An Extended Dose–Response Model for Microbial Responses to Ionizing Radiation

Siasou, Eleni; Johnson, David; Willey, Neil

doi:10.3389/fenvs.2017.00006

Cited by 14 publications

(10 citation statements)

References 36 publications

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“…The extent to which these two factors interact can be explored by removing or fixing the background and, for example, introducing mutator genes to change the mutation rate in a radiation‐agnostic manner (de Visser et al., ). The relevance of this question is highlighted in studies from environmental toxicology, where a picture is emerging that microbial responses to the radiation background are linked both to exposure time and the dose rate (Siasou, Johnson, & Willey, ). Here again, clear measurements of radiation responses to very low radiation levels can provide clarity as to how the impacts of natural radiation should be quantified.…”

Section: Possible Applications Of Low Background Studiesmentioning

confidence: 99%

Understanding low radiation background biology through controlled evolution experiments

Lampe

Breton

Sarramia

et al. 2017

Evolutionary Applications

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Biological experiments conducted in underground laboratories over the last decade have shown that life can respond to relatively small changes in the radiation background in unconventional ways. Rapid changes in cell growth, indicative of hormetic behaviour and long‐term inheritable changes in antioxidant regulation have been observed in response to changes in the radiation background that should be almost undetectable to cells. Here, we summarize the recent body of underground experiments conducted to date, and outline potential mechanisms (such as cell signalling, DNA repair and antioxidant regulation) that could mediate the response of cells to low radiation backgrounds. We highlight how multigenerational studies drawing on methods well established in studying evolutionary biology are well suited for elucidating these mechanisms, especially given these changes may be mediated by epigenetic pathways. Controlled evolution experiments with model organisms, conducted in underground laboratories, can highlight the short‐ and long‐term differences in how extremely low‐dose radiation environments affect living systems, shining light on the extent to which epimutations caused by the radiation background propagate through the population. Such studies can provide a baseline for understanding the evolutionary responses of microorganisms to ionizing radiation, and provide clues for understanding the higher radiation environments around uranium mines and nuclear disaster zones, as well as those inside nuclear reactors.

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Section: Possible Applications Of Low Background Studiesmentioning

confidence: 99%

Understanding low radiation background biology through controlled evolution experiments

Lampe

Breton

Sarramia

et al. 2017

Evolutionary Applications

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“…These works give some examples of microbial species and melanized fungi with a high tolerance to radioactivity. However, research works in natural environments with high ionizing radiation and on the evolution of microbial populations in these environments are very scarce ( Siasou et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Diversity of Microfungi in a High Radon Cave Ecosystem

et al. 2022

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Castañar Cave is a clear example of an oligotrophic ecosystem with high hygrothermal stability both seasonal and interannual and the particularity of registering extraordinary levels of environmental radiation. These environmental conditions make the cave an ideal laboratory to evaluate both the responses of the subterranean environment to sudden changes in the matter and energy fluxes with the exterior and also any impact derived from its use as a tourist resource under a very restrictive access regime. In 2008, a fungal outbreak provoked by a vomit contaminated the sediments which were removed and subsequently treated with hydrogen peroxide. Fungal surveys were carried out in 2008 and 2009. The visits were resumed in 2014. Here, 12 years after the outbreak, we present an exhaustive study on the cave sediments in order to know the distribution of the different fungal taxa, as well as the prevalence and spatio-temporal evolution of the fungi caused by the vomit over the years under the conditions of relative isolation and high radiation that characterize this cave.

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“…However, above the determined threshold the radiation dose-damage continues in a linear manner. This is known as the "threshold" model (e.g., Mancuso et al, 2012;Siasou et al, 2017; Figure 1). Since the midtwentieth century, the generally accepted model for describing an organism's radiation dose-response relationship has been the linear no-threshold (LNT) model (Muller, 1946; Figure 1), which was further supported by the National Research Council (NRC) (2006).…”

Section: Introductionmentioning

confidence: 99%

There's Plenty of Room at the Bottom: Low Radiation as a Biological Extreme

Wadsworth

Cockell

Murphy

et al. 2020

Front. Astron. Space Sci.

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The effects of high radiation as a biological extreme have historically been, and continue to be, extensively researched in the fields of radiation biology and astrobiology. However, the absence of radiation as an extreme has received relatively limited attention from the scientific community, with its effects on life remaining unclear. The currently accepted model of the radiation dose-damage relationship for organisms is the linear no-threshold (LNT) model, which predicts a positive linear correlation between dose and damage that intercepts at zero dose corresponding to zero damage. Despite its widespread implementation, the LNT model is continuously being challenged by various new models, with the hormesis model as one of its main competitors. This model also postulates damage at high doses but, in contrast to the LNT model, it predicts beneficial stimulation of growth at low doses. Experiments to date have not yet been able to conclusively validate or dismiss either of these models. The aim of the collaborative Subsurface Experiment of Life in Low Radiation (SELLR) project was to test these competing models on prokaryotes in a well-characterised environment and provide a robust experimental set up to investigate low radiation in terrestrial and non-terrestrial environments. Bacterial growth assays using Bacillus subtilis and Escherichia coli were performed under ultra low ionising radiation in the Boulby International Subsurface Astrobiology Laboratory (BISAL) facilities of the Boulby Underground Laboratory at Boulby mine (Redcar & Cleveland, UK) and were used to investigate effects on viability and signs of preconditioning. No significant effect on bacterial growth was observed from exposure to radiation doses ranging from 0.01 times the levels of background radiation typically found in terrestrial surface environments to 100 times that background. Additionally, no preconditioned susceptibility to stress was observed in the bacterial strains grown in sustained low radiation. These data suggest that the extremes of low radiation do not alter growth parameters of these two organisms and that an improved model should be considered for prokaryotes, consisting of a dose-damage response with a threshold at ultra low radiation. We discuss the implications of these data for low radiation as a novel microbiological "extreme."

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An Extended Dose–Response Model for Microbial Responses to Ionizing Radiation

Cited by 14 publications

References 36 publications

Understanding low radiation background biology through controlled evolution experiments

Understanding low radiation background biology through controlled evolution experiments

Diversity of Microfungi in a High Radon Cave Ecosystem

There's Plenty of Room at the Bottom: Low Radiation as a Biological Extreme

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