Low-intensity Exposures via Luminescent Bioassays of Different Complexity: Cells, Enzyme Reactions and Fluorescent Proteins

Current paper reviews applications of luminescence bioassays for monitoring low-intensity factors, namely, radioactivity of different types (alpha, beta and gamma), and bioactive compounds (humic substances and fullerenols). Luminescence intensity is taken as a physiological parameter of luminous organisms. High rates of luminescence response can provide (1) a proper number of experiments under comparable conditions and, therefore, proper statistical processing, with this being highly important for ‘noisy’ low-dose exposures; (2) non-genetic, i.e. biochemical and physicochemical mechanisms of cellular response, in accordance to “exposome” concept. Bioassays based on luminous marine bacteria, their enzymes, and fluorescence coelenteramide-containing proteins were used to compare results of low-intensity exposures at cellular, biochemical and physicochemical levels, respectively. Results of the cellular exposures were discussed in terms of hormesis concept. Bioluminescence time dependence under low-dose radiation exposures corresponded to hormesis or threshold models; no bioluminescence monotonic dependency on intensity of exposure (dose rate, radioactivity, concentration) was found. Bioluminescence activation and absence of its dependency on intensity of exposure can be accepted as features of cellular adaptive response. Changes of biological luminescence were analyzed and discussed for bioassays of lower organization level – enzymes and florescent protein.