Hespeels, B. | Search bioRxiv

bioRxiv2024

Transgenerational chromosome repair in the asexual bdelloid rotifer Adineta vaga

Homologous recombination is an essential DNA repair mechanism that 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.

evolutionary biology↗

bioRxiv2023

Ionizing radiation responses are incidental to desiccation responses in the bdelloid rotifer Adineta vaga

BackgroundThe remarkable resistance to ionizing radiation found in anhydrobiotic organisms, such as some bacteria, tardigrades, and bdelloid rotifers has been hypothesized to be incidental to the desiccation resistance. Both stresses produce reactive oxygen species and cause damage to DNA and other macromolecules. However, this hypothesis has only been investigated in a few species. ResultsIn this study, we analyzed the transcriptomic response of the bdelloid rotifer Adineta vaga to desiccation and to low- (X-rays) and high- (Fe) LET radiation to highlight the molecular and genetic mechanisms triggered by both stresses. We identified numerous genes encoding antioxidants, but also chaperones, that are constitutively highly expressed, which may contribute to the protection of proteins against oxidative stress during desiccation and ionizing radiation. We also detected a transcriptomic response common to desiccation and ionizing radiation with the over-expression of genes mainly involved in DNA repair and protein modifications but also genes with unknown functions being bdelloid-specific. A distinct transcriptomic response specific to rehydration was also found, with the over-expression of genes mainly encoding Late Embryogenesis Abundant proteins, specific Heat Shock Proteins, and glucose repressive proteins. ConclusionsThese results suggest that the extreme resistance of bdelloid rotifers to radiation might indeed be a consequence of their capacity to resist complete desiccation. This study paves the way to functional genetic experiments on A. vaga targeting promising candidate proteins playing central roles in radiation and desiccation resistance.

molecular biology↗