title: Developmental alterations and endocrine-disruptive responses in farmed Nile crocodiles (Crocodylus niloticus) exposed to contaminants from the Crocodile River, South Africa.
abstract: In the present study, the developmental (including fertility) and endocrine-disruptive effects in relation to chemical burden in male and female Nile crocodiles (Crocodylus niloticus), from a commercial crocodile farm in the Brits district, South Africa, exposed to various anthropogenic aquatic contaminants from the natural environment was investigated. Hepatic transcript levels for vitellogenin (Vtg), zona pellucida (ZP) and ERα (also in gonads) were analyzed using real-time PCR. Plasma estradiol-17β (E2), testosterone (T) and 11-ketotestosterone (11-KT) were analyzed using enzyme immunoassay. Gonadal aromatase and hepatic testosterone metabolism (6β-hydroxylase (6β-OHase)) were analyzed using biochemical methods. Overall, there is high and abnormal number (%) of infertile and banded eggs during the studied reproductive seasons, showing up to 57 and 34% of infertile eggs in the 2009/2010 and 2013/2014 seasons, respectively. In addition, the percentage of banded eggs ranged between 10 and 19% during the period of 2009-2014 seasons. While hepatic ERα, Vtg, ZP mRNA and testosterone 6β-OHase, were equally expressed in female and male crocodiles, gonadal ERα mRNA and aromatase activity were significantly higher in females compared to male crocodiles. On the other hand, plasma T and 11-KT levels were significantly higher in males, compared to female crocodiles. Principal component analysis (PCA) produced significant grouping that revealed correlative relationships between reproductive/endocrine-disruptive variables and liver contaminant burden, that further relates to measured contaminants in the natural environment. The overall results suggest that these captive pre-slaughter farm crocodiles exhibited responses to anthropogenic aquatic contaminants with potentially relevant consequences on key reproductive and endocrine pathways and these responses may be established as relevant species endocrine disruptor biomarkers of exposure and effects in this threatened species.
authors: Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway. Electronic address: arukwe@bio.ntnu.no.
authors: Augustine
authors: A
authors: Arukwe
authors: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
authors: Jan
authors: J
authors: Myburgh
authors: Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
authors: Håkon A
authors: HA
authors: Langberg
authors: Department of Zoology, University of Ibadan, Ibadan, Nigeria.
authors: Aina O
authors: AO
authors: Adeogun
authors: Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway.
authors: Idunn Godal
authors: IG
authors: Braa
authors: Helmholtz center for Environmental Research UFZ, Department of Analytical Chemistry, Leipzig, Germany.
authors: Monika
authors: M
authors: Moeder
authors: Department of Environmental Sciences, University of California, Riverside, CA 92521, United States.
authors: Daniel
authors: D
authors: Schlenk
authors: Department of Environmental Sciences, University of California, Riverside, CA 92521, United States.
authors: Jordan Paul
authors: JP
authors: Crago
authors: Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors: Francesco
authors: F
authors: Regoli
authors: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
authors: Christo
authors: C
authors: Botha
mesh_terms: D000489:Alligators and Crocodiles / Q000254:growth & development / Q000502:physiology*; D000818:Animals; D052244:Endocrine Disruptors / Q000633:toxicity; D004781:Environmental Exposure; D005260:Female; D006066:Gonads / Q000187:drug effects*; D048788:Growth and Development / Q000187:drug effects*; D008297:Male; D012098:Reproduction / Q000187:drug effects; D045483:Rivers / Q000737:chemistry*; D013019:South Africa; D013256:Steroids / Q000097:blood; D014819:Vitellogenins / Q000097:blood; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D052244:Endocrine Disruptors; D013256:Steroids; D014819:Vitellogenins; D014874:Water Pollutants, Chemical
keywords: Biomarkers; Crocodile River (Limpopo); Crocodylus niloticus; Endocrine-disruption; Environmental contaminants; Reproductive effects