PARENT SESSION
22 - Biochemical, Cellular and Molecular Background of Biomarkers
8:00 AM to 6:30 PM, Monday, 13 May 2002
Exhibition Area

(22-30) CITYFISH: Occurrence of DNA strand breaks in liver of chub from UK rivers.

Winter, Matt^*,1, Hayes, Ruth¹, Ceradini, Sergio², Butler, Pat¹, Taylor, Ted¹, Chipman, James¹, ¹ School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, UK² CESI Environmental Unit, Milan, Italy

ABSTRACT- As part of the EU "CityFish" project (http://www.biosciences.bham.ac.uk/labs/taylor/cityfish.htm), work was undertaken on rivers within Birmingham UK, which exhibited different degrees of heavy metal and PAH contamination. Bioavailable heavy metal and PAH levels, as determined using passive samplers (DGTs and SPMDs), were higher in the river Cole (e.g Zn 1.95 mg/l, and total PAH 24.97 ng/l), compared with the relatively clean reference site on the river Blythe (0.08 mg/l and 6.9 ng/l). The effect of exposure on a resident coarse fish population (chub, Leuciscus cephalus) was assessed using a number of biomarkers including DNA strand breaks (via comet assay). A small, non-significant difference was seen in DNA strand breakage between the two sites (17.0 ± 0.9 and 15.3 ± 1.1 % tail DNA respectively; Mean ± SEM, n = 6 fish). To investigate further, hatchery-reared chub were exposed to conditions at the Cole in cages for 4 weeks. No difference in DNA strand-break levels was observed between Cole-exposed, and aquarium-maintained animals (17.3 ± 1.5 and 16.1 ± 0.7 % tail DNA respectively; Mean ± SEM, n = 8 fish). Either contamination levels at this site were not sufficient to induce DNA strand breakage or there was an induction of protective mechanisms limiting such effects. The latter are under investigation including analysis of metallothionein induction. Wild chub were also sampled from a third site (river Tame) exhibiting even greater levels of heavy metal contamination (e.g. Zn at 17.6 mg/l). A significant increase in the mean level of % tail DNA over that measured from the Blythe site was seen (18.9 ± 1 and 15.3 ± 1.1% tail DNA respectively; Mean ± SEM, n = 6 fish, p<0.05, Dunnetts test).

Key words: chub, comet, DNA, biomarker