Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aquaculture The first case of induced gynogenesis in Neotropical fishes using the yellowtail tetra (Astyanax altiparanae) as a model organism Nivaldo Ferreira do Nascimento a,b, ⁎ , Paulo Sérgio Monzani b , Matheus Pereira-Santos c , Daiane Niedzielski b , José Augusto Senhorini b , Luciano Andrade Silva d , Laura Satiko Okada Nakaghi a , George Shigueki Yasui b a Aquaculture Center, Sao Paulo State University, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP 14884-900, Brazil b Laboratory of Fish Biotechnology, National Center for Research and Conservation of Continental Fish, Chico Mendes Institute of Biodiversity Conservation, Rodovia Pref. Euberto Nemésio Pereira de Godoy, Pirassununga, SP 13630-970, Brazil c Federal Rural University of Rio de Janeiro, BR-465 km 7, Seropédica, RJ 23897000, Brazil d Laboratory of Theriogenology Dr. O. J. Ginther, Department of Veterinary Medicine – FZEA, University of Sao Paulo, Avenida Duque de Caxias Norte 225, Pirassununga, SP 13630-080, Brazil ARTICLE INFO Keywords: Chromosome set manipulation Sex determination Sex ratios Microsatellite marker ABSTRACT Gynogenesis is a chromosome manipulation technique applicable on the production of all-female populations, generation of inbred or clonal lines and identification of genetic sex determination mechanisms in fish. Therefore, the aim of this study was induce meiotic gynogenesis in Astyanax altiparanae and determine the genetic basis of sex determination. Firstly, we evaluated the best UV-irradiation dosage in order to inactivate sperm genome, preserving the capacity of egg activation without the genetic material contribution to the off- spring. After the fertilization using the inactivated sperm, diplodization was achieved by heat-shock (40 °C; 2 min) by suppression of the 2nd polar body extrusion. Diploid control and gynogenetic individuals were raised until 240 days. The gynogenetic offspring were confirmed by genotyping using microsatellite markers and the sex ratio of gynogenetic progenies suggests that most data fit to a XX/XY model of sex determination. However, unexpected sex ratios were also observed and possible reasons are discussed. This was the first protocol of induced gynogenesis in a Neotropical fish and such a procedure may be used to produce clonal linage of fish and for future mass production of monosex populations in A. altiparanae and other related species. 1. Introduction Gynogenesis is a term used for the generation of uniparental or partenogenetic offspring derived exclusively from the maternal genome (Arai and Fujimoto, 2018). In fish, this reproductive biotechnology may be induced and involves two steps including 1) the inactivation of sperm genome, and 2) diploidization of ovule genome in order to produce viable offspring. Inactivation of sperm genome is generally achieved using ultraviolet (UV) irradiation causing structural damage and leading to no functional contribution of the paternal genome in the resultant offspring (Lebeda et al., 2014). However, the inactivated spermatozoa may still present motility and the ability to activate em- bryo development. Diploidization is then necessary in order to produce viable gynogenetic progenies, since haploid status in fish results in mortality during the early stages (Pan et al., 2017; Tvedt et al., 2006). Diploidization is achieved by thermal or pressure shocks (Arai and Fujimoto, 2018; Dunham, 2004) in order to suppress the meiosis II (Zou et al., 2011) or mitosis I (Meng et al., 2016). Gynogenetic fish has potential interest for aquaculture and can be used to produce monosex populations and clonal lineages (Hou and Liu, 2018; Komen and Thorgaard, 2007). This reproductive biotechnique can also be applied to elucidate the mechanism of sex-determining in fish (Devlin and Nagahama, 2002; Wang and Cai, 2018). In this regard, besides a range of sex determination types are observed in fish, it is known that some fish species present predominantly the same genetic mechanism observed for the vast majority of birds or mammals, where 1) the male are heterogametic and classified as XY and females are XX or 2) the female are heterogametic and classified as ZW and males are WW (Whitehead et al., 2012). Consequently, if the female are homo- gametic, all gynogenetic progenies will be females (XX), as observed for Gasterosteus aculeatus (Samonte-Padilla et al., 2011) and Gadus morhua (Whitehead et al., 2012). On the other hand, if the females are https://doi.org/10.1016/j.aquaculture.2019.734432 Received 24 May 2019; Received in revised form 23 August 2019; Accepted 27 August 2019 ⁎ Corresponding author at: Aquaculture Center, Sao Paulo State University, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP 14884-900, Brazil. E-mail address: nivaldotec@yahoo.com.br (N.F.d. Nascimento). Aquaculture 514 (2020) 734432 Available online 05 September 2019 0044-8486/ © 2019 Elsevier B.V. All rights reserved. T