Details

Autor(en) / Beteiligte

• Tosuji, Hiroaki
• Seki, Yukari
• Kyozuka, Keiichiro

Titel

Two phases of calcium requirement during starfish meiotic maturation

Ist Teil von

• Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, 2007-06, Vol.147 (2), p.432-437

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2007

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• During meiosis in oocytes of the starfish, Asterina pectinifera, a Ca 2+ transient has been observed. To clarify the role of Ca 2+ during oocyte maturation in starfish, an intracellular Ca 2+ blocker, TMB-8, was applied. The oocyte maturation induced by 1-methyladenine (1-MA) was blocked by 100 μM TMB-8. Reinitiation of meiosis with germinal vesicle breakdown (GVBD) and the following chromosome condensation did not take place. Maturation-promoting factor (MPF) activity did not increase and GVBD and chromosome condensation did not occur. Ca 2+ transient observed immediately after 1-MA application in control oocytes was also blocked by TMB-8. When calyculin A, which activate the MPF directly, was applied to the oocytes instead of 1-MA in seawater containing 100 μM TMB-8, GVBD and chromosome condensation were blocked. Cytoplasmic transplantation studies confirmed that MPF was activated, although TMB-8 blocked GVBD. These results show that TMB-8 blocked the increase of MPF activity induced by 1-MA and the process of active MPF inducing GVBD and subsequent chromosome condensation. Together with the above phenomena, it is conceivable that there are two phases of Ca 2+ requirement during starfish oocyte maturation. These are the activation of MPF, moreover, GVBD, and the subsequent chromosome condensation.