标题：Melatonin bio-synthesizing enzyme genes ( Tph1 , Aanat1 , Aanat2 , and Hiomt ) and their temporal pattern of expression in brain and gut of a tropical carp in natural environmental conditions
摘要：Abstract The study demonstrates the temporal pattern of expression of melatonin bio-synthesizing enzyme genes (Tph1, Aanat1, Aanat2, and Hiomt) in the brain and gut of a tropical carp (Catla catla) on a daily and seasonal basis under natural photo-thermal conditions. The measurement of melatonin in brain and gut (both in vivo and in vitro) demonstrated a higher content in gut, with evidence of melatonin bio-synthesizing machinery in both tissues. All melatonin bio-synthesizing gene expressions in these two tissues were negatively correlated (except Aanat1 in brain and Hiomt in the gut) with the water temperature on an annual cycle. The higher expression of Aanat2 gene, rather than Aanat1, signifies the importance of Aanat2 isoform in the melatonin production in tropical carp. Furthermore, the Aanat2 and Hiomt genes are highly expressed in the gut. Analysis of the rhythm and acrophase of expression of these genes in the brain and gut imply a pineal-independent melatonin synthesizing machinery in these two organs, possibly involving both environmental and endogenous cues for the regulation of melatonin rhythm to synchronize the physiology of the animal.
