TY - JOUR
T1 - Effects of 17β-trenbolone on Eastern and Western mosquitofish (Gambusia holbrooki and G. affinis) anal fin growth and gene expression patterns
AU - Brockmeier, Erica K.
AU - Ogino, Yukiko
AU - Iguchi, Taisen
AU - Barber, David S.
AU - Denslow, Nancy D.
N1 - Funding Information:
This study was supported by the University of Florida (UF) College of Veterinary Medicine Faculty Grant . Additional support was provided by the U.S. Environmental Protection Agency Science to Achieve Results Fellowship 91728101-0 (EB), the National Science Foundation East Asia and Pacific Summer Institutes Fellowship OISE-1106889 (EB), and a grant from the Ministry of Education, Culture, Sports, Science and Technology and the Ministry of the Environment of Japan (TI) . The contents of this article are solely the responsibility of the authors and do not necessarily represent the views of any of the funding agencies.
PY - 2013/3/5
Y1 - 2013/3/5
N2 - The Eastern and Western mosquitofish (Gambusia holbrooki and G. affinis) are potential bioindicator organisms for endocrine disruptors. Male mosquitofish have an elongated anal fin (gonopodium) used for internal fertilization whose formation is driven by androgens. Normal female mosquitofish have a normal, rounded anal fin which undergoes elongation into a gonopodium structure when female mosquitofish are exposed to androgenic chemicals. Significant issues with using mosquitofish as a bioindicator include the lack of knowledge on how anal fin growth in females corresponds to endpoints relevant to biological integrity and the lack of information on the molecular pathways that regulate anal fin growth. The objectives of this study were to understand how androgen-induced anal fin elongation relates to changes in endpoints related to the female reproductive system and to understand how anal fin elongation occurs in androgen-exposed female mosquitofish. To achieve these objectives, adult female G. holbrooki were exposed to a vehicle control or one of three doses of the androgen 17β-trenbolone (TB) at nominal concentrations of 0.1, 1 or 10 μg TB/L. Anal fin measurements were taken and livers were used for quantitative polymerase chain reaction analysis of vitellogenin (vtg) mRNA expression at multiple time points. 10 μg TB/L induced anal fin elongation after 7 days of treatment (one-way ANOVA, p< 0.05) as did 0.1 and 1 μg TB/L at later time points (one-way ANOVA, p< 0.05). 10 μg TB/L significantly reduced hepatic vtg gene expression at all time points assessed (one-way ANOVA, p< 0.05). There was no correlation between anal fin elongation levels and vtg gene expression (Spearman's ρ, p> 0.05). In a separate experiment, female G. holbrooki and G. affinis were exposed to the vehicle control or 1 μg TB/L. Anal fins were used for qualitative gene expression analysis of the genes sonic hedgehog (shh), muscle segment homeobox C (msxC), and fibroblast growth factor receptor 1 (fgfr1) by in situ hybridization. Shh was expressed in the distal tip of the gonopodium while msxC and fgfr1 were more widely expressed along the same anal fin rays during androgen exposure. These data provide insight into the molecular pathways involved in anal fin elongation and pave the way for future work toward developing the mosquitofish into a bioindicator organism for endocrine disruptors.
AB - The Eastern and Western mosquitofish (Gambusia holbrooki and G. affinis) are potential bioindicator organisms for endocrine disruptors. Male mosquitofish have an elongated anal fin (gonopodium) used for internal fertilization whose formation is driven by androgens. Normal female mosquitofish have a normal, rounded anal fin which undergoes elongation into a gonopodium structure when female mosquitofish are exposed to androgenic chemicals. Significant issues with using mosquitofish as a bioindicator include the lack of knowledge on how anal fin growth in females corresponds to endpoints relevant to biological integrity and the lack of information on the molecular pathways that regulate anal fin growth. The objectives of this study were to understand how androgen-induced anal fin elongation relates to changes in endpoints related to the female reproductive system and to understand how anal fin elongation occurs in androgen-exposed female mosquitofish. To achieve these objectives, adult female G. holbrooki were exposed to a vehicle control or one of three doses of the androgen 17β-trenbolone (TB) at nominal concentrations of 0.1, 1 or 10 μg TB/L. Anal fin measurements were taken and livers were used for quantitative polymerase chain reaction analysis of vitellogenin (vtg) mRNA expression at multiple time points. 10 μg TB/L induced anal fin elongation after 7 days of treatment (one-way ANOVA, p< 0.05) as did 0.1 and 1 μg TB/L at later time points (one-way ANOVA, p< 0.05). 10 μg TB/L significantly reduced hepatic vtg gene expression at all time points assessed (one-way ANOVA, p< 0.05). There was no correlation between anal fin elongation levels and vtg gene expression (Spearman's ρ, p> 0.05). In a separate experiment, female G. holbrooki and G. affinis were exposed to the vehicle control or 1 μg TB/L. Anal fins were used for qualitative gene expression analysis of the genes sonic hedgehog (shh), muscle segment homeobox C (msxC), and fibroblast growth factor receptor 1 (fgfr1) by in situ hybridization. Shh was expressed in the distal tip of the gonopodium while msxC and fgfr1 were more widely expressed along the same anal fin rays during androgen exposure. These data provide insight into the molecular pathways involved in anal fin elongation and pave the way for future work toward developing the mosquitofish into a bioindicator organism for endocrine disruptors.
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U2 - 10.1016/j.aquatox.2012.12.007
DO - 10.1016/j.aquatox.2012.12.007
M3 - Article
C2 - 23314276
AN - SCOPUS:84872201123
VL - 128-129
SP - 163
EP - 170
JO - Aquatic Toxicology
JF - Aquatic Toxicology
SN - 0166-445X
ER -