Yannick Andéol

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We have characterized a cDNA which contains the entire coding sequence of a Xenopus laevis ras protein. The deduced amino acid sequence reveals a strong homology (92%) to human Ki-ras 2B protein. ras expression has been studied both qualitatively and quantitatively during Xenopus development. ras is expressed as a maternal mRNA in oocytes and early embryos(More)
Using an in vivo heterologous system to study the stability of Xenopus laevis RNA injected into axolotl (Ambystoma mexicanum) fertilized eggs, we have previously observed unexpected fluctuations in RNA level during early development [Andéol et al., Differentiation 63 (1998) 69-79]. In this study, we further characterize this phenomenon and establish its(More)
We have set up a heterologous in vivo system to study gene regulation at the post-transcriptional level during early development. This system uses two amphibian species, Xenopus laevis and Ambystoma mexicanum (axolotl), the development of which is three to four times slower than that of X. laevis. The stability of three different synthetic X. laevis c-myc(More)
After fertilization in axolotl, the synchronous cell cleavages are triphasic (S, G2 and M phases). Midblastula transition (MBT) begins at the ninth cleavage and is the consequence of lengthening of cell cycles. By spectrofluorometry and incorporation of 3H thymidine into the nuclear DNA followed by autoradiography on individual cells, the time at which a G1(More)
We have previously reported a post-transcriptional RNA amplification observed in vivo following injection of in vitro synthesized transcripts into axolotl oocytes, unfertilized (UFE) or fertilized eggs. To further characterize this phenomenon, low speed extracts (LSE) from axolotl and Xenopus UFE were prepared and tested in an RNA polymerization assay. The(More)
The M phase promoting factor (MPF) is a dimer composed of a catalytic Cdk1 subunit and a Cyclin B regulatory subunit. We have characterized a cDNA containing the entire coding sequence of an axolotl Cyclin B1 protein that is able to promote MPF activity when added to a fraction from prophase I oocytes that contains monomeric Cdk1. The axolotl cyclin B1 gene(More)
The products of the Wntgene family play an essential role in several aspects of embryo patterning. We have investigated the post-transcriptional regulation of three of these genes: Awnt-1, Awnt-5A and Awnt-5B during axolotl (Ambystoma mexicanum) oogenesis, oocyte maturation and early development. We show that Awnt-1, Awnt-5A and Awnt-5B mRNAs are maternally(More)
We have used the axolotl oocyte (Ambystoma mexicanum Shaw) to study the stability of exogenously injected Xenopus RNAs. Three different cellular developmental stages have been analysed: (1) the growing oocyte (stage III-IV of vitellogenesis), (2) the full-grown oocyte at the end of vitellogenesis (stage VI) and (3) the progesterone-matured stage VI oocyte.(More)
Activity of Cdc2, the universal inducer of mitosis, is regulated by phosphorylation and binding to cyclin B. Comparative studies using oocytes from several amphibian species have shown that different mechanisms allow Cdc2 activation and entry into first meiotic division. In Xenopus, immature oocytes stockpile pre-M-phase promoting factor (MPF) composed of(More)