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International Journal of Marine Science 2014, Vol.4, No.44, 1-14
http://ijms.biopublisher.ca
11
we show that hepatic antioxidant enzymes are in fact
suitable biomarkers for monitoring physiological
adaptations to habitat type, forage, and contaminants
exposure. The interspecies variations of hepatic
antioxidants in elasmobranchs in this study may
reflect the specific adaptations to the oxidative stress
and protective mechanisms against oxidative damage
caused environmental pollution. Through multiple
studies, we have shown that the ray and skate are
more polluted than dogfish (Sole et al., 2009;
Rudneva et al., 2012). In this study we document the
antioxidant
defense
response
of
benthic
elasmobranchs was higher than in dogfish.
The differences in hepatic antioxidant defense of
Black Sea elasmobranch species correlated with the
differences of oligopeptides concentration and
aminotransferase level. High relationships were
indicated between oligopeptides level and SOD
(r=0.92), CAT (r=0.99) and PER (r=0.75). Significant
links were observed also between SOD and ALT
(r=0.58) and SOD and AST (r=0.69), high correlations
were shown between CAT and ALT (r=0.98), PER and
ALT (r=0.82), PER and AST (r=0.89) and negative
relationships were noted between GR and both
aminotransferases (r=-0.99). Toxicants, including
trace elements may bind carboxyl, amino, sulfhydryl,
phosphate and other groups of proteins, and modify
enzyme activities, membrane structure and its
permeability. The changes of aminotransferase
activities cause the disturbances of Kreb’s cycle ( Van
der Oost et al., 2003). Thus, decrease of enzymatic
activity in the liver of skates may result from
increased exposure to them due to the ingestion of
toxicant-containing sediments and food, because
accumulation of toxicants in fish tissues, particularly
in the liver, may damage hepatocytes, enzyme
structure and inhibit their activity.
5 Conclusions
The interspecies variations of hepatic antioxidant
enzyme activities between sharks and rays may be
connected with high pollution and deficient oxygen
concentrations in the benthic environment.
Specifically, the increased hepatic antioxidant enzyme
activity in the two benthic species in this study may be
the result of increased protection to decreasing oxygen
and hypoxic conditions. The hepatic aminotransferase
activity was higher in dogfish than in ray and skate.
The differences between ray, skate and shark are very
important from an evolutionary and ecotoxicological
view point, because ray and skate are benthic forms
and could be used as biomonitors in the Black Sea
ecosystem. In terms of hypoxic/anoxic conditions in
benthic biotops of Black Sea three tested
elasmobranchs may be considered suitable for
understanding the adaptation of the marine organisms
to the oxygen deficit in deep sea, and especially to the
high concentrations of hydrogen sulphyde in the case
of Black Sea.
A number of environmental factors, both biotic and
abiotic, influence fish metabolic rate and biochemical
characteristics. Pollutants may induce changes in
metabolism and oxidative stress in aquatic organisms
and modulate their biochemical characteristics. Thus,
the analysis of enzyme activities in fish tissues is
important to understand the adaptive ability of
elasmobranchs to survive in increasing amounts of
marine pollution. In conclusion, the biochemical and
physiological variables in this study may be suitable
for monitoring mechanisms of adaptation in the
marine environment, not just for the species in the
Black Sea, but also for elasmobranchs across the
world’s oceans.
Acknowledgements
We would like to express our gratitude to Dr.
Katherine H. Haman, University of Georgia for all her
efforts for improving this manuscript, great help,
scientific comments, edition it and support. Thank for
anonymous referees. We would like to thank to the
fishermen of the Institute of the Biology of the
Southern Seas (Sevastopol, Ukraine) for providing the
examined fish species.
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