Developmental Trenbolone Exposure Affects Adult Breeding Behavior, Fecundity and Morphology of Xenopus tropicalis
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1
Northern Arizona University, Biological Sciences, United States
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2
US Environmental Protection Agency, Mid-Continent Ecology Division, United States
Trenbolone acetate is a synthetic androgen used as a growth promoter in the cattle industry. Its metabolite 17β-trenbolone (17β-T) has been detected downstream from cattle feedlots. It could be a concern to wildlife near these areas as previous studies show 17β-T exposure affects reproductive endpoints in fishes. This study evaluated the impact of developmental aqueous exposure to17β-T on adult breeding behavior, fecundity and morphology in the Western clawed frog, Xenopus tropicalis. Tadpoles were exposed to 17β-T (0, 3.7, 11, 33 or 100 ng/L) in 4 L of water using a flow-through system until metamorphosis then raised to adulthood in clean water. Breeding trials, using pairs within exposure levels (n=10; n=9 for 100 ng/L), were conducted to evaluate the number and viability of eggs released. None of the females in the 100 ng/L treatment and only one female from the 33 ng/L treatment released eggs. There was no difference in the number of eggs released and the proportion of eggs that were viable among the control and two lower exposure treatments. Breeding behaviors from the trials were also filmed and evaluated. During the first three hours of behavior observation, there was no difference in the number of male clasp attempts (Kruskal-Wallis: p=0.13), but there was a decrease in time frogs spent in amplexus for the highest treatment (Kruskal-Wallis: p=0.037). Frogs were then euthanized and tissues were collected to evaluate morphological endpoints and brain gene expression (not reported here). Males and females did not differ in body size, or mass of body mass specific liver, kidneys, gonads or fat bodies. Females exposed to100 ng/L 17β-T did not develop oviducts, and only two females exposed to 33 ng/L 17β-T had completely developed oviducts. Our results demonstrate that developmental exposure to 17β-T impacts reproduction in an aquatic vertebrate by acting at multiple endpoints.
Keywords:
Xenopus tropicalis,
Behavior,
endocrine disruption,
fecundity,
trenbolone
Conference:
ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology, Ann Arbor, United States, 11 Jul - 13 Jul, 2011.
Presentation Type:
Oral Presentation
Topic:
Endocrine disruption
Citation:
Miranda
RA,
Olmstead
AW,
Blake
LS,
Degitz
SJ,
Garcia
DR,
Owolabi
AA and
Propper
CR
(2011). Developmental Trenbolone Exposure Affects Adult Breeding Behavior, Fecundity and Morphology of Xenopus tropicalis.
Front. Endocrinol.
Conference Abstract:
ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology.
doi: 10.3389/conf.fendo.2011.03.00032
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Received:
22 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Mr. Robert A Miranda, Northern Arizona University, Biological Sciences, Flagstaff, AZ, United States, ram257@nau.edu