Differences in Pineal Clock Genes and Melatonin Production Between Atlantic Salmon and European Seabass

Atlantic salmon showed no rhythmic expression of the melatonin-synthesizing gene Aanat2, while European seabass exhibited circadian Aanat2 expression.

• The pineal gland in teleost fish is important for producing melatonin, which regulates biological rhythms.
• Different teleost species may have distinct mechanisms controlling melatonin production, influenced by both internal and external signals.
• In Atlantic salmon, rhythmic expression of certain clock genes was not observed in vitro, suggesting limited clock regulation in this context.
• In vivo studies revealed rhythmic expression of some clock genes in Atlantic salmon, indicating potential external regulation.
• European seabass displayed circadian expression of Aanat2, highlighting species-specific differences in melatonin production regulation.
• Genomic analysis indicated that the regulatory sequences of Aanat2 in Atlantic salmon differ from those in European seabass and other teleosts, suggesting a loss of functional regulation.

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