Appropriateness of Largemouth Bass as a Model Species for Detection of Endocrine Dissruption

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Date
2015Author
Kim, Christine
Leasca, Angela
Liu, Winston
Patel, Shivani
Poulsen, Laura
Shah, Shefali
Throwe, Taylor
Tripu, Renuka
Advisor
Yonkos, Lance
DRUM DOI
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Intersex in largemouth bass (Micropterus salmoides) has been correlated with
regional anthropogenic activity, but has not been causally linked to environmental
factors. Four groups of hatchery-reared largemouth bass (LMB) and fathead minnows
(FHM) of varying ages and sex were exposed to aqueous poultry litter mixtures, 17β-
estradiol (E2), and controls. Water samples were analyzed for estrogens through liquid
chromatography tandem mass spectrometry and estrogenicity through the bioluminescent
yeast estrogen screen assay. Fish plasma was analyzed for the egg yolk protein
vitellogenin (Vtg) using enzyme–linked immunosorbent assay and gonad tissue was
examined histologically for enumeration of testicular oocytes (TO). Water chemistry
revealed typical E2 conversion to Estrone with subsequent decay over the exposure
periods. A modest prevalence of TO (9.4%) was detected with no apparent treatment
effect. While significant Vtg induction was found in E2 exposed FHM, minimal Vtg
induction was found in male LMB. Despite field findings of intersex in male LMB, this
species may be poorly suited for laboratory investigations into endocrine disruption.