259 INVOLVEMENT OF Ca2+/CALMODULIN-DEPENDENT PROTEIN KINASE II IN THE SPONTANEOUS ACTIVATION IN RAT OOCYTES
Notice bibliographique
Résumé
Immediately after recovery from the oviduct, rat metaphase-arrested oocytes are very sensitive to spontaneous activation (SA), which is characterized by resumption of meiotic division followed by the cytoplasmic scattering of chromosomes. Although it has been shown that proteasome inhibitor is effective in stopping SA, it is likely that an upstream event is controlling SA. Constitutively active Ca2+/calmodulin-dependent protein kinase II (CaMKII) triggers cyclin B destruction and release from MII arrest. To investigate the kinetics and mechanism of rat spontaneous oocyte activation, we (1) compared SA status after different periods of aging in oviducts and examined the effects of hyalurondiase treatment, (2) compared SA between Ca2+-free and Ca2+-containing conditions, (3) examined the pattern of SA after using CaMII inhibitor and proteasome inhibitor, and (4) analyzed the activity of CaMKII at different times after oocyte collection. Oocytes were collected from three 4-wk-old PMSG-primed Sprague Dawley rats. ANOVA Tukey-Kramer HSD was used for statistical analysis using a P value of 0.05. Each experiment contained at least four replicates with at least 100 oocytes. Experiment 1: Oocytes were collected at different times post-hCG injection (14, 18, 22 h) and cumulus cells were removed before or after 2 h of in vitro culture with hyaluronidase. There was no difference in SA due to oocyte aging in oviducts or hyalurondiase treatment. Experiment 2: Oocytes were cultured in Ca2+-containing and Ca2+-free KSOM for 2 h after collection at different times (14, 18, 22 h) post hCG injection. Although there were no differences among Ca2+-containing KSOM culture groups (91%, 82%, and 90%, respectively), Ca2+-free KSOM significantly decreased SA at 14, 18, and 22 h post-hCG (19%, 43%, and 51%, respectively). Experiment 3: Oocytes were treated with different doses of inhibitor of CaMKII, myr-AIP (10, 20, 50, 100 µM), and proteosome inhibitor MG132 (10, 20, 50, 100 µM) after oocyte collection. Fifty and 100 µM myr-AIP induced significantly lower SA (36%, and 17%) than 0, 10, 20 µM (91%, 65%, and 53%, respectively). Moreover, higher concentrations of MG132 (50 and 100 µM) induced significantly lower SA rates (6% and 5%) than 0, 10, 20 µM (91%, 41%, and 22%, respectively). We also investigated the effect of short exposures to myr-AIP and MG132 during the first 2 min post-recovery. The myr-AIP group produced significantly lower SA compared to control and MG132-treated groups. Experiment 4: Oocytes collected at different times (0, 10, 20, 30, 60 and 90 min) were used for CaMKII activity assay. CaMKII activity increased at 20 min and remained high for 30 min followed by decreased activity by 60 min. In conclusion, CaMKII seems to be one of the upstream signals that causes rat oocytes to spontaneously activate after recovery. Financial support was provided by NSERC and Canada Research Chairs.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| 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) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».