Data from: Physical, chemical, and functional properties of neuronal membranes vary between species of Antarctic notothenioids differing in thermal tolerance

Disruption of neuronal function is likely to influence limits to thermal
tolerance. We hypothesized that with acute warming the structure and
function of neuronal membranes in the Antarctic notothenioid fish
Chaenocephalus aceratus are more vulnerable to perturbation than membranes
in the more thermotolerant notothenioid Notothenia coriiceps. Fluidity was
quantified in synaptic membranes, mitochondrial membranes, and myelin from
brains of both species of Antarctic fishes. Polar lipid compositions and
cholesterol contents were analyzed in myelin; cholesterol was measured in
synaptic membranes. Thermal profiles were determined for activities of two
membrane-associated proteins, acetylcholinesterase (AChE) and
Na+/K+-ATPase (NKA), from brains of animals maintained at ambient
temperature or exposed to their critical thermal maxima (CTMAX). Synaptic
membranes of C. aceratus were consistently more fluid than those of N.
coriiceps (P < 0.0001). Although the fluidities of both myelin and
mitochondrial membranes were similar among species, sensitivity of myelin
fluidity to in vitro warming was greater in N. coriiceps than in C.
aceratus (P < 0.001), which can be explained by lower cholesterol
contents in myelin of N. coriiceps (P < 0.05). Activities of both
enzymes, AChE and NKA, declined upon CTMAX exposure in C. aceratus, but
not in N. coriiceps. We suggest that hyper-fluidization of synaptic
membranes with warming in C. aceratus may explain the greater stenothermy
in this species, and that thermal limits in notothenioids are more likely
to be influenced by perturbations in synaptic membranes than in other
membranes of the nervous system.