title: Biomarkers of whale shark health: a metabolomic approach.
abstract: In a search for biomarkers of health in whale sharks and as exploration of metabolomics as a modern tool for understanding animal physiology, the metabolite composition of serum in six whale sharks (Rhincodon typus) from an aquarium collection was explored using (1)H nuclear magnetic resonance (NMR) spectroscopy and direct analysis in real time (DART) mass spectrometry (MS). Principal components analysis (PCA) of spectral data showed that individual animals could be resolved based on the metabolite composition of their serum and that two unhealthy individuals could be discriminated from the remaining healthy animals. The major difference between healthy and unhealthy individuals was the concentration of homarine, here reported for the first time in an elasmobranch, which was present at substantially lower concentrations in unhealthy whale sharks, suggesting that this metabolite may be a useful biomarker of health status in this species. The function(s) of homarine in sharks remain uncertain but it likely plays a significant role as an osmolyte. The presence of trimethylamine oxide (TMAO), another well-known protective osmolyte of elasmobranchs, at 0.1-0.3 mol L(-1) was also confirmed using both NMR and MS. Twenty-three additional potential biomarkers were identified based on significant differences in the frequency of their occurrence between samples from healthy and unhealthy animals, as detected by DART MS. Overall, NMR and MS provided complementary data that showed that metabolomics is a useful approach for biomarker prospecting in poorly studied species like elasmobranchs.
authors.affiliation: Georgia Aquarium Research Center, Georgia Aquarium, Atlanta, Georgia, USA. adove@georgiaaquarium.org
authors.forename: Alistair D M
authors.initials: AD
authors.lastname: Dove
authors.forename: Johannes
authors.initials: J
authors.lastname: Leisen
authors.forename: Manshui
authors.initials: M
authors.lastname: Zhou
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Byrne
authors.forename: Krista
authors.initials: K
authors.lastname: Lim-Hing
authors.forename: Harry D
authors.initials: HD
authors.lastname: Webb
authors.forename: Leslie
authors.initials: L
authors.lastname: Gelbaum
authors.forename: Mark R
authors.initials: MR
authors.lastname: Viant
authors.forename: Julia
authors.initials: J
authors.lastname: Kubanek
authors.forename: Facundo M
authors.initials: FM
authors.lastname: Fernández
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood*; D006304:Health Status; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry / Q000379:methods; D055432:Metabolomics / Q000379:methods*; D008744:Methylamines / Q000097:blood; D010848:Picolinic Acids / Q000097:blood*; D025341:Principal Component Analysis; D012754:Sharks / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D008744:Methylamines; D010848:Picolinic Acids; C005855:trimethyloxamine; C010981:homarine