| First Author | Sumerel JL | Year | 2001 |
| Journal | Dev Biol | Volume | 234 |
| Issue | 2 | Pages | 425-40 |
| PubMed ID | 11397011 | Mgi Jnum | J:69959 |
| Mgi Id | MGI:2135833 | Doi | 10.1006/dbio.2001.0260 |
| Citation | Sumerel JL, et al. (2001) Cyclin E and its associated cdk activity do not cycle during early embryogenesis of the sea Urchin. Dev Biol 234(2):425-40 |
| abstractText | Female sea urchins store their gametes as haploid eggs. The zygote enters S-phase 1 h after fertilization, initiating a series of cell cycles that lack gap phases. We have cloned cyclin E from the sea urchin Strongylocentrotus purpuratus. Cyclin E is synthesized during oogenesis, is present in the germinal vesicle, and is released into the egg cytoplasm at oocyte maturation. Cyclin E synthesis is activated at fertilization, although there is no increase in cyclin E protein levels due to continuous turnover of the protein. Cyclin E protein levels decline in morula embryos, while cyclin E mRNA levels remain high. After the blastula stage, cyclin E mRNA and protein levels are very low, and cyclin E expression is predominant only in cells that are actively dividing. These include cells in the left coelomic pouch, which forms the adult rudiment in the embryo. The cyclin E present in the egg is complexed with a protein kinase. Activity of the cyclin E/cdk2 changes little during the initial cell cycles. In particular, cyclin E-cdk2 levels remain high during both S-phase and mitosis. Our results suggest that progression through the early embryonic cell cycles in the sea urchin does not require fluctuations in cyclin E kinase activity. Copyright 2001 Academic Press. |
