The vertebrate pineal hormone melatonin is produced by the brown algaPterygophora californicaand mimics dark effects on growth rate in the light

摘要

Melatonin, a methoxylated indoleamine, plays a role as a mediator of darkness in animals as well as in the unicellular algaGonyaulax polyedraStein and was recently detected in higher plants. We report on the first finding of melatonin in a multicellular alga, the brown algaPterygophora californicaRupr. Melatonin was identified in juvenile sporophytes ofP. californicaby two independent methods, reverse-phase high-performance liquid chromatography (HPLC) with electrochemical detection, and radioimmunoassay. Another indolic metabolite, 5-methoxytryptophol, was also indentified by HPLC. The rapid decline of growth rate upon the onset of darkness inP. californicais mimicked by melatonin in the light, with increasing efficiency from 5 × 10−5M to 5 × 10−4M, while no effect was obtained at