Metamorphic competence in urodeles: Observations on the induction of gill resorption and its relationship to acid phosphatase

Abstract

Larvae of Ambystoma maculatum (Amblystoma punctatum) and Triturus (Notophthalmus) viridescens at stage 42 were used to study gill resorption and the role of acid phosphatase in this phenomenon. Concentrations of 8 × 10 −2 μg/ml, 8 × 10 −3 μg/ml, 4 × 10 −3 μg/ml and 8 × 10 −4 μg/ml of 3,5,3-triiodothyronine were administered in the water surrounding the animals. It was found that beginning on day 3 of treatment the animals in the highest concentration group began to respond and that by day 7 gill resorption was complete. The animals in the 8 × 10 −3 μg/ml concentration group began resorption on day 7 and completed resorption by day 30. Animals receiving 4 × 10 −3 μg/ml were seen to proceed only to resorption of filaments by the end of the 30-day period. Those in the lowest concentration showed a response identical to the controls which received no T 3 treatment. A second group of animals was treated with 8 × 10 −2 μg/ml of T 3 and were killed at daily intervals, the gills were removed, homogenized, clarified, and subjected to polyacrylamide gel electrophoresis at 4°C. The gels were stained for acid phosphatase activity, and the reacted gels were quantified. Animals at day 7 showed a 13-fold increase in acid phosphatase activity.