PT  - JOURNAL ARTICLE
AU  - Paul Simion
AU  - Jitendra Narayan
AU  - Antoine Houtain
AU  - Alessandro Derzelle
AU  - Lyam Baudry
AU  - Emilien Nicolas
AU  - Marie Cariou
AU  - Nadège Guiglielmoni
AU  - Djampa KL Kozlowski
AU  - Florence Rodriguez Gaudray
AU  - Matthieu Terwagne
AU  - Julie Virgo
AU  - Benjamin Noel
AU  - Patrick Wincker
AU  - Etienne GJ Danchin
AU  - Martial Marbouty
AU  - Bernard Hallet
AU  - Romain Koszul
AU  - Antoine Limasset
AU  - Jean-François Flot
AU  - Karine Van Doninck
TI  - Homologous chromosomes in asexual rotifer <em>Adineta vaga</em> suggest automixis
AID  - 10.1101/2020.06.16.155473
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.06.16.155473
4099  - http://biorxiv.org/content/early/2020/06/17/2020.06.16.155473.short
4100  - http://biorxiv.org/content/early/2020/06/17/2020.06.16.155473.full
AB  - The several hundreds of species of bdelloid rotifers are notorious because they represent an ancient clade comprising only asexual lineages1. Moreover, most bdelloid species have the ability to withstand complete desiccation and high doses of ionizing radiation, being able to repair their DNA after massive genome breakage2. To better understand the impact of long-term asexuality and DNA breakage on genome evolution, a telomere-to-tolemere reference genome assembly of a bdelloid species is critical3, 4. Here we present the first, high quality chromosome-scale genome assembly for the bdelloid A. vaga validated using three complementary assembly procedures combined with chromosome conformation capture (Hi-C) data. The different assemblies reveal the same genome architecture and using fluorescent in situ hybridization (FISH), we demonstrate that the A. vaga genome is composed of six pairs of homologous chromosomes, compatible with meiosis. Moreover, the synteny between homoeologous (or ohnologous) chromosomes is also preserved, confirming their paleotetraploidy. The diploid genome structure of A. vaga and the presence of very long homozygous tracts show that recombination between homologous chromosomes occurs in this ancient asexual scandal, either during DSB repair or during meiotic pairing. These homozygosity tracts are mainly observed towards the chromosome ends in the clonal A. vaga suggesting signatures of a parthenogenetic mode of reproduction equivalent to central fusion automixis, in which homologous chromosomes are not segregated during the meiotic division.Competing Interest StatementThe authors have declared no competing interest.