Sexual reversion of gynogenetic zebrafish (Danio rerio) larvae

• Grant number: 19/08039-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2019
• End date: July 31, 2020
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
• Principal Investigator: Hirla Costa Silva Fukushima
• Grantee: Isadora Fontes Baumgartner
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

This scientific initiation proposal is part of an ample project resulting from a partnership between UFSCar and USP biotechnology aimed at generating technologies that allow the production of Zebrafish with genetic (inbred) and sanitary control (free of specific pathogens - SPF) for use in research in Brazil. Zebrafish is a groundbreaking experimental model in biomedical research around the world and its employment is able to increase the efficiency of research and substantially reduce its costs. However, Brazil does not have Zebrafish producers with defined genetics, and in this context, the project aims to produce zebrafish SPF isogenic for use in researches of educational institutions, companies and government. It is proposed the production of the Zebrafish inbred model from the use of the ginogenesis, which consists in the chromosomal manipulation of newly fertilized embryos and generating the production of 100% female clones (maternal genetic material only). This project will standardize an effective methodology for sexual reversion of a part of the gyngenetic progeny to allow the crossing of these animals between them, that is, males (sexually reverted) and females from the same offspring will cross each other naturally (F2 x F2) to produce Zebrafish inbred 100% homozygous females. The effectiveness of two methodologies described in the literature for sexual reversal of fish will be evaluated, (i) hormonal treatment of larvae with 17±-methyltestosterone within 24 hours after fertilization up to 15 days of age; (ii) heat treatment of larvae from the 18th to the 32th day post fertilization (dpf), when they will be kept at 36°C. To verify the effectiveness of the treatments the sexual organs will be evaluated by histology. Once the efficacy of the sexual reversal is confirmed, the animals will be mated with females to evaluate the ability to reproduce and the offspring will be evaluated. All standardization will be evaluated with larvae of conventional animals (not inbred) for later application in gynogenic animals. In this way, it is intended to initiate communication between aquaculture, bioterrorism and biomedical research programs, guaranteeing the generation of defined animals with no variation induced by genetic and sanitary factors, and the results may contribute to supporting scientific methods that guarantee the application of the 3Rs (replacement, refinement, reduction) principle and to optimize the reproducibility and competitiveness of Brazilian research in the world scenario.