Anuran Calcitonins are Diverse in Lower Vertebrates.

We investigated the nucleotide sequences of cDNA fragments coding calcitonin from ultimobranchial glands in 2 species of urodelans (1 salamander and 1 newt) and 4 species of anurans (1 toad and 3 frogs) by the reverse transcription polymerase chain reaction (RT-PCR) method and rapid amplification of cDNA ends (RACE)-PCR method. The salamander and newt calcitonins were each 97% and 94% similar to the lungfish and caiman calcitonins that we have already reported, in the amino acid sequences. However, anuran calcitonins were not only dissimilar (63-81%) to the lungfish and caiman calcitonins but also diversified (59-91%) even among anurans. The sequence identity of toad calcitonin was always low (59-66%) among anurans.