The role of IRX5 gene in sex differentiation in medakas (Oryzias latipes)

• Grant number: 21/01254-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2021
• End date: May 31, 2022
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Inland Water Fishery Resources
• Principal Investigator: Rafael Henrique Nóbrega
• Grantee: Larissa Vendramini
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The process of sexual determination invertebrates can be classified as mechanisms of genetic sex determination (GSD), or as mechanisms of environmental sex determination (ESD). The fish species Oryzias latipes, also known as medaka, is considered a model organism for studies of sexual determination and differentiation, presenting GSD and heterogametic system XX / XY whose "master" gene is the dmrt1bY. However, much remains to be known about the genes involved in the sexual differentiation cascade of fish, as well as in other vertebrates. Recent studies in our laboratory (FAPESP 18/16595-7; 19/19874-7) demonstrated that the gene of the Iroquois family, IRX5, had its expression elevated in undifferentiated gonads of sea bass (Centropomus undecimalis) treated with 17²- estradiol. This result suggests that IRX5 may be involved in the ovarian sexual differentiation of sea bass, as well as in other fish. For this reason, this project aims to evaluate the role of IRX5 through analysis of gene and functional expression using medaka as a model. To address the objectives, analyzes of differential expression of IRX5 in females (XX) and males (XY) from medaka will be performed by qPCR, followed by knockout using CRISPR/Cas9 technique, in order to identify phenotypic changes resulting from loss of IRX5 function. These studies will help to elucidate the role of IRX5 in the mechanisms involved in the sexual differentiation of fish, and may have a major impact on the understanding of this process in other vertebrates, as well as in applied areas of aquaculture, such as for sex control. (AU)