Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2016 Dec 20;11(12):e0168884.
doi: 10.1371/journal.pone.0168884. eCollection 2016.

Tolerance to Gamma Radiation in the Marine Heterotardigrade, Echiniscoides sigismundi

K Ingemar Jönsson  1 , Thomas L Hygum  2 , Kasper N Andersen  2 , Lykke K B Clausen  2 , Nadja Møbjerg  2
Affiliations

Tolerance to Gamma Radiation in the Marine Heterotardigrade, Echiniscoides sigismundi

K Ingemar Jönsson et al. PLoS One. .

Abstract

Tardigrades belong to the most radiation tolerant animals on Earth, as documented by a number of studies using both low-LET and high-LET ionizing radiation. Previous studies have focused on semi-terrestrial species, which are also very tolerant to desiccation. The predominant view on the reason for the high radiation tolerance among these semi-terrestrial species is that it relies on molecular mechanisms that evolved as adaptations for surviving dehydration. In this study we report the first study on radiation tolerance in a marine tardigrade, Echiniscoides sigismundi. Adult specimens in the hydrated active state were exposed to doses of gamma radiation from 100 to 5000 Gy. The results showed little effect of radiation at 100 and 500 Gy but a clear decline in activity at 1000 Gy and higher. The highest dose survived was 4000 Gy, at which ca. 8% of the tardigrades were active 7 days after irradiation. LD50 in the first 7 days after irradiation was in the range of 1100-1600 Gy. Compared to previous studies on radiation tolerance in semi-terrestrial and limnic tardigrades, Echiniscoides sigismundi seems to have a lower tolerance. However, the species still fits into the category of tardigrades that have high tolerance to both desiccation and radiation, supporting the hypothesis that radiation tolerance is a by-product of adaptive mechanisms to survive desiccation. More studies on radiation tolerance in tardigrade species adapted to permanently wet conditions, both marine and freshwater, are needed to obtain a more comprehensive picture of the patterns of radiation tolerance.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Mean proportion of adult Echiniscoides sigismundi showing activity after exposure to different doses of gamma radiation.
The figure shows estimates from four different time points after irradiation, from 24h to 7 days. Error bars represent standard errors of the mean from 3 repeats, each with approx. 20 animals.
Fig 2
Fig 2. Dose-response curves showing the proportion of active Echiniscoides sigismundi after different doses of gamma radiation, at activity assessments 24h, 48h, 72h and 7 days after irradiation.
Data for non-irradiated samples were excluded. Each data point shows the proportion of active tardigrades out of approx. 20 animals. LD50 values (with 95% confidence intervals in parentheses) obtained from dose-response fitting and the statistical support of the regressions are given within each graph.
See this image and copyright information in PMC

References

    1. Wright JC, Westh P, Ramløv H. Cryptobiosis in tardigrade. Biol Rev. 1992; 67: 1–29.
    1. Wright JC. Cryptobiosis 300 years on from van Leuwenhoek: what have we learned about tardigrades? Zool Anz. 2001; 240: 563–582.
    1. Møbjerg N, Halberg KA, Jørgensen A, Persson D, Bjørn M, Ramløv H, et al. Survival in extreme environments—on the current knowledge of adaptations in tardigrades. Acta Physiol (Oxf). 2011; 202(3): 409–420. - PubMed
    1. May RM, Maria M, Guimard J. Action différentielle des rayons x et ultraviolets sur le tardigrade Macrobiotus areolatus, a l’état actif et desséché. Bull Biol Fr Belg. 1964; 98: 18.
    1. Jönsson KI, Harms-Ringdahl M, Torudd J. Radiation tolerance in the eutardigrade Richtersius coronifer. Int J Radiat Biol. 2005; 81: 649–656. 10.1080/09553000500368453 - DOI - PubMed