Methylsulfone polycglorinated biphenyl and 2,2-bis(chlorophenyl)-1,1-dichloroethylene metabolites in beluga whale (<i>Delphinapterus leucas</i>) from the St. Lawrence river estuary and western Hudson bay, Canada
Bibliographic record
Abstract
Abstract Kowledge is limited regarding methylsulfone (MeSO2)-polychlorinated biphenyl (PCB), and especially MeSO2–2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE), metabolites in cetacean species. We hypothesized that the ability of beluga whale (Delphinapterus leucas) to biotransform PCB and DDE compounds, and to form and degrade their MeSO2 PCB and -DDE metabolites, is related to the capacity for xenobiotic metabolism. Adipose biopsies were collected from male and female beluga whale from distinct populations in the St. Lawrence River estuary (STL) and western Hudson Bay (WHB), Canada, which are contrasted by the exposure to different levels of cytochrome P450 enzyme-inducing, chlorinated hydrocarbon contaminants. The PCBs, DDTs, DDEs, 28 MeSO2 metabolites of 14 meta-para chlorine-unsubstituted PCBs, and four MeSO2 metabolites of 4,4′- and 2,4′-DDE were determined. The mean concentrations of total (Σ-) MeSO2-PCB in male STL beluga (230 ng/g), and ratios of Σ-MeSO2-PCB to Σ-PCB (0.05) and Σ-precursor-PCB (0.17) were approximately twofold higher, whereas the Σ-precursor-PCB to Σ-PCB ratio was approximately twofold lower, than in male WHB beluga. Both populations had a low formation capacity for MeSO2-PCBs with ≥six chlorines (<4% of Σ-MeSO2-PCBs). The congener patterns were dominated by trichloro- and tetrachloro-MeSO2-PCBs, and tetrachloro- and pentachloro-MeSO2-PCBs in WHB and STL animals, respectively. In addition to 2- and 3-MeSO2-4,4′-DDE, two unknown MeSO2-2,4′-DDEs were detected. The mean 3-MeSO2-4,4′-DDE concentration in STL beluga (1.2 ng/g) was much greater than in WHB (<0.01 ng/g) animals. The concentrations of 4,4′-DDE, and not 3-MeSO2-4,4′-DDE, increased with age in male STL animals. We demonstrated that sulfone formation and clearance is related to metabolic capacity, and thus PCB, DDE, and MeSO2-PCB and -DDE toxicokinetics differ for STL and WHB beluga. In the past, the capacity of odontocetes for PCB and DDE biotransformation leading to persistent sulfone metabolites has been underestimated. More information is needed for other cetacean species and marine mammals. The results of this study indicate that MeSO2-PCBs and -DDEs need to be included in the toxicologic risk assessment of PCB and DDT exposure in odontocetes, and perhaps for cetaceans in general.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".