Multivariate statistical analysis of metabolomics profiles in tissues of polar bears (Ursus maritimus) from the Southern and Western Hudson Bay subpopulations

• Published in: Polar biology Vol. 41; no. 3; pp. 433 - 449
• Main Authors: Morris, A. D., Letcher, R. J., Dyck, M., Chandramouli, B., Fisk, A. T., Cosgrove, J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2018; Springer; Springer Nature B.V
• Subjects: Amines; Amino acids; Analysis; Anthropogenic factors; Aquatic mammals; Arginine; Biogenic amines; Biological effects; Biomedical and Life Sciences; Ecology; Fatty acids; Glutamine; Hexoses; Human influences; Isotope ratios; Leucine; Life Sciences; Liquid chromatography; Liver; Males; Marine mammals; Mass spectrometry; Mass spectroscopy; Metabolites; Metabolomics; Microbiology; Multivariate analysis; Multivariate statistical analysis; Muscles; Oceanography; Original Paper; Physiological aspects; Plant Sciences; Polar bear; Polar bears; Predators; Profiles; Ratios; Sphingomyelin; Stable isotopes; Statistical analysis; Statistical methods; Subpopulations; Tissue; Ursus maritimus; Vasoactive intestinal peptide; Zoology; Hudson Bay; Partial least squares discriminant analysis (PLS-DA); Metabolomics; ); Polar bears; Multivariate analysis; Hudson Bay
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-017-2200-6

Polar bears ( Ursus maritimus ) are apex predators of the Arctic, which exposes them to an array of natural and anthropogenic stress factors. Metabolomics analysis profiles endogenous metabolites that reflect the response of biological systems to stimuli, and the effects of multiple stressors can be assessed from an integrated perspective. A targeted, quantitative, liquid chromatography–mass spectrometry-based metabolomics platform [219 metabolites including amino acids, biogenic amines, acylcarnitines, phosphatidylcholines (PCs), sphingomyelins, hexoses (Hex), and fatty acids (FAs)] was applied to the muscle and liver of polar bears from the Southern and Western Hudson Bay (Canada) subpopulations (SHB and WHB, respectively). Multivariate statistics were then applied to establish whether bears were discriminated by sex and/or subpopulation. Five metabolites identified by variable importance projection (VIP) discriminated the hepatic profiles of SHB males and females (Hex, arginine, glutamine, one PC, one sphingomyelin), while fifteen metabolites (primarily PCs along with leucine) contrasted the livers of males from SHB and WHB. Metabolite profiles in the muscle of male and female bears could not be differentiated; however, the muscles of SHB and WHB males were discriminated primarily by PCs and FAs. Stable isotope ratios (δ 13 C and δ 15 N) were variably related to metabolites; δ 13 C was correlated with some VIP metabolite concentrations, particularly in comparisons of male bears from SHB and WHB, suggesting an influence of dietary differences. However, δ 15 N and age exhibited few, relatively weak correlations with metabolites. The metabolite profiles discriminating the sexes and subpopulations may have utility for future assessments regarding the effects of specific stressors on the physiology of Hudson Bay polar bears.