Epididymosomes Transfer Epididymal Sperm Binding Protein 1 (ELSPBP1) to Dead Spermatozoa During Epididymal Transit in Bovine1
Bibliographic record
Abstract
Previously, we showed that epididymal sperm binding protein 1 (ELSPBP1) characterizes spermatozoa already dead before ejaculation in bovine. In this study, we investigated the presence of ELSPBP1 in bull genital tract as well as its acquisition by spermatozoa during epididymal transit. As assessed by real-time RT-PCR, ELSPBP1 was highly expressed in the caput and the corpus epididymis but was present in lower expression levels in the testis and the cauda epididymis. Immunohistochemistry revealed the same expression pattern. However, Western blot on tissue homogenates showed some discrepancies, as ELSPBP1 was found in a comparable concentration all along the epididymis. This difference was due to the presence of ELSPBP1 in the epididymal fluid. In both caput and cauda epididymal fluid, ELSPBP1 was associated with the epididymosomes, small membranous vesicles secreted by epithelial cells of the epididymis and implicated in the transfer of proteins to spermatozoa. As assessed by immunocytometry, ELSPBP1 was found on a subset of dead spermatozoa in caput epididymis but was found on all dead spermatozoa in cauda epididymis. To assess ELSPBP1 acquisition by spermatozoa, caput epididymal spermatozoa were incubated with cauda epididymosomes under various conditions. ELSPBP1 detection by immunocytometry assay revealed that only spermatozoa already dead before incubation were receptive to ELSPBP1 transfer by epididymosomes. This receptivity was enhanced by the presence of zinc in the incubation medium. This specificity for a sperm subpopulation suggests that an underlying mechanism is involved and that ELSPBP1 could be a tag for the recognition of dead spermatozoa during epididymal transit.
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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 | 0.000 |
| 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 | 0.001 |
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".