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RP4 Endocrine Disruption in Invertebrates: History, Regulation and Future Research
(FLY-1117-807801) Estradiol decreases, and atrazine may decrease, Krebs cycle succinate reduction in the freshwater mussel.
Blake, J1, Chen, A1, Flynn, K1, 1 Adelphi University, Garden City, NY, USA
ABSTRACT- Atrazine (ATR) is an herbicide and suspected endocrine disrupter, it may have estrogen-like activity which could include effects on the Krebs cycle. Here, laboratory-acclimated adult freshwater mussels (Elliptio complanata), were treated for 72 hours with ecologically-relevant atrazine concentrations of 1.5, 15, or 150 ug/l (n=8/tank), corresponding to 0.1, 1, and 10 times the EPA level of concern for atrazine in aquatic ecosystems. Estradiol and the ethanol solvent were positive and negative controls, respectively. After exposure, mussels were sacrificed and soft tissue containing gonad and hepatopancreas frozen at -80 °C for no more than eight months, thawed, then homogenized in a 7.2pH sugar phosphate buffer, and centrifuged for 1 min at 200X G followed by 10 min at 1300X G to isolate mitochondria. Supernatant was added to cuvettes containing a color changing oxidizing agent, dichlorophenol indophenol (DCPIP) and buffer, or buffer alone. Succinate was added to each and absorbances at 600nm recorded every 5 minutes for 30 minutes and control values subtracted. Two way analysis of variance (ANOVA) using time and treatment as variables indicated no interaction but a significant overall difference in succinate reduction among treatment groups (p<0.001). The Games Howell post hoc test revealed a significant difference from control only in the estradiol-treated group, at 5.9% less than control (p<0.05). Low and high ATR groups were 2.9 and 2.2% less than control, respectively, and not significantly different from the estradiol group. Mid atrazine, however, was significantly above estradiol and almost equal to control, at 0.3% above. These data suggest that estradiol decreases Krebs cycle activity and that atrazine may, like other endocrine disrupters and other endpoints, produce a non-linear dose response to ATR. Further studies are warranted to determine if ATR effects biochemical activity.
Key words: endocrine disruption, invertebrate, estrogen, atrazine
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