SPERM DNA INTEGRITY AND CYTOSOLIC CALCIUM LEVELS ARE ASSOCIATED WITH THE IN VIVO FERTILITY OF BOVINE SEMEN
Bibliographic record
Abstract
Cryopreserved bull sperm are less fertile than fresh due to sub-lethal damage that has not been fully characterized, although premature capacitation due to the freeze-thaw process may be partly responsible. Also, cryo-induced DNA damage would reduce the ability of the sperm to produce a viable embryo. Two experiments were therefore conducted on 14 bulls (1–4 semen batches/bull) classified into high- and low-fertility groups. In Experiment 1, we tested the hypothesis that sperm chromatin stability is related to bull fertility (as 56-day non-return rates) using the Sperm Chromatin Structure Assay (SCSA) on cryopreserved sperm at 0 and 7 h of incubation in conditions to mimic the female genital tract (Talp- BSA, 38.5°C, 5% CO2). In Experiment 2, we tested a second hypothesis, that the cytosolic calcium level of cryopreserved sperm is related to bull fertility using the fluorescent calcium indicator, indo-1, again at 0 and 7 h of incubation in physiological conditions. Additional functional sperm parameters, including motility (using CASA) and viability (using eosin – nigrosin) were assessed in Exp 1. In Exp 2, chlortetracycline fluorescence (CTC) patterns, sperm motility (CASA) and viability (measured by eosinnigrosin and propidium iodide (PI) during the evaluation of cytosolic calcium levels) were also assessed. The results of Exp 1 showed that the percentage of sperm with a high DNA fragmentation index (%DFI) was higher (P < .05) for bulls in the low fertility group immediately after thawing (0 h of incubation), indicating that DNA damage does reduce the fertilizing potential of the male. Moderate, significant correlations (ranging from −.54, P < .05, to −.74, P < .01) were obtained between %DFI and functional parameters, suggesting that DNA and functional damage are associated but do not necessarily occur concomitant with each other or are induced by the same stimuli. For Exp 2, internal calcium levels were negatively correlated with bull fertility after 7 h of incubation (P < .03), supporting previous reports that high calcium impairs sperm fertilizing capacity, possibly due to precocious capacitation or the onset of spontaneous acrosome reactions. In Exp 1, bull fertility correlated with total and progressive sperm motility (r = −.58 and r = −.55, P < .05, respectively) at 0 h, confirming their utility as a general predictor of fertilizing ability. Such correlation was not observed in Exp 2, however, this is likely because the sperm were centrifuged prior to calcium measures, but not before the SCSA. Cytosolic calcium correlated negatively with the percentages of motile sperm at 0 h (r = −.58, P < .05) and viable sperm (using PI) at 7 h of incubation (r = −.76, P < .01). Cytosolic calcium correlated positively with the percentages of CTC pattern B at 0 h (r = .67, P < .01) and negatively with pattern F at 7 h of incubation (r = −.53, P < .05). Together, these data indicate that relatively high cytosolic calcium levels occur in pattern B (capacitated) sperm, reflecting a common mechanism of compromised function in the context of cryopreserved semen used for artificial insemination. In conclusion, sperm DNA stability, cytosolic calcium levels, motility and viability are all related to fertility in vivo, and might serve as predictors of bull fertilizing capacity. (Thanks to L'Alliance Boviteq for supplying the semen and fertility data and to NSERC for financing. S I Peris was supported by the Egyptian government.) (poster)
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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 | 0.001 |
| 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 | 0.001 | 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".