Perikarya and nerve fibers containing a substance immunologically related to CCK-8 were detected in the nervous system of Nereis, a marine annelid worm. The most noteworthy immunostaining was seen in cell bodies, localized at the periphery of the brain, within nuclei 5, 6, 7, 9, 10, 13, 14, 15, 17, 20, 23-24. Immunoreactive fibers were also found in the neuropile without any particular grouping. Numerous other "positive" perikarya occur in the medioventral portion of the ventral nerve cord, and in the ventral and dorsal parts of the suboesophageal ganglion. In addition to the cell bodies in the cerebral external layer, immunoreactive axons were abundantly observed in the connectives between the ganglia. Moreover, our results demonstrate CCK-like staining in neurons showing variations in size and shape, and in affinity for paraldehyde fuchsin. The present results support the hypothesis that this peptide may exert a role as neurotransmitter or neuromodulator in annelids.
The primary sequence of the low-molecular-mass cadmium-binding protein metalloprotein I I of Nereis diversicolor (Hediste diversicolor, recent denomination) has been determined. This protein is composed of 119 amino acids and has 80.8% identity with the Lett. 285,[25][26][27]. The fact that iron, which normally binds to myohemerythrin, is not found to be associated with the cadmium-binding protein metalloprotein I1 in cadmium-exposed animals could be the result of the complete abolition of the iron-binding capacity of the protein due to the binding of cadmium.In the animal kingdom, exposition to cadmium leads to the uptake of the metal and its binding to low-molecularmass-proteins. In vertebrates, Cd is bound mainly to the metallothionein that is characterized by a high cysteinc content and the absence of aromatic amino acids. The metallothionein binds not only Cd but also metals such as zinc, copper and mercury. This is possible through the formation of metalthiolate clusters (Kay et a]., 1991).In invertebrates, two main types of low-molecular-mass Cd-binding proteins (Cd-BP) have been reported (Stone and Overnell, 1985). The first group consists of metallothioneinlike proteins that have structural identities with mammalian metallothioneins (Lerch et a]., 1982;Nemer et al., 1985;Brouwer et al., 1989;Roesijadi et al., 1989;Slice et al., 1990). The second group of low-molecular-mass Cd-BP is represented by the non-metallothionein-like proteins that have a low cysteine content and often possess aromatic amino acids (Dohi et al., 1983;Fowler and Megginson, 1986: Stone et a]., 1986; Bauer-Hilty et al.. 1989).In the case of annelids, few studies have been performed on the Cd-BP, although the animals rcpresent an important part of the endofauna largely distributed over terrestrial, freshwater and marine ecosystems that are, in many instances, subjected to strong toxic-metal contamination. In the Cor-respondenre m S. Demuynck,
Immunocytochemical studies have shown that peptides like Phe-Met-Arg-Phe-NH2 (FMRFamide) are widely distributed throughout the nervous system of three Nereidae. In Nereis diversicolor we have isolated these peptides from an extract of total worms by affinity chromatography and two steps of reversed-phase high-performance liquid chromatography. The sequences of the purified peptides have been determined by amino acid sequencing and on the basis of their reactivity with an anti-FMRFamide serum specific for the determinant Arg-Phe-NH,. Two primary structures have been established: Phe-Thr-Arg-Phe-NH2 (FTRFamide) and Phe-Met-Arg-Phe-NH2 (FMRFamide). Furthermore a methionine sulfoxide derivative of the FMRFamide has been identified. We have synthesized the FTRFamide peptide and in all cases, the native peptides were indistinguishable from the synthetic counterparts. The structure of the two native peptides and of the methionyl sulfoxide derivate have been confirmed by fast-atom-bombardment and tandem mass spectrometry. [6, 71, crustaceans [8-lo], insects [ll-131, and vertebrates [ l l , 141. FMRFamide immunoreactivities have been observed in various tissues: central and peripheral nervous systems, gastrointestinal tract and reproductive system. These observations suggest that a family of FMRFamide-like peptides exists within the animal kingdom. Several of the peptides responsible for these immunoreactivities have been isolated and sequenced in molluscan as well as in non-molluscan taxa. It appears that generally the FMRFamide-like invertebrates peptides are characterized by the carboxy-terminal tetrapeptide Phe-Xaa-Arg-Phe-NH2 in which Xaa is Met, Leu or Ile and they can differ in having various extended aminoterminal sequences. It was demonstrated that FMRFamide and related peptides are encoded in multiple copies by a single Correspondence to B. Baratte, Laboratoire d'Endocrinologie des Invertebres,
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