Protein kinase C is an important signaling mediator associated with motility of intact sea urchin spermatozoa
Bibliographic record
Abstract
Numerous kinases and phosphatases are most likely implicated in sperm motility initiation and maintenance. Data on these signaling molecules were mostly obtained from studies conducted on in vitro demembranated-reactivated sperm models but are not necessarily representative of the in vivo situation. We therefore investigated the effect of a variety of cell-permeable chemicals, mostly kinase inhibitors, on the motility initiation and maintenance of intact sea urchin spermatozoa. Among the 20 substances tested, the protein kinase C (PKC) inhibitor chelerythrine was the most potent, arresting motility at concentrations starting from 1.5-2 mumol l(-1). Motility was also inhibited by two other PKC inhibitors as well as staurosporine. Furthermore, these inhibitors prevented the motility-associated increase in phosphorylation of at least four PKC substrates. These phospho-PKC target proteins, as assessed with an antibody specific to phosphorylated motifs of PKC substrates, were found to be associated with the flagellum, either in the Triton X-100 soluble portion or the axoneme (Triton X-100 insoluble). A phosphorylated PKC-like enzyme was also detected by immunoblotting in the flagellum, as well as a significant 50 kDa PKC cleavage product. Taken together, the data strongly indicate for the first time that, in vivo, which means on intact spermatozoa, PKC is a key signaling mediator associated with the maintenance of sea urchin sperm motility.
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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) | 0.002 | 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".