Transgenerational chromosome repair in the asexual bdelloid rotifer Adineta vaga.

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 asexual species known for its remarkable resilience to extreme genotoxic stresses. Genomic analyses reveal that A. vaga uses meiotic recombination to promote spontaneous crossovers and gene conversion during oogenesis and to repair the genome in response to DNA damage. The data also support a model of transgenerational DNA repair, termed break-induced homologous extension repair (BIHER), in which broken chromosomes are progressively restored over multiple generations. Our findings suggest that meiotic BIHER, coupled with the holocentric structure of chromosomes, may represent a key adaptation of life in extreme environments.