2006 Fiscal Year Final Research Report Summary

Mechanisms of Initiation of DNA replication after fertilization in Starfish eggs

Research Project

Project/Area Number	17570157
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Cell biology
Research Institution	Tokyo Institute of Technology
Principal Investigator	TACHIBANA Kazunori Tokyo Institute of Technology, Research associate, 大学院生命理工学研究科, 助手 (60212031)
Project Period (FY)	2005 – 2006
Keywords	DNA replication / Lisence / meiosis / fertilization / Mcm / Cdc6 / Cdc45 / oocyte maturation
Research Abstract	Cdc6 is a member of nucleotide-dependent loading factors of Mcm (mini-chromosome maintenance) proteins. We have cloned starfish Cdc6 cDNA and raised its antibody that recognized Cdc6 protein on chromatin by immuno fluorescent microscopy. Very low level of Cdc6 protein was identified in immature oocytes of starfish. After resumption of meiosis Cdc6 increased 5-10 times of initial level. Using morpholino oligonucleoties(M0) to knockdown Cdc6. Microinjection of MO inhibited more than 90% of expression of Cdc6 during oocyte, maturation. Surprisingly, Cdc6 on the chromatin in the Cdc6 knockdown oocytes, eggs and embryos was same level as in the control eggs that were injected with control (beta-globin) morpholino. Furthermore, the Ced6 knocked down embryos developed at least gastrula. These results suggest that cells require very small amount of Cdc6 (1/5-1110 of normal level) to replicate DNA.

(2 results)