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Using Plasma Vitellogenin in Loggerhead Sea Turtles to Assess Reproductive Maturation and Estrogen‐Like Contaminant Exposure



Raquel Corniuk, Jennifer Lynch, Michael Arendt, Joanne Braun-McNeill, David Owens, Roldan Valverde, John Kucklick, Patricia McClellan-Green


Vitellogenin (VTG), an egg yolk precursor, is abnormally produced by male and juvenile oviparous species after exposure to estrogens. Plasma VTG in loggerhead sea turtles (Caretta caretta) helped us understand their reproductive maturation and investigate it as a biomarker of contaminant exposure. The presence of VTG was screened in plasma from 404 loggerheads from the northwestern Atlantic Ocean using a freshwater turtle antibody in western blots. The concentrations of VTG were semiquantified using band intensities calibrated to results from a loggerhead antibody enzyme‐linked immunoassay. The detection and concentrations of VTG were in (from highest to lowest): nesting females, in‐water adult females, subadult females, smaller females, unknown sex, and males. Loggerheads from this region begin vitellogenesis at ≅77 cm straight carapace length. We classified VTG expression as abnormal in nine male or juvenile turtles. Organochlorine contaminant (OC) concentrations were measured in blood and/or fat biopsies of some turtles. One abnormal VTG female had the second highest fat polychlorinated biphenyl (PCB) and 4,4′‐dichlorodiphenyldichloroethylene concentrations among 43 VTG‐negative juveniles. The nine VTG‐abnormal turtles had blood PCB concentrations 8.5% higher, but not significantly different, than 46 VTG‐negative juveniles (p = 0.453). In turtles less than 77 cm, blood PCB concentrations were significantly, but weakly, correlated with semiquantified VTG concentrations (tau = 0.1, p = 0.004). Greater blood OC concentrations were found in adult females than in males, which motivated the creation of a conceptual model of OC, VTG, and hormone concentrations across a reproductive cycle. A decision tree is also provided incorporating VTG as a sexing tool. Abnormal VTG expression cannot conclusively be linked to endocrine disruption caused by these OC concentrations. Studies should further investigate causes of abnormal VTG expression in wild sea turtles.
Environmental Toxicology and Chemistry


endocrine disruption, endocrine disrupting chemicals, reptile, endocrinology, persistent organic pollutants, organic contaminants


Corniuk, R. , Lynch, J. , Arendt, M. , Braun-McNeill, J. , Owens, D. , Valverde, R. , Kucklick, J. and McClellan-Green, P. (2023), Using Plasma Vitellogenin in Loggerhead Sea Turtles to Assess Reproductive Maturation and Estrogen‐Like Contaminant Exposure, Environmental Toxicology and Chemistry, [online],, (Accessed April 17, 2024)
Created March 21, 2023, Updated May 26, 2023