Metabolism of PCBs by the Deepwater Sculpin ( Myoxocephalus thompsoni )

ArticleinEnvironmental Science and Technology 35(24):4747-52 · January 2002with1 Reads
DOI: 10.1021/es015571l · Source: PubMed
Abstract
Methylsulfonyl-PCBs (MeSO2-PCBs) are hydrophobic organic contaminants that bioaccumulate in the environment similar to their parent molecules, PCBs. Previously, MeSO2-PCBs have primarily been identified in tissues of birds, humans, and other mammals. However, evidence now supports formation of these metabolites in deepwater sculpin, Myoxocephalus thompsoni, a benthic forage fish predominant in the Great Lakes. The ability of deepwater sculpin to form MeSO2-PCBs is unprecedented for a freshwater fish species and presents a novel biochemical pathway for organochlorine metabolism. Additionally, this appears to be a unique PCB metabolic pathway resulting in a reduction of as much as 10% in the sculpin PCB burden, which is further transformed into another class of organic contaminants in the Great Lakes ecosystem.
    • "Additionally, it is possible that carp do not have the capacity to produce OH-PCBs in the short period of time used in the present study, while arene oxide intermediatesdthe initial step in PCB metabolismdmay have been generated, but cannot be detected by the method used. As for MeSO 2 -PCBs, even though significant concentrations have been detected in wild fish species (Stapleton et al., 2001; Zeng et al., 2014a; Zhang et al., 2012), no MeSO 2 -PCBs have been discovered in laboratory studies so far. A previous study suggested that fish do not possess appreciable sulfone-forming capacity (Letcher et al., 2000 ). "
    [Show abstract] [Hide abstract] ABSTRACT: Metabolites of polychlorinated biphenyls (PCBs) in fish are difficult to detect in vivo due to the complexity of biometabolism. In the present study, atropisomeric fraction analysis of chiral PCB congeners and compound-specific isotopic analysis (CSIA) were applied to trace the biotransformation of PCBs in fish by exposure of common carp (Cryprinus carpio) to the commercial PCB mixture Aroclor 1242. Stereoselective elimination of the chiral PCB congeners 91, 95, and 136 was observed, indicating a stereoselective biotransformation process. The δ(13)C values of PCBs 5/8, 18, and 20/33 in fish were increased compared with those in the spiked food, while PCBs 47/48 and 49 showed significant heavy isotope depletion. These results suggested a significant biotransformation of the corresponding individual PCB congeners although the potential PCB metabolites, hydroxylated PCBs (OH-PCBs) and methylsulfone PCBs (MeSO2-PCBs), were not detected in the fish tissue samples throughout this experiment. The results of the present study demonstrated that a combination of chiral analysis and CSIA is a promising new approach for investigating the biotransformation of PCBs in biota.
    Full-text · Article · Jun 2016
    • "The average concentration ratios of RMeSO 2 -PCBs/RPCBs in northern snakehead (0.00032) were much lower than those examined in plasma of glaucous gull (0.01 in females and 0.007 in males on average) (Verreault et al. 2005) and whole blood of polar bear (0.19 on average) (Sandala et al. 2004). These results indicated that the bioaccumulation or biotransformation of PCBs in fish was much lower than that in birds or mammals perhaps due to the lower CYP2B- like activity (Stapleton et al. 2001). The chiralities of several chiral PCB congeners were analyzed to gain insight into the enantioselective fate process of PCBs. "
    [Show abstract] [Hide abstract] ABSTRACT: Halogenated organic pollutants (HOPs)—including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), polybromobiphenyls (PBBs), dechlorane plus (DP), tetrabromobisphenol A (TBBPA), and hexabromocyclododecanes (HBCDs) as well as PCB metabolites (methylsulfone [MeSO2-]) and hydroxylated (OH-) PCBs and OH-PBDEs—were determined in the serum of mud carp and northern snakehead from an electronic-waste (e-waste) site in South China. The average concentrations (mean ± SD) of ΣPCBs, ΣPBDEs, ΣOCPs, ΣPBBs, ΣTBBPA, ΣHBCDs, and ΣDP were 1410 ± 324, 70 ± 20, 3.0 ± 0.4, 2.8 ± 0.8, 1.6 ± 0.4, 1.0 ± 0.2, and 0.3 ± 0.03 ng/g wet weight (ww) in mud carp and 6430 ± 781, 468 ± 49, 22.4 ± 1.1, 7.0 ± 0.6, 2.9 ± 2.3, 5.5 ± 1.1, and 4.6 ± 0.6 ng/g ww in northern snakehead, respectively. MeSO2-PCBs, OH-PCBs, and OH-PBDEs were detected at a total concentration of 0.44 ± 0.03 and 9.7 ± 0.3 ng/g ww in mud carp and northern snakehead, respectively. The congener profiles of PCBs, PBDEs, OH/MeSO2-PCBs, and OH-PBDEs were found to be significantly different between the two fish species, possibly as a result of species-specific bioaccumulation and/or metabolism of the HOPs. Chirality of ten PCB congeners and α-HBCD, as well as the f anti values of DP in the serum samples, supported the species-specific biotransformation of HOPs. Furthermore, the presence of covaried and counter-varied enantiomeric fractions of PCBs between the two fish species indicated species- and congener-specific enantiomer enrichment of PCBs.
    Full-text · Article · May 2014
    • "PCBs 101, 118, 138, 149, 153, 170 and 180 are high chlorinated congeners, and presented higher contribution for PCB contamination in the three mullet species from the Mondego estuary. High chlorinated congeners are slowly eliminated metabolically (Stapleton et al., 2001; Wu et al., 2008), less volatile and more resistant to microbial degradation (Bazzanti et al., 1997; Zhou et al., 2001), therefore more persistent in the environment. So, once in the organism they tend to bioaccumulate, as they are not readily metabolized and excreted (Borga et al., 2001). "
    [Show abstract] [Hide abstract] ABSTRACT: Polychlorinated biphenyls (PCBs) are lipophilic contaminants that tend to accumulate in organisms. PCBs were detected in Chelon labrosus, Liza aurata and Liza ramada, along different age groups. L. ramada presented the highest concentration, and it increased with age, whereas C. labrosus and L. aurata concentration remained constant. L. ramada high concentration can be attributed to its ecological niche, since this species is able to accumulate PCBs along its different age groups even in low environmental contamination conditions. PCBs 101, 118, 138, 149, 153, 170 and 180 were the congeners that more contributed to these species contamination, being PCB 138 and 153 the congeners with higher concentration. Mullets are edible in many countries, being important in fisheries and aquaculture. L. ramada is the most common mullet for capture and human consumption. All species presented concentrations below the regulation limit establish by the European Union, and therefore safe for human consumption.
    Article · Jun 2013
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