Philippe Guerrier

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Meiosis reinitiation has been triggered via electrophoretic driving of Ca++ into the cortex of Xenopus laevis oocytes freed from functional follicle cells by collagenase treatment. Mg++ could not be substituted for Ca++. Ca++ induced maturation resembles progesterone induced maturation in so far both are inhibited by cycloheximide, give rise to amplifiable(More)
In contrast to the situation found in the bivalves Barnea candida and Spisula solidissima, prophase-arrested oocytes of Ruditapes philippinarum cannot be fertilized when removed from the ovary. They must first undergo germinal vesicle breakdown under the influence of the neurohormone serotonin (5-HT), which drives them to a second block occurring in(More)
Prophase-arrested oocytes of Ruditapes philippinarum cannot be fertilised or stimulated by excess KCl, in contrast to the situation found in other bivalve species such as Barnea and Spisula. However, these oocytes can be triggered to reinitiate meiosis following treatment by serotonin or several pharmacological agents (calcium ionophores, thapsigargin, weak(More)
The specificity of the 1-methyladenine receptors, which are localized on the cell membrane of starfish oocytes, has been investigated in Marthasterias glacialis and Asterias rubens. Ability of N-1-substituted adenines to trigger the release of meiosis inhibition is conserved, or even increased, when the methyl group is replaced by larger substituent groups.
Full grown mature oocytes of the prosobranch gastropod mollusc Patella or the bivalves Mytilus or Ruditapes provide an excellent model for studying the mechanisms which trigger cyclin degradation and exit from the M phase. They are naturally arrested in metaphase of the first maturation division and their fertilization or artificial activation rapidly(More)
In Pleurodeles waltl and Ambystoma mexicanum, which exhibit physiological polyspermy, the membrane potential in most eggs did not change in any consistent pattern during 45 min after fertilization; in some cases, a slow hyperpolarization began 5 to 15 min after insemination and continued for 10-15 min. These eggs then slowly depolarized, reaching a stable(More)
Prophase-arrested oocytes of Ruditapes philippinarum can not be fertilized or stimulated by a depolarizing agent such as an excess of KCl, in contrast to the situation found in Crassostrea gigas. We have performed a comparative study between the two situations found in these species. In vitro, both of these oocytes can be triggered to reinitiate meiosis(More)