Differences in PAH tolerance between Capitella species: Underlying biochemical mechanisms

Authors

Lis Bach, Roskilde UniversityFollow
Annemette Palmqvist, Roskilde UniversityFollow
Lene Juel Rasmussen, Roskilde UniversityFollow
Valery E. Forbes, University of Nebraska-LincolnFollow

Date of this Version

9-2005

Citation

Aquatic Toxicology 74:4 (September 30, 2005), pp. 307–319; doi:10.1016/j.aquatox.2005.06.002

Comments

Copyright © 2005 Elsevier B.V. Used by permission.

Abstract

The polychaete Capitella capitata consists of a species complex within which differences in tolerance to tox­icants have been observed. For example, it has been shown that Capitella sp. S is more sensitive (e.g., in terms of survival, growth and reproduction) to PAH and other stressors than the more opportunistic Capi­tella sp. I, which is able to take up and biotransform the PAH fluoranthene (Flu). In the present study, an in­vestigation was performed to examine whether differences in tolerance between Capitella species sp. I and sp. S are due to differences in biotransformation, measured as the amount of Flu-metabolites produced by worms. We exposed both sibling species to sediment contaminated with 21 and 26 μg Flu/g dry weight sed for 10–15 days. We found that Capitella sp. I took up more Flu from the sediment than sp. S (346 μg Flu eq./g dry weight worm versus 219 μg Flu eq./g dry weight worm, respectively), but as sp. I was much more effective at biotransforming this PAH (62% versus 11%, respectively of total Flu), the net amounts of parent Flu accumulated by the two species were similar. We found significant differences in the subcellu­lar distribution of Flu and its metabolites between sibling species, with sp. I accumulating mostly in the cy­tosol and sp. S accumulating mostly in the membrane fraction. A previous study by our group showed Flu to be genotoxic to sp. I upon biotransformation. In the present study, we found no detectable genotoxicity in sp. S following Flu exposure. Our results demonstrate that DNA damage is tightly coupled to biotrans­formation ability and that other aspects of PAH toxicity (e.g., membrane disruption) are more relevant than DNA damage for predicting tolerance differences between these species.