Tolerance to gamma-irradiation in eggs of the tardigrade Richtersius coronifer depends on stage of development

  • Ingemar Jönsson | ingemar.jonsson@hkr.se Kristianstad University, Sweden.
  • Eliana Beltran-Pardo Pontificia Universidad Javeriana, Colombia.
  • Siamak Haghdoost Stockholm University, Sweden.
  • Andrzej Wojcik Stockholm University, Sweden.
  • Rosa María Bermúdez-Cruz Instituto Politécnico Nacional, Mexico.
  • Jaime E. Bernal Villegas Pontificia Universidad Javeriana, Colombia.
  • Mats Harms-Ringdahl Stockholm University, Sweden.

Abstract

Tardigrades are known as one of the most radiation tolerant animals on Earth, and several studies on tolerance in adult tardigrades have been published. In contrast, very few studies on radiation tolerance of embryonic stages have been reported. Here we report a study on tolerance to gamma irradiation in eggs of the eutardigrade Richtersius coronifer. Irradiation of eggs collected directly from a natural substrate (moss) showed a clear dose-response, with a steep decline in hatchability at doses up to 0.4 kGy followed by a relatively constant hatchability around 25% up to 2 kGy, and a decline to ca. 5% at 4 kGy above which no eggs hatched. Analysis of the time required for eggs to hatch after irradiation (residual development time) showed that hatching of eggs after exposure to high doses of gamma radiation was associated with short residual development time. Since short residual development time means that the egg was irradiated at a late developmental stage, this suggests that eggs were more tolerant to radiation late in development. This was also confirmed in another experiment in which stage of development at irradiation was controlled. No eggs irradiated at the early developmental stage hatched, and only one egg at middle stage hatched, while eggs irradiated in the late stage hatched at a rate indistinguishable from controls. This suggests that the eggs are more sensitive to radiation in the early stages of development, or that tolerance to radiation is acquired only late in development, shortly before the eggs hatch, hypotheses that are not mutually exclusive. Our study emphasizes the importance of considering specific cell cycle phases and developmental stages in studies of tolerance to radiation in tardigrades, and the potential importance of embryonic studies in revealing the mechanisms behind the radiation tolerance of tardigrades and other cryptobiotic animals.

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Author Biographies

Ingemar Jönsson, Kristianstad University
School of Education and Environment
Eliana Beltran-Pardo, Pontificia Universidad Javeriana
Instituto de Genética Humana
Siamak Haghdoost, Stockholm University
Department of Molecular Biosciences, The Wenner-Gren Institute
Andrzej Wojcik, Stockholm University
Department of Molecular Biosciences, The Wenner-Gren Institute
Rosa María Bermúdez-Cruz, Instituto Politécnico Nacional
Centro de Investigación y Estudios Avanzados
Jaime E. Bernal Villegas, Pontificia Universidad Javeriana
Instituto de Genética Humana
Mats Harms-Ringdahl, Stockholm University
Department of Molecular Biosciences, The Wenner-Gren Institute
Published
2013-05-03
Section
12th International Symposium on Tardigrada
Supporting Agencies
The study was supported by the Magnus Bergwall Foundation and the Swedish Space Agency
Keywords:
radiation tolerance, radio-resistance, tardigrades, Richtersius coronifer.
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How to Cite
1.
Jönsson I, Beltran-Pardo E, Haghdoost S, Wojcik A, Bermúdez-Cruz RM, Bernal Villegas JE, Harms-Ringdahl M. Tolerance to gamma-irradiation in eggs of the tardigrade Richtersius coronifer depends on stage of development. jlimnol [Internet]. 3May2013 [cited 19Nov.2019];72(1s):e9. Available from: https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2013.s1.e9