[14p-1F-1~11] Frontier of Plasma Medicine

[14p-1F-4] Effect of Non-thermal Plasma on DNA molecules and Bio-particles

〇Akira Mizuno¹ (1.TUT)

Keywords:Plasma jet,Radical reactions,Plasma exposure to living cells

Mechanism of inactivation of bio-particles exposed to non-thermal plasma, NTP, has been studied using S. cerevisiae, B. subtilis, E. coli and bacteriophages. States of different biological components were monitored during the course of inactivation. Analysis of green fluorescent protein, GFP, introduced into E.coli cells proved that NTP causes a prominent protein damages without cutting peptide bonds. We have invented a biological assay which evaluates in vivo DNA damage of the bacteriophages. Different doses of the plasma were applied to wet state of λ phages. From the discharged λ phages, DNA was purified and subjected to in vitro DNA packaging reactions. The re-packaged phages consist of the DNA from discharged phages and brand-new coat proteins. Survival curves of the re-packaged phages showed extremely large D value (D=25 s) compared to the previous D value (D=3 s) from the discharged phages. The results indicate that DNA damage hardly contributed to the inactivation, and the damage in coat proteins is responsible for inactivation of the phages. We also monitored DNA damage in yeast cells exposed to Ar or He plasma jet. We have used the yeast-based genotoxicity assay system, which is based on the transcriptional induction of a Saccharomyces cerevisiae with a RNR2-lacZ reporter plasmid in response to DNA damaging agents and agents that interfere with DNA synthesis. Similar to the alkylating agent or UV radiation, the He plasma jet treatment induced high level of RNR2-lacZ expression. These results strongly suggest that non-thermal atmospheric pressure plasmas treatment could cause genotoxic effects via cellular DNA damages.