Improved Comet assay for the assessment of UV genotoxicity in Mediterranean sea urchin eggs

Abstract

Gametes and embryos of broadcast spawners are exposed to a wide range of chemical and physical stressors which may alone, or in conjunction, have serious consequences on reproductive outcomes. In this study, two Mediterranean echinoid species, Paracentrotus lividus and Sphaerechinus granularis, were chosen as models to study the genotoxicity of UV radiation (UVR) on the eggs of broadcast-spawning marine invertebrates. The single cell gel electrophoresis, or Comet assay, was successfully adapted to assess DNA strand breakage in sea urchin eggs. The results demonstrated that the genetic material of sea urchin eggs is susceptible to environmentally realistic UV exposure. The induction of DNA damage in the irradiated unfertilized eggs suggests that the previously described defense mechanisms in sea urchin eggs do not completely protect the egg's DNA against UV toxicity. Taken together, our results suggest that UV-impairment of the genetic integrity of the eggs might have a role in postfertilization failures and abnormal embryonic development. Although both species were vulnerable to UVR, embryonic development was less dramatically impaired in P.Lividus. This observation supports the postulation that species inhabiting shallower environments possess more efficient mechanisms to overcome UV-induced DNA alterations. The present demonstration of the utility and sensitivity of the Comet assay to evaluate DNA integrity in eggs from marine invertebrates opens new perspectives for monitoring the long-term effects of environmental exposure on populations and for the routine screening of substances for genotoxicity in marine systems.

Diatom-derived oxylipins induce cell death in sea urchin embryos activating caspase-8 and caspase 3/7

“…They are constantly exposed to a number of pollutants (Bellas et al, 2008a;Rosen et al, 2008). Sea urchins have been adopted as an excellent model system to study the ecotoxicological response of marine invertebrates to environmental pollutants (Geraci et al, 2004;Bonaventura et al, 2005;Cakal Arslan and Parlak, 2007;Bellas et al, 2008b;Nahon et al, 2008). Echinoderms are world-wide in their distribution and are extremely important in structuring benthic marine communities.…”

Sea urchin embryos as an in vivo model for the assessment of manganese toxicity: developmental and stress response effects

“…Sea urchins are recognized as an excellent model system for eco-embryo-and geno-toxicological studies (Geraci et al 2004;Bonaventura et al 2005;Cakal Arslan and Parlak 2007;Bellas et al 2008b;Nahon et al 2008). Stress proteins play a critical role in a complex defence mechanism, enhancing cell survival under adverse environmental conditions as well as in normal cellular homeostasis (Diller 2006).…”

Embryonic development and skeletogenic gene expression affected by X-rays in the Mediterranean sea urchin Paracentrotus lividus

“…However, when the emerging rapid anthropogenic changes, including ionising radiations, are beyond the range limits of the protective mechanisms of the embryo, teratology is likely to occur. The species-specificity of sensitivity to ionising radiations should be also taken into consideration, as demonstrated by a report in which two Mediterranean echinoid species, Paracentrotus lividus and Sphaerechinus granularis, were chosen as models to study the genotoxicity of UV radiation (Nahon et al 2008). In fact, although both species were vulnerable to UV, embryonic development was less dramatically impaired in P. lividus, supporting the assumption that species living in shallower environments possess more powerful mechanisms to cope with UV-induced DNA damage.…”