1. 1. Among the thyroxine precursors diiodothyrosine, and in the serotonin series serotonin, had the strongest growth enhancing effect on Tetrahymena. 2. 2. The toxicity of tyrosine was directly related to the number of iodine atoms present in the molecule. 3. 3. The basic amino acid molecules exerted a concentration-dependent growth-promoting effect on Tetrahymena. 4. 4. The experimental observations suggest that while serotonin, had a more active influence on Tetrahymena than its precursors, the vertebrate hormone thyroxine was inferior in activity to its precursors, which also appear at lower levels of phylogenesis. 5. 5. This suggests the presence of hormone receptors in Tetrahymena, but also the phylogenetic immaturity of these.
|Number of pages||4|
|Journal||Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology|
|Publication status||Published - 1980|
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