Porcine Sperm Capacitation and Tyrosine Kinase Activity Are Dependent on Bicarbonate and Calcium but Protein Tyrosine Phosphorylation Is Only Associated with Calcium1
Bibliographic record
Abstract
Mammalian sperm undergo capacitation in the female reproductive tract or under defined conditions in vitro. Although capacitation is now considered to be mediated by intracellular signaling events, including protein phosphorylation, the regulation of the transduction mechanisms is poorly understood. The objective of the present study was to evaluate the importance of medium components on capacitation of porcine sperm, the appearance of an M(r) 32 000 sperm protein (p32), and activity of a tyrosine kinase (TK-32). As determined by the ability of the sperm to undergo the A23187-induced acrosome reaction, pig sperm require bicarbonate and calcium but not BSA for capacitation in vitro. The appearance of p32 was assessed by immunoblotting SDS-extracted and separated sperm proteins using an anti-phosphotyrosine antibody. The appearance of p32 requires calcium, although p32 appears even in the absence of bicarbonate in the incubation medium, demonstrating that the appearance of this tyrosine phosphoprotein is not a final end point of pig sperm capacitation. An in-gel tyrosine kinase renaturation assay showed that TK-32 activity depends on calcium and bicarbonate in the incubation medium. Immunoprecipitation experiments using an anti-phosphotyrosine antibody and inhibitor demonstrated that p32 and TK-32 are different proteins. These data indicate that the signal transduction mechanisms of capacitation in pig sperm are different from those in other mammals, suggesting that certain species specificity may exist with respect to this phenomenon.
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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) | 0.001 | 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) | 0.003 | 0.001 |
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".