Yves Thouveny

Muscle dedifferentiation and contractile protein synthesis during post-traumatic regeneration by Owenia fusiformis (polychaete annelid)

During anterior traumatic regeneration of the polychaete annelid Owenia fusiformis, we have observed by electron microscopy the dedifferentiation processes of muscle cells. The dedifferentiated cells are reminiscent of undifferentiated myoblasts. They form the blastema and redifferentiate in muscle cells in the regenerate. The in vivo and in vitro biochemical studies of the biosynthesis of contractile proteins, as markers of the terminal differentiation programme of the muscle cells, showed that gene expression correlated with the terminal differentiation programme (at last for muscle cells) seemed unaffected. It seems in fact that contractile protein synthesis is regulated partly at the translational level during traumatic regeneration in the invertebrate.

Variations of chromatin-associated proteins during the prereplicative phase of traumatic regeneration of the polychaete annelid Owenia fusiformis

Abstract We previously demonstrated, during the prereplicative phase of traumatic regeneration, an increase of transcription of poly(A) + -RNA which was correlated to variations in the accessibility of DNA in the chromatin to different probes. In this paper, we study the variations at the chromatin-associated protein level. In chromatin extracted from normal and from 12 h regenerating animals, quantitative and qualitative changes (modifications of the electrophoretic pattern and phosphorylation) were found in non-histone proteins extractable by low ionic concentration (probably ribonucleoproteins).

Presence in invertebrate genomes of sequences characterized by the repetition of the triplet CCPurine.

In Drosophila melanogaster (Dm), polypeptidic domains have been found in different morphogenetic genes. Two types of them are characterized by the repetition of nucleotidic triplets: the M repeat (CAX) and the paired repeat (CAXCCX). In this paper we described a third type of repeat isolated from the genome of a Polychaete annelid: Owenia fusiformis. This repeat is characterized by the repetition of the triplet CCPurine. Phylogenetic studies showed the presence of this repeat in all the invertebrate genomes tested (eight copies in Dm genome) while we failed to detect it in vertebrate genomes.