The sperm journey in the excurrent duct: functions of microvesicles on sperm maturation and gene expression along the epididymis
Bibliographic record
Abstract
Mammalian spermatozoa are differentiated, but unable to fertilize as they leave the testis. In order to acquire fertilizing ability and forward motility properties, the male gamete has to transit the epididymis. This process is collectively known as sperm maturation. The epididymis is a single convoluted tubule located between the vas efferens and the vas deferens; sperm epididymal transit takes 3 to 15 days depending on the species. Protein synthesis in the epididymis is highly active in response to androgen stimulation, and the underlying gene expression pattern shows great variability along this organ. For decades it has been recognized that interactions between the transiting spermatozoa and the intraluminal compartment of the epididymis govern complex modifications of sperm macromolecular composition that are necessary for sperm maturation. There is increasing interest in extracellular microvesicles that modulate cell-cell interactions in many physiological systems: such vesicles are found in the intraluminal compartment of the epididymis are called epididymosomes. We have shown that the epididymosome protein composition varies along the epididymis, and that a subset of these proteins is selectively transferred to the male gamete. These proteins are targeted to different sperm sub-compartments and are proposed to be involved in both the acquisition of fertilizing ability and forward motility properties. More recently, we used a bovine model to show that different subpopulations of epididymosomes are present in the fluid of a given epididymal segment. One of these subpopulations is proposed to be involved in the transfer of specific proteins by a membrane fusion process mediated by tetraspanin complexes, whereas another population of epididymosomes is involved in a mechanism that protects epididymal sperm against degenerating ones. Micro RNAs (miRNAs) are constituents of epididymosomes and microarray analyses have shown that the miRNA population characterizing epididymosomes varies with the site of collection along the epididymis. With the knowledge that miRNAs modulate transcriptional activity and that the pattern of gene expression shows great variation along the epididymis, we provide experimental evidence to support that miRNAs associated with epididymosomes modulate gene expression in the distal portion of their region of secretion along the male tract. Taken together, our work shows that microvesicles are one of the major players in the mechanisms underlying sperm maturation and modulation of gene expression along the epididymis. Clinical applications of these results will also be presented. The work described in this abstract was supported by grants from the Natural Sciences and Engineering Research Council of Canada.
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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 | 0.001 |
| 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".