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(161) DNA strand breaks and micronucleus in Perna viridis as effective biomarkers for monitoring environmental genotoxicants. Siu, William1, Lam, Paul1, 1 ABSTRACT- Levels of DNA strand breaks in the hepatopancreas tissue of green-lipped mussels, Perna viridis, exposed to 0, 0.3, 3 and 30 ugl-1 (nominal concentrations) of benzo[a]pyrene were monitored over 24 days under laboratory conditions. The levels of DNA strand breaks significantly increased in mussels exposed to 0.3 and 3 ugl-1 B[a]P for one day. The strand break levels remained significantly higher than the control until day 3 and day 6 for the 0.3 ugl-1 and 3 ugl-1 treatment groups, respectively. After 12 days, the levels of strand breaks of both groups gradually returned to the same level as that of the control. No increase in DNA strand breaks was observed in mussels exposed to 30 ugl-1 B[a]P in the first 12 days of exposure, but a significant increase was evident from day 12 to day 24. It is hypothesized that a threshold level of B[a]P in the tissue should be reached before a repair mechanism for strand breakage is elicited. In another experiment, mussels were exposed to a mixture of B[a]P, anthracene, fluoranthene, pyrene, Key words: DNA strand breaks, micronucleus, Perna viridis, benzo[a]pyrene |
-HCH, aldrin, dieldrin and p,p'-DDT over 28 days under various dosing regimes. Micronucleus frequency in the gill cells of the mussels was determined every 7 days. Micronucleus frequency was found to increase with concentrations of the toxicant mixtures, and a clear dose- and time-response relationship was observed. The micronucleus frequency remained significantly higher than the control value even after the dosing had been stopped.