Investigating the long-term effects of chronic radiation exposure on cellular mechanisms

Despite decades of research into radiation effects on wildlife, controversy remains concerning the dose rate at which significant impacts occur for different types of organisms1. Recent studies around sites of reactor accidents Chernobyl (1986) and Fukushima (2011) have indicated potential biological effects in the field which are at odds with our expectations from laboratory studies2. Furthermore, in humans exposed to radiation from the Mayak Nuclear Facility, the cellular impact of chronic radiation, as observed in increase somatic mutations, frequency of micronuclei, and nitric oxide and apoptosis in peripheral blood lymphocytes, seems to affect ‘radiosensitive humans’ but not every individual3. Given there is increasing interest in understanding how and why sensitivity to radiation exposure varies between individuals, there is a need to better understand the effects of radiation not only on whole organisms, but also on cellular functions and to link the impact of exposure to a distinct physiological effect.
Within this project we will expose two well characterised model organisms, namely the waxmoth larvae (Galleria mellonella) and the freshwater protozoa Tetrahymena thermophila to a constant source of radiation, in our radiation facility, which mimics the radiation conditions in contaminated environments. Next, we will compare the impact of chronic radiation on these organisms through the study of a range of biochemical and immunological responses, such as gene/protein expression, melanisation, phagocytosis, reactive oxygen species (ROS) production/accumulation, etc.
This project fits within the remit of the Grand Challenges outlined by the Industrial Strategy Policy paper on “Clean Growth”. As the global economy moves into low carbon technologies, which may include nuclear energy, it is crucial that we have a better understanding of how cells are affected by chronic low dose radiation. This will ultimately help with the current public debate as well as inform government policy into the use of nuclear as a source of energy.
The project will utilise the specialist experimental facilities at the University of Stirling for radiation exposure experiments. The student will expose the model organisms to a constant, low-dose radiation for fixed periods of time. S/he will assess the immunity of these model organisms by challenging them with bacterial and/or fungal pathogens. S/he will also study genotoxic effects and oxidative stress, via fluorescence microscopy, flow cytometry or plate readers. Furthermore, regulation of specific genes will be determined by transcriptomics using RNA extracted from either the hemocytes (G. mellonella) or entire cells (T. thermophila). Any interesting up- or down- regulated genes will be analysed by western blots.
The precise objectives of this PhD could be tailored around the interests and expertise of the applicant. For more information, please see the advert posted on the NERC IAPETUS website:
http://www.iapetus.ac.uk/iap2-18-65-investigating-the-long-term-effects-of-chronic-radiation-exposure-on-immunity/