| Autor: |
R, Hardeland, B, Fuhrberg, H, Uría, G, Behrmann, T J, Meyer, S, Burkhardt, B, Poeggeler |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas. 29(1) |
| ISSN: |
0100-879X |
| Popis: |
The marine bioluminescent dinoflagellate Gonyaulax polyedra is capable of producing various indoleamines. The first enzyme in their formation, tryptophan hydroxylase, exhibits a high-amplitude circadian rhythm with a maximum during photophase. Hydroxyindole-O-methyltransferase shows a biphasic pattern with a major maximum during scotophase. 5-Methoxylated indoleamines, such as melatonin and 5-methoxytryptamine, peak at the beginning and in the second half of scotophase, respectively. A drop in temperature from 20 to 15 degrees C leads to dramatic increases of melatonin, up to more than 50 ng/mg protein. This effect may explain why a lower temperature sensitizes this organism to photoperiodic, indoleamine-mediated induction of asexual cysts. Melatonin can be catabolized either enzymatically or non-enzymatically. The non-enzymatic pathway involves free radicals, e.g., photooxidant cation radicals, and leads to the formation of N1-acetyl-N2- formyl-5-methoxykynuramine. Enzymatic catabolism comprises deacetylation to 5-methoxytryptamine and formation of 5-methoxytryptophol. 5-Methoxytryptamine represents a key substance acting as a stimulator of bioluminescence and a mediator of the encystment response. It opens proton channels in the membrane of an intracellular acidic vacuole system which is loaded by the action of a V-type ATPase, as shown by experiments using bafilomycin A1. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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