In Vitro cellular bioluminescence assay and organism-level responses to low-dose tritium irradiation

The paper studies physiological parameters of two organisms of different organizational levels - cells and animals - under low-dose radioactive exposure to tritium (<1.57 mGy); luminescence intensity of luminous marine bacteria Photobacterium phosphoreum and physiological characteristics of high organisms (rabbits) were under investigation. Two-level parameters of rabbits were analyzed: general clinical characteristics (body temperature, respiratory rate, heart rate, weight, etc.) and clinical-hematological parameters of peripheral rabbit blood (i.e. phagocytic activity of leukocytes). Tritiated water (HTO) was used as a source of tritium. Luminous bacteria exhibited both activation and inhibition of bioluminescence under low-dose tritium exposure (<0.35 mGy). General clinical characteristics of rabbits were within the physiological norm at 0.14-1.57 mGy. However, 0.14 mGy HTO exposure increased phagocytic activity, while 0.60 and 1.57 mGy doses suppressed it, demonstrating stimulatory and radiotoxic effects, respectively. Hence, the similarity in dose-response patterns between bacterial and rabbit cells was demonstrated. The radioprotective effects of humic substances (HS, a product of natural oxidative decomposition of soil organic matter) were also evaluated in both organisms. HS counteracted HTO toxicity in bacteria and rabbits, restoring physiological parameters (bioluminescence intensity and leukocyte phagocytic activity) to near-control levels (HTO-free conditions). As a result, a new approach has been proposed, that the rapid bacterial assay could be used to predict the cellular responses in higher organisms under low-dose radiation exposure; it can contribute to early warning of damage to higher organisms under chronic exposure. Further research is needed in accordance with this approach.