Transgenerational chromosome repair in the asexual bdelloid rotifer Adineta vaga

Antoine Houtain, Marc Llirós, Boris Hespeels, Emilien Nicolas, Paul Simion, Julie Virgo, Anne‐Catherine Heuskin, Thomas Lenormand, Bernard Hallet, Karine Van Doninck

Homologous recombination is an essential DNA repair mechanism that also promotes chromosome pairing and ensures allele segregation during meiosis in sexual organisms. Here, we explore the dual function of homologous recombination in the bdelloid rotifer Adineta vaga, an ancient asexual species known for its remarkable resilience to extreme genotoxic stresses. Genomic analyses reveal that A. vaga uses meiotic recombination, both to promote spontaneous crossovers and gene conversion during oogenesis and to repair the genome in response to DNA damage. Our study identifies a novel transgenerational DNA repair mechanism, termed break induced homologous extension repair (BIHER), which operates on single DNA ends to repair fragmented chromosomes over successive generations. Our findings suggest that meiotic BIHER, coupled with the holocentric structure of chromosomes, represents a key adaptation of life in extreme environments.