SELLR (the Subsurface Experiment of Life in Low Radiation) project is probing a so far poorly understood area of biology. It is well established that the exposure of living cells to radiation can prove harmful, either through cell damage or genetic mutations, but little research has been conducted into how organisms react to environments devoid of radiation. As a result of contributions from Earth's own naturally occuring radiation but mainly cosmic rays from space, life is continually bathed in an almost irreducible background. However, due to Boulby Underground Laboratory's unique location, researchers have access to a low radiation environment in which experiments of this nature can be conducted.
At present there exists a number of models which describe the relationship of radiation exposure to risk factor, the two models of note being the 'Linear No-Threshold Model' and the 'Hormetic Model'. The former describes a standard direct proportionality between exposure and risk, with greater exposure generating greater risk, whereas the latter depicts a more complex, non-linear relationship. The Hormetic Model postulates that at high extremes of exposure, a greater risk is observed due to inhibition, while at low extremes negative risk is seen as a result of increased stimulation; an ideal environment would fall between the two. The data generated from SELLR will help to confirm any one of the theories or may even generate a model of its own.
The setup of SELLR is simple; grow a batch of genetically identical, quickly reproducing bacteria and split the batch into two. Contain the first batch in as low a radiation environment as possible whilst exposing the second batch to a simulated background. Monitor the growth of both samples as they multiply and compare. The growth curves produced from such observations contain a mine of information, showing researchers in some detail how the bacteria are coping in the varying environments.
This work is being conducted by researchers from the University of Edinburgh.