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International Journal of Marine Science 2014, Vol.4, No.52, 1-9
http://ijms.biopublisher.ca
7
bivalves and other marine molluscs. The calculated
safe concentrations for
M. philippinarum
were 0.2, 2.2,
28.8, 23.4 and 0.07µg. L
-1
for Cu, Cd, Pb, Zn and Hg,
respectively.
Recently considerable attention has been paid to study
the expression of morphological nuclear abnormalities
such as micronuclei, nuclear buds and nuclear blebs in
MN test (Cavas and Ergene-Gozukara, 2005). MN and
BN assays may be useful systems for
in-situ
detection
of genotoxic agents in the aquatic environment
(Bolognesi et al.,
2004) and also non-specific
biomarkers of genotoxicity that can reflect different
forms of stress (Burgeot et al.,
1995; Bolognesi and
Fenech, 2012). The results of the present study
showed the induction of MN and BN in marine mussel,
M. philippinarum
exposed to copper, cadmium, lead,
zinc and mercury and maximum frequencies were
detected in mercury exposed animals.
Similarly
C. chanos
exposed to anthracene and benzo
[a] pyrene under acute and chronic tests using
continuous flow through bioassay methods found
significant increase in frequency of MN and BN and
this increase was function of exposure period as well
as concentration of anthracene and benzo [a] pyrene
and maximum abnormalities in MN and BN were
observed in the highest concentration i.e., 69.8 % and
91.2 %, respectively (Palanikumar et al.,
2012b).
The MN and other binuclei of blood cells of
Oreochromis niloticus
exposed to textile industrial
waste water increased corresponding increase in
exposure period and concentration of waste water
although both micronuclei and binuclei decreased in
erythrocytes (Cavas and Ergene-Gozukara, 2003).
They stated that the differences between two types of
cell was related to cellular kinetics and cellular
renewal or this was due to the fact that gill cells were
directly exposed to contaminated waters.
Micronuclei and cellular abnormalities in haemolymph
and gill tissues of
Mytilus galloprovincialis
and
Zosterisessor ophiocephalus
collected at Venice
Lagoon, Italy were observed, it was reported that MN
frequency was between 33% and 37%, respectively
(Venier and Zampieron, 2005) and they pointed out
that the species naturally existing in the Lagoon were
continuously exposed to pollution causing genetic
damage. In the present study, there was some
frequency of MN and BN observed in the control
animals. In another study, the MN frequency of
Mediterranean mussel
Mytilus galloprovincialis
collected from natural environment and also those
exposed to benzopyrene in the laboratory was higher
in gills (about 8.5 %) than that in haemolymph (about
48%) (Dolcetti and Venier, 2002). They stated that
MN frequency was correspondingly increased with
increase in pollution load i.e., the dose may cause
higher impact to aquatic organisms. Similarly, in the
present study, the dose dependent increase in MN
frequency was noticed.
Lead may involve direct damage to DNA which
affecting the stabilization of chromatin or by
interaction of metal with repair processes (Hartwig et
al., 1990) and also may induce micronuclei by
disturbing the function of microtubule (Bonacker et al.,
2005). Like, Cd induces the single stand DNA breaks
generated by direct Cd-DNA interactions as well as
by the action of incision nuclease and/or
DNA-glycosylases during DNA repair (Privezentsev
et al., 1996).
MN test was shown to be sensitive in monitoring
domestic pollution and proposed as bioindicator in
routine pollution monitoring in the coastal ecosystems
(Izquierdo et al., 2003; Bolognesi and Hayashi, 2011;
Bolognesi and Fenech, 2012). MN assessment in
haemolymph and gills of
M. galloprovincialis
collected from Thermaikos and Strymonikos Bays
(South Greece) between July and October, 2001 found
no significant difference between seasons (Dailianis et
al., 2003). Therefore it might be used as standard
method in monitoring of pollution of coastal
ecosystems (Bolognesi and Fenech, 2012).
In the present study,
M. philippinarum
exposed to Cu,
Cd, Pb, Zn and Hg showed an increasing micronuclei
(MN) and binuclei (BN) induction when exposed
increasing concentration of metal. The dose-related
induction of MN by pollutants such as heavy metals
zinc chloride (Majone et al., 1988), copper, cadmium
and mercury (Bolognesi et al., 1999; Koukouzika and
Dimitriadis, 2008) have been reported in gill cells and
haemocytes of mussels.
On comparison with MN and BN frequencies, the
mean BN frequency of
Modiolus phillipinarum
exposed to acute concentrations of all five metals was