NIMA-related kinase 1 (NEK1) is a serine/threonine and tyrosine kinase that is highly expressed in mammalian germ cells. Mutations in Nek1 induce anemia, polycystic kidney and infertility. In this study we evaluated the role of NEK1 in meiotic spindle formation in both male and female gametes. Our results show that the lack of NEK1 provokes an abnormal organization of the meiosis I spindle char...

Meiotic synchrony in the genus Coprinus has permitted the sequential study of spindle pole body (SPB) behaviour through the meiotic process. The SPBs are monoglobular in the young basidia immediately after the last premeiotic mitosis. From 10 to 15 h before karyogamy until pachytene, spindle pole bodies are not found. They become conspicuous in diplotene and persist until the completion of meio...

The ultrastructure of spindle formation during the first meiotic division in oocytes of the Strepsipteran insect Xenos peckii Kirby (Acroschismus wheeleri Pierce) was examined in serial thick (0.25-micron) and thin sections. During late prophase the nuclear envelope became extremely convoluted and fenestrated. At this time vesicular and tubular membrane elements permeated the nucleoplasm and fo...

Accurate positioning of spindles is essential for asymmetric mitotic and meiotic cell divisions that are crucial for animal development and oocyte maturation, respectively. The predominant model for spindle positioning, termed "cortical pulling," involves attachment of the microtubule-based motor cytoplasmic dynein to the cortex, where it exerts a pulling force on microtubules that extend from ...

In vitro studies of meiotic maturation of mouse oocytes have been carried out in the presence of several drugs. The individual steps of nuclear progression, including dissolution of the nuclear (germinal vesicle) membrane, condensation of dictyate chromatin into compact bivalents, formation of the first metaphase spindle, and extrusion of the first polar body, are each susceptible to one or mor...

background: routine oocytes cryopreservation remained an elusive technique in the wide ranges of available assisted reproductive technologies. the microtubules of oocytes are vulnerable to cryoprotectants and thermal change during cryopreservation. objective: the effects of a vitrification protocol were investigated on the spindle and chromosome configurations of mice oocytes cryopreserved at t...

During cell division, a bipolar array of microtubules forms the spindle through which the forces required for chromosome segregation are transmitted. Interestingly, the spindle as a whole is stable enough to support these forces even though it is composed of dynamic microtubules, which are constantly undergoing periods of growth and shrinkage. Indeed, the regulation of microtubule dynamics is e...

In most sexually reproducing organisms, the fundamental process of meiosis is implemented concurrently with two differentiation programs that occur at different rates and generate distinct cell types, sperm and oocytes. However, little is known about how the meiotic program is influenced by such contrasting developmental programs. Here we present a detailed timeline of late meiotic prophase dur...

Microtubules in spindles are too dense to resolve by light microscopy, even with super-resolution methods. Using a new method based on laser-ablation techniques, Brugués et al. present the first quantitative characterization of the vertebrate meiotic spindle and propose an assembly mechanism for building this architecture.

Klebba and Galletta et al. reveal that the scaffold protein Asterless (Asl) regulates centriole duplication by controlling turnover of the kinase Plk4. Cells must duplicate their centri-oles once, and only once, per cell cycle. In interphase, the master regulator of centriole duplication, Plk4, triggers its own destruction by homodimerizing and phosphorylating itself. In mitosis, however, the p...