Genotoxicity of Ni2+ in Xenopus: Search for the Molecular Mechanisms

This chapter describes the initial steps in search for the molecular mechanisms whereby Ni²⁺ causes genotoxicity, using embryos of the South African clawed toad, Xenopus laevis, as the experimental system. Xenopus embryos have been used in embryological research for over a century and have recently come under close scrutiny at the molecular level, stemming from the discovery that growth factors related to mammalian oncogenes are involved in cell-signalling processes that specify cell fate during Xenopus embryogenesis. New experimental models and analytical techniques have been developed in order to study the molecular mechanisms of Ni²⁺-induced genotoxicity and teratogenicity. Xenopus laevis embryos were found to be readily permeable to Ni²⁺ during early cleavage stages, providing a suitable species for investigations of Ni²⁺ uptake and embryotoxicity. Proteins from individual Xenopus eggs and embryos were probed by the Ni²⁺-blotting technique, revealing an intensely labelled Ni-binding protein, which may be involved in the uptake and embryotoxicity of Ni²⁺ in Xenopus.