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The influence of lipid‐extraction and long‐term DMSO preservation on carbon (δ 13 C) and nitrogen (δ 15 N) isotope values in cetacean skin
Author(s) -
Newsome Seth D.,
Chivers Susan J.,
Berman Kowalewski Michelle
Publication year - 2018
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/mms.12454
Subject(s) - dimethyl sulfoxide , isotopes of nitrogen , δ13c , preservative , chemistry , isotope analysis , isotope , extraction (chemistry) , nitrogen , isotopes of carbon , stable isotope ratio , environmental chemistry , ecology , biology , chromatography , food science , organic chemistry , total organic carbon , physics , quantum mechanics
Stable isotope analysis ( SIA ) has rapidly become a useful tool to study the ecology of wild animal populations, especially for elusive, wide‐ranging predators like marine mammals. The development of projectile biopsy techniques resulted in the collection of thousands of cetacean tissue samples that were archived in a dimethyl sulfoxide ( DMSO ) solution for long‐term, multidecadal preservation. Here we examine the influence of DMSO preservation on carbon (δ 13 C) and nitrogen (δ 15 N) values by comparing a set of paired delphinid skin samples stored frozen without preservative and in DMSO for up to 22 yr. Treatment of paired frozen and DMSO ‐preserved skin in a 2:1 chloroform:methanol solution yielded similar δ 13 C and δ 15 N values, revealing that DMSO and lipid contamination have similar isotopic effects on skin, and that these effects can be removed using routine lipid‐extraction methods. Further, amino acid concentrations in DMSO ‐preserved and frozen skin tissue were similar, providing independent evidence of minimal protein alteration due to preservation. Access to a rich archive of skin samples preserved in DMSO will expand our ability to examine temporal and spatial variability in the isotope values of cetaceans, which will aid our understanding of how their ecology has been influenced by historical changes in environmental conditions.