Fullerenols are nanosized water-soluble polyhydroxylated derivatives of fullerenes, specific allotropic form of carbon, bioactive compounds and perspective pharmaceutical agents. Antioxidant activity of fullerenols was studied in model solutions of organic and inorganic toxicants of oxidative type – 1,4-benzoquinone and potassium ferricyanide. Two fullerenol preparations were tested: С60О2–4(ОН)20–24 and mixture of two types of fullerenols С60О2–4(ОН)20–24+С70О2–4(ОН)20–24. Bacteria-based and enzyme-based bioluminescent assays were used to evaluate a decrease in cellular and biochemical toxicities, respectively. Additionally, the enzyme-based assay was used for the direct monitoring of efficiency of the oxidative enzymatic processes. The bacteria-based and enzyme-based assays showed similar peculiarities of the detoxification processes: (1) ultralow concentrations of fullerenols were active (ca 10–17–10−4 and 10–17–10−5 g/L, respectively), (2) no monotonic dependence of detoxification efficiency on fullerenol concentrations was observed, and (3) detoxification of organic oxidizer solutions was more effective than that of the inorganic oxidizer. The antioxidant effect of highly diluted fullerenol solutions on bacterial cells was attributed to hormesis phenomenon; the detoxification was concerned with stimulation of adaptive cellular response under low-dose exposures. Sequence analysis of 16S ribosomal RNA was carried out; it did not reveal mutations in bacterial DNA. The suggestion was made that hydrophobic membrane-dependent processes are involved to the detoxifying mechanism. Catalytic activity of fullerenol (10−8 g/L) in NADH-dependent enzymatic reactions was demonstrated and supposed to contribute to adaptive bacterial response.

The mechanism of biological activation by beta-emitting radionuclide tritium was studied. Luminous marine bacteria were used as a bioassay to monitor the biological effect of tritium with luminescence intensity as the physiological parameter tested. Two different types of tritium sources were used: HTO molecules distributed regularly in the surrounding aqueous medium, and a solid source with tritium atoms fixed on its surface (tritium-labeled films, 0.11, 0.28, 0.91, and 2.36 MBq/cm2). When using the tritium-labeled films, tritium penetration into the cells was prevented. The both types of tritium sources revealed similar changes in the bacterial luminescent kinetics: a delay period followed by bioluminescence activation. No monotonic dependences of bioluminescence activation efficiency on specific radioactivities of the films were found. A 15-day exposure to tritiated water (100 MBq/L) did not reveal mutations in bacterial DNA. The results obtained give preference to a "non-genomic" mechanism of bioluminescence activation by tritium. An activation of the intracellular bioluminescence process develops without penetration of tritium atoms into the cells and can be caused by intensification of trans-membrane cellular processes stimulated by ionization and radiolysis of aqueous media. ON THE MECHANISM OF BIOLOGICAL ACTIVATION BY TRITIUM AbstractThe mechanism of biological activation by beta-emitting radionuclide tritium was studied. Luminous marine bacteria were used as a bioassay to monitor the biological effect of tritium with luminescence intensity as the physiological parameter tested. Two different types of tritium sources were used: HTO molecules distributed regularly in the surrounding aqueous medium, and a solid source with tritium atoms fixed on its surface 0.11, 0.28, 0.91, and 2.36 MBq/cm 2 ). When using the tritiumlabeled films, tritium penetration into the cells was prevented. The both types of tritium sources revealed similar changes in the bacterial luminescent kinetics: a delay period followed by bioluminescence activation. No monotonic dependences of bioluminescence activation efficiency on specific radioactivities of the films were found. A 15-day exposure to tritiated water (100 MBq/L) did not reveal mutations in bacterial DNA. The results obtained give preference to a "non-genomic" mechanism of bioluminescence activation by tritium. An activation of the intracellular bioluminescence process develops without penetration of tritium atoms into the cells and can be caused by intensification of trans-membrane cellular processes stimulated by ionization and radiolysis of aqueous media.

Luminous marine bacteria are widely used as a bioassay with luminescence intensity being a physiological parameter tested. The purpose of the study was to determine whether bacterial genetic alteration is responsible for bioluminescence kinetics change under low-dose radiation exposure. Alpha-emitting radionuclide 241Am and betaemitting radionuclide 3H were used as sources of low-dose ionizing radiation. Changes of bioluminescence kinetics of Photobacterium Phosphoreum in solutions of 241Am(NO3)3, 7 kBq/L, and tritiated water, 100 MBq/L, were studied; bioluminescence kinetics stages (absence of effect, activation, and inhibition) were determined. Bacterial suspension was sampled at different stages of the bioluminescent kinetics; the doses accumulated by the samples did not exceed 1 Gy, being close to a tentative limit of a low-dose interval. Sequence analysis of 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose alpha and beta radiation. Previous results on bacterial DNA exposed to lowdose gamma radiation (0.25 Gy) were analyzed and compared to those for alpha and beta irradiation. A conclusion was made that DNA mutations are not associated with bacterial bioluminescence activation and inhibition under the applied conditions of low-dose alpha, beta, and gamma radioactive exposure. To view all the submission files, including those not included in the PDF, click on the manuscript title on your EVISE Homepage, then click 'Download zip file'. Abbreviations:ROS -Reactive Oxygen Species HTO -tritiated water ABSTRACTLuminous marine bacteria are widely used as a bioassay with luminescence intensity being a physiological parameter tested. The purpose of the study was to determine whether bacterial genetic alteration is responsible for bioluminescence kinetics change under low-dose radiation exposure. Alpha-emitting radionuclide 241 Am and betaemitting radionuclide 3 H were used as sources of low-dose ionizing radiation. Changes of bioluminescence kinetics of Photobacterium Phosphoreum in solutions of 241 Am(NO 3 ) 3 , 7 kBq/L, and tritiated water, 100 MBq/L, were studied; bioluminescence kinetics stages (absence of effect, activation, and inhibition) were determined. Bacterial suspension was sampled at different stages of the bioluminescent kinetics; the doses accumulated by the samples did not exceed 1Gy, being close to a tentative limit of a low-dose interval. Sequence analysis of 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose alpha and beta radiation. Previous results on bacterial DNA exposed to low-dose gamma radiation (0.25 Gy) were analyzed and compared to those for alpha and beta irradiation. A conclusion was made that DNA mutations are not associated with bacterial bioluminescence activation and inhibition under the applied conditions of low-dose alpha, beta, and gamma radioactive exposure.

Electron microscopical studies of the nucleoid structure of hydrogen bacteria using ultrahin sections and spread DNA from bacterial cell lysates revealed a different DNA packaging in the cell. A compact state of the major part of DNA at all growth stages and stability of nucleosome-like structures were shown. The use of antibodies to HU protein of E. coli labelled by protein A-colloidal gold demonstrated the immunological relationship between HU protein of E. coli and histone-like proteins of Alcaligenes eutrophus and their possible role in the nucleosome-like DNA packaging in procariotic genome.