Meeting Abstract

78.4  Tuesday, Jan. 6  Mercury (II) bioaccumulation and antioxidant physiology in four aquatic insects BUCHWALTER, DB*; FLIPPIN, JL; XIE, L; North Carolina State University; North Carolina State University; North Carolina State University david_buchwalter@ncsu.edu

We examined Hg(II) bioaccumulation and compartmentalization patterns in conjunction with antioxidant responses in four aquatic insect species two mayflies (Maccaffertium modestum and Isonychia sp) and two caddis flies (Chimarra sp and Hydropsyche betteni). Global antioxidant capabilities differed among unexposed larvae, with both caddis fly species exhibiting elevated antioxidant activities relative to the mayflies. We were able to account for these differences by examining the constitutive activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione S-transferase (GST), in the four species. We also examined levels of reduced and oxidized glutathione and cysteine in the insects. Glutathione peroxidase and SOD were the most responsive to Hg exposure, with GPx catalytic activity increasing between 50 to 310%. Superoxide dismutase activity decreased between 35 and 50%. This SOD suppression was shown to be dose-dependent in both caddis flies, but the strength of this suppression did not appear to be related to rates of uptake. Surprisingly little Hg (<10%) was found in heat-stable cytosolic protein subcellular compartment in each of the four species, suggesting that Hg was not well detoxified. By combining bioaccumulation studies with other physiological measures, we can begin to better understand the consequences of trace metal pollutants in nature.