Effect of elevated temperature on membrane lipid saturation in Antarctic notothenioid fish
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Abstract
Homeoviscous adaptation (HVA) is a key cellular response by which fish protect their membranes against thermal stress. We investigated evolutionary HVA (long time scale) in Antarctic and non-Antarctic fish. Membrane lipid composition was determined for four Perciformes fish: two closely related Antarctic notothenioid species (Trematomus bernacchii and Pagothenia borchgrevinki); a diversified related notothenioid Antarctic icefish (Chionodraco hamatus); and a New Zealand species (Notolabrus celidotus). The membrane lipid compositions were consistent across the three Antarctic species and these were significantly different from that of the New Zealand species. Furthermore, acclimatory HVA (short time periods with seasonal changes) was investigated to determine whether stenothermal Antarctic fish, which evolved in the cold, stable environment of the Southern Ocean, have lost the acclimatory capacity to modulate their membrane saturation states, making them vulnerable to anthropogenic global warming. We compared liver membrane lipid composition in two closely related Antarctic fish species acclimated at 0 °C (control temperature), 4 °C for a period of 14 days in Trematomus bernacchii and 28 days for Pagothenia borchgrevinki, and 6 °C for 7 days in both species. Thermal acclimation at 4 °C did not result in changed membrane saturation states in either Antarctic species. Despite this, membrane functions were not compromised, as indicated by declining serum osmolality, implying positive compensation by enhanced hypo-osmoregulation. Increasing the temperature to 6 °C did not change the membrane lipids of P. borchgrevinki. However, in T. bernacchii, thermal acclimation at 6 °C resulted in an increase of membrane saturated fatty acids and a decline in unsaturated fatty acids. This is the first study to show a homeoviscous response to higher temperatures in an Antarctic fish, although for only one of the two species examined.
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2018. Effect of elevated temperature on membrane lipid saturation in Antarctic notothenioid fish. PeerJ Preprints 6:e26472v1 https://doi.org/10.7287/peerj.preprints.26472v1note This preprint is not peer-reviewed. You may wish to reference the subsequent peer-reviewed version of this article.
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Supplemental Information
Raw Data of percent phospholipid fatty acids, membrane cholestrol and osmolality in fish species and thermally aclimated Antarctic fish species
Each work sheet includes raw data of the respective figure or table mentioned in the file name .
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Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Vanita C Malekar conceived and designed the experiments, performed the experiments, analyzed the data, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.
James D Morton conceived and designed the experiments, reviewed drafts of the paper.
Richard N Hider performed the experiments, reviewed drafts of the paper.
Robert H Cruickshank conceived and designed the experiments, contributed reagents/materials/analysis tools, reviewed drafts of the paper, project Administration and supervision.
Simon Hodge analyzed the data, prepared figures and/or tables, reviewed drafts of the paper.
Victoria J Metcalf conceived and designed the experiments, performed the experiments, reviewed drafts of the paper.
Animal Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):
Canterbury University, New Zealand
Field Study Permissions
The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers):
Antarctica New Zealand
Funding
The field study for this experiment was supported by Antarctica New Zealand. Funding for biochemical analysis and paper writing was supported by Lincoln University New Zealand. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.