Search

The aim of the present study was to investigate the effects of norgestrel (NGT) on gonadal development in adult zebrafish. Adult zebrafish were exposed to NGT for 14 d at 871 ng L−1 for microarray analysis, and a follow-up experiment was conducted to further study the targeted pathway in adult zebrafish after exposure to NGT at 6.7, 83, and 912 ng L−1 by quantitative polymerase chain reaction (qPCR) and histological analysis. The microarray analysis revealed that 11 545 transcripts were identified. Gene ontology analysis showed organ development, system development, multicellular organismal development, single-organism developmental process, and developmental process were significantly enriched. A Venn diagram displayed 434 target genes involved in organ development, and these genes were common in these 5 development-related processes. Kyoto Encyclopedia of Genes and Genomes analysis showed that the notch signaling pathway was the top toxicity pathway, and it was selected as the target pathway for further qPCR analysis. The qPCR analysis revealed significant and dose-dependent alterations of most target genes involved in the notch signaling pathway in the gonads, even at an environmentally relevant concentration of 6.7 ng L−1. The transcriptional patterns were consistent with the notch signaling cascade. In addition, NGT significantly increased the frequency of mature sperm and decreased the frequency of immature sperm at all concentrations. Meanwhile, NGT treatment increased the percentage of mature vitellogenic oocytes and atretic follicles at 912 ng L−1 but decreased the percentage of immature vitellogenic oocytes. Thus, the present study demonstrated significant developmental toxicity in the gonad of adult zebrafish even at environmentally relevant NGT concentrations. Environ Toxicol Chem 2017;36:3267-3276. © 2017 SETAC [ABSTRACT FROM AUTHOR]

Traditional duckweed toxicity tests only measure plant growth inhibition as an endpoint, with limited effects-based data. The present study aimed to investigate whether Fourier-transform infrared (FTIR) spectroscopy could enhance the duckweed ( Lemna minor L.) toxicity test. Four chemicals (Cu, Cd, atrazine, and acetochlor) and 4 metal-containing industrial wastewater samples were tested. After exposure of duckweed to the chemicals, standard toxicity endpoints (frond number and chlorophyll content) were determined; the fronds were also interrogated using FTIR spectroscopy under optimized test conditions. Biochemical alterations associated with each treatment were assessed and further analyzed by multivariate analysis. The results showed that comparable x% of effective concentration (EC x) values could be achieved based on FTIR spectroscopy in comparison with those based on traditional toxicity endpoints. Biochemical alterations associated with different doses of toxicant were mainly attributed to lipid, protein, nucleic acid, and carbohydrate structural changes, which helped to explain toxic mechanisms. With the help of multivariate analysis, separation of clusters related to different exposure doses could be achieved. The present study is the first to show successful application of FTIR spectroscopy in standard duckweed toxicity tests with biochemical alterations as new endpoints. Environ Toxicol Chem 2017;36:346-353. © 2016 SETAC [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol-A (TBBPA) is the most widely used brominated flame retardant. However, little is known about its biotransformation by algae in aquatic environments. The authors investigated transformations of TBBPA by 6 freshwater green microalgae and identified its transformation products. Transformation experiments were conducted under axenic conditions in a laboratory for 10 d. The results showed that TBBPA could be transformed by the selected microalgae, with nearly complete removal by Scenedesmus quadricauda and Coelastrum sphaericum following 10-d incubation. Five transformation products were positively identified by mass spectrometry: TBBPA sulfate, TBBPA glucoside, sulfated TBBPA glucoside, TBBPA monomethyl ether, and tribromobisphenol-A. The mechanisms involved in the biotransformation of TBBPA include sulfation, glucosylation, O-methylation, and debromination, which could be an important step for its further degradation. This suggests that microalgae can play an important role in the fate of TBBPA in aquatic environments. The present study is the first report on algal transformation of TBBPA, and the proposed transformation products could have significant environmental implications. Environ Toxicol Chem 2014;33:1705-1711. © 2014 SETAC [ABSTRACT FROM AUTHOR]

Soil contamination of antimicrobials has become an increasing concern because of the potential risks to the soil microbial ecosystem and human health. The present study investigated sorption and desorption behaviors of oxytetracycline (OTC) and ofloxacin (OFL) in 3 typical soils (A, B, and C), and evaluated the antibacterial activity of soil -adsorbed compounds to a pure sensitive strain Escherichia coli ATCC 25922. The results showed different sorption and desorption behaviors of OTC and OFL in the 3 soils, behaviors that were mainly influenced by soil organic matter content and cation exchange capacity (CEC) as well as pH value. In addition, complexation and cation-exchange reactions were shown to be the main sorption mechanisms. Strong adsorption was found in soil B (with a high organic matter content) and in soil C (with high CEC), whereas enhanced desorption was observed in soil A (with low organic matter content). The results also demonstrated that soil-bound antimicrobials retained antibacterial activity toward E. coli. Opposite patterns of antibacterial activity were found for the 2 antimicrobials in the 3 soils: A > B > C for OFL; and C > B > A for OTC. This finding suggests that soil -bound antimicrobials could still exert selective pressure on soil bacteria although less effectively in comparison with the dissolved forms. Environ Toxicol Chem 2014;33:776-783. © 2014 SETAC [ABSTRACT FROM AUTHOR]

