Mitotic events

Krek, W and Nigg, E. A. (1991b). Mutations of p34c 2 phosphorylation sites induce premature mitotic events in HeLa cells evience for a double block to p34c 2 kinase activation in vertebrates. EMBO J. 10 3331-3341. 

Lohka, M. J., Hayes, M. K., and Mailer, J. (1988). Purification of maturation-promoting factor, an intrinsic regulator of early mitotic events. Proc. Natl. Acad. Sci. USA 85 3009-3013. 

Lohka MJ, Hayes MK, Mailer JL 1988 Purification of maturation-promoting factor, an intracellular regulator of early mitotic events. Proc Natl Acad Sci USA 85 3009—3013 Mailer JL, Butcher FR, Krebs EG 1979 Early effects of progesterone on levels of cyclic adenosine 3 5 -monophosphate in Xenopus oocytes. J Biol Chem 254 579-582 Masui Y 1967 Relative roles of the pituitary, follicle cells, and progesterone in the induction of oocyte maturation in Ranapipiens. J Exp Zool 166 365-375 Masui Y, Markert CL 1971 Cytoplasmic control of nuclear behavior during meiotic maturation of frog oocytes. J Exp Zool 177 129-145... 

Saxon ML, Zhao X, Black JD (1994) Activation of protein kinase C isozymes is associated with post-mitotic events in intestinal epithelial cells in situ. J Cell Biol 126 747-763... 

Bursts of HA deposition correlate with mitosis.41 13 Elevated levels promote cell detachment, in preparation for mitosis, as cells leave tissue organization, and enter the transient autonomy required for the mitotic event to occur. Cells must then degrade that HA after mitosis has occurred, to regain adhesiveness, and to reenter the social contract. The prediction is that HA synthesis occurs as... 

Ghosh S, Paweletz N, Armas-Portela R. 1989. Post-metaphase mitotic events in cells treated with dinitrophenol. Indian J Exp Biol 27 317-323. 

Mitotic cyclin-CDK activates early mitotic events... 

To test the functions of cyclin B In these cell-cycle events, all mRNAs in the egg extract were degraded by digestion with a low concentration of RNase, which then was Inactivated by addition of a specific inhibitor. This treatment destroys mRNAs without affecting the tRNAs and rRNAs required for protein synthesis, since their degradation requires much higher concentrations of RNase. When sperm nuclei were added to the RNase-treated extracts, the In nuclei replicated their DNA, but the increase in MPF activity and the early mitotic events (chromosome condensation and nuclear envelope disassembly), which the untreated extract supports, did not occur (Figure... 

A EXPERIMENTAL FIGURE 21-9 Cycling of MPF activity and mitotic events in Xenopus egg extracts depend on synthesis and degradation of cyclin B. In all cases, MPF activity and cyclin B concentration were determined at various times after addition of sperm nuclei to a Xenopus egg extract treated as Indicated In each panel. Microscopic observations determined the occurrence of early mitotic events (blue shading),... 

In these experiments, chromosome decondensation and nuclear envelope assembly (late mitotic events) coincided with decreases in the cyclin B level and MPF activity. To determine whether degradation of cyclin B is required for exit from mitosis, researchers added a mutant mRNA encoding a nondegradable cyclin B to a mixture of RNase-treated Xenopus egg extract and sperm nuclei. As shown in Figure 2 l-9d, MPF activity Increased in parallel with the level of the mutant cyclin B, triggering condensation of the sperm chromatin and nuclear envelope disassembly (early mitotic events). However, the mutant cyclin B produced in this reaction never was degraded. As a consequence, MPF activity remained elevated, and the late mitotic events of chromosome decondensation and nuclear envelope formation were both blocked. This experiment demonstrates that the fall in MPF activity and exit from mitosis depend on degradation of cyclin B. 

Phosphorylation of Nuclear Lam ins and Other Proteins Promotes Early Mitotic Events... 

B-type cyclins Clbl and Clb2, expressed in G2, form heterodimers with the CDK that stimulate mitotic events. 

Pereira, G., and E. Schiebel. 2001. The role of the yeast spindle pole body and the mammalian centrosome in regulating late mitotic events. Curr Opin. Cell Biol. 13 762-769. 

De Souza, C. P., Ellem, K. A., Gabrielli, B. G. (2000). Centrosomal and cytoplasmic Cdc2/cyclin B1 activation precedes nuclear mitotic events. Experimental Cell Research, 257, 11-21. 

Vagnarelli, P., Earnshaw, W. C. (2004). Chromosomal passengers The four-dimensional regulation of mitotic events. Chromosoma, 113, 211-222. 

Nakagawa, J., Kitten, G. T., and Nigg, E. A. (1989). A somatic cell-derived system (or studying both eariy and late mitotic events in vitro. J. Cell Sci. 94,449-462. 

Carrasco, E., Blum, M., Weickert, C. S., and Casper, D. (2003). Epidermal growth factor receptor expression is related to post-mitotic events in cerebellar development Regulation by thyroid hormone. Brain Res. Dev. Brain Res. 140, 1-13. 

Other fluorogenic dyes, such as DAPI, ethidium bromide and the cyanine dyes, bind to DNA and/or RNA and undergo changes in fluorescence intensity of up to 1000-fold. Depending on the probe, these compounds can be used to image fixed cells or track mitotic events. Combinations of probes with different specificities for single-stranded, double-stranded and ribosomal RNA have been used to characterize the quantity and conformation of nucleic acids throughout the cell cycle. 

The stages of mitosis are well known, although much remains to be learned about the mechanisms and the control of the mitotic events. Classically, mitosis is divided into four stages prophase, metaphase, anaphase, and telophase (see, for example. Ham, 1957 McIntosh et al., 1969). 

Lohka MJ, Hayes MK, MaUer JL (1988) Purification of maturation-promoting fector, an intracellular regulator of early mitotic events. Proc Natl Acad Sci U S A 85 3009-3013... 

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