Nucleotide excision repair pathway assessment in DNA exposed to low-intensity red and infrared lasers

Abstract

Low-intensity lasers are used for prevention and management of oral mucositis induced by anticancer therapy, but the effectiveness of treatment depends on the genetic characteristics of affected cells. This study evaluated the survival and induction of filamentation of Escherichia coli cells deficient in the nucleotide excision repair pathway, and the action of T4endonuclease V on plasmid DNA exposed to low-intensity red and near-infrared laser light. Cultures of wild-type (strain AB1157) E. coli and strain AB1886 (deficient in uvrA protein) were exposed to red (660 nm) and infrared (808 nm) lasers at various fluences, powers and emission modes to study bacterial survival and filamentation. Also, plasmid DNA was exposed to laser light to study DNA lesions produced in vitro by T4endonuclease V. Low-intensity lasers:i) had no effect on survival of wild-type E. coli but decreased the survival of uvrA protein-deficient cells,ii) induced bacterial filamentation, iii) did not alter the electrophoretic profile of plasmids in agarose gels, andiv) did not alter the electrophoretic profile of plasmids incubated with T4 endonuclease V. These results increase our understanding of the effects of laser light on cells with various genetic characteristics, such as xeroderma pigmentosum cells deficient in nucleotide excision pathway activity in patients with mucositis treated by low-intensity lasers.

Low-level laser effects on bacterial cultures submitted to heat stress

“…These results indicate that, at least in wild type cultures, laserinduced effects on cells submitted to heat stress are dependent on laser wavelength, which is different than the laser-induced effects on cells submitted to hyposmotic [8] and hyperosmotic stress [9]. Previous results obtained in our laboratory demonstrated that laser-induced effects are dependent on the repair of oxidative DNA lesions [11,19,22,24]. However, the effects of low-level lasers on bacterial cells deficient in SOS response have not yet been evaluated and we hypothesize that these responses could play a key role given that a laser-induced filamentation phenotype was demonstrated in previous studies [21][22][23].…”

Low-power infrared laser on survival, proliferation, and reactive oxygen species levels in Escherichia coli cultures

“…However, such lasers in continuous-wave and pulsed emission modes were able to decrease the transformation capacity of pBSK plasmids in E. coli proficient in DNA repair mechanisms (AB1157) and in E. coli BH20, which is deficient in DNA repair mechanism [25]. Another low-power infrared laser (808 nm) in continuous-wave [27,28] and pulsed [20] emission modes was also not able to alter the electrophoretic profile of the bacterial plasmids. These results suggest that exposure to low-power infrared lasers, at least at the fluences or energies used for photobiomodulation, does not cause single-and double-strand DNA breaks.…”

“…Bacterial suspensions were then spread onto petri dishes containing 2.0% agar (Kasvi) and the rich medium and incubated (37 • C for 18 h). The bacterial colonies formed were counted, and the survival fraction was calculated [20].…”

“…Escherichia coli cultures are low-cost, fast, and easy-todo cell cultures, and survival curves of such cultures have been used as an experimental model to evaluate both direct and indirect (free radicals) cytotoxic and genotoxic effects of nonionizing and ionizing radiation on survival [18,19]. In addition, the electrophoretic profile of bacterial plasmids in agarose gels has been used to evaluate the induction of singleand double-strand DNA breaks by exposure to radiation [20,21]. 2 ′ ,7 ′ Dichlorodihydrofluorescein diacetate (H 2 DCFDA) has been used to evaluate intracellular reactive oxygen species (ROS) levels.…”

Desenvolvimento de um modelo biofísico para a descrição do processo de reparo de quebra-dupla em DNA

“…Contudo, há evidências de que, para ondas de luz com determinadas frequências, pode-se induzir ou desencadear alguns processos biológicos que são naturalmente controlados por proteínas (Cosic et al, 2015;Fonseca et al, 2015;Peidaee et al 2015;Peidaee et al, 2012;Biswas, 2009;Cosic et al, 2006;Kujawa et al, 2004;Cosic, 1990). Todos esses efeitos, com frequências características à da luz, implicaram a ativação de proteínas envolvendo energias de natureza e ordens iguais à radiação eletromagnética da luz.…”