The oocyte regulates GDF9 and BMP15 expression in bovine cumulus cells
Bibliographic record
Abstract
Unlike in the mouse, the presence of the oocyte is not required for expansion of the cumulus-oocyte complex (COC) in cattle. However, we have previously demonstrated that oocyte secreted factors, although not absolutely required, do enhance cumulus expansion in cattle. Major oocyte secreted factors regulating COC maturation are members of the TGFβ family, BMP15 and GDF9. Previous data suggest that BMP15 and GDF9 are expressed in bovine cumulus cells. Thus, the existence of an intra-cumulus loop mediated by TGFβ signalling in cattle constitutes an interesting hypothesis. In this study, we tested the hypothesis that BMP15 and GDF9 are expressed in cumulus cells during IVM in cattle and that mRNA abundance is regulated by the oocyte.COCs were aspirated from follicles 3-8 mm in diameter and COCs (grade 1 or 2) were divided in three groups: intact COCs (COC), oocytectomized COCs (OOX), and OOX plus denuded oocytes (DO). Oocytectomy was performed by aspiration of the ooplasm with a micromanipulator. COCs were matured in groups of 20 for 4 or 22 hours (n = 4/time). IVM was performed in TCM199 with Earl’s salts supplemented with either FSH (1µg/mL) or AREG (100 µg/mL), 0.4% BSA, 22 µg/Ml sodium pyruvate, 75µg/mL of amikacin at 38,5°C and 5.5%CO2 in humid atmosphere. Abundance of mRNA encoding BMP15 and GDF9 in cumulus cells was assessed by real-time RT-PCR using Power SybrGreen (LifeTech®) and CYC-A as the housekeeping gene. Effects of treatments were analysed by ANOVA and groups were compared with the Tukey test.Expression of BMP15 and GDF9 mRNA was detected in bovine cumulus cells. PCR cycle numbers were on average 29 and 28 for BMP15 and GDF9, respectively, at 4 hours of culture, and 29 and 31, at 22 hours of culture. Oocytectomy significantly reduced BMP15 and GDF9 mRNA expression in COCs cultured with AREG for 4 or 22 hours, but not with FSH. Co-culture of OOX with DO restored BMP15 and GDF9 expression . In conclusion, these data suggest that BMP15 and GDF9 mRNA expression in bovine cumulus cells is regulated by the oocyte. This effect is abolished by supra-physiological levesl of FSH used in IVM in cattle.
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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 | 0.001 | 0.001 |
| 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".