In many animals, female meiotic spindles are assembled in the absence of centrosomes, the major microtubule (MT)-organizing centers. How MTs are formed and organized into meiotic spindles is poorly understood. Here we report that, in Caenorhabditis elegans, Aurora A kinase/AIR-1 is required for the formation of spindle microtubules during female meiosis. When AIR-1 was depleted or its kinase ac...

After a long period of quiescence at dictyate prophase I, termed the germinal vesicle (GV) stage, mammalian oocytes reenter meiosis by activating the Cdc2-cyclin B complex (maturation-promoting factor [MPF]). The activity of MPF is regulated by Wee1/Myt1 kinases and Cdc25 phosphatases. In this study, we demonstrate that the sequestration of components that regulate MPF activity in distinct subc...

Biologically active recombinant porcine FSH (rec-pFSH) free from the cognate pituitary glycoprotein hormone LH was produced. It was synthesized by a baculovirus vector-insect cell system using two cDNAs encoding the glycoprotein alpha and FSH beta subunits. Its antigenicity was the same as that of pFSH prepared from the pituitary. Glycosylation of rec-pFSH was shown by tunicamycin treatment but...

Epigenetic modifications of the genome, such as histone H2A variants, ensure appropriate gene activation or silencing during oogenesis and preimplantation embryo development. We examined global localization and expression of the histone H2A variants, including H2A.Bbd, H2A.Z and H2A.X, during mouse oogenesis and preimplantation embryo development. Immunocytochemistry with specific antibodies ag...

It is known that amphibian oocytes undergo maturation through the formation and activation of maturation-promoting factor (MPF) in response to stimulation by the maturation-inducing hormone progesterone; however, the signal transduction pathway that links the hormonal stimulation on the oocyte surface to the activation of MPF in the oocyte cytoplasm remains a mystery. The aim of this study was ...

BACKGROUND The aim of this study was to assess effects of cysteamine as an anti-oxidant on rate of in vitro maturation of oocyte and determination of its effects on spindle size and shape. METHODS Pre-mature mice were primed with pregnant mare stimulating gonadotrophin (PMSG) and germinal vesicle (GV) stage oocytes were obtained 48 h after. The oocytes were cultured in tissue culture medium (...

We examined the reorganization of actin filaments and microtubules during Xenopus oocyte maturation. Surrounding the germinal vesicle (GV) in immature oocytes, the cytoplasmic actin filaments reorganized to accumulate beneath the vegetal side of the GV, where the microtubule-organizing center and transient microtubule array (MTOC-TMA) assembled, just before GV breakdown (GVBD). Immediately afte...

A single ribosomal protein (Mr, 32,000) becomes phosphorylated during progesterone-induced in vitro maturation of Xenopus laevis oocytes. The protein is identified as 40S ribosomal protein S6. Phosphorylation of S6 is monitored by incorporation of 32Pi and by two-dimensional polyacrylamide gel electrophoresis. S6 is minimally phosphorylated in unstimulated oocytes. After progesterone treatment,...

Mammalian oocytes are arrested in prophase of the first meiotic division. Progression into the first meiotic division is driven by an increase in the activity of maturation-promoting factor (MPF). In mouse oocytes, we find that early mitotic inhibitor 1 (Emi1), an inhibitor of the anaphase-promoting complex (APC) that is responsible for cyclin B destruction and inactivation of MPF, is present a...

Wen-Shiun Yueh and Ching-Fong Chang (2000) Morphological changes and competence of maturing oocytes in the protandrous black porgy, Acanthopagrus schlegeli. Zoological Studies 39(2): 114-122. The study objectives aimed to investigate the morphological changes of oocytes during final oocyte maturation and ovulation, and the maturational competence of oocytes to respond to maturation-inducing ste...