ISSN 10630740, Russian Journal of Marine Biology, 2010, Vol. 36, No. 4, pp. 311–315. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © V.V. Slobodskova, E.E. Solodova, E.N. Slinko, V.P. Chelomin, 2010, published in Biologiya Morya.
Any organism, irrespective of its position in the
evolutionary hierarchy, has key metabolic biochemical
systems whose damage can be regarded as a biomarker
of inevitable and irreversible destructive processes.
Among the major reliable indicators, alterations
(damage) in the structure of DNA, which is the main
carrier of genetic information, are most important.
Moreover, there are grounds to believe that DNA
damage is one of the early stages in a cascading process
leading to negative consequences. Understanding of
its early mechanisms is particularly important for ade
quate evaluation of the toxicity of chemicals.
This is of primary importance for the study of the
toxicity of heavy metals, a large and widespread group
of pollutants of the aquatic environment, which are
accumulated and retained for a long period by organ
isms. Among trace metals found in the tissues of vari
ous aquatic inhabitants, cadmium occupies a notice
able place: it actively inhibits their vital processes and,
hence, the formation of nutrients. Extensive literature
data suggest that bivalve mollusks in particular are able
to concentrate this metal [5, 17, 31]. It is believed that
the ecological danger from cadmium lies in conse
quences that are associated with its accumulation in
the organism. Recently, increased attention has been
given to the study of the ecological and toxicological
aspects of the interaction of aquatic organisms with
this element, which, due to its physico–chemical
properties and biological features, is a potential threat
to biological systems.
Biochemical studies have shown that cadmium is a
typical polytropic chemical agent, which is able to
interact with various macromolecules and cell struc
tures and cause a broad spectrum of negative bio
The article was translated by the authors.
chemical alterations, from inhibition of individual
enzymes and metabolic systems to damage of mem
brane structures [1, 6, 10, 11, 38]. From the ecotoxi
cological viewpoint, the ability of cadmium to induce
oxidative stress is of particular interest , which is
thought to be a leading pathogenetic mechanism that
is responsible for disturbances of cellular metabolism
The causes for the multiple manifestations of cad
mium toxicity have not been studied completely,
although there is no doubt that such studies are needed
because cadmium is present in all components of eco
systems. Experimental research performed in mam
malian and human cell cultures has provided evidence
for the genotoxicity of cadmium: it exhibits carcino
genic and mutagenic properties and is able to initiate
DNAstrand breaks and to cause chromosome aberra
tions [24, 27]. Extensive studies in this direction have
recently been performed using the comet assay, which
allows the detection of DNA damage in individual
cells with high accuracy [2, 3, 13, 21, 35]. However, no
attention has been paid to the interaction of cadmium
with the DNA molecule in marine invertebrate cells.
The aim of our work was an experimental investiga
tion of the effect of cadmium accumulation on the
extent of DNA damage (as assessed by DNA migra
tion in individual cells and the length of the comet tail)
in the gill cells of the estuarine bivalve
MATERIAL AND METHODS
Sexually mature (20–30 mm) individuals of the
were used in this
investigation. This species is widely distributed in the
Sea of Japan, from East Korean Gulf to the western
Evaluation of the Genotoxicity of Cadmium in Gill Cells of the Clam
Using the Comet Assay
V. V. Slobodskova, E. E. Solodova, E. N. Slinko, and V. P. Chelomin
Pacific Oceanological Institute, Far East Division, Russian Academy of Sciences, Vladivostok, 690041 Russia
Received November 19, 2009
—Cadmiuminduced DNA degradation in gill cells of the clam
using the comet assay (singlecell gel electrophoresis). Accumulation of highly toxic cadmium in the gill cells
of bivalve is accompanied by damage to the cell genome, which is revealed as DNA migration in the comet
assay. The main mechanisms of Cd effects on the integrity of the DNA structure are discussed.
Accumulation, cadmium, bivalves,
, genotoxicity, comet assay, DNA damage.