Cloning, phylogenetic analysis and tissue distribution of melatonin bio-synthesizing enzyme genes (<i>Tph1, Aanat1, Aanat2</i>and<i>Hiomt</i>) in a tropical carp,<i>Catla catla</i>

Abstract

The surface dwelling tropical carp Catla catla is gaining importance as a model for the study on the impact of ever-changing aquatic environment as well as chronobiology. Melatonin is the only chronobiotic molecule and act as the neurohormonal messenger in the synchronization of environmental stimuli and the body physiology. Therefore, the sequence analysis of the major enzymes involved in the bio-synthesis of this indole amine is the prime requisite. The present study is an attempt to clone the full-length sequences of melatonin biosynthesising enzyme genes, Tryptophan hydroxylase 1 (Tph1), Arylalkylamine N-acetyltransferase (Aanat1 and Aanat2) and Hydroxyindole-O-methyltransferase (Hiomt) in any tropical fish. This study has identified two subtypes of Aanat (1 &2) as it was found in other teleost. The distribution of these enzymes were found in nine tissues (brain, pineal organ, retina, gut, liver, skeletal muscle, heart, kidney and ovary) which include both central and peripheral units. This finding is signifying the presence of melatonin bio-synthesizing machinery in all major tissues/organs of this tropical carp. High sequence similarities of these genes among teleost revealed a conserved pattern of evolution and the presence of melatonin bio-synthesising enzyme gene transcripts in all major tissues makes it a prominent candidate to be used as model for the chronobiological studies.