Molecular characterization of heterotic hybrids of the Red Stirling and Chitralada lines of Nile tilapia (Oreochromis niloticus)

Author(s)

Marcos Edgar Herkenhoff

• Document type: Doctoral Thesis
• Press: Botucatu. 2017-10-04.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
• Defense date: 2017-08-11
• Advisor: Danillo {UNESP] Pinhal

Abstract

Nile tilapia (Oreochromis niloticus) has great economic importance in world fish farming. To attend the commercial demand, several lines were developed, among them: Chitralada, with fast growth, and Red Stirling, with red color fillet of pink, which is more appreciated by the consumer. With the aim to combine the main characteristic of these lines, a crossbreed was developed, which also showed heterosis. Although crossbreeding between lines, or species, is a common breeding strategy for producing animals with heterosis, the molecular mechanisms that affect gene expression and biological pathways to create this phenotype still understood. Genetic research on fish showed the direct and indirect interference of several genes in animal performance, especially genes related to the GH/IGF axis and myostatin (MSTN). In addition, a class of non-coding RNAs, microRNAs (miRNAs), play a key role in regulating many biologically known pathways, mainly growth-related. Therefore, this study aimed to evaluate the GH/IGF axis genes expression and MSTN; determine the miRNAs involved and their targets; and the protein involved in the heterosis fenotype. Morphometric parameters, such as weight and length, were collected from the 4th to the 6th month of life. Biological samples were also collected from the Chitralada and Red Stirling, and their crossbreed (7/8 Chitralada). For the analysis of gene expression by RT-qPCR, brain, liver and white muscle samples were collected, ; for miRNA analysis, samples of white muscle were used, as well as ESI-q-TOF and shotgun GH/IGF axis genes were sup-regulated and the MSTN downregulated in crossbreed in relation to their parents. Analysis of the miRNAs showed that let-7, miR-122, miR-194 and miR-219 in the crossbreed are associated with the qPCR data. Regarding the comparison of the miRNAs and with the proteins, several miRNAs showed to be sub expressed and consequently there was increase in the expression of the proteins that have targets of these miRNAs in their genes. We conclude that there is an action of miRNAs on proteins associated with the metabolic pathways and may be responsible for heterosis in Nile tilapia. (AU)

• FAPESP's process: 14/03062-0 - Molecular characterization of heterotic hybrid from Red Stirling and Chitralada lines of Nile Tilapia (Oreochromis niloticus)
• Grantee: Marcos Edgar Herkenhoff
• Support Opportunities: Scholarships in Brazil - Doctorate