Long-term storage at –20°C compromises fatty acid composition of polar bear adipose biopsies

• Published in: Marine Ecology Progress Series
• Main Authors: Lacombe, Rose M., Atwood, Todd C., Peacock, Elizabeth, Remili, Anaïs, Dietz, Rune, Sonne, Christian, McKinney, Melissa A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2024
• Subjects: Blubber; Degradation; Diet; Feeding ecology; Frozen storage; Marine mammal; Polyunsaturated fatty acids; PUFA; Ursus maritimus
• Online Access: https://pure.au.dk/portal/en/publications/33872321-22f4-4e7d-a561-1fab810902b4; https://doi.org/10.3354/meps14501; http://www.scopus.com/inward/record.url?scp=85192285159&partnerID=8YFLogxK

This study aimed to gain insight into the influence of storage time and temperature on fatty acid (FA) signatures of biopsies of marine mammal adipose/blubber tissues. To examine storage effects, biopsy-type slices from larger pieces of adipose tissues from 2 polar bears Ursus maritimus were stored at either –20 or –80°C and subsequently analyzed for fatty acid composition initially (before storage), after 4 yr, and after 9 yr. At –20°C, after both 4 and 9 yr, proportions of polyunsaturated FAs significantly decreased, and proportions of monounsaturated FAs increased. Proportions of saturated FAs significantly increased only after 9 yr at –20°C in samples of 1 individual. After 4 and 9 yr of storage at –80°C, proportions of the 3 FA classes did not significantly change overall. Intra-individual differences in FA proportions increased over time in –20°C conditions, further pointing to biases stemming from inadequate storage conditions. These findings support the need to store biopsied fatty tissues (or other similarly thin and/or small adipose/ blubber samples) at or below –80°C to adequately preserve FA signatures in samples over time for retrospective applications such as dietary studies.