Enter the Tardigrade: The Animal Kingdom’s Tough Cookie

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If you thought that the most resilient creature was the polar bear or the rattlesnake, think again. One species that has been making headlines recently – known for its talent to withstand extreme conditions, is the Tardigrade. And by extreme, I mean incredibly extreme cold and hot temperatures, extreme radiation, and pressure, thanks to a series experiments conducted by various labs around the world exposing Tardigrades to hostile environments to see whether they would survive at all. I wonder what PETA thought about this.

The Tardigrade aptly nick-named the Water Bear due to it's bear-like resemblance

The Tardigrade aptly nick-named the Water Bear due to it’s bear-like resemblance

Thankfully, the Tardigrade out-shined in all these trials and mostly emerged in flying colors. It is undoubtedly the toughest creature to walk, or more precisely, crawl on planet earth that its DNA is being scrutinised to get any clues of its survival tactics.

Last year, the Tardigrade’s genome (Hypsibius dujardini) had been completely sequenced by a research group in North Carolina and had left the researchers completely baffled about this species more than ever. The study showed that over 6000 genes of its genome was borrowed from elsewhere, probably from another organism such as a bacteria, what scientists call as horizontal gene transfer[1]. However, this was slammed by another group of researchers in Edinburgh that HGT to such a measure was deemed as an erroneous finding and concluded bacterial contamination may have contributed to the presence of a large amount of foreign genes in the Tardigrade genome [2].

Tardgrades curl up to form a Tun during adverse conditions. Copyright Willow Gabriel and Bob Goldstein

Tardgrades curl up to form a Tun during adverse conditions. Copyright Willow Gabriel and Bob Goldstein

But recently, the Tardigrade genes were further investigated by a group of scientists from the University of Tokyo to see what made them most resilient to stress especially that of dehydration and irradiation[3]. The presence of a miracle protein in these animals called as dsup aided the creature to withstand adverse conditions and when incorporated into a culture of human cells was found to be able to withstand radiations up to 40% as well.

Investigating the Tardigrade genome might help scientists to delve deeper into the mechanisms of stress resistance, DNA repair and also give hints for cryobiology breakthroughs.

Another interesting fact would be that even though Tardigrades are widely distributed and since they possess the superpowers of resilience, it would be interesting to know whether this creature has ever survived elsewhere in space? This would be an interesting topic for exobiologists to ponder on.

The infographic below gives away some interesting trivia we know about these creatures so far.

tardigrade tenacity

[1] Boothby, T.C., Tenlen, J.R., Smith, F.W., Wang, J.R., Patanella, K.A., Nishimura, E.O., Tintori, S.C., Li, Q., Jones, C.D., Yandell, M. and Messina, D.N., 2015. Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade. Proceedings of the National Academy of Sciences,112(52), pp.15976-15981.

[2] Koutsovoulos, G., Kumar, S., Laetsch, D.R., Stevens, L., Daub, J., Conlon, C., Maroon, H., Thomas, F., Aboobaker, A.A. and Blaxter, M., 2016. No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini. Proceedings of the National Academy of Sciences,113(18), pp.5053-5058.

[3] Hashimoto, T., Horikawa, D.D., Saito, Y., Kuwahara, H., Kozuka-Hata, H., Shin, T., Minakuchi, Y., Ohishi, K., Motoyama, A., Aizu, T. and Enomoto, A., 2016. Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein. Nature Communications,7.

Featured image Credit & Copyright: Nicole Ottawa & Oliver Meckes / Eye of Science