Photoperiodism and effects of indoleamines in a unicellular alga, Gonyaulax polyedra.
Mediation of photoperiodic effects by indoleamines, especially melatonin, is known in higher vertebrates. A similar mechanism may occur in a unicellular alga, the dinoflagellate Gonyaulax polyedra. This organism entered the dormant stage of a cyst upon short-day treatment at lowered temperatures. Interruption of darkness by 2 hours of light prevented cyst formation, even when the overall duration of light was the same as in cyst-inducing short days. When given in a noninducing photoperiod, melatonin and an analog, 5-methoxytryptamine, substances that had previously been shown to occur in Gonyaulax, provoked cyst formation. Methoxylated indoleamines may play a role as mediators of darkness in this unicellular, in a similar way as in vertebrates, suggesting a common biochemical basis of photoperiodism.
Balzer
I
I
Zoologisches Institut, Universität Göttingen, Federal Republic of Germany.
Hardeland
R
R
D008735:5-Methoxytryptamine / Q000494:pharmacology*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D004141:Dinoflagellida / Q000187:drug effects / Q000502:physiology*; D008027:Light; D008550:Melatonin / Q000494:pharmacology*; D010507:Periodicity; D013696:Temperature
D008735:5-Methoxytryptamine; D008550:Melatonin