1,10-PHENANTHROLINE AND XENOPUS-LAEVIS TERATOLOGY

Frog oocytes and embryos have long served as traditional subjects of e mbryological research providing structural and functional information for the interpretation of the biological processes underlying developm ent. A large number of various chemical agents induce typical teratolo gical changes in frog embryos. However, the effects of metal deficienc y of the first transition and IIB series or of chelating agents specif ic for these metals have never been examined in the frog. Multidentate chelating agents, including 1,10-phenanthroline (OP), which coordinat e metals through N, O or S donor atoms are teratogenic also but in a m anner characteristic for this class of reagents and completely differe nt from those referred to above. Exposure to 10(-5) M OP causes maxima l malformations with minimal mortality inducing craniofacial and skele tal abnormalities with failure of eye, head and other organ formation in 74% of frog embryos. In contrast, the non chelating analogue 1,7-ph enanthroline (MP) has no effect at this concentration. A concentration of 10(-3) M OP is lethal. The known characteristics of either zinc an d/or iron complexes with OP as well as the concentrations of these ele ments in frog oocytes and embryos are consistent with the hypothesis t hat the teratological observations are due to an effect of OP on eithe r zinc or iron proteins. (C) 1994 Academic Press, Inc.