Genomic structure characterization of Kiss1 gene from Trachinotus ovatus and its expression responses to the feed types

Kisspeptins are a family of neuropeptides encoded by the Kiss genes and play important roles in the reproduction and the regulation energy balance in vertebrate. In order to identify the sequence information of Trachinotus ovatus Kiss1 (ToKiss1) and its expression response to the different feed types, ToKiss1 was cloned from the T. ovatus based on its genome sequences and transcriptome sequences, then the expression level of ToKiss1 in liver and intestine tissues were analyzed by qRT-PCR. ToKiss1 is approximately 2 768 bp in length with 3 exons and 2 introns. The whole length of ToKiss1 cDNA was 505 bp, including a 312 bp open reading frame (ORF) encoding 104 amino acids, in which there are a signal peptide and one kisspeptin-10 domain (YNLNSFGLRY). Its tertiary structure consisted of two α-helices and was similar to a pail. Phylogeny analysis proved that the kisspeptin-1 in Osteichthyes has distant relationship with the kisspeptin-1 in Mammalia, Amphibian and Reptilia. The qRT-PCR tissue expression analysis indicated that ToKiss1 mRNA was expressed in brain, intestine, stomach, spleen and muscle with the highest expression level in brain. Feed types significantly affected the expression profile of intestinal ToKiss1 mRNA. The transcription level of intestinal ToKiss1 mRNA in T. ovatus fed with pelleted feed was higher than in those fed with iced fish, and the T. ovatus fed with iced squid had lowest ToKiss1 mRNA expression. However, feed types did not significantly affect the expression profile of hepatic ToKiss1 mRNA. All those results indicated that kisspeptin may play a critical role in digestion and absorption functions of the T. ovatus. The research for the first time focuses on expression difference of ToKiss1 mRNA in liver and intestine of Osteichthyes by feeding different feed types, which benefits further studies on the feeding regulation physiological mechanism of Kiss1 gene of teleost fish.