Sex chromosomes are generally derived from a pair of classical type-A chromosomes, and relatively few alternative models have been proposed up to now.1,2 B chromosomes (Bs) are supernumerary and dispensable chromosomes with non-Mendelian inheritance found in many plant and animal species3,4 that have often been considered as selfish genetic elements that behave as genome parasites.5,6 The observation that in some species Bs can be either restricted or predominant in one sex7-14 raised the interesting hypothesis that Bs could play a role in sex determination.15 The characterization of putative B master sex-determining (MSD) genes, however, has not yet been provided to support this hypothesis. Here, in Astyanax mexicanus cavefish originating from Pachón cave, we show that Bs are strongly male predominant. Based on a high-quality genome assembly of a B-carrying male, we characterized the Pachón cavefish B sequence and found that it contains two duplicated loci of the putative MSD gene growth differentiation factor 6b (gdf6b). Supporting its role as an MSD gene, we found that the Pachón cavefish gdf6b gene is expressed specifically in differentiating male gonads, and that its knockout induces male-to-female sex reversal in B-carrying males. This demonstrates that gdf6b is necessary for triggering male sex determination in Pachón cavefish. Altogether these results bring multiple and independent lines of evidence supporting the conclusion that the Pachón cavefish B is a "B-sex" chromosome that contains duplicated copies of the gdf6b gene, which can promote male sex determination in this species.

Department of Plant Physiology and Biophysics Julius von Sachs Institute of the University Wuerzburg D 97082 Wuerzburg Germany

INRAE GeT PlaGe Genotoul 31326 Castanet Tolosan France

INRAE LPGP 35000 Rennes France

INRAE LPGP 35000 Rennes France; Department of Ecology and Evolution University of Lausanne Lausanne Switzerland

INRAE LPGP 35000 Rennes France; Department of Ecology and Evolution University of Lausanne Lausanne Switzerland; Swiss Institute of Bioinformatics Lausanne Switzerland

INRAE LPGP 35000 Rennes France; Université Paris Saclay CNRS Institut des Neurosciences Paris Saclay 91198 Gif sur Yvette France

Institut de Génomique Fonctionnelle IGF CNRS INSERM Univ Montpellier F 34094 Montpellier France

Institut des Sciences de l'Evolution de Montpellier CNRS Université de Montpellier IRD 34095 Montpellier France

Institute of Neuroscience University of Oregon Eugene OR USA

Laboratory of Fish Genetics Institute of Animal Physiology and Genetics Czech Academy of Sciences Rumburská 89 27721 Liběchov Czech Republic

Laboratory of Fish Genetics Institute of Animal Physiology and Genetics Czech Academy of Sciences Rumburská 89 27721 Liběchov Czech Republic; Department of Zoology Faculty of Science Charles University Viničná 7 12844 Prague Czech Republic

Severtsov Institute of Ecology and Evolution Russian Academy of Sciences Moscow Russia

SIGENAE GenPhySE Université de Toulouse INRAE ENVT Castanet Tolosan France

SIGENAE UMIAT INRAE Castanet Tolosan France

Université Paris Saclay CNRS Institut des Neurosciences Paris Saclay 91198 Gif sur Yvette France

University Clinic Jena Institute of Human Genetics 07747 Jena Germany

Xiphophorus Genetic Stock Center Department of Chemistry and Biochemistry Texas State University San Marcos TX 78666 USA

Xiphophorus Genetic Stock Center Department of Chemistry and Biochemistry Texas State University San Marcos TX 78666 USA; Department of Developmental Biochemistry University of Wuerzburg D 97074 Wuerzburg Germany

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Wright AE, Dean R, Zimmer F, and Mank JE (2016). How to make a sex chromosome. Nat. Commun 7, 12087. PubMed PMC

Furman BLS, Metzger DCH, Darolti I, Wright AE, Sandkam BA, Almeida P, Shu JJ, and Mank JE (2020). Sex chromosome evolution: so many exceptions to the rules. Genome Biol. Evol 12, 750–763. PubMed PMC

D’Ambrosio U, Alonso-Lifante MP, Barros K, Kovařík A, Mas de Xaxars G, and Garcia S (2017). B-chrom: a database on B-chromosomes of plants, animals and fungi. New Phytol. 216, 635–642. PubMed

Jones N (2017). New species with B chromosomes discovered since 1980. Nucleus 60, 263–281.