Benzotriazoles (BTs) and benzotriazole ultraviolet (UV) stabilizers (BUVSs) are commonly used industrial and household chemicals, but little is known about their dissipation behavior in the soil environment associated with biosolid application. The authors investigated the occurrence and dissipation of 4 BTs (BT, 5-methyl-1H-benzotriazole [5-TT], 5-chloro-1H-benzotriazole [CBT], and 5,6-dimethyl-1H-benzotriazole [XT]) and 5 BUVSs (UV-326, UV-327, UV-328, UV-329, and UV-P) in biosolid-amended soil of 3 trial sites (Zhejiang, Hunan, and Shandong) in China following 2 treatments (treatment 1: a single application of biosolid; treatment 2: repeated application of biosolid). The results showed that except for CBT and XT, the other 7 compounds could be detected in most of the biosolid and biosolid-amended soils at levels of a few to tens of nanograms per gram and that the concentrations of the 7 compounds for treatment 2 were obviously higher than those for treatment 1. In the 1-yr monitoring of the Shandong site, 2 BTs (BT and 5-TT) and 5 BUVSs (UV-326, UV-327, UV-328, UV-329, and UV-P) were significantly dissipated in the biosolid-amended soils. The field half-lives of BT and 5-TT ranged from 217 d to 345 d, while those for the BUVSs ranged between 75 d and 218 d. The field half-lives of target compounds in soil were found to be comparable to the modeling results. The results suggest the persistence of BTs and BUVSs in soil environments with quite slow dissipation rates. Environ Toxicol Chem 2014;33:761-767. © 2013 SETAC [ABSTRACT FROM AUTHOR]

Biodegradation of the ultraviolet (UV) filter benzophenone-3 (BP-3) was investigated in the laboratory to understand its behavior and fate under oxic and anoxic (nitrate, sulfate, and Fe [III]-reducing) conditions. Biodegradation experiments were conducted in microcosms with 10% of activated sludge and digested sludge under oxic and anoxic conditions, respectively. Benzophenone-3 was well degraded by microorganisms under each redox condition. Under the redox conditions studied, the biodegradation half-life for BP-3 had the following order: oxic (10.7 d) > nitrate-reducing (8.7 d) > Fe (III)-reducing (5.1 d) > sulfate-reducing (4.3 d) ≥ anoxic unamended (4.2 d). The results suggest that anaerobic biodegradation is a more favorable attenuation mechanism for BP-3. Biodegradation of BP-3 produced two products, 4-cresol and 2,4-dihydroxybenzophenone, under oxic and anoxic conditions. Biotransformation of BP-3 to 2,4-dihydroxybenzophenone by way of demethylation of the methoxy substituent ( O-demethylation) occurred in cultures under each redox condition. The further biotransformation of 2,4-dihydroxybenzophenone to 4-cresol was inhibited under oxic, nitrate-reducing, and sulfate-reducing conditions. Environ. Toxicol. Chem. 2012;31:289-295. © 2011 SETAC [ABSTRACT FROM AUTHOR]

Laboratory biodegradation batch studies were performed to investigate the degradation behavior of six selected UV filters, namely benzophenone-3 ( BP-3), 3-(4-methylbenzylidene) camphor (4- MBC), Octyl 4-methoxycinnamate ( OMC), Octocrylene ( OC), 2-(3- t-butyl-2-hydroxy-5-methylphenyl)-5-chloro benzotriazole ( UV-326), and 2-(2'-hydroxy-5'-octylphenyl)-benzotriazole ( UV-329) in an aquifer microcosm (groundwater and aquifer sediment mixture) under aerobic and anaerobic (nitrate, sulfate, and Fe( III) reducing) conditions within 77 d. The results from the biodegradation experiments showed that the six UV filters were degraded well in the aquifer materials under different redox conditions. Rapid biodegradation was observed for BP-3 and OMC in the aquifer materials, with their half-lives of 1.5-8.8 d and 1.3-5.2 d, respectively. In most cases, aerobic conditions were more favorable for the degradation of the UV filters in aquifer materials. Relatively slow degradation of 4- MBC, UV-326, and UV-329 under anaerobic conditions was noted with their half-lives ranging between 47 d and 126 d, indicating potential persistence in anaerobic aquifers. The results showed that redox conditions could have significant effects on biodegradation of the UV filters in aquifers. [ABSTRACT FROM AUTHOR]