Abstract
BACKGROUND: The biological effects of spaceflight remain incompletely understood, even in humans (Homo sapiens), and are largely unexplored in non-traditional models such as bdelloid rotifers. RESULTS: This study analyzes the transcriptomic changes experienced by Adineta vaga, a bdelloid rotifer aboard the International Space Station (ISS), using RNA sequencing. The aim was to investigate the overall effect of spaceflight in Low Earth Orbit (LEO) on these organisms. To this end, new hardware was developed to enable autonomous culturing of rotifers with minimal astronaut intervention. The study revealed significant transcriptomic changes, with 18.61% of genes showing differential expression in response to microgravity and radiation. These changes included upregulation of genes involved in protein synthesis, RNA metabolic processes, and DNA repair. Notably, the study also found a significant enrichment of foreign genes (Horizontal Gene Transfers: HGTs) among the genes that were either over- or under-expressed during spaceflight, suggesting that HGTs play a role in bdelloids' adaptability to new and potentially atypical environments. CONCLUSIONS: This research not only enhances our understanding of how organisms respond to microgravity but also proposes A. vaga as a valuable model for future studies in space biology.