title: Inhibition of protein synthesis elicits early grey crescent formation in the axolotl oocyte.
abstract: In the axolotl (Ambystoma mexicanum Shaw), it was recently shown that cycloheximide (CH) could induce early grey crescent formation (EGC) in non-activated oocytes, maturing in vitro (Grinfeld and Beetschen 1982). Since it was not proved that EGC was a consequence of protein synthesis inhibition rather than a side-effect of the drug, experiments were performed using microinjections of a quite different inhibitor, diphtheria toxin (DT). This toxin also appeared to elicit EGC. Incorporation of (3H) leucine into oocyte proteins in the presence of increasing DT concentrations (10-11to 10-6M) was then investigated. The frequency of EGC closely parallels the level of protein synthesis inhibition, which is higher in symmetrized oocytes. The lowest CH concentration which can still elicit EGC also exerts a fairly strong inhibition of (3H) leucine incorporation into proteins. It is concluded that protein synthesis inhibition in the late maturing oocyte actually creates specific conditions which allow cytoplasmic rearrangements to occur, leading to grey crescent formation. These results support the interpretation that (a) proteinic inhibitor (s) of symmetrization could be synthesized in the normal maturing oocyte.
authors.affiliation: Laboratoire de Biologie générale, ERA CNRS n° 327, Université Paul-Sabatier, 118 route de Narbonne, F-31062, Toulouse, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Gautier
authors.affiliation: Laboratoire de Biologie générale, ERA CNRS n° 327, Université Paul-Sabatier, 118 route de Narbonne, F-31062, Toulouse, France.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Beetschen
keywords: Axolotl oocyte; Diphtheria toxin; Grey crescent; Protein synthesis inhibition