Folate Transport in Mouse Cumulus-Oocyte Complexes and Preimplantation Embryos1
Bibliographic record
Abstract
Endogenous folate stores are required in preimplantation embryos of several species, but how folates are accumulated and whether they can be replenished has not been determined. Folates are generally taken up into cells by specific transporters, mainly the reduced folate carrier RFC1 (SLC19A1 protein) and the high-affinity folate receptors FOLR1 and FOLR2. Quantitative RT-PCR showed that Slc19a1 mRNA was expressed in mouse cumulus-oocyte complexes (COCs) and oocytes, whereas Folr1 showed expression only in preimplantation embryos, increasing from the 2-cell stage onward. The mRNAs encoding Folr2 and the intestinal folate transporter Slc46a1 were not detected. Methotrexate (MTX), an antifolate often used as a model substrate for folate transport, exhibited saturable transport in COCs and in preimplantation embryos starting at the 2-cell stage. However, folate transport characteristics differed between COCs and embryos. In COCs, transport of MTX and the reduced folate leucovorin was inhibited by the anion transport inhibitor SITS that blocks RFC1 but was insensitive to dynasore, a specific dynamin inhibitor that instead inhibits folate receptor-receptor mediated endocytosis, whereas the opposite was found in 2-cell embryos and blastocysts. The inhibitor profile and transport properties of MTX and leucovorin in COCs correspond to established transport characteristics of RFC1 (SLC19A1), whereas those in 2-cell embryos and blastocysts correspond with those of FOLR1, consistent with the mRNA expression patterns. Considerable folate was accumulated in COCs via RFC1, but the presence of cumulus cells did not enhance folate accumulation in the enclosed oocyte, indicating a lack of transfer from cumulus to oocyte.
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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) | 0.000 | 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".