Meeting Abstract
Arylalkylamine N-acetyltransferase (aaNAT) is the enzyme that catalyzes the transacetylation of acetyl-CoA to arylalkylamines. In mammals, aaNAT is a rate-limiting enzyme for the synthesis of melatonin from serotonin regulating circadian rhythm. In insects, aaNATs are involved in multiple physiological responses including melatonin synthesis, aromatic neurotransmitter inactivation and cuticle sclerotization. In the present study, a cDNA encoding putative aaNAT (Liv-aaNAT) was identified as a differentially expressed gene from white leg shrimp, Litopenaeus vannamei after the low-salinity (12‰) stress. The full length cDNA (639 bp) of Liv-aaNAT encoded a protein with 213 amino acids. End-point RT-PCR showed that the hepatopancreas is the major production site. In order to estimate biological functions of Liv-aaNAT, RNA-silencing technique was applied using Liv-aaNAT-specific double-stranded RNA (dsRNA). We injected 1, 10, 50 pmol of the dsRNA into the abdominal muscle of each shrimp and level of its knockdown were measured at 1, 3, and 5 days after injection. Injection of 50 pmol dsRNA effectively suppressed Liv-aaNAT expression (96 %) and dopamine level in hemolymph was also measured after Liv-aaNAT RNA interference. In order to know the effects of Liv-aaNAT knockdown, 50 pmol of dsRNA were injected for and several stress were challenged and mortality was measured. This study will help us to extend knowledge about biological roles of Liv-aaNAT in the immune response in decapod crustaceans.
