DNA breathing dynamics in the presence of a terahertz field

Abstract

We consider the influence of a terahertz field on the breathing dynamics of double-stranded DNA. We model the spontaneous formation of spatially localized openings of a damped and driven DNA chain, and find that linear instabilities lead to dynamic dimerization, while true local strand separations require a threshold amplitude mechanism. Based on our results we argue that a specific terahertz radiation exposure may significantly affect the natural dynamics of DNA, and thereby influence intricate molecular processes involved in gene expression and DNA replication.Spectroscopic techniques in the terahertz range are currently emerging as new tools for the investigation of biological macromolecules (1). In spite of the experimental difficulties (caused by the water's giant Debye dipole moment, which leads to a substantial dielectric relaxational loss in the THz range) a notable amount of research effort is being devoted to the development of sophisticated THz bio-imaging (2). Nevertheless, very little is known about THz-radiation's influence on biological systems, and the mechanisms that govern this influence. The possibility that low frequency electromagnetic radiation may affect genetic material, enzymatic reactions, etc. was introduced long ago (3), and since then has been a subject of constant debate. The energy of such radiation is too low to directly disrupt any chemical bonds or cause electronic transitions. Only a resonance-type interaction might lead to an appreciable, biological effect. In biomolecules such interactions are possible through the ubiquitous hydrogen bonds that have energies in the THz range. Numerous in vivo and in vitro experiments have been conducted to clarify low frequency radiation's ability to cause biological effects, such as chromosomal aberration, genetic damage etc. The experimental studies have been conducted under a variety of conditions, but mostly at frequencies below 0.01 THz, power below 1 mW/ cm 2 , and short exposure times. The data collected in these conditions led to mixed conclusions: some studies reported significant genetic damages while others, although similar, showed none (4). The major international research project, "THz-bridge" (5), which was specifically concerned with THz radiation genotoxicity concluded that: under some specific conditions of exposure, change in membrane permeability of liposomes was detected and an induction of genotoxicity was observed to occur in lymphocytes. Hence, this project confirmed the existence of THz genotoxicity, but it remains unclear under which specific conditions such effects occur.Recent measurements confirm that only extended (6 hours) exposure to a weak THz field can cause genomic instability in human lymphocytes (6). Independently, it was reported that © 2010 Elsevier B.V. All rights reserved. *Corresponding author. Tel: 1-505-667-5003 fax: 505-665-7652 boian@lanl.gov (B. S. Alexandrov).. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our...

Invited Review Article: Current State of Research on Biological Effects of Terahertz Radiation

“…In addition to conventional thermal effects, however, several researchers have proposed that THz radiation may also induce low-level thermal, nonthermal, or more appropriately, microthermal effects. These theories were initially hypothesized by Frohlich et al in 1971 [99, 100], and more recent studies propose that these microthermal effects are mediated through the direct coherent excitation of biomolecules [99] or linear/nonlinear resonance mechanisms [101,102].…”

Modeling terahertz heating effects on water

“…However recent research by Alexaandrov et al [30] has indicated that under certain conditions (high power, long exposure time and the right frequency) the THz field might be able unzip double-stranded DNA, creating bubbles in the double strand that could significantly interfere with processes such as gene expression and DNA replication. Note that these results are all numerical and have not yet been experimentally verified.…”

Excitation of Bubbles and Breathers in DNA and Their Interaction with the Charge Carriers

“…Отметим, что исследование динамики ДНК, находящейся под внешним воздействием, представляет самостоятельный интерес, в частности, стимулированный быстрым развитием терагерцовых технологий [28], однако в рамках настоящей работе мы ограничиваемся лишь демонстрацией принципиальных возможностей такого способа возбуждения молекулы ДНК.…”