TY  - JOUR
TI  - Thimerosal triggers meiosis reinitiation in oocytes of the Japanese clam Ruditapes philippinarum by eliciting an intracellular Ca2+ surge.
AU  - Lippai, M
AU  - Gobet, I
AU  - Tomkowiak, M
AU  - Durocher, Y
AU  - Leclerc, C
AU  - Moreau, M
AU  - Guerrier, P
T2  - The International Journal of Developmental Biology
AB  - Ovarian oocytes of the bivalve mollusc Ruditapes philippinarum are arrested during first meiotic prophase. Release from this blockade is triggered by the neurohormone serotonin (5HT or 5-hydroxytryptamine), which promotes germinal vesicle breakdown and drives these oocytes to a second arrest in metaphase I. 5HT action involves binding to a specific G protein-coupled receptor which results in a transient rise in IP3 and in the intracellular free Ca2+ concentration. Here we analyze the cytological effects and mode of action of the sulphydryl reagent thimerosal which could also trigger meiosis reinitiation in Ruditapes. No metaphase I spindle formed under these conditions since thimerosal was found to be able to preclude or reverse tubulin polymerization when applied to prophase- or to metaphase-arrested oocytes, respectively. Our results strongly suggest that the common final target for 5HT and thimerosal actions consists in a transient rise in internal free Ca2+ level that we could follow using Fluo3/AM as a probe. The effect of thimerosal in promoting oocyte maturation and increasing intracellular free Ca2+ concentration was improved by excess KCI. In addition, thimerosal, but not KCI, was found to facilitate 5HT-induced maturation at subthreshold hormone concentrations which, by themselves, did not produce an intracellular Ca2+ surge. These data suggest that thimerosal may inhibit Ca2+ pumps of the endoplasmic reticulum and unmask the plasma membrane voltage-sensitive Ca2+ channels which also appear after 5HT-induced GVBD.
PY  - 1995
VL  - 39
IS  - 2
SP  - 401
EP  - 407
J2  - Int. J. Dev. Biol.
LA  - en
SN  - 0214-6282
SN  - 1696-3547
UR  - https://ijdb.ehu.eus/article/7669551
Y2  - 2024/11/24/07:38:17
ER  -