Camacho JPM (2005). B chromosomes. In The Evolution of the Genome, Gregory TR, ed. (Academic Press; ), pp. 223–286.

Camacho JPM, Sharbel TF, and Beukeboom LW (2000). B-chromosome evolution. Philos. Trans. R. Soc. Lond. B Biol. Sci 355, 163–178. PubMed PMC

Beladjal L, Vandekerckhove TTM, Muyssen B, Heyrman J, de Caesemaeker J, and Mertens J (2002). B-chromosomes and male-biased sex ratio with paternal inheritance in the fairy shrimp Branchipus schaefferi (Crustacea, Anostraca). Heredity 88, 356–360. PubMed

Favarato RM, Braga Ribeiro L, Ota RP, Nakayama CM, and Feldberg E (2019). Cytogenetic characterization of two metynnis species (Characiformes, Serrasalmidae) reveals B chromosomes restricted to the females. Cytogenet. Genome Res 158, 38–45. PubMed

Néo DM, Filho OM, and Camacho JPM (2000). Altitudinal variation for B chromosome frequency in the characid fish Astyanax scabripinnis. Heredity 85, 136–141. PubMed

Vicente VE, Moreira-Filho O, and Camacho JP (1996). Sex-ratio distortion associated with the presence of a B chromosome in Astyanax scabripinnis (Teleostei, Characidae). Cytogenet. Cell Genet 74, 70–75. PubMed

Stange ER, and Almeida-toledo LF (1993). Supernumerary B chromosomes restricted to males in Astyanax scabripinnis (Pisces, Characidae). Rev. Bras. Genet 16, 601–615.

Clark FE, Conte MA, Ferreira-Bravo IA, Poletto AB, Martins C, and Kocher TD (2017). Dynamic sequence evolution of a sex-associated B chromosome in Lake Malawi cichlid fish. J. Hered 108, 53–62. PubMed

Clark FE, and Kocher TD (2019). Changing sex for selfish gain: B chromosomes of Lake Malawi cichlid fish. Sci. Rep 9, 20213. PubMed PMC

Yoshida K, Terai Y, Mizoiri S, Aibara M, Nishihara H, Watanabe M, Kuroiwa A, Hirai H, Hirai Y, Matsuda Y, and Okada N (2011). B chromosomes have a functional effect on female sex determination in Lake Victoria cichlid fishes. PLoS Genet. 7, e1002203. PubMed PMC

Camacho JPM, Schmid M, and Cabrero J (2011). B chromosomes and sex in animals. Sex Dev. 5, 155–166. PubMed

Hanlon SL, and Hawley RS (2018). B chromosomes in the Drosophila genus. Genes (Basel) 9, 470. PubMed PMC

Martis MM, Klemme S, Banaei-Moghaddam AM, Blattner FR, Macas J, Schmutzer T, Scholz U, Gundlach H, Wicker T, Šimková H, et al. (2012). Selfish supernumerary chromosome reveals its origin as a mosaic of host genome and organellar sequences. Proc. Natl. Acad. Sci. USA 109, 13343–13346. PubMed PMC

Valente GT, Conte MA, Fantinatti BEA, Cabral-de-Mello DC, Carvalho RF, Vicari MR, et al. (2014). Origin and evolution of B chromosomes in the cichlid fish Astatotilapia latifasciata based on integrated genomic analyses. Mol. Biol. Evol 31, 2061–2072. PubMed

Ahmad SF, Jehangir M, Cardoso AL, Wolf IR, Margarido VP, Cabral-de-Mello DC, O’Neill R, Valente GT, and Martins C (2020). B chromosomes of multiple species have intense evolutionary dynamics and accumulated genes related to important biological processes. BMC Genomics 21, 656. PubMed PMC

