Fractionation of stable carbon isotopes of tissue fatty acids in Atlantic pollock (<i>Pollachius virens</i>)
Bibliographic record
Abstract
Abstract Reliable estimates of diet to tissue fractionation of fatty acid ( FA ) stable carbon isotopes are essential for the development of techniques employing these biomarkers. In this work, Atlantic pollock ( Pollachius virens ) was used as a model species to investigate fractionation arising from metabolic processes during assimilation of dietary FA into serum and liver; we also examined fractionation occurring from mobilization of FA from liver during fasting. Pollock were fed diets containing FA of known isotopic composition, and serum and liver were collected postprandially and after fasting. Lipids were isolated from these tissues, and four polyunsaturated FA ( PUFA ), 18:2n‐6, 18:3n‐3, 20:5n‐3, and 22:6n‐3, within triacylglycerols ( TAG ), a specific lipid class associated with fat storage, were analyzed for their stable carbon isotope ratios. For 18:2n‐6, 20:5n‐3, and 22:6n‐3, there was no discrimination between diet and serum in postprandially sampled fish, suggesting that fractionation did not occur during hydrolysis and esterification for most PUFA examined here during digestion and transfer into serum. There was a similar lack of fractionation for all four FA between fasted liver and serum, indicating that the assembly of these FA into TAG and their release into serum were not associated with fractionation. However, apparent fractionation was variable and inconsistent for all FA between diet and postprandial liver, indicating a failure of liver TAG to fully reflect the new diet. These data will allow δ 13 C values of three PUFA in postprandial serum to be incorporated into mixing models to estimate recent diet in gadoids. Further controlled feeding studies, under conditions that elicit physiological responses that are similar to those of fish in their natural environment, will be necessary before reliable estimates of longer‐term diet, derived from δ 13 C in liver FA , will be possible.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.009 | 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 teacher head, 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".