The Effect of Internalized Paramagnetic Nanoparticles on Caenorhabditis elegans Locomotion in the Presence of Magnetic Field

Caenorhabditis elegans nematodes are broadly used to investigate the impact of environmental factors on animal physiology and behavior. Here, C. elegans with internalized paramagnetic nanoparticles were placed inside a magnetic field (MF) to explore its effects on locomotion. We hypothesized that internalized paramagnetic nanoparticles combined with external MF affect C. elegans’ locomotion machinery. To test our hypothesis, we used adult C. elegans fed on bacteria mixed with paramagnetic nanoparticles of 1 μm, 100, and 40 nm diameter. The presence of nanoparticles inside the worms’ body (alimentary canal, body muscle) was verified by fluorescent and electron microscopy. A custom-made software was used to track freely moving C. elegans in the absence or presence of MF, sequentially, for 200 + 200 s. We used established metrics to quantify locomotion-related parameters, including posture, motion, and path features. Key attributes of C. elegans locomotion (stay ratio, forward over backward motion, speed) were affected only in worms with internalized nanoparticles of 100 nm in the presence of MF (reduced speed, increased stay ratio, decreased forward/backward ratio), in contrast to untreated worms. Our work shows that internalized particles of specific properties affect C. elegans locomotion under MF. Hence, it contributes to clarifying the effects of MF and activated nanoparticles on C. elegans locomotion, thus fueling further research.