Pansonato-Alves JC, Serrano É, Utsunomia R, Camacho JPM, da Costa Silva GJ, Vicari MR, et al. (2014). Single origin of sex chromosomes and multiple origins of B chromosomes in fish genus Characidium. PLoS ONE 9, e107169. PubMed PMC

Serrano-Freitas ÉA, Silva DMZA, Ruiz-Ruano FJ, Utsunomia R, Araya-Jaime C, Oliveira C, et al. (2020). Satellite DNA content of B chromosomes in the characid fish Characidium gomesi supports their origin from sex chromosomes. Mol. Genet. Genomics 295, 195–207. PubMed

Conte MA, Clark FE, Roberts RB, Xu L, Tao W, Zhou Q, Wang D, and Kocher TD (2021). Origin of a giant sex chromosome. Mol. Biol. Evol 38, 1554–1569. PubMed PMC

Zhou Q, Zhu HM, Huang QF, Zhao L, Zhang GJ, Roy SW, et al. (2012). Deciphering neo-sex and B chromosome evolution by the draft genome of Drosophila albomicans. BMC Genomics 13, 109. PubMed PMC

Piscor D, and Parise-Maltempi PP (2016). Microsatellite organization in the B chromosome and A chromosome complement in Astyanax (Characiformes, Characidae) species. Cytogenet. Genome Res 148, 44–51. PubMed

Kavalco KF, and De Almeida-Toledo LF (2007). Molecular cytogenetics of blind mexican tetra and comments on the karyotypic characteristics of genus Astyanax (Teleostei, Characidae). Zebrafish 4, 103–111. PubMed

Ebrahimzadegan R, Houben A, and Mirzaghaderi G (2019). Repetitive DNA landscape in essential A and supernumerary B chromosomes of Festuca pratensis Huds. Sci. Rep 9, 19989. PubMed PMC

Mizoguchi SMHN, and Martins-Santos IC (1997). Macro- and microchromosomes B in females of Astyanax scabripinnis (Pisces, Characidae). Hereditas 127, 249–253.

de Brito Portela-Castro AL, Ferreira Júlio Júnior H, and Belini Nishiyama P (2000). New occurrence of microchromosomes B in Moenkhausia sanctaefilomenae (Pisces, Characidae) from the Parana River of Brazil: analysis of the synaptonemal complex. Genetica 110, 277–283. PubMed

Houben A (2017). B chromosomes - a matter of chromosome drive. Front. Plant Sci 8, 210. PubMed PMC

Jones RN, González-Sánchez M, González-García M, Vega JM, and Puertas MJ (2008). Chromosomes with a life of their own. Cytogenet. Genome Res 120, 265–280. PubMed

McGaugh SE, Gross JB, Aken B, Blin M, Borowsky R, Chalopin D, Hinaux H, Jeffery WR, Keene A, Ma L, et al. (2014). The cavefish genome reveals candidate genes for eye loss. Nat. Commun 5, 5307. PubMed PMC

Ahmad SF, and Martins C (2019). The modern view of B chromosomes under the impact of high scale omics analyses. Cells 8, 156. PubMed PMC

Blavet N, Yang H, Su H, Solanský P, Douglas RN, Karafiátová M, Šimková L, Zhang J, Liu Y, Hou J, et al. (2021). Sequence of the supernumerary B chromosome of maize provides insight into its drive mechanism and evolution. Proc. Natl. Acad. Sci. USA 118, e2104254118. PubMed PMC

Navarro-Domínguez B, Ruiz-Ruano FJ, Cabrero J, Corral JM, López-León MD, Sharbel TF, et al. (2017). Protein-coding genes in B chromosomes of the grasshopper Eyprepocnemis plorans. Sci. Rep 7, 45200. PubMed PMC

Ruiz-Ruano FJ, Cabrero J, López-León MD, Sánchez A, and Camacho JPM (2018). Quantitative sequence characterization for repetitive DNA content in the supernumerary chromosome of the migratory locust. Chromosoma 127, 45–57. PubMed

Christoffels A, Koh EGL, Chia JM, Brenner S, Aparicio S, and Venkatesh B (2004). Fugu genome analysis provides evidence for a whole-genome duplication early during the evolution of ray-finned fishes. Mol. Biol. Evol 21, 1146–1151. PubMed

