Long-term persistence of supernumerary B chromosomes in multiple species of Astyanax fish

Silva, Duílio Mazzoni Zerbinato De Andrade, Ruiz-Ruano, Francisco J., Utsunomia, Ricardo, Martín-Peciña, María, Castro, Jonathan Pena, Freire, Paula Paccielli, Carvalho, Robson Francisco, Hashimoto, Diogo T., Suh, Alexander, Oliveira, Claudio, Porto-Foresti, Fábio, Artoni, Roberto Ferreira, Foresti, Fausto and Camacho, Juan Pedro M. (2021) Long-term persistence of supernumerary B chromosomes in multiple species of Astyanax fish. BMC Biology, 19 (1). ISSN 1741-7007

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Background Eukaryote genomes frequently harbor supernumerary B chromosomes in addition to the “standard” A chromosome set. B chromosomes are thought to arise as byproducts of genome rearrangements and have mostly been considered intraspecific oddities. However, their evolutionary transcendence beyond species level has remained untested. Results Here we reveal that the large metacentric B chromosomes reported in several fish species of the genus Astyanax arose in a common ancestor at least 4 million years ago. We generated transcriptomes of A. scabripinnis and A. paranae 0B and 1B individuals and used these assemblies as a reference for mapping all gDNA and RNA libraries to quantify coverage differences between B-lacking and B-carrying genomes. We show that the B chromosomes of A. scabripinnis and A. paranae share 19 protein-coding genes, of which 14 and 11 were also present in the B chromosomes of A. bockmanni and A. fasciatus, respectively. Our search for B-specific single-nucleotide polymorphisms (SNPs) identified the presence of B-derived transcripts in B-carrying ovaries, 80% of which belonged to nobox, a gene involved in oogenesis regulation. Importantly, the B chromosome nobox paralog is expressed > 30× more than the A chromosome paralog. This indicates that the normal regulation of this gene is altered in B-carrying females, which could potentially facilitate B inheritance at higher rates than Mendelian law prediction. Conclusions Taken together, our results demonstrate the long-term survival of B chromosomes despite their lack of regular pairing and segregation during meiosis and that they can endure episodes of population divergence leading to species formation.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 03 Apr 2021 01:29
Last Modified: 24 Nov 2021 03:06
URI: https://ueaeprints.uea.ac.uk/id/eprint/79617
DOI: 10.1186/s12915-021-00991-9

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