBBPA and its metabolites well under anaerobic conditions.
基金supported by the Special Environmental Protection Foundation for Public Welfare Project (201209016) the National High Technology Research and Development Program of China (2007AA061602)
文摘A method for the selective separation of polychlorinated naphthalene (PCNs), hexabromocyclododecanes (HBCDs) and tetrabro-mobisphenol A (TBBPA) in complex matrices was developed. In the present study, the type of sorbents and the volume and composition of eluting solvents were investigated in detail. Under the optimal conditions, the recoveries of PCNs, HBCDs and TBBPA in different fractions were determined with liquid/gas chromatography tandem mass spectrometry (LC or GC-MS/MS), which was nearly close to 100%. To investigate the feasibility of the developed method, it was applied to isolate target compounds from spiked soil extracts. PCNs, HBCDs and TBBPA could be subsequently eluted with hexane, hexane/dichloromethane (1:1), and hexane/dichloromethane (1:3), and the recoveries of the analysts from three fractions were satisfactory (70.9%-107%) with the exception of -HBCD at low levels. The results indicated that the method exhibited good performance for the selective separation of PCNs, HBCDs and TBBPA and showed great potential in sample pretreatment in terms of alleviating influence from different class of impurities to some extent.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB14040102)the National Natural Science Foundation of China(No.21377153)
文摘We developed the T3-induced Xenopus metamorphosis assay, which is supposed to be able to sensitively detect thyroid hormone(TH) signaling disruption of chemicals. The present study aimed to validate the T3-induced Xenopus metamorphosis assay by re-evaluating the TH signaling antagonism of tetrabromobisphenol A(TBBPA), a known TH signaling disruptor. According to the assay we developed, Xenopus tadpoles at stage 52 were exposed to 10–500 nmol/L TBBPA in the presence of 1 nmol/L T3. After 96 hr of exposure, TBBPA in the range of 10–500 nmol/L was found to significantly inhibit T3-induced morphological changes of Xenopus tadpoles in a concentration-dependent manner in term of body weight and four morphological endpoints including head area(HA), mouth width(MW), unilateral brain width/brain length(ULBW/BL), and hind-limb length/snout-vent length(HLL/SVL).The results show that these endpoints we developed are sensitive for characterizing the antagonistic effects of TBBPA on T3-induced metamorphosis. Following a 24-hr exposure,we found that TBBPA antagonized expression of T3-induced TH-response genes in the tail,which is consistent with previous findings in the intestine. We propose that the tail can be used as an alternative tissue to the intestine for examining molecular endpoints for evaluating TH signaling disruption. In conclusion, our results demonstrate that the T3-induced Xenopus metamorphosis assay we developed is an ideal in vivo assay for detecting TH signaling disruption.