Vandepoele K, De Vos W, Taylor JS, Meyer A, and Van de Peer Y (2004). Major events in the genome evolution of vertebrates: paranome age and size differ considerably between ray-finned fishes and land vertebrates. Proc. Natl. Acad. Sci. USA 101, 1638–1643. PubMed PMC

Feron R, Zahm M, Cabau C, Klopp C, Roques C, Bouchez O, et al. (2020). Characterization of a Y-specific duplication/insertion of the anti-Mullerian hormone type II receptor gene based on a chromosome-scale genome assembly of yellow perch, Perca flavescens. Mol. Ecol. Resour 20, 531–543. PubMed PMC

Kamiya T, Kai W, Tasumi S, Oka A, Matsunaga T, Mizuno N, et al. (2012). A trans-species missense SNP in Amhr2 is associated with sex determination in the tiger pufferfish, Takifugu rubripes (fugu). PLoS Genet. 8, e1002798. PubMed PMC

Rafati N, Chen J, Herpin A, Pettersson ME, Han F, Feng C, Wallerman O, Rubin C-J, Péron S, Cocco A, et al. (2020). Reconstruction of the birth of a male sex chromosome present in Atlantic herring. Proc. Natl. Acad. Sci. USA 117, 24359–24368. PubMed PMC

Li M, Sun Y, Zhao J, Shi H, Zeng S, Ye K, et al. (2015).A tandem duplicate of anti-Müllerian hormone with a missense SNP on the Y chromosome is essential for male sex determination in Nile Tilapia, Oreochromis niloticus. PLoS Genet. 11, e1005678. PubMed PMC

Hattori RS, Murai Y, Oura M, Masuda S, Majhi SK, Sakamoto T, Fernandino JI, Somoza GM, Yokota M, and Strüssmann CA (2012).A Y-linked anti-Müllerian hormone duplication takes over a critical role in sex determination. Proc. Natl. Acad. Sci. USA 109, 2955–2959. PubMed PMC

Pan Q, Feron R, Yano A, Guyomard R, Jouanno E, Vigouroux E, et al. (2019). Identification of the master sex determining gene in Northern pike (Esox lucius) reveals restricted sex chromosome differentiation. PLoS Genet. 15, e1008013. PubMed PMC

Reichwald K, Petzold A, Koch P, Downie BR, Hartmann N, Pietsch S, Baumgart M, Chalopin D, Felder M, Bens M, et al. (2015). Insights into sex chromosome evolution and aging from the genome of a short-lived fish. Cell 163, 1527–1538. PubMed

Gautier A, Sohm F, Joly J-S, Le Gac F, and Lareyre J-J (2011). The proximal promoter region of the zebrafish gsdf gene is sufficient to mimic the spatio-temporal expression pattern of the endogenous gene in Sertoli and granulosa cells. Biol. Reprod 85, 1240–1251. PubMed

Nakamura S, Kobayashi D, Aoki Y, Yokoi H, Ebe Y, Wittbrodt J, and Tanaka M (2006). Identification and lineage tracing of two populations of somatic gonadal precursors in medaka embryos. Dev. Biol 295, 678–688. PubMed

Sawatari E, Shikina S, Takeuchi T, and Yoshizaki G (2007). A novel transforming growth factor-β superfamily member expressed in gonadal somatic cells enhances primordial germ cell and spermatogonial proliferation in rainbow trout (Oncorhynchus mykiss). Dev. Biol 301, 266–275. PubMed

Imarazene B, Beille S, Jouanno E, Branthonne A, Thermes V, Thomas M, et al. (2020). Primordial germ cell migration and histological and molecular characterization of gonadal differentiation in Pachón cavefish Astyanax mexicanus. Sex Dev. 14, 80–98. PubMed

Dalla Benetta E, Antoshechkin I, Yang T, Nguyen HQM, Ferree PM, and Akbari OS (2020). Genome elimination mediated by gene expression from a selfish chromosome. Sci. Adv 6, z9808. PubMed PMC

