60 High lipid exposure during in vitro maturation alters the lipid profile of bovine oocyte and benefits blastocyst development
Bibliographic record
Abstract
Lipid metabolism provides a potent source of energy and has an important role in the acquisition of oocyte competence. However, there are conflicting reports about how lipid exposure during in vitro maturation (IVM) impacts the gamete and further embryo development. In this study, we performed IVM of oocytes in the presence of lipid-rich culture media and used a broad lipid screening to accurately map the impact on the lipid profile and developmental potential. For that, nonpolar lipids were extracted from fetal bovine serum (FBS) with organic solvents (Bligh-Dyer method) and then used to supplement IVM medium (TCM-199 bicarbonate + 10% FBS, hormones, pyruvate and antibiotics). COCs obtained from abattoir ovaries were submitted to IVM (4 biological replicates) in 2 groups: OC (control; IVM medium) and OHL (high lipid; IVM medium supplemented with extra 10% FBS nonpolar lipids). After 24 h, we collected mature oocytes and those remaining followed to IVF and then to IVC (synthetic oviductal fluid with amino acids, SOFaa, with 5% FBS) for 7 days at 38.5°C, 20% O2, and 5% CO2 in air in high humidity. Expanded blastocysts were collected (BC and BHL) and blastocyst rates were assessed. Lipid extracts of individual oocytes and embryos (n = 10/group) were analysed by multiple reaction monitoring (MRM)-profiling mass spectrometry. A total of 379 lipids from 10 classes were investigated [triacylglycerol (TAG), cholesteryl esters (CE), free fatty acids (FFA), acyl-carnitine, sphingomyelin (SM) and phospholipids derived from choline (PC), ethanolamine (PE), glycerol (PG), serine (PS), and inositol (PI)]. Exploratory data analysis was performed by principal component analysis (PCA; Metaboanalyst 4.0), and fold-change (FC) values were calculated based on the relative intensity of lipid ions (FC > 2 and P < 0.05). IVC rates were compared by t-test (α = 5%). PCA revealed a clear distinction in the lipid content for both oocytes and blastocysts (control vs. treated). More specifically, there was 2-fold enrichment for total TAG and CE in control groups and a 1.5-fold enrichment for total FFA in the treated groups at the oocyte and the blastocyst stages. Surprisingly, the average blastocyst rate was higher in the group derived from oocytes exposed to a high-lipid environment (41.56 ± 7.73 vs. 22.62 ± 1.67; P = 0.003), which led us to investigate specific lipid ions. Groups OHL and BHL had increased contents of structural and signalling phospholipids (PC, SM, PE, and PS) and up to 3 times more oleic and linoleic acids, which have been associated with improved oocyte maturation and blastocyst development. Here, we demonstrate how distinct lipid exposures during IVM can robustly alter the lipid profile of oocytes. But more interestingly, it is clear that these are long-term effects, still observed at the blastocyst stage. More studies are required to verify the metabolic impact of this alternative lipid supplementation; however, these results indicate that high lipid exposure is not necessarily detrimental and, at a certain point, may even counteract lipid accumulation commonly observed during in vitro embryo production.
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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 | 0.000 | 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) | 0.002 | 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".