Human Sperm Chromatin Undergoes Physiological Remodeling During In Vitro Capacitation and Acrosome Reaction
Bibliographic record
Abstract
Capacitation (CAP) and acrosome reaction (AR) are sequential processes of sperm activation. Beside the known ionic, membrane, and transduction events and final release of proteolytic enzymes that help sperm movement toward the egg, chromatin changes, such as a physiological remodeling, are also possible. Our aims were to ascertain that CAP and AR do not induce DNA damage and to evaluate changes occurring in the human sperm head during these physiological processes using cytochemical stains. Percollpurified spermatozoa from normal donors were incubated in Biggers, Whitten, and Whittingham medium ± fetal cord serum ultrafiltrate (CAP inducer) and then with lysophosphatidylcholine (AR inducer). CAP and AR were associated with increases in aniline blue (AB, for histones; ∼70%) and toluidine blue (TB, for chromatin compaction; ∼40%) staining but had no influence on that of chromomycin A3 (for protamines). The increase (∼40%) in iodoacetamide-fluorescein (IAF, for sulfhydryl groups) staining observed during CAP was absent after AR. CAP and AR did not damage DNA (percentage of DNA fragmentation index remained low) nor affect histone content. CAP, and even more AR, primed sperm heads to decondense (∼80% and ∼140% increases, respectively) when challenged with sodium dodecyl sulfate + dithiothreitol. Interestingly, induced decondensation correlated with all other tests (CAP, AB, TB, and IAF). Therefore, the data strongly support a physiological remodeling of nondamaged human sperm chromatin during CAP and AR, and modifications are probably interlinked and help prepare chromatin for postfertilization events.
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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".