PARENT SESSION

PW08 Aquatic Ecotoxicology II
Exhibit Hall
8:00 AM - Wednesday

(PW116) Evaluating the energetic costs of vitellogenin induction in the larval mummichog.

Kelly, S¹, Speed, K¹, ¹ Piedmont College, Demorest, GA, USA

ABSTRACT- While the induction of vitellogenin (VTG) by estrogenic compounds in fish is well documented, the consequences of such induction remain elusive. Previous work demonstrated that 17-estradiol (E2) induced VTG in larval Fundulus heteroclitus, a life-stage where VTG is not produced under normal conditions. To evaluate the potential energetic costs of such induction (via protein metabolism), we monitored the production of ammonia by larval Fundulus exposed to 0.1 M E2. Initial studies utilized the phenate method for ammonia quantification in water samples collected every other day over a two-week period. Results of the repeated measures ANOVA analysis indicated that both the solvent control (SC; ethanol at 0.1% v:v) and E2 exposures showed significantly depressed ammonia production relative to the controls. There was no significant difference in the ammonia production between SC and E2 exposures. The experiment was repeated, but ammonia measurements were conducted using a selective ion probe, as this method did not necessitate the extensive chemical manipulation of the samples required by the phenate method. Results from this study were virtually identical to those of the phenate method. To rule out the interference of ethanol (EtOH) with the detection of ammonia, water samples lacking fish were spiked with a known concentration of ammonia. The presence of EtOH in the samples had no effect on the detection of ammonia in the samples. Thus, these studies suggest that ethanol, one of the most common solvents used in toxicological studies, alters the physiology of the test organisms. The biological significance of this finding is currently unknown. Additional studies utilizing EtOH and dimethylsulfoxide (DMSO) as solvents in E2 exposures are underway.

Key words: mummichog, energetics, xenoestrogen, ammonia