title: Nitric oxide signals postovulatory aging-induced abortive spontaneous egg activation in rats.
abstract: OBJECTIVE
  The aim of this study was to determine whether an increase of intracellular nitric oxide (NO) level signals postovulatory aging-induced abortive spontaneous egg activation (SEA) in rats.
  
  
  METHODS
  Freshly ovulated eggs (arrested at metaphase-II stage; M-II) were cultured in vitro for 3 hours to induce postovulatory egg aging. The morphological changes, inducible nitric oxide synthase (iNOS) expression, NO, cytosolic free Ca(2+), 3',5' cyclic guanosine monophosphate (cGMP), cell division cycle 25B (Cdc25B) and Wee1 levels, specific phosphorylation (pThr-14/Tyr-15) as well as total cyclin-dependent kinases-1 (Cdk1) (PSTAIRE) levels were analyzed.
  
  
  RESULTS
  Postovulatory aging induced generation of NO possibly through an iNOS-mediated pathway. The increase in NO level was associated with augmented cytosolic free Ca(2+) as well as cGMP levels in aged eggs. A significant increase in Wee1 level and decrease of Cdc25B level were observed in aged eggs. An accumulation of phosphorylated Cdk1 (pThr-14/Tyr-15) level was observed in aged eggs, while total Cdk1 (PSTAIR) level remained unchanged.
  
  
  CONCLUSIONS
  Our study demonstrates that generation of NO through an iNOS-mediated pathway increases cytosolic free Ca2+and cGMP levels. High levels of these signal molecules trigger the accumulation of phosphorylated Cdk1 in aged eggs. Thus, NO signals the accumulation of phosphorylated Cdk1 and induces postovulatory aging-induced abortive SEA in the rat.
authors.forename: Karuppanan V
authors.initials: KV
authors.lastname: Premkumar
authors.forename: Shail K
authors.initials: SK
authors.lastname: Chaube
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase; D002118:Calcium / Q000378:metabolism; D002453:Cell Cycle; D016922:Cellular Senescence; D006152:Cyclic GMP / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008677:Metaphase; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D010060:Ovulation; D010766:Phosphorylation; D059705:Polar Bodies; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D020687:cdc25 Phosphatases / Q000378:metabolism
chemical_list: D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C000605789:Wee1 protein, rat; D011505:Protein-Tyrosine Kinases; D016203:CDC2 Protein Kinase; C548796:Cdk1 protein, rat; D018844:Cyclin-Dependent Kinases; C000605790:Cdc25B protein, rat; D020687:cdc25 Phosphatases; D006152:Cyclic GMP; D002118:Calcium
keywords: Abortive SEA; Cdk1; NO; Postovulatory egg aging; Rat