, Volume 28, Issue 9, pp 1085–1104 | Cite as

Immune function in Trachemys scripta following exposure to a predominant brevetoxin congener, PbTx-3, as a model for potential health impacts for sea turtles naturally exposed to brevetoxins

  • Catherine J. WalshEmail author
  • Courtney Cocilova
  • Jessica Restivo
  • Leanne Flewelling
  • Sarah Milton


Many species of marine life in southwestern Florida, including sea turtles, are impacted by blooms of the toxic dinoflagellate, Karenia brevis. Sublethal exposure to toxins produced by K. brevis has been shown to impact sea turtle health. Since all sea turtles in the Gulf of Mexico have protected status, a freshwater turtle, Trachemys scripta, was used as a model for immune system effects following experimental exposure to a predominant brevetoxin congener in K. brevis blooms, PbTx-3. Exposure to PbTx-3 was oral or intratracheal and health effects were assessed using a suite of immune function parameters: innate immune function (phagocytosis, plasma lysozyme activity), adaptive immune function (lymphocyte proliferation), and measures of oxidative stress (superoxide dismutase (SOD) and glutathione-S-transferase (GST) activity in plasma). Inflammation was also measured using plasma protein electrophoresis. In addition, differential expression of genes in peripheral blood leukocytes was determined using suppression subtractive hybridization followed by real-time PCR of specific genes. The primary immune effects of sublethal brevetoxin exposure in T. scripta following PbTx-3 administration, appear to be an increase in oxidative stress, a decrease in lysozyme activity, and modulation of immune function through lymphocyte proliferation responses. Plasma protein electrophoresis showed a decreased A:G ratio which may indicate potential inflammation. Genes coding for oxidative stress, such as thioredoxin and GST, were upregulated in exposed animals. That sublethal brevetoxin exposures impact immune function components suggests potential health implications for sea turtles naturally exposed to toxins. Knowledge of physiological stressors induced by brevetoxins may contribute to the ultimate goal of developing directed treatment strategies in exposed animals for reduced mortality resulting from red tide toxin exposure in sea turtles.


Brevetoxins Red tide Immune system Pond slider Freshwater turtle 



enzyme-linked immunosorbent assay




superoxide dismutase




polymerase chain reaction


suppression subtractive hybridization


real-time PCR




hen egg white lysozyme


Absorbance units


reduced glutathione


peripheral blood leukocytes


Concanavalin A








T-cell receptor


heat shock protein



The authors would like to acknowledge funding from NOAA NOS National Center for Coastal Ocean Science (Grant No. NA11NOS4780058). The authors would like to acknowledge Mote Marine Laboratory for use of facilities; J Balmer and C Coppola for roles in initial experiments; B Carter and P Larkin for conducting SSH, primer design, and qPCR experiments. The research was funded by NOAA Grant numbers NA11NOS4780031 (SLM) and NA11NOS4780058 (CJW) and is publication number ECO878 from the Ecology and Oceanography of Harmful Algal Blooms Program (ECOHAB).


This research was funded by NOAA Grant numbers NA11NOS4780031 (SLM) and NA11NOS4780058 (CJW).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. The protocols with animals were approved by FAU IACUC. This article does not contain studies with human participants performed by any of the authors.


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Authors and Affiliations

  1. 1.Marine Immunology Program, Mote Marine LaboratorySarasotaUSA
  2. 2.Florida Atlantic UniversityBoca RatonUSA
  3. 3.Florida Fish and Wildlife Conservation CommissionSt. PetersburgUSA

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