Faculty Opinions recommendation of Erp1/Emi2 is essential for the meiosis I to meiosis II transition in Xenopus oocytes.

2007 ◽  
Author(s):  
Joan Ruderman
Keyword(s):  
Xenopus Oocytes ◽  
Meiosis I

scholarly journals Activation of the anaphase-promoting complex and degradation of cyclin B is not required for progression from Meiosis I to II in Xenopus oocytes

2001 ◽  
Vol 11 (7) ◽  
pp. 508-513 ◽  
Author(s):  
Frédéric E. Taieb ◽  
Stefan D. Gross ◽  
Andrea L. Lewellyn ◽  
James L. Maller
Keyword(s):  
Xenopus Oocytes ◽  
Cyclin B ◽  
Anaphase Promoting Complex ◽  
Meiosis I

Meiosis-specific cell cycle regulation in maturing Xenopus oocytes

1994 ◽  
Vol 107 (11) ◽  
pp. 3005-3013 ◽  
Author(s):  
K. Ohsumi ◽  
W. Sawada ◽  
T. Kishimoto
Keyword(s):  
Cell Cycle ◽  
Meiotic Division ◽  
Cell Cycle Regulation ◽  
Xenopus Oocytes ◽  
Kinase Activity ◽  
S Phase ◽  
Cell Cycles ◽  
Minute Interval ◽  
Cycle Regulation ◽  
Meiosis I

Meiotic cell cycles differ from mitotic cell cycles in that the former lack S-phase in the interphase between meiosis I and meiosis II. To obtain clues for mechanisms involved in the cell cycle regulation unique to meiosis, we have examined changes in chromosomal morphology and H1 kinase activity during a meiotic period from metaphase I (MI) to metaphase II (MII) in Xenopus oocytes. Using populations of oocytes that underwent germinal vesicle breakdown (GVBD) within a 10 minute interval, we found that the kinase activity declined gradually during the 60 minute period after GVBD and then increased steadily during the following 80 minute interval, showing remarkable differences from the rapid drop and biphasic increase of the kinase activity in intermitotic periods (Solomon et al. (1990) Cell 63, 1013–1024; Dasso and Newport (1990) Cell 61, 811–823). We also found that the exit from MI lagged, by more than 30 minutes, behind the time of lowest H1 kinase activity, whereas the two events took place concomitantly at the end of meiosis II and mitosis. Consequently, the H1 kinase activity was already increasing during the first meiotic division. When H1 kinase activation at MII was delayed by a transient inhibition of protein synthesis after GVBD, oocytes were able to support formation of interphase nuclei and DNA replication between the first meiotic division and the MII arrest, indicating that the cell cycle entered S-phase between meiosis I and meiosis II. These results strongly suggest that the machinery required for entering S-phase has been established in maturing oocytes by the end of meiosis I.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Erp1/Emi2 is essential for the meiosis I to meiosis II transition in Xenopus oocytes

2007 ◽  
Vol 303 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Munemichi Ohe ◽  
Daigo Inoue ◽  
Yoshinori Kanemori ◽  
Noriyuki Sagata
Keyword(s):  
Xenopus Oocytes ◽  
Meiosis I

scholarly journals Absence of Wee1 ensures the meiotic cell cycle in Xenopus oocytes

2000 ◽  
Vol 14 (3) ◽  
pp. 328-338
Author(s):  
Nobushige Nakajo ◽  
Satoshi Yoshitome ◽  
Jun Iwashita ◽  
Maki Iida ◽  
Katsuhiro Uto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Interphase Nucleus ◽  
Xenopus Oocytes ◽  
Ectopic Expression ◽  
S Phase ◽  
Translational Repression ◽  
Meiotic Cell ◽  
Mitotic Inhibitor ◽  
Meiosis I

Meiotic cells undergo two successive divisions without an intervening S phase. However, the mechanism of S-phase omission between the two meiotic divisions is largely unknown. Here we show that Wee1, a universal mitotic inhibitor, is absent in immature (but not mature)Xenopus oocytes, being down-regulated specifically during oogenesis; this down-regulation is most likely due to a translational repression. Even the modest ectopic expression of Wee1 in immature (meiosis I) oocytes can induce interphase nucleus reformation and DNA replication just after meiosis I. Thus, the presence of Wee1 during meiosis I converts the meiotic cell cycle into a mitotic-like cell cycle having S phase. In contrast, Myt1, a Wee1-related kinase, is present and directly involved in G2 arrest of immature oocytes, but its ectopic expression has little effect on the meiotic cell cycle. These results strongly indicate that the absence of Wee1 in meiosis I ensures the meiotic cell cycle in Xenopus oocytes. Based on these results and the data published previously in other organisms, we suggest that absence of Wee1 may be a well-conserved mechanism for omitting interphase or S phase between the two meiotic divisions.

scholarly journals Xenopus oocyte maturation does not require new cyclin synthesis.

1991 ◽  
Vol 114 (4) ◽  
pp. 767-772 ◽  
Author(s):  
J Minshull ◽  
A Murray ◽  
A Colman ◽  
T Hunt
Keyword(s):  
Protein Synthesis ◽  
Oocyte Maturation ◽  
Antisense Oligonucleotides ◽  
Xenopus Oocyte ◽  
Xenopus Oocytes ◽  
Cyclin A ◽  
Cyclin B1 ◽  
Meiotic Metaphase ◽  
Pass Through ◽  
Meiosis I

Progesterone induces fully grown, stage VI, Xenopus oocytes to pass through meiosis I and arrest in metaphase of meiosis II. Protein synthesis is required twice in this process: in order to activate maturation promoting factor (MPF) which induces meiosis I, and then again after the completion of meiosis I to reactivate MPF in order to induce meiosis II. We have used antisense oligonucleotides to destroy maternal stores of cyclin mRNAs, and demonstrate that new cyclin synthesis is not required for entry into either meiosis I or II. This finding is consistent with the demonstration that stage VI oocytes contain a store of B-type cyclin polypeptides (Kobayashi, H., J. Minshull, C. Ford, R. Golsteyn, R. Poon, and T. Hunt. 1991. J. Cell Biol. 114:755-765). Although approximately 70% of cyclin B2 is destroyed at first meiosis, the surviving fraction, together with a larger pool of surviving cyclin B1, must be sufficient to allow the reactivation of MPF and induce entry into second meiotic metaphase. Since stage VI oocytes do not contain any cyclin A, our results show that cyclin A is not required for meiosis in Xenopus. We discuss the possible nature of the proteins whose synthesis is required to induce meiosis I and II.

Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim
Keyword(s):  
Chromosome Segregation ◽  
New Technologies ◽  
Early Prophase ◽  
Unique Role ◽  
Kinetochore Assembly ◽  
M Phase ◽  
In Vivo Analysis ◽  
Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

Sign in / Sign up

Export Citation Format

Share Document