Age-dependent changes in toxicity of N-nitroso compounds to Japanese medaka (Oryzias latipes) embryos

摘要: Abstract Three different developmental stages of embryonated eggs Oryzias latipes were exposed to 2-h pulses a number concentrations MNU, MNNG, and DENA. Lethality teratogenic endpoints assessed through 24 h posthatch. MNU (≥2.5 mM) MNNG (≥0.75 exposure at the multicell stage was lethal, but same during early organogenesis largely teratogenic. Four days before hatching, embryos very resistant proceeded hatch normally; 7.5 mM required significantly reduce percent normal hatch. Effects DENA equivocal only seen stage. In order differentiate between potential changes in chorion permeability, toxicity per cell, three series radiolabeled compounds varying hydrophobicity, apparent uptake measured. There no differences rate or equilibrium concentration any stages. These results suggest that, as mammals, certain development are more susceptible than others, that these result embryo sensitivity rather chemical bioavailability. The most sensitive indicator posthatch inflation swimbladder. Other terata included pericardial edema, anisophthalmia, partial rupture chorion.