DEVELOPMENT OF AN IN-VIVO GENOTOXICITY ASSAY USING THE MARINE WORM PLATYNEREIS-DUMERILII (POLYCHAETA, NEREIDAE)

An in vivo genotoxicity test system has been developed using the embry o-larval stages of the marine annelid, Platynereis dumerilii (Polychae ta: Nereidae). This species is representative of an ecologically impor tant group of marine invertebrates, it is amenable to laboratory cultu re and has a well defined and stable karyotype (2n = 28) which is suit able for the analysis of a range of cytogenetic endpoints, including c hromosomal aberrations (CAs) and sister chromatid exchanges (SCEs). An evaluation of the cell cycle kinetics using the embryo-larval stages allowed selection of exposure times for cytogenetic work. Subsequently , la-h-old embryos were exposed to reference mutagens, dissolved in se a water, in the presence of 5-bromodeoxyuridine (BrdU) for 12 h (SCE a nalysis) or 8 h (CA analysis) at 15 +/- 1 degrees C, by which time the y had reached the first larval stage (20-24 h). Dose response-relation ships for cytotoxicity, SCEs and CAs were observed for both direct act ing mutagens (methyl methanesulfonate, mitomycin C) and mutagens which require metabolic activation (cyclophosphamide, benzo[a]pyrene). The sensitivity of the embryo-larval stages of P. dumerilii to both direct and indirect acting mutagens, their suitability for laboratory cultur e, together with the presence of a good karyotype and chromosome morph ology for cytogenetic analyses, makes this species a potentially valua ble in vivo model for marine genotoxicity testing.