Nur U, Werren JH, Eickbush DG, Burke WD, and Eickbush TH (1988). A “selfish” B chromosome that enhances its transmission by eliminating the paternal genome. Science 240, 512–514. PubMed

Jones RN (2018).Transmission and drive involving parasitic B chromosomes. Genes (Basel) 9, E388. PubMed PMC

Bernardino ACS, Cabral-de-Mello DC, Machado CB, Palacios-Gimenez OM, Santos N, and Loreto V (2017). B chromosome variants of the grasshopper Xyleus discoideus angulatus are potentially derived from pericentromeric DNA. Cytogenet. Genome Res 152, 213–221. PubMed

Stevens JP, and Bougourd SM (1994). Unstable B-chromosomes in a European population of Allium schoenoprasum L. (Liliaceae). Biol. J. Linn. Soc. Lond 52, 357–363.

Ruban A, Schmutzer T, Wu DD, Fuchs J, Boudichevskaia A, Rubtsova M, et al. (2020). Supernumerary B chromosomes of Aegilops speltoides undergo precise elimination in roots early in embryo development. Nat. Commun 11, 2764. PubMed PMC

Mi L-Z, Brown CT, Gao Y, Tian Y, Le VQ, Walz T, and Springer TA (2015). Structure of bone morphogenetic protein 9 procomplex. Proc. Natl. Acad. Sci. USA 112, 3710–3715. PubMed PMC

Wang X, Fischer G, and Hyvönen M (2016). Structure and activation of pro-activin A. Nat. Commun 7, 12052. PubMed PMC

Malinauskas T, Peer TV, Bishop B, Mueller TD, and Siebold C (2020). Repulsive guidance molecules lock growth differentiation factor 5 in an inhibitory complex. Proc. Natl. Acad. Sci. USA 117, 15620–15631. PubMed PMC

Klammert U, Mueller TD, Hellmann TV, Wuerzler KK, Kotzsch A, Schliermann A, Schmitz W, Kuebler AC, Sebald W, and Nickel J (2015). GDF-5 can act as a context-dependent BMP-2 antagonist. BMC Biol. 13, 77. PubMed PMC

Hwang WY, Fu Y, Reyon D, Maeder ML, Tsai SQ, Sander JD, Peterson RT, Yeh J-RJ, and Joung JK (2013). Efficient genome editing in zebrafish using a CRISPR-Cas system. Nat. Biotechnol 31, 227–229. PubMed PMC

Cheng H, Concepcion GT, Feng X, Zhang H, and Li H (2021). Haplotype-resolved de novo assembly using phased assembly graphs with hifiasm. Nat. Methods 18, 170–175. PubMed PMC

Durand NC, Shamim MS, Machol I, Rao SSP, Huntley MH, Lander ES, and Aiden EL (2016). Juicer provides a one-click system for analyzing loop-resolution Hi-C experiments. Cell Syst. 3, 95–98. PubMed PMC

Dudchenko O, Batra SS, Omer AD, Nyquist SK, Hoeger M, Durand NC, Shamim MS, Machol I, Lander ES, Aiden AP, and Aiden EL(2017).De novo assembly of the Aedes aegypti genome using Hi-C yields chromosome-length scaffolds. Science 356, 92–95. PubMed PMC

Li H (2018). Minimap2: pairwise alignment for nucleotide sequences. Bioinformatics 34, 3094–3100. PubMed PMC

Birney E, Clamp M, and Durbin R (2004). GeneWise and Genomewise. Genome Res. 14, 988–995. PubMed PMC

Kim D, Langmead B, and Salzberg SL (2015). HISAT: a fast spliced aligner with low memory requirements. Nat. Methods 12, 357–360. PubMed PMC

Pertea M, Pertea GM, Antonescu CM, Chang T-C, Mendell JT, and Salzberg SL (2015). StringTie enables improved reconstruction of a transcriptome from RNA-seq reads. Nat. Biotechnol 33, 290–295. PubMed PMC

Grabherr MG, Haas BJ, Yassour M, Levin JZ, Thompson DA, Amit I, Adiconis X, Fan L, Raychowdhury R, Zeng Q, et al. (2011). Full-length transcriptome assembly from RNA-seq data without a reference genome. Nat. Biotechnol 29, 644–652. PubMed PMC

