ISSN 1022-7954, Russian Journal of Genetics, 2009, Vol. 45, No. 3, pp. 304–307. © Pleiades Publishing, Inc., 2009.
Original Russian Text © V.A. Chistyakov, M.A. Sazykina, M.A. Kolenko, G.G. Chervyakov, A.V. Usatov, 2009, published in Genetika, 2009, Vol. 45, No. 3, pp. 349–353.
Genotoxic effects of different regions of the ultravi-
olet (UV) light spectrum are mediated via different
mechanisms. The main products of DNA damage
caused by 200–280 nm UV light (ultraviolet C) are
pyrimidine dimers forming DNA upon absorption of
light quanta . Ultraviolet A (320–400 nm) and ultra-
violet B (280–320 nm), which are not absorbed by
nucleic acids, can induce in cells a cascade of photore-
actions accompanied by the generation of reactive oxy-
gen species (ROSs). As this takes place, pyrimidine
dimers are effectively repaired by the systems of error-
free excision repair, while the products of a free-radical
DNA attack, especially such as links with proteins and
crosslinks, are repaired far less effectively and with a
wide involvement of the error-prone repair systems.
Therefore, near ultraviolet is a serous inducer of human
skin carcinoma, despite lower energy of its quanta [2–5].
Most of solar ultraviolet reaching the earth surface is
represented by 300–400 nm radiation . This range
seems to be optimal for selecting protective substances.
In practice, mostly sunscreen products, i. e. substances
screening the skin from the light, are used to protect
aginst the carcinogenic effect of solar radiation .
Their efﬁciency is limited by a variety of factors,
mainly by the impossibility of creating a stable ﬁlm of
necessary thickness. The solution of the problem of
defence against the negative effects of solar energy
must be based on a complex approach that integrates
the work of various mechanisms. This determines the
importance of searching for compounds able to protect
the cell from genotoxic effects of ultraviolets A and B.
Obviously, the wider the list of such substances, the
more possibilities for producing highly effective com-
A number of publications describe the antioxidant
effect of the methylene blue dye (
ylthionine) that belongs to the group of thiasines and is
widely used in biology and medicine. This substance is
able to penetrate easily in living cells and to scavenge
reactive oxygen species in concentrations differing by
several orders of magnitude from toxic ones . Yet,
the photosensibilizing activity of methylene blue was
described . Thus, the study of the capacity of this
compound to modify destructive effects induced by
photoinduction of ROSs is surely of interest.
MATERIALS AND METHODS
A variant of the SOS-lux test previously employed
for studying the antimutagenic effects of some natural
compounds was used in this work as a system for
assessing genotoxicity of the exposure under study [9–
11]. The reporter of the SOS response was lux-operon.
strain PT-1 (C600(pPLS-1)) car-
rying the pPLS-1 plasmid, in which the operon of
bioluminescence is under the control of the SOS pro-
moter, was used . To control effects unrelated to
SOS induction, the PT-5 (C600(pPLS-5)) strain whose
lux-operon is under the control of a consitutive pro-
moter was used .
strains were grown in LB medium.
0.1 ml of overnight
culture was placed in 50 ml
of the medium and incubated in a thermostat for 1 h at
C. One ml of the culture was placed in a 40-mm
plastic Petri dish without a cover, which was irradiated
with UV light with a wavelength of 300–400 nm using
Methylene Blue as a Suppessor of the Genotoxic Effect
of Ultraviolet Radiation with a Wavelength of 300–400 nm
V. A. Chistyakov
, M. A. Sazykina
, M. A. Kolenko
G. G. Chervyakov
, and A. V. Usatov
Research Institute of Biology, South Federal University, Rostov-on-Don, 344090 Russia;
Taganrog State University of Radioengineering,Taganrog, 347928 Russia
Received December 20, 2007
—Ultraviolet radiation with a wavelength of 300–400 nm is characteristic of sunlight at the earth sur-
face and causes DNA damage mediated by energy transfer to O
with the transformation of the latter in the sin-
glet state. In connection with this, scavengers of reactive oxygen species (ROSs) are potential protectors against
the genotoxic effect of this kind of radiation. It was found that the methylene blue dye at doses differing by
several orders of magnitude from those that are toxic for humans is able to suppress completely the SOS
response induced by UV with a wavelength of 300–400 nm in