title: Detection of a synthetic sex steroid in the American crocodile (Crocodylus acutus): Evidence for a novel environmental androgen.
abstract: Endocrine-disrupting contaminants (EDC's) are well known to alter sexual differentiation among vertebrates via estrogenic effects during development, particularly in organisms characterized by temperature-dependent sex determination. However, substances producing androgenic effects typically lack potency when tested in laboratory settings and are virtually unstudied in field settings. Here, we assay levels of a synthetic androgen, 17α-methyltestosterone (MT), in a heavily male-biased population of American crocodiles in the Tempisque River Basin of Costa Rica based on the recent hypothesis that this chemical is an EDC in developing crocodilian embryos. The presence of MT was documented in all field-collected samples of egg yolk and in plasma of all age classes in among population of crocodiles. Hatchlings exhibited higher plasma MT concentrations (102.1 ± 82.8 ng/mL) than juveniles (33.8 ± 51.5) and adults (25.9 ± 20.8 ng/mL). Among populations, crocodiles captured in the Tempisque River (62.9 ± 73.7 ng/mL) were higher in MT concentration than those from Tarcoles (13.3 ± 11.4 ng/mL) and negative controls (0.001 ± 0.0002 ng/mL). A mechanism for the bio-transport of MT and its subsequent effects is proposed.
authors.affiliation: Department of Biology, Tennessee Technological University, PO Box 5063, Cookeville, TN 38505, USA. Electronic address: cmmurray@tntech.edu.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Murray
authors.affiliation: Department of Chemistry, McNeese State University, Lake Charles, LA, USA. Electronic address: mmerchant@mcneese.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Merchant
authors.affiliation: Scales and Tails of Ohio, Lakewood, OH 44107, USA. Electronic address: m.easter05@gmail.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Easter
authors.affiliation: Palo Verde Biological Station, Organization for Tropical Studies, Guanacaste, Costa Rica. Electronic address: spa_sergio@hotmail.com.
authors.forename: Sergio
authors.initials: S
authors.lastname: Padilla
authors.affiliation: Biodiversity and Evolutionary Biology "Cavanilles" Institute, University of Valencia, Valencia, Spain. Electronic address: davinia.beneyto@uv.es.
authors.forename: Davinia B
authors.initials: DB
authors.lastname: Garrigós
authors.affiliation: Palo Verde Biological Station, Organization for Tropical Studies, Guanacaste, Costa Rica; Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica. Electronic address: msasamarin@gmail.com.
authors.forename: Mahmood
authors.initials: M
authors.lastname: Sasa Marin
authors.affiliation: Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA. Electronic address: guyercr@auburn.edu.
authors.forename: Craig
authors.initials: C
authors.lastname: Guyer
mesh_terms: D000489:Alligators and Crocodiles / Q000378:metabolism*; D000728:Androgens; D000818:Animals; D003364:Costa Rica; D052244:Endocrine Disruptors; D004784:Environmental Monitoring; D004967:Estrogens; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D008297:Male; D008777:Methyltestosterone; D045483:Rivers; D013256:Steroids; D014481:United States; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D000728:Androgens; D052244:Endocrine Disruptors; D004967:Estrogens; D012739:Gonadal Steroid Hormones; D013256:Steroids; D014874:Water Pollutants, Chemical; D008777:Methyltestosterone
keywords: Crocodylus; Endocrine disrupting contaminants; Environmental androgen; Methyltestosterone