X Chromosome Inactivation

http://link.springer.com/content/pdf/10.1007%2F978-1-4419-9863-7_101633.pdf

Publisher Summary This chapter reviews the early Xenopus cycle and the history of cell cycle extracts. The early Xenopus cell cycles are controlled by the activation and inactivation of a protein kinase named maturation-promoting factor (MPF). MPF is also known as the cdc2 kinase and growth-associated histone H1 kinase, and consists of two principal subunits, the catalytic p34cdc2 subunit and cyclin. Activation of MPF induces both mitosis and meiosis, whereas its inactivation triggers the onset of anaphase and the progression into interphase. The fluctuation of MPF activity in early Xenopus embryos is discussed in the chapter. The chapter discusses the methods for preparing and utilizing frog cell cycle extracts. Female frogs are primed for ovulation by injecting them with pregnant mare serum gonadotropin (PMSG) and then induced to ovulate by a subsequent injection of human chorionic gonadotropin (HCG). The chapter also describes sperm nucleus preparation.

Cell cycle extracts.

Systems-Level Dissection of the Cell-Cycle Oscillator: Bypassing Positive Feedback Produces Damped Oscillations

Fertilization is the fundamental process in which two gametes - sperm and oocyte - fuse to generate a zygote that will form a new multicellular organism. In most vertebrates, oocytes await fertilization while arrested at metaphase of meiosis II. This resting state can be stable for many hours and depends on a cytoplasmic activity termed cytostatic factor (CSF). Recently, members of the novel Emi/Erp family of proteins have been put forward as important components of CSF. These proteins inhibit the anaphase-promoting complex/cyclosome (APC/C), which acts at the very core of the cell cycle regulatory machinery. Initially, Xenopus early mitotic inhibitor 1 (Emi1) was proposed to be a component of CSF, but newer work suggests that a structural relative, Emi-related protein 1 (Erp1/Emi2), is essential for maintenance of CSF arrest in Xenopus. Most importantly, studies on Erp1/Emi2 regulation have led to a detailed molecular understanding of the Ca2+-mediated release from CSF arrest that occurs upon fertilization.

/pdf/cytostatic-factor-an-activity-that-puts-the-cell-cycle-on-3d4ptb4qun.pdf

X Chromosome Inactivation

References

Cell cycle extracts.

Systems-Level Dissection of the Cell-Cycle Oscillator: Bypassing Positive Feedback Produces Damped Oscillations

Cytostatic factor: an activity that puts the cell cycle on hold

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