THE ACTIVITY OF AMINO ACID TRANSPORT SYSTEMS IS DYNAMIC IN GROWING AND MATURING MOUSE OOCYTES
Bibliographic record
Abstract
In the ovarian follicle, the surrounding granulosa cells support oocyte development at least partly by supplying it with metabolic substrates, including amino acids. In pre-implantation embryos, characterization of amino acid requirements and activity of transport systems during development has helped lead to the optimization of embryo culture conditions. However, little is known about these systems in oocytes or follicles. Determining the activity of amino acid transport systems and the changes in their activity at different stages of oocyte development could help optimize media for oocyte growth and maturation in vitro, as well as increase the understanding of how the oocyte gains its independence from granulosa cells to exist as a healthy, competent gamete. Our objective was to survey the activity of amino acid transport systems in growing and maturing mouse oocytes. Using radio-labeled amino acids, we first assessed the activity of transport systems in freshly-collected GV and MI oocytes and MII eggs. The initial test for the presence of a transport system included demonstrating saturable transport of a preferred substrate and inhibition of its transport by a established competitive inhibitor. As previously shown, system GLY (Glyt1) was inactive in GV oocytes but activity developed at the MI stage and then increased 3 fold at the MII stage. Beta-amino acid transporter (system Beta) activity was not detected in GV oocytes and appeared at the MI stage, remaining constant in MII stage oocytes. In contrast, system b0,+ activity was present at a constant level throughout meiotic maturation, as assessed with test substrates arginine, lysine and glutamine. System L (leucine-preferring) activity was also present at all stages of maturation but decreased by approximately 40% between the MI and MII stages. Cystine transport was found to occur via system xc−; activity was present throughout maturation but increased a little more than 2-fold between the MI and MII stages. Finally, system ASC was found to account for constant alanine transport activity at all stages of maturation, whereas activities of systems CAT, N, A, XAG− and B0,+ were not detected. Our preliminary data indicate that at least some of these amino acid transport systems develop in the oocyte during oocyte growth. Together, our data indicate that, in the oocyte, the activities of some amino acid transport systems develop and change during meiotic maturation, possibly as a response to oocyte independence from the granulosa cells, which begins at ovulation. Supported by the Program on Oocyte Health, Canadian Institutes of Health Research, Institute of Human Development, Child and Youth Health (HGG62293). (poster)
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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 | 0.001 | 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".