A duplicated copy of id2b is an unusual sex-determining candidate gene on the Y chromosome of arapaima (Arapaima gigas)

Made available in DSpace on 2022-04-28T19:46:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-12-01 Julius-Maximilians-Universität Würzburg Arapaima gigas is one of the largest freshwater fish species of high ecological and economic importance. Overfishing and habitat destruction are severe threats to the remaining wild populations. By incorporating a chromosomal Hi-C contact map, we improved the arapaima genome assembly to chromosome-level, revealing an unexpected high degree of chromosome rearrangements during evolution of the bonytongues (Osteoglossiformes). Combining this new assembly with pool-sequencing of male and female genomes, we identified id2bbY, a duplicated copy of the inhibitor of DNA binding 2b (id2b) gene on the Y chromosome as candidate male sex-determining gene. A PCR-test for id2bbY was developed, demonstrating that this gene is a reliable male-specific marker for genotyping. Expression analyses showed that this gene is expressed in juvenile male gonads. Its paralog, id2ba, exhibits a male-biased expression in immature gonads. Transcriptome analyses and protein structure predictions confirm id2bbY as a prime candidate for the master sex-determiner. Acting through the TGFβ signaling pathway, id2bbY from arapaima would provide the first evidence for a link of this family of transcriptional regulators to sex determination. Our study broadens our current understanding about the evolution of sex determination genetic networks and provide a tool for improving arapaima aquaculture for commercial and conservation purposes. Developmental Biochemistry Biocenter University of Wuerzburg, Am Hubland The Xiphophorus Genetic Stock Center Department of Chemistry and Biochemistry Texas State University, San Marcos Biochemistry and Cell Biology Biocenter University of Wuerzburg, Am Hubland Sigenae GenPhySE INRAE ENVT Université de Toulouse MIAT INRA Université de Toulouse, Chemin de Borde Rouge INRAE LPGP Department of Ecology and Evolution University of Lausanne and Swiss Institute of Bioinformatics Embrapa Amazônia Ocidental Embrapa Pesca E Aquicultura Reproductive and Molecular Biology Group Department of Morphology Institute of Biosciences UNESP GeT-PlaGe INRAE Genotoul Leibniz-Institute of Freshwater Ecology and Inland Fisheries IGB, Müggelseedamm 301 & 310 Amphibian Research Center Hiroshima University Comprehensive Cancer Center Mainfranken University Hospital Reproductive and Molecular Biology Group Department of Morphology Institute of Biosciences UNESP