Haas BJ, Delcher AL, Mount SM, Wortman JR, Smith RK Jr., Hannick LI, et al. (2003). Improving the Arabidopsis genome annotation using maximal transcript alignment assemblies. Nucleic Acids Res. 31, 5654–5666. PubMed PMC

Stanke M, Keller O, Gunduz I, Hayes A, Waack S, and Morgenstern B (2006). AUGUSTUS: ab initio prediction of alternative transcripts. Nucleic Acids Res. 34, W435–9. PubMed PMC

Gel B, and Serra E (2017). karyoploteR: an R/Bioconductor package to plot customizable genomes displaying arbitrary data. Bioinformatics 33, 3088–3090. PubMed PMC

Kõressaar T, Lepamets M, Kaplinski L, Raime K, Andreson R, and Remm M (2018). Primer3_masker: integrating masking of template sequence with primer design software. Bioinformatics 34, 1937–1938. PubMed

Wingett SW, and Andrews S (2018). FastQ Screen: a tool for multigenome mapping and quality control. F1000Res. 7, 1338. PubMed PMC

Li H (2013). Aligning sequence reads, clone sequences and assembly contigs with BWA-MEM. arXiv, arXiv:1303.3997. https://arxiv.org/abs/1303.3997.

Li H, Handsaker B, Wysoker A, Fennell T, Ruan J, Homer N, Marth G, Abecasis G, and Durbin R; 1000 Genome Project Data Processing Subgroup (2009). The Sequence Alignment/Map format and SAMtools. Bioinformatics 25, 2078–2079. PubMed PMC

Kofler R, Pandey RV, and Schlötterer C (2011). PoPoolation2: identifying differentiation between populations using sequencing of pooled DNA samples (Pool-Seq). Bioinformatics 27, 3435–3436. PubMed PMC

Krieger E, and Vriend G (2014). YASARA View - molecular graphics for all devices-from smartphones to workstations. Bioinformatics 30, 2981–2982. PubMed PMC

Sander JD, Maeder ML, Reyon D, Voytas DF, Joung JK, and Dobbs D (2010). ZiFiT (Zinc Finger Targeter): an updated zinc finger engineering tool. Nucleic Acids Res. 38, W462–8. PubMed PMC

Hinaux H, Pottin K, Chalhoub H, Père S, Elipot Y, Legendre L, et al. (2011). A developmental staging table for Astyanax mexicanus surface fish and Pachón cavefish. Zebrafish 8, 155–165. PubMed

Elipot Y, Legendre L, Père S, Sohm F, and Rétaux S (2014). Astyanax transgenesis and husbandry: how cavefish enters the laboratory. Zebrafish 11, 291–299. PubMed

Gharbi K, Gautier A, Danzmann RG, Gharbi S, Sakamoto T, Høyheim B, et al. (2006). A linkage map for brown trout (Salmo trutta): chromosome homeologies and comparative genome organization with other salmonid fish. Genetics 172, 2405–2419. PubMed PMC

Durand NC, Robinson JT, Shamim MS, Machol I, Mesirov JP, Lander ES, and Aiden EL (2016). Juicebox provides a visualization system for Hi-C contact maps with unlimited zoom. Cell Syst. 3, 99–101. PubMed PMC

Powell DL, García-Olazábal M, Keegan M, Reilly P, Du K, Díaz-Loyo AP, Banerjee S, Blakkan D, Reich D, Andolfatto P, et al. (2020). Natural hybridization reveals incompatible alleles that cause melanoma in swordtail fish. Science 368, 731–736. PubMed PMC

Du K, Stöck M, Kneitz S, Klopp C, Woltering JM, Adolfi MC, Feron R, Prokopov D, Makunin A, Kichigin I, et al. (2020). The sterlet sturgeon genome sequence and the mechanisms of segmental rediploidization. Nat. Ecol. Evol 4, 841–852. PubMed PMC

She R, Chu JS-C, Wang K, Pei J, and Chen N (2009). GenBlastA: enabling BLAST to identify homologous gene sequences. Genome Res. 19, 143–149. PubMed PMC

