80 Energetic substrate availability affects the metabolome profile in bovine sperm
Bibliographic record
Abstract
Bovine spermatozoa are specialised cells that require high ATP production for flagellar movement and other physiological events necessary for fertilization. Glycolysis and oxidative phosphorylation (OXPHOS) are the most studied energy pathways in sperm cells and involve metabolites such as glucose, pyruvate, and lactate. Although glycolysis has been described as the preferential pathway for ATP generation in bovine spermatozoa, other metabolites may also be used, leading to distinct metabolome profiles. Thus, the objective of this work was to characterise the metabolome profile of culture media derived from sperm cells incubated in the presence of different energy substrates for ATP production. For that, a semen straw from one bull (n = 3) previously tested for IVF was thawed and motile sperm were separated by Percoll gradient, washed and resuspended in FertTalp medium (FT) without capacitator agents (Parrish et al. 1989 Biol. Reprod. 41, 683–699) to a final concentration of 30 × 106cells mL−1. Then, samples were centrifuged and resuspended in 5 different groups: positive control (PC, FT supplemented with 2 mM glucose, 0.2 mM pyruvate, and 11 mM lactate); negative control (NC, FT without energy substrates); Glu (FT and 3.5 mM glucose); Pyr (FT and 0.11 mM pyruvate), and Lac (FT and 5.5 mM lactate). Samples were incubated at 38.5°C, 5% CO2 in high humidity for 15 and 45 min. After incubation, samples were centrifuged and supernatant was collected and analysed by Raman spectroscopy as previously described (Santos et al. 2015 Biomed. Opt. Express 6, 2830–2839; https://doi.org/10.1364/BOE.6.002830). Data were preprocessed and submitted to principal component (PCA) and loading plot analysis (LP) by using Minitab software (Minitab Ltd.). The results showed that after 15 min of incubation, the metabolic profiles were similar for the PC, Glu, and Lac groups, suggesting that they present similar metabolic activity. NC and Pyr were a separate cluster, indicating that pyruvate is not metabolized through OXPHOS in this phase. LP analysis comparing Glu and Pyr groups indicated phosphatidylserine, phenylalanine, DNA/RNA, and lipids as the most distinct metabolites. After 45 min, PC and Pyr had a similar metabolome profile, whereas NC, Glu, and Lac clustered together, suggesting that for long-period incubation OXPHOS takes place as the preferential pathway for energy production in bovine sperm cells. At this time, the comparison of Glu versus Pyr revealed phosphatidylserine, proline, phenylalanine, carboxylic acid, DNA/RNA, proteins, and lipids as the most different metabolites between groups. Based on these results, we hypothesised that the glycolysis to OXPHOS transition may be a consequence of the depletion of glycolytic enzymes, leading the sperm cells to use distinct pathways for long-term maintenance of ATP production. In conclusion, our data showed that the metabolome profile of bovine spermatozoa varies according to the period of incubation and substrates availability for energy production. However, more studies are necessary to characterise the ability of these metabolites to maintain sperm motility and viability. This research was funded by FAPESP 2017/18384-0.
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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 | 0.001 |
| 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".