Fully grown G 2 -arrested Xenopus oocytes resume meiosis in vitro upon exposure to hormonal stimulation. Progesterone triggers oocyte meiosis resumption through a Ras-independent pathway that involves a p39 Mpk1 activation induced by insulin is dependent upon p39Mos synthesis. Raf complete phosphorylation appears to require the MEK/MAPK pathway activation both in progesterone and insulin-stimulated oocytes.

Trace metals, whether essential such as Cu and Zn or nonessential such as Cd, are taken up by aquatic invertebrates from both food and solutions. After ingestion, the metal is transported around the body, perhaps to be accumulated in particular target organs or even to be excreted (Rainbow, 1998). In most invertebrates, body concentrations of the non-essential metal Cd do not appear to be regulated (Rainbow, 1985;Amiard et al., 1987;Rainbow, 1998). Metal toxicity is often postulated to arise from reactions occurring in the cytosol, through nonspecific binding of the metal to non-thionein ligands, which are physiologically important molecules (metalloenzymes or small peptides such as glutathione) and are inactivated by metal binding (Mason and Jenkins, 1995). Control of intracellular metal toxicity and detoxification of accumulated trace metals is generally achieved via the production of metal-binding ligands that sequester metals. These cellular ligands can be found in the particulate fraction of the cells such as mineral deposits, granules or lysosomes (George, 1990;Mason and Jenkins, 1995) and in the cytosol such as metallothioneins (Engel and Roesijadi, 1987). Metallothioneins, a family of low molecular mass cysteine-rich proteins, have been shown to occur in most zoological taxa (Amiard and Cosson, 1997). However, in polychaetous annelids this type of protein has not yet been isolated.Nereis diversicolor (Hediste diversicolor, recent denomination) is a polychaete living in the mud of estuaries which, in Europe, is routinely contaminated by heavy metals. Previous work (Nejmeddine et al., 1988) showed that in animals exposed to Cd the metal was bound to two pools of proteins of high molecular mass (metalloprotein I, MPI, >67·kDa) and low molecular mass (MPII, of about 20·kDa). MPI is the extracellular hemoglobin of this annelid (Demuynck and Dhainaut-Courtois, 1993). The primary structure of MPII isolated from whole worms was different from that of a metallothionein, consisting of 119 amino acid residues with only one cysteine residue , but shares 80.8% identity with the myohemerythrin isolated by Takagi and Cox (1991) from the same species. MPII is a Cd-binding protein but is not a metallothionein. Metallothioneins are known to be induced by essential (Cu or Zn) and non-essential (Cd) metals and are thought to be important both in the detoxification of trace metals and in the metabolism of intracellular Cu and Zn, as in the scavenging of reactive oxygen species (Palmiter, 1998;Klaassen et al., 1999). However, MPII appeared to correspond to a myohemerythrinlike pigment, known to play a mainly respiratory role and with no known function of detoxification. Immunocytochemical studies showed that MPII is located in granulocytes I Isolated guts of Nereis diversicolor revealed the existence of a cadmium-binding protein, the MPII, belonging to the group of hemerythrins and myohemerythrins. The presence of MPII in the cells of the intestine was demonstrated by immunocytochemistry, using anti-MPII, a monoclonal antibod...

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Numerous genes belonging to the ets gene family have been described for a few years. The founder of this family is the v-ets proto-oncogene, which is the viral counterpart of the chicken c-ets-1 proto-oncogene. Main research was carried out both on Vertebrates, Drosophila and the nematod Caenorhabditis elegans. Previously, two genes of this family named Nd ets and Nd erg, were isolated in the polychaete annelid Hediste (Nereis) diversicolor. Here we have described the isolation of one gene from the ets family in another polychaete annelid named Perinereis cultrifera. By polymerase chain reaction using degenerated primers, we have amplified an approximatively 515 pb genomic region encoding the ETS domain and another domain designed as "R" domain by Qi et al. (1992) and which can mediate transactivation. By using this method for isolating members of the ets gene family, we are going to realize a phylogenetic study of the phylum of polychaete annelids.