Pasquier J, Cabau C, Nguyen T, Jouanno E, Severac D, Braasch I, Journot L, Pontarotti P, Klopp C, Postlethwait JH, et al. (2016). Gene evolution and gene expression after whole genome duplication in fish: the PhyloFish database. BMC Genomics 17, 368. PubMed PMC

Völker M, and Ràb P (2015). Direct chromosome preparation from regenerating fin tissue. In Fish Cytogenetic Techniques: Ray-Fin Fishes and Chondrichthyans, Ozouf-Costaz C, Pisano E, Foresti F, and de Almeida Toledo LF, eds. (CRC Press; ), pp. 37–41.

Sember A, Bohlen J, Šlechtová V, Altmanová M, Symonová R, and Ráb P (2015). Karyotype differentiation in 19 species of river loach fishes (Nemacheilidae, Teleostei): extensive variability associated with rDNA and heterochromatin distribution and its phylogenetic and ecological interpretation. BMC Evol. Biol 15, 251. PubMed PMC

Ráb P, and Roth P (1988). Cold-blooded vertebrates. Methods of Chromosome Analysis (Czechoslovak Biological Society Publishers; ), pp. 115–124.

Bertollo L, Cioffi M, and Moreira-Filho O (2015). Direct chromosome preparation from freshwater teleost fishes. In Fish Cytogenetic Techniques: Ray-Fin Fishes and Chondrichthyans, Ozouf-Costaz C, Pisano E, Foresti F, and de Almeida Toledo LF, eds. (CRC Press; ), pp. 21–26.

Haaf T, and Schmid M (1984). An early stage of ZW/ZZ sex chromosome differentiation in Poecilia sphenops var. melanistica (Poeciliidae, Cyprinodontiformes). Chromosoma 89, 37–41.

Ahmed A-R, Leon BL, and Thomas L (2020). Glass needle-based chromosome microdissection–How to set up probes for molecular cytogenetics? Video J. Clin. Res 2, 100004VAM08AR2020.

Yang F, Trifonov V, Ng BL, Kosyakova N, and Carter NP (2009). Generation of paint probes by flow-sorted and microdissected chromosomes. In Fluorescence In Situ Hybridization (FISH) – Application Guide Springer Protocols Handbooks, Liehr T, ed. (Springer; ), pp. 35–52.

Yang F, and Graphodatsky AS (2009). Animal probes and ZOO-FISH. In Fluorescence In Situ Hybridization (FISH) – Application Guide Springer Protocols Handbooks, Liehr T, ed. (Springer; ), pp. 323–346.

Zwick MS, Hanson RE, Islam-Faridi MN, Stelly DM, Wing RA, Price HJ, and McKnight TD (1997). A rapid procedure for the isolation of C0t-1 DNA from plants. Genome 40, 138–142. PubMed

Yano CF, Bertollo LA, Ezaz T, Trifonov V, Sember A, Liehr T, et al. (2017). Highly conserved Z and molecularly diverged W chromosomes in the fish genus Triportheus (Characiformes, Triportheidae). Heredity 118, 276–283. PubMed PMC

Kochakpour N (2009). Immunofluorescent microscopic study of meiosis in zebrafish. Methods Mol. Biol 558, 251–260. PubMed

Kochakpour N, and Moens PB (2008). Sex-specific crossover patterns in Zebrafish (Danio rerio). Heredity 100, 489–495. PubMed

Levan A, Fredga K, and Sandberg AA (1964). Nomenclature for centromeric position on chromosomes. Hereditas 52, 201–220.

Louis A, Muffato M, and Roest Crollius H (2013). Genomicus: five genome browsers for comparative genomics in eukaryota. Nucleic Acids Res. 41, D700–D705. PubMed PMC

Parey E, Louis A, Cabau C, Guiguen Y, Roest Crollius H, and Berthelot C (2020). Synteny-guided resolution of gene trees clarifies the functional impact of whole-genome duplications. Mol. Biol. Evol 37, 3324–3337. PubMed

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Evolution of B Chromosomes: From Dispensable Parasitic Chromosomes to Essential Genomic Players