WAVELENGTH DEPENDENT FORMATION OF THYMINE DIMERS AND (6‐4)PHOTOPRODUCTS IN DNA BY MONOCHROMATIC ULTRAVIOLET LIGHT RANGING FROM 150 TO 365 nm

Abstract

We investigated the wavelength dependence of cyclobutane thymine dimer and (6-4)photoproduct induction by monochromatic UV in the region extending from 150 to 365 nm, using an enzyme-linked immunosorbent assay with two monoclonal antibodies. Calf thymus DNA solution was irradiated with 254-365 nm monochromatic UV from a spectrograph, or with 220-300 nm monochromatic UV from synchrotron radiation. Thymine dimers and (6-4)photoproducts were fluence-dependently induced by every UV below 220 nm extending to 150 nm under dry condition. We detected the efficient formation of both types of damage in the shorter UV region, as well as at 260 nm, which had been believed to be the most efficient wavelength for the formation of UV lesions. The action spectra for the induction of thymine dimers and (6-4)photoproducts were similar from 180 to 300 nm, whereas the action spectrum values for thymine dimer induction were about 9- and 1.4-fold or more higher than the values for (6-4)photoproduct induction below 160 nm and above 313 nm, respectively.

Estimating the risk of squamous cell cancer induction in skin following nonlinear optical imaging

“…On the other hand, when observing the CPD level relation with variation UVC irradiance, partial saturation is evident above the energy dose of 250 Jm À2 . A consistent UVC: UVA ratio of 10 4.1 : 1 was obtained for UVC dose up to 250 Jm À2 , which was in agreement with the study of Matsunaga et al [24]. The ratio decreases with UVC irradiance above 250 Jm À2 and drops to 10 3.25 : 1 at 1035 Jm À2 .…”

“…On the other hand as seen in Figure 2, CPD production for UVC stayed linear till 250 Jm À2 and partial saturation is evident above this energy dose. The UVC : UVA ratio obtained in the UV dose calibration experiments were compared with the ratio found to be 10 4.0-4.5 : 1 in the study of Matsunaga et al [24]. A consistent UVC : UVA ratio of 10 4.1 : 1 was obtained for UVC dose up to 250 Jm À2 and the ratio dropped to 10 3.25 : 1 at 1035 Jm À2 .…”

Two Glycosylase/Abasic Lyases from Neisseria mucosaThat Initiate DNA Repair at Sites of UV-induced Photoproducts

“…The exposure of DNA to UV light results in the formation of several photoproducts including cyclobutane pyrimidine dimers, photoproducts, and Dewar photoproducts (1,2). Cyclobutane pyrimidine dimers are the most common lesions produced by exposure of DNA to short wavelengths of UV light (below 295 nm).…”

Inhibitory Effects of Long-Wave Ultraviolet Radiation of Isolated Chicken Liver Nuclei on the Mg2+-Dependent Transition of Chromatin Structure.

“…Long-wave ultraviolet radiation, ultraviolet A (UVA) radiation, of which the wavelength is from 320 to 400 nm, constitutes more than 90% of terrestrial UV solar energy on the earth's surface. UVA radiation causes cell death and mutation, although a much higher fluence of UVA raditation is necessary to induce these biological responses than that of ultraviolet B (UVB) radiation, from 290 to 320 nm, and ultraviolet C (UVC) radiation, from 200 to 290 nm [17,20,21].UVA radiation has been reported to induce several types of DNA damage, such as strand breaks [10,12,16], base modification [8,9,15] and DNA-protein crosslinks [11,14]. Because UVA rays are not directly absorbed by DNA and their biological effects depend strongly on the presence of oxygen, UV rays of this wavelength probably exert their effects through indirect mechanisms in which endogenous photosensitizers, such as NADH/NADPH and riboflavin, absorb UVA photons to generate reactive oxygen species (ROS) [7,19,21].…”

“…UVA radiation has been reported to induce several types of DNA damage, such as strand breaks [10,12,16], base modification [8,9,15] and DNA-protein crosslinks [11,14]. Because UVA rays are not directly absorbed by DNA and their biological effects depend strongly on the presence of oxygen, UV rays of this wavelength probably exert their effects through indirect mechanisms in which endogenous photosensitizers, such as NADH/NADPH and riboflavin, absorb UVA photons to generate reactive oxygen species (ROS) [7,19,21].…”