Our miracle micro-animal, the tardigrade.

Have you ever wondered what it would feel like to withstand the damaging effects of radiation? Worry not, because tardigrades have recently become a source of hope. This micro-animal (Figure 1) possesses a protein, termed Dsup (short for Damage suppressor) that allows it to survive X-ray radiation (Hashimoto, et al., 2016). Interestingly, this protein can be used to enhance radiation protection in human cells.

First, how exactly does radiation cause damage to humans? There are two main pathways, direct and indirect, by which radiation affects DNA molecules in human cells (Figure 2). In the direct method, radiation hits the DNA molecule directly, disrupting its molecular structure. Such disruption can cause cell damage, which may later lead to genetic abnormalities such as carcinogenesis, or apoptosis (cell death) (Desouky, Ding and Zhou, 2015). Even more destructive is the indirect method, whereby radiation hits the most abundant of all molecules in cells, water (H₂O), which makes up about 70 % of a cell (Saha, 2013). When radiation hits H₂O, free radicals such as hydroxyl (OH·) are produced, which are highly reactive due to their characteristic unpaired electron, causing molecular structural damage (Desouky, Ding and Zhou, 2015).

Although the exact mechanisms by which the Dsup protein acts is still elusive, it has been confirmed that the Dsup protein can be co-localized (merged) with nuclear DNA in HEK 293T (human embryonic kidney) cells (Figure 3) in order to exhibit effects similar to those seen in tardigrades when subjected to radiation (Hashimoto et al., 2016). Furthermore, there is promising evidence for the co-localization technqiue: when Dsup was merged with human cells, the effects of radiation on the cells had been suppressed by ~40 % (Hashimoto, et al., 2016). Imagine being able to conduct this process on the macro level, perhaps using human skin cells. Some might say that the ability to suppress damage from radiation could then mimic a radiation force field! (However, the cells would be suppressing damage as opposed to deflecting it.) Although achieving an effect at the level of a force field has not yet been attempted–at least not by Hashimoto’s team–the Dsup protein’s confirmed damage-suppressing power holds much potential for the future.

The tardigrade is our miracle micro-animal. With deeper understanding of the biochemical pathways that the tardigrade employs to generate the Dsup protein and the physical processes involved in the merging of the Dsup protein with parts of human cells, we behold a future in which radiation is of minimal threat to human health. The applications are wide­–branching from facilitating cancer radiation treatment and shielding workers better in nuclear facilities to growing crops in extreme environments such as that of Mars. All in all, protection from the adverse effects of radiation is, in fact, possible, thanks to our little friend, the tardigrade.

Works Cited

Desouky, O., Ding, N. and Zhou, G., 2015. Targeted and non-targeted effects of ionizing radiation. Journal of Radiation Research and Applied Sciences, [e-journal] 8(2), pp.247–254. https://doi.org/10.1016/j.jrras.2015.03.003.

Fox-Skelly, J., 2015. Figure 1: Tardigrades return from the dead. [image online] Available at: <http://www.bbc.com/earth/story/20150313-the-toughest-animals-on-earth> [Accessed 6 Nov. 2017].

Hashimoto, T., Horikawa, D.D., Saito, Y., Kuwahara, H., Kozuka-Hata, H., Shin-I, T., Minakuchi, Y., Ohishi, K., Motoyama, A., Aizu, T., Enomoto, A., Kondo, K., Tanaka, S., Hara, Y., Koshikawa, S., Sagara, H., Miura, T., Yokobori, S., Miyagawa, K., Suzuki, Y., Kubo, T., Oyama, M., Kohara, Y., Fujiyama, A., Arakawa, K., Katayama, T., Toyoda, A. and Kunieda, T., 2016. Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein. Nature Communications, [e-journal] 7(1). http://dx.doi.org/10.1038/ncomms12808.

Saha, G.B., 2013. Physics and Radiobiology of Nuclear Medicine. [e-book] New York: Springer-Verlag. Available at: <http://www.springer.com/us/book/9781461440116> [Accessed 12 Nov. 2017].