Implication of Calmodulin‐Dependent Phosphodiesterase Type 1 During Bovine Sperm Capacitation
Bibliographic record
Abstract
Phosphodiesterases (PDEs) are enzymes that degrade cyclic nucleotides. The calcium-calmodulin dependent PDE type 1 (PDE 1) and the cyclic adenosine monophosphate (cAMP)-specific PDE type 4 (PDE 4) have been implicated in sperm function. We tested the hypothesis that specific PDEs regulate capacitation of bovine sperm in a manner independent of those that mediate motility. Our objectives were to determine the effects of inhibiting PDE 1 and PDE 4 on capacitation and motility, and to compare these effects to those of heparin, which is necessary for capacitation of bull sperm in vitro. Fresh sperm were supplemented either with 15 microg/mL heparin (positive control) or the PDE inhibitors vinpocetine (specific for PDE 1) and rolipram (specific for PDE 4), and then incubated for 5 hours. At 0, 3, and 5 hours, samples were assayed for capacitation and motility parameters according to the chlortetracycline (CTC) fluorescent pattern B and computer-assisted sperm analysis, respectively. A higher percentage of CTC pattern B sperm relative to heparin controls was observed at 0 and 3 hours when sperm were incubated with vinpocetine. After 5 hours, the percentage of heparin- and vinpocetine-treated sperm showing pattern B did not differ (P >.05). Rolipram did not affect CTC patterns (P >.05; n = 4). Vinpocetine and heparin both reduced the percentage of progressively motile sperm after 3 and 5 hours, but vinpocetine reduced it more than heparin (P <.05; n = 4). Rolipram transiently increased linearity versus sperm with heparin (P <.05; n = 4). To further test the hypothesis that PDE 1 inhibition permits capacitation, we conducted in vitro fertilization. Vinpocetine did not support the ability of sperm to penetrate homologous oocytes (n = 5). Although cAMP regulation by PDE 1 may occur early during capacitation, downstream events appear to prevent full capacitation from occurring prematurely.
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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 | 0.000 | 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".