Influence of D-penicillamine and beta-aminopropionitril on the metamorphosis of Rana temporaria.

Tadpoles of Rana temporaria (size 5-7 mm) were kept in solutions of D-penicillamine (DPA), beta-aminopropionitril (betaAPN), and L-thyroxine at different concentrations for 18 days. The influence of the substances on metamorphosis was investigated. In low concentrations (1 or 10 mg/100 ml) D-penicillamine accelerates the process of metamorphosis. At these concentrations investigated skeletal malformations could not be observed. A content of 100 mg of DPA/100 ml is toxic. After 8 days of exposure only 4 of the 15 test animals had survived. In all concentrations investigated, beta-aminopropionitril has a toxic action. In low concentration (1 mg/100 ml) deformities are found which could be described as bending of the femur and twisting of the whole hind limb. The animals are non-viable, they die shortly after termination of metamorphosis. Higher concentrations (10 or 100 mg/100 ml) are lethal within the first 10 days. L-thyroxine (0.01 mg/100 ml) shows the wellknown metamorphosis-accelerating effect.