Abstract
Radiation damages many cellular components and disrupts cellular functions, and was previously reported to impair locomotion in the model organism Caenorhabditis elegans. However, the response to even higher doses is not clear. First, to investigate the effects of high-dose radiation on the locomotion of C. elegans, we investigated the dose range that reduces whole-body locomotion or leads to death. Irradiation was performed in the range of 0–6 kGy. In the crawling analysis, motility decreased after irradiation in a dose-dependent manner. Exposure to 6 kGy of radiation affected crawling on agar immediately and caused the complete loss of motility. Both γ-rays and carbon-ion beams significantly reduced crawling motility at 3 kGy. Next, swimming in buffer was measured as a motility index to assess the response over time after irradiation and motility similarly decreased. However, swimming partially recovered 6 h after irradiation with 3 kGy of γ-rays. To examine the possibility of a recovery mechanism, in situ GFP reporter assay of the autophagy-related gene lgg-1 was performed. The fluorescence intensity was stronger in the anterior half of the body 7 h after irradiation with 3 kGy of γ-rays. GFP::LGG-1 induction was observed in the pharynx, neurons along the body, and the intestine. Furthermore, worms were exposed to region-specific radiation with carbon-ion microbeams and the trajectory of crawling was measured by image processing. Motility was lower after anterior-half body irradiation than after posterior-half body irradiation. This further supported that the anterior half of the body is important in the locomotory response to radiation.
Highlights
Living organisms are frequently exposed to radiation
Little is known about the effects of higher doses on locomotion
We focused on motility in another condition, in S-basal buffer solution, and thrashing motion) assay shown in Figure 5A, swimming was evaluated from immediately evaluated swimming of irradiated worms
Summary
Living organisms are frequently exposed to radiation. On Earth, we are exposed to natural radiation, and to artificial radiation, such as γ rays and X-rays, from medical devices and nuclear accidents. In addition to X-rays and γ rays, there are several types of particle radiation in space such as neutrons and heavy ions. Radiation damages living organisms by directly affecting cellular components with its energy. There are indirect damaging effects of reactive oxygen species (ROS) produced by the ionization of water molecules in the cells by radiation. Irradiation of 4–7 Gy is usually fatal, resulting in death of 50% of individuals 1–2 months after exposure (half-lethal dose) [1]. The 10% lethal dose for Adineta vaga (tetraploid rotifer) is
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