Investigating an increase in Florida manatee mortalities using a proteomic approach

Area of Science:

• Marine Mammal Health
• Proteomics
• Environmental Toxicology

Background:

• Two major Florida manatee (Trichechus manatus latirostris) mortality events occurred in 2013 on the Atlantic and Gulf coasts.
• The Indian River Lagoon (IRL) event had an unknown cause with signs of cold stress, while the Southwest Florida event was linked to a Karenia brevis red tide.

Purpose of the Study:

• To investigate the underlying physiological changes in manatees during these two distinct mortality episodes.
• To identify specific protein biomarkers associated with each mortality cause using proteomic techniques.

Main Methods:

• Serum samples from affected manatees and controls were analyzed using two-dimensional difference in gel electrophoresis (2D-DIGE) and isobaric tags for relative and absolute quantification (iTRAQ) LC-MS/MS.
• Key protein level changes were identified and validated, including Western Blot confirmation for complement C4-A in the red tide group.

Main Results:

• Manatees from the IRL showed elevated levels of proteins such as kininogen-1, alpha-1-microglobulin, histidine-rich glycoprotein, properdin, and complement C4-A.
• Manatees affected by red tide exhibited increased levels of ceruloplasmin, pyruvate kinase, angiotensinogen, complement C4-A, and complement C3.
• Identified proteins are involved in acute-phase response, amyloidosis, copper/iron homeostasis, and complement pathways.

Conclusions:

• Distinct proteomic profiles were observed between the IRL and red tide manatee mortality events.
• These protein changes suggest specific physiological stress responses, including inflammation and complement activation, in affected manatees.
• Proteomics offers a valuable approach for understanding manatee health and identifying causes of mortality events.