Cyclodextrin-Loaded Cholesterol Increases the Resistance of Goat Sperm to Cold Shock and Cryopreservation in Skim Milk but Not Egg Yolk Extender.
Notice bibliographique
Résumé
The demand for goat produce in North America has spectacularly increased over the past decade, however, the productivity of the herd does not meet industry requirements. Artificial insemination (AI) using semen from genetically-superior males is a well-established strategy for herd improvement and greatly benefited the goat industry in France and the dairy cattle industry worldwide. Cryopreservation, however, decreases the viability and motility of goat sperm while inducing spontaneous capacitation (“cryo-capacitation”) and acrosome reactions (AR). Sperm from species with high membrane cholesterol:phospholipid ratios can resist cooling. To test the hypothesis that enhancing the cholesterol content of goat sperm would improve cold tolerance, fresh semen aliquots were treated with 0, 0.2, 1, 2.5 or 5 mg/mL cholesterol-loaded methyl-beta-cyclodextrin (CLC; corresponding to 0, 9.8, 49, 122.5 and 245 μg/mL cholesterol) in PBS and cold shocked (20 min, −20C). Spontaneous AR increased due to cold shock but were completely prevented by >1 mg/mL CLC (P < 0.05; n = 3), suggesting that CLC increases membrane cholesterol: phospholipid ratio to moderate phase transitions associated with cold shock. To confirm that CLC increases sperm cholesterol content, fresh sperm in PBS were treated with or without 150 μg/mL cholesterol alone, 3 mg/mL cyclodextrin alone, or 3 mg/mL CLC (corresponding to 150 μg/mL cholesterol). Lipids were extracted by the Folch method adapted for sperm and cholesterol was assayed using Lieberman-Burchard reagent. CLC increased sperm cholesterol levels 3-fold compared to other treatments (P < 0.05; n = 3), indicating that higher cholesterol is indeed related to the cold-resistance of these CLC-treated sperm. Furthermore, cholesterol incorporation requires cyclodextrin as a carrier-molecule. These results suggest that that enriching sperm cholesterol levels using CLC would improve sperm resistance to cryopreservation. Work on other species, however, demonstrates only modest increases in sperm quality and no improvement in fertility following CLC treatment in traditional egg yolk-based extenders. We hypothesised, therefore, that a skim milk-based extender would more effectively permit the CLC to exchange with and protect sperm. Semen aliquots were treated with 0, 0.5, 1, 2, 3 and 4 mg/mL CLC (corresponding to 0, 24.5, 49, 122.5, 147 and 196 μg/mL cholesterol) and then cryopreserved in egg yolk- or skim milk-based extender (8 treatments/ejaculate; n=8). Without CLC, there was no difference in sperm quality between extenders after thawing. However, the percentages of motile, progressively motile, or uncapacitated sperm (“pattern F” according to the chlortetracycline fluorescence assay) increased with 1, 2 and 3 mg/mL CLC in skim milk extender even during incubation after thawing for 3 h at 38.5°C (P < 0.05), with 3 mg/mL being optimal (P < 0.05). In contrast, CLC treatment did not alter the post-thaw quality of sperm in egg yolk extender. Together, our data indicate that cyclodextrin-mediated delivery of exogenous cholesterol improves the tolerance of goat sperm to cold temperatures and that this transfer is biologically more effective in skim milk-based relative to egg yolk-based extenders. Therefore, it is tempting to speculate that in vivo fertility could be improved for semen cryopreserved with between 1 and 3 mg/mL CLC in skim milk-based extender. Thanks to CRSAD for animal support. Financed by NSERC & MAPAQ.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».