Domestication of radiation sensitive Caenorhabditis Elegans strains suitable for liquid culture systems in long-term space mission.

With the continuous advancement of manned deep-space exploration, the need for effective radiation-risk assessment and protection is increasingly urgent. There is a need to screen space radiation-sensitive Caenorhabditis elegans strains suitable for long-term microfluidic chip-based cultivation and observation in space on orbit. In the study, green fluorescently protein-labeled nematode strains carrying stress-related genes (involved in stress response, DNA-damage, germ-cell apoptosis) were selected. Nematode strains that significantly responded to Co60γ-ray radiation stimulation were screened and further domesticated using C. elegans Maintenance Medium (CeMM) liquid culture. Results indicated that under simulated γ-radiation (40 mSv), fluorescent proteins expression was significantly upregulated in TJ356 strain (marked by DAF-16) and CL2166 strain (marked by GST-4). Subsequently, single nematodes from TJ356 and CL2166-maintained in liquid medium for >30 days and successfully decontaminated-both retained radiosensitivity, exhibiting 1.27- and 2.73-fold fluorescence upregulation post-UVC irradiation (254 nm, 1400 J/m²). In CeMM, both strains reached adulthood with body lengths >500 μm and head thrashing frequencies ≥10 events/10 s, while TJ356 demonstrated more stable locomotor activity during prolonged cultivation. Average fluorescence intensity of TJ356 increased progressively with development and remained consistently above 30 arbitrary units (AU), while that of CL2166 decreased gradually but stayed above 10 AU. Multivariate evaluation identified TJ356 as the optimal radiation-sensitive strain. During the subsequent 33-day on-orbit cultivation experiment in the Chinese Space Station, the average body length of TJ356 nematodes in the flight group increased from 657.95 to 822.11 μm and showed 1.51-2.51-fold fluorescence elevation compared to ground control. The results confirm the space-environment sensitivity of TJ356 and its feasibility for long-term individual observation.