Development of a comet-FISH assay for the detection of DNA damage in hemocytes of Crassostrea gigas

Aquat Toxicol. 2015 Apr:161:189-95. doi: 10.1016/j.aquatox.2015.01.022. Epub 2015 Jan 29.

Abstract

In this work, the DNA-damaging effect of hydrogen peroxide on the structural integrity of nucleolar organizer regions (NORs) was studied for the first time by comet-FISH in the Pacific oyster Crassostrea gigas. Global DNA damage was assessed in hemocytes using an alkaline version of the comet assay. Next, NOR sensitivity was analyzed by mapping major rDNA repeat unit by fluorescence in situ hybridization (FISH) on the same comet slides. Exposure of hemocytes to 100 μM of hydrogen peroxide induced a significant increase in both DNA damage and number of FISH-signals of major ribosomal genes versus the control. Moreover, a significant positive correlation was shown between DNA damage as measured by the comet assay (percentage of DNA in comet tail) and the number of signals present in comet tails. This study demonstrates the potential value of the comet-FISH assay for the study of DNA damage induced by genotoxicant exposure of target genes. It offers a perspective for better understanding the impact of genotoxicity on animal physiology and fitness.

Keywords: Comet assay; Comet-FISH; Crassostrea gigas; Genotoxicity; Hydrogen peroxide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Comet Assay*
  • Crassostrea / drug effects*
  • DNA Damage / drug effects*
  • Hemocytes / drug effects
  • Hydrogen Peroxide / toxicity
  • In Situ Hybridization, Fluorescence*
  • Toxicity Tests / methods*
  • Water Pollutants, Chemical / toxicity

Substances

  • Water Pollutants, Chemical
  • Hydrogen Peroxide