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Life on Earth evolved under a specific set of environmental conditions, including consistent gravitational and magnetic fields. However, planned human missions to Mars in the coming decades will expose terrestrial organisms to radically different conditions, with Martian gravity being approximately 38% of Earth's and a significantly reduced magnetic field. Understanding the combined effects of these factors is crucial, as they may impact biological systems that evolved under different conditions. In this study, we investigated the effects of simulated Martian gravity and hypomagnetic fields on the nematode Caenorhabditis elegans across six generations. We used an integrated experimental setup consisting of clinostats to mimic the reduced Martian gravity, and Merritt coil magnetic cages to model the decreased Martian magnetic fields. We assessed behavioral, morphological, and physiological responses of C. elegans. High-throughput automated assays revealed significant reductions in motor output and morphological dimensions for animals in the Mars treatment compared to matched earth-like controls. We assessed neurological function by means of chemotaxis assays and found a progressive decline in performance for worms raised under the Martian paradigm compared to Earth controls. Our results show that worms grown under Martian-like conditions exhibit progressive physiological alterations across generations, suggesting that the unique environment of Mars might pose challenges to biological function and adaptation. These findings contribute to understanding how living organisms may respond to the combined effects of reduced gravity and hypomagnetic fields, providing insights relevant for future human exploration and potential colonization of Mars. 

Abstract Once considered mere structural support cells in the nervous system, glia have recently been demonstrated to play pivotal roles in sensorimotor processing and to directly respond to sensory stimuli. However, their response properties and contributions to sensory-induced behaviors remain little understood. InCaenorhabditis elegans, the amphid sheath glia (AMsh) directly respond to aversive odorants and mechanical stimuli, but their precise transduction machinery and their behavioral relevance remain unclear. We investigated the role of AMsh in mechanosensation and their impact on escape behaviors inC. elegans. We found that nose touch stimuli in immobilized animals induced a slow calcium wave in AMsh, which coincided with the termination of escape reversal behaviors. Genetic ablation of AMsh resulted in prolonged reversal durations in response to nose touch, but not to harsh anterior touch, highlighting the specificity of AMsh’s role in distinct escape behaviors. Mechanotransduction in AMsh requires the α-tubulin MEC-12 and the ion channels ITR-1 and OSM-9, indicating a unique mechanosensory pathway that is distinct from the neighboring ASH neurons. We find that GABAergic signaling mediated by the GABA-A receptor orthologs LGC-37/8 and UNC-49 play a crucial role in modulating the duration of nose touch-induced reversals. We conclude that in addition to aversive odorant detection, AMsh mediate mechanosensation, play a pivotal role in terminating escape responses to nose touch, and provide a mechanism to maintain high sensitivity to polymodal sensory stimuli. SignificancePolymodal nociceptive sensory neurons have the challenge of multitasking across sensory modalities. They must respond to dangerous stimuli of one modality, but also adapt to repeated nonthreatening stimuli without compromising sensitivity to harmful stimuli from different modalities. Here we show that a pair of glia in the nematodeC. elegansmodulate the duration of nose-touch induced escape responses. We identify several molecules involved in the transduction of mechanical stimuli in these cells and show that they use the signaling molecule GABA to modulate neural function. We propose a mechanism through which these glia might function to maintain this polysensory neuron responsive to dangerous stimuli across different modalities.