Pig oocytes at metaphase II were activated by penetration of spermatozoa in cycloheximide-free and cycloheximide-containing fertilisation media. The precise nuclear stage, and the kinetics of degradation of cyclin B1 and dephosphorylation of MAP kinase were assessed after insemination. After maturation culture, 96% of oocytes reached metaphase II. At 6 h after insemination in cycloheximide-free...

A simple and efficient method for the maintenance of Acheta domeslicus spermatocytes in vitro while permitting microscopic observation during meiotic maturation is described. The method allows the study of the factors effecting normal maturation and is applicable to other organisms. Three media are described: MM 100 contains only salts in the concentrations found in Acheta hemolymph; MMIOI cont...

Sister chromatid separation and cyclin degradation in mitosis depend on the association of the anaphase-promoting complex (APC) with the Fizzy protein (Cdc20), leading to the metaphase/anaphase transition and exit from mitosis [1--3]. In Xenopus, after metaphase of the first meiotic division, only partial cyclin degradation occurs, and chromosome segregation during anaphase I proceeds without s...

Oocytes of almost all vertebrates become arrested at metaphase II to await fertilization. Arrest is achieved with the participation of a protein complex known as cytostatic factor (CSF) that stabilizes histone H1 kinase activity. MOS and mitogen-activated protein kinase (MAPK) are important components of CSF. Strain LT/Sv mice, and strains related to LT/Sv, produce a high percentage of atypical...

When metaphase II-arrested mouse oocytes (M II) are activated very soon after ovulation, they respond abortively by second polar body extrusion followed by another metaphase arrest (metaphase III, M III; Kubiak, 1989). The M II/M III transition resembles the natural transition between the first and second meiotic metaphases (M I/M II). We observed that a similar sequence of events takes place d...

Cytostatic factor (CSF) arrests vertebrate eggs in metaphase of meiosis II through several pathways that inhibit activation of the anaphase-promoting complex/cyclosome (APC/C). In Xenopus, the Mos-MEK1-MAPK-p90(Rsk) cascade utilizes spindle-assembly-checkpoint components to effect metaphase arrest. Another pathway involves cyclin E-Cdk2, and sustained cyclin E-Cdk2 activity in egg extracts caus...

Maturation of immature bovine oocytes requires cytoplasmic polyadenylation and synthesis of a number of proteins involved in meiotic progression and metaphase-II arrest. Aurora serine-threonine kinases--localized in centrosomes, chromosomes, and midbody--regulate chromosome segregation and cytokinesis in somatic cells. In frog and mouse oocytes, Aurora A regulates polyadenylation-dependent tran...

Zona-free oocytes of the mouse were inseminated at prometaphase I or metaphase I of meiotic maturation in vitro, and the behavior of the sperm nuclei within the oocyte cytoplasm was examined. If the oocytes were penetrated by up to three sperm, maturation continued during subsequent incubation and became arrested at metaphase II. Meanwhile, each sperm nucleus underwent the following changes. Fi...