Application of the comet and micronucleus assays to butterfish (Pholis gunnellus) erythrocytes from the Firth of Forth, Scotland

This report describes an investigation of genotoxic effects in an inter-tid al fish species sampled along a pollution gradient in the Firth of Forth, S cotland, UK. The comet assay is an electrophoretic technique for measuring DNA breakage in nuclei from individual cells and has only recently been app lied to field investigations of genotoxicity. The measurement of nuclear an omalies (NA), such as the presence of micronuclei (MN) and 'lobes', has bee n successfully utilised in many field studies of genotoxic effects of conta minated sediments. These two techniques were applied to nucleated red blood cells (RBC) from the butterfish, Pholis gunnellus. The comet assay was ada pted and validated for use in this species. Fish were sampled from the inne r Firth of Forth, which has a legacy of industrial contamination and the ou ter Firth of Forth which is comparatively clean. The analysis of DNA strand breakage using this technique did not reveal any significant differences b etween animals sampled from inner and outer zones of the Firth. In contrast , MN and NA frequencies were elevated in the inner polluted zone of the Fir th compared to the outer zone. This study suggests: (I) there are genotoxic effects associated with contaminants in the inner Firth of Forth, and (2) the comet assay may not be a suitable genotoxicity biomarker in fish. (C) 2 001 Elsevier Science Ltd. All rights reserved.