Gas chromatography–mass spectrometry analysis on effects of thermal shock on the fatty acid composition of the gills of the Antarctic teleost, Trematomus bernacchii

Abstract

Environmental contextGlobal warming is an important problem for life on Earth, and there is an increasing need to understand how organisms respond to rising temperatures. We show that an Antarctic fish, the emerald rockcod, can acclimate to thermal shock by modifying the fatty acid composition and total lipid content in its gills. This study contributes to our understanding of how the physiology of Antarctic life could be influenced by climate change. AbstractAs a result of rising temperatures in the Antarctic seawater, there is an increasing interest to investigate the capacities for inducing a temperature acclimation response in Antarctic organisms. We analysed the effect of a thermal shock on the fatty acid (FA) composition of gills of the Antarctic notothenioid Trematomus bernacchii. To perform the quantification of fatty acids in gills, we applied an analytical method based on a fast microwave-assisted extraction (MAE) of lipids from a lyophilised sample, a base-catalysed trans-esterification of lipid extract to obtain fatty acid methyl esters (FAMEs), and their separation and identification by gas chromatography–mass spectrometry. The percentage of lipids extracted with MAE preceded by sample lyophilisation, 0.6 ± 0.3 % ww (wet weight), was consistent with the lipids obtained by the official Bligh and Dyer method, 0.8 ± 0.3 % ww. These data are among the first ever published for T. bernacchii. Specimens, caught in Terra Nova Bay (Ross Sea), were held in different tanks at 0, +1 and +2 °C, for 1, 5 and 10 days. In general, thermal shock produced an alteration in total lipid content, an increase in the percentage of saturated FAs, a decrease in mono-unsaturated FAs, and a variable response of poly-unsaturated FAs (an increase in specimens exposed to 0 and +1 °C, a decrease in those exposed to +2 °C). A chemometric approach based on principal component analysis indicated that temperature and exposure time influenced the composition of FAs in the gills, probably through an alteration of the metabolic pathways of FAs. This is the first study ever published on the FA composition of total lipids in gills of T. bernacchii exposed to high temperatures. This study demonstrates that T. bernacchii is capable of rapidly acclimating to a thermal shock, and contributes to increasing the knowledge on the effect of temperature on Antarctic notothenioids.