Gastrointestinal Uptake and Distribution of Copper in Rainbow Trout
Bibliographic record
Abstract
A single dose of radioactive copper ((64)Cu or new Cu) was infused into the stomach of rainbow trout (Oncorhynchus mykiss) to model dietary copper (Cu) uptake under conditions of a normal nutritional dose and optimum environmental temperature (16 degrees C, 0.117 microg Cu g(-)(1 )body mass). The distribution of new Cu to the gut and internal organs occurred in two phases: rapid uptake by the gut tissues (almost complete by 24 h post-infusion) followed by slower uptake by the internal organs. By 72 h, 60 % of the dose had been excreted, 19 % was still retained in the gut tissue, 10 % remained in the lumen and 12 % had been absorbed across the gut and partitioned amongst the internal organs. A reduction in water temperature of 10 degrees C (to 6 degrees C) significantly retarded components of new Cu distribution (movement of the bolus along the gut and excretion); nonetheless, by 72 h, the fraction absorbed by all the internal organs was similar to that at 16 degrees C. An increase in water temperature of 3 degrees C (to 19 degrees C) caused a pronounced increase in internal organ uptake by 24 h to approximately double the uptake occurring at 16 degrees C. The uptake of new Cu by the gut tissue had a low temperature coefficient (Q(10)<1) consistent with simple diffusion, while the temperature coefficient for transfer of new Cu from gut tissue to the internal organs was high (Q(10)>2), consistent with facilitated transport. Internally, the liver and gall bladder (including bile) were the target organs for dietary Cu partitioning since they were the only organs that concentrated new Cu from the plasma. Individual tissues differed in terms of the exchange of their background Cu pools with new Cu. The background Cu in the walls of the gastrointestinal tract (excluding stomach) exchanged 45-94 % with new Cu from the gut lumen, while tissues such as the stomach, gills, kidney, carcass and fat had 5-7 % exchangeable background Cu. The liver, heart, spleen, ovary, bile and plasma had only 0.2-0.8 % exchangeable background Cu. The gastrointestinal tissues appear to act as a homeostatic organ, regulating the absorption of nutritional (non-toxic) doses of Cu (0. 117 microg g(-)(1 )body mass day(-)(1)) by the internal organs. Within the dose range we used and at optimal temperature (16 degrees C), the new Cu content of the gut tissues fluctuated, but absorption of new Cu by the internal organs remained relatively constant. For example, predosing the fish with non-radioactive Cu caused new Cu absorption by the gut tissues to double and decreased new Cu excretion from 38 to 1.5 %, but had no effect on new Cu uptake by the internal organs. Feeding fish after application of the normal liquid dose of new Cu also had no effect on new Cu uptake by the internal organs, even though the presence of food in the digestive tract reduced the binding of new Cu to the gut tissues and assisted with the excretion of new Cu. The gut was therefore able to regulate new Cu internalization at this dosage. Higher new Cu doses (10, 100 and 1000 times the normal dose), however, evoked regurgitation and increased new Cu excretion within 4 h of application but did not elevate new Cu levels in gut tissue beyond a threshold of approximately 40 microg of new Cu. Only at the highest dose (1000 times the normal dose, 192 microg g(-)(1 )body mass), equivalent to toxic concentrations in the daily diet (7000 microg Cu g(-)(1 )dry mass food), was the buffering capacity of the gut overwhelmed, resulting in an increase in internal new Cu uptake.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".