We have examined the potential role of fatty acid oxidation (FAO) in AMP-activated protein kinase (AMPK)-induced meiotic maturation. Etomoxir and malonyl CoA, two inhibitors of carnitine palmitoyl transferase-1 (CPT1), and thus FAO, blocked meiotic induction in dbcAMP-arrested cumulus cell-enclosed oocytes (CEO) and denuded oocytes (DO) by the AMPK activator, AICAR. C75, an activator of CPT1 an...

The meiotic cell cycle of mammalian oocytes starts during embryogenesis and then pauses until luteinizing hormone (LH) acts on the granulosa cells of the follicle surrounding the oocyte to restart the cell cycle. An essential event in this process is a decrease in cyclic GMP in the granulosa cells, and part of the cGMP decrease results from dephosphorylation and inactivation of the natriuretic ...

Rabbit oocytes from preovulatory follicles resume meiosis up to metaphase II in normal delay when cultured in TC 199 supplemented with rabbit and calf sera and chick embryo extract. They are fertilizable, but such oocytes are unable to assume transformation of the sperm head into a normal nucleus, the male pronucleus. Rabbit preovulatory follicle can be maintained in healthy conditions for at l...

Water deficit during male meiosis in wheat (Triticum aestivum L.) causes pollen sterility. With a view to identifying the internal trigger for this failure, it was found that water stress specifically impairs the activities of vacuolar and cell-wall invertases in anthers prior to the arrest of pollen development. The enzymes are affected only when water deficit occurs around meiosis. Three inve...

Physical removal of mammalian cumulus-oocyte complexes (COCs) from ovarian follicles results in spontaneous resumption of meiosis, largely because of a decrease in cAMP concentrations, causing asynchrony between cytoplasmic and nuclear maturation and decreased oocyte developmental competence. The aim of this study was to modulate cAMP concentrations within ovine COCs to delay spontaneous nuclea...

The meiotic cell cycle in mammalian oocytes commences in the fetal ovary, proceeds up to the diplotene stage of the first prophase, and is arrested around birth at a G2-like phase. Reinitiation of meiosis, which occurs immediately before ovulation, represents the transition from G2 to M phase of the cell cycle. Resumption of meiosis is associated with a reduction in cAMP concentrations within t...