Molecular characterization of heterotic hybrid from Red Stirling and Chitralada lines of Nile Tilapia (Oreochromis niloticus)

Abstract

The Nile tilapia (Oreochromis niloticus) is an economically important farmed fish in different countries and particularly in Brazil. Crossbreding has been carried out between two strains of Nile tilapia - Red color Stirling and wild type Chitralada strains. This crossing combines superior performance of Chitrlada strain with red dominant red coloration of Stirling strain. Although crossbreding is a usual breeding strategy to produce within species hybrids with hybrid vigor, the molecular mechanisms of heterosis that affects gene expression and biological pathways to produce heterosis phenotypic effects. Accordingly, some genes (IGF-1, IGF-2, IGF-3 and myostatin) have been shown to be directly correlated to weight gain and other important faming phenotypes. Furthermore, a class of non-coding RNAs, known as microRNAs (miRNAs), has recently emerged as key molecules in the regulation of gene expression. In the present project, we aim at investigating the heterosis by using polymorphism analysis, expression profiles and protein products of the genes IGF-1, IGF-2, IGF-3 and myostatin using Sanger sequencing and qPCR. Also, the proposal will evaluate the transcriptome of miRNAs by RNA-Seq and evaluate the protein composition of muscle tissue by MALDI-TOF. As a perspective, it is expected to determine the mechanisms by which genes and regulators associated with heterosis act, and generating data with potential future applicability in the productive sector. It is noteworthy that this proposal is linked to a larger project to characterize miRNAs, currently in development (Regular Research Support FAPESP - 2012/15589-7). (AU)