Altered gonadal expression of TGF-β superfamily signaling factors in environmental contaminant-exposed juvenile alligators

J Steroid Biochem Mol Biol. 2011 Oct;127(1-2):58-63. doi: 10.1016/j.jsbmb.2011.01.004. Epub 2011 Jan 18.


Environmental contaminant exposure can influence gonadal steroid signaling milieus; however, little research has investigated the vulnerability of non-steroidal signaling pathways in the gonads. Here we use American alligators (Alligator mississippiensis) hatched from field-collected eggs to analyze gonadal mRNA transcript levels of the activin-inhibin-follistatin gene expression network and growth differentiation factor 9. The eggs were collected from Lake Woodruff National Wildlife Refuge, a site with minimal anthropogenic influence, and Lake Apopka, a highly contaminated lake adjacent to a former EPA Superfund site. The hatchling alligators were raised for 13 months under controlled conditions, thus limiting differences to embryonic origins. Our data reveal sexually dimorphic mRNA expression in 13-month-old alligator gonads similar to patterns established in vertebrates with genetic sex determination. In addition, we observed a relationship between lake of origin and mRNA expression of activin/inhibin subunits α and βB, follistatin, and growth differentiation factor 9. Our study suggests that embryonic exposure to environmental contaminants can affect future non-steroidal signaling patterns in the gonads of a long-lived species.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Activins / biosynthesis
  • Alligators and Crocodiles / metabolism*
  • Animals
  • Endocrine Disruptors / toxicity*
  • Environmental Exposure*
  • Environmental Pollutants / toxicity*
  • Female
  • Follistatin / biosynthesis
  • Gonads / drug effects*
  • Gonads / metabolism
  • Growth Differentiation Factor 9 / biosynthesis
  • Inhibins / metabolism
  • Male
  • Ovum
  • Sex Determination Processes / drug effects
  • Signal Transduction*
  • Transforming Growth Factor beta / metabolism*


  • Endocrine Disruptors
  • Environmental Pollutants
  • Follistatin
  • Growth Differentiation Factor 9
  • Transforming Growth Factor beta
  • Activins
  • Inhibins