Loving the extremes: Extremophile radio-resistance and its link to human space radiobiology.

Space radiation is at the moment one of the main hurdles for human deep space exploration. Efficient countermeasures have to be developed to make the idea of ’the first human on Mars’ possible. An angle of investigation are the intrinsic mechanisms of radio-resistant organisms. The best studied organism is the bacteria Deinococcus radiodurans. Its protective mechanism( s) provide them with the tools to survive radiation doses of 5000 Gy. Moreover, these mechanisms are also capable to protect radio-sensitive bacteria Escherichia coli through transferring them. Another radio-resistant organism is the eukaryotic rotifer Adineta vaga. This thesis aimed to investigate whether the radio-protective mechanism(s) of these organisms could shield Normal Human Dermal Fibroblasts (NHDFs) against radiation exposure. We hypothesized that extract obtained from the rotifers would be able to allow fibroblasts to survive at higher radiation doses. However, this effect was not observed. Molecular changes in the NHDFs were also anticipated. A decrease in inflammatory components was hypothesized together with a decreased carbonylation state of proteins. The antioxidant concentration within the NHDFs were on the other hand expected to increase after radiation exposure of NHDFs. Significant increases in inflammatory cytokines and levels of protein carbonylation were obtained respectively using a Milliplex assay and a protein carbonylation assay. However, these significant changes were only observed in NHDFs irradiated with 10 Gy. Antioxidants concentration was determined using a FRAP assay, unfortunately, this question remained unanswered due to solvent variability. In general, we saw small significant and non-significant alterations due to treating NHDFs with rotifer extract. However, these observations were often not in line with our expectations based on previous research. As this thesis was intended as a pilot study, performing experimental repeats is required, together with additional research into the radio-resistant mechanisms at play in Adineta vaga.