Meeting Abstract
Mitochondrial performance is dependent on the action of proteins embedded within the inner mitochondrial membrane, and thus the composition of the mitochondrial membrane is likely to be a key determinant of mitochondrial function and whole-organism performance. Because of the profound effect of temperature on the properties of membranes, we predicted that thermal acclimation and local adaptation of populations to different temperatures would be associated with variation in mitochondrial membrane lipids and mitochondrial respiratory capacity. We assessed this prediction with northern and southern subspecies of Atlantic killifish (Fundulus heteroclitus) acclimated to a range of temperatures using high-resolution lipid analyses to measure mitochondrial phospholipid headgroups and headgroup-specific fatty acid remodeling, and high-resolution respirometry to assess mitochondrial respiratory capacity. Acclimation resulted in compensatory changes in mitochondrial respiratory capacity in both subspecies. In addition, northern F. heteroclitus exhibited greater mitochondrial respiratory capacity across acclimation temperatures, which is consistent with previously observed subspecies differences in whole-organism aerobic metabolism. Mitochondrial phospholipids were altered following thermal acclimation and differed between subspecies. These effects were largely driven by increased polyunsaturated fatty acid content, consistent with homeoviscous adaptation. These results support a role for mitochondrial function in the response to thermal stress and provide evidence of lipid remodeling as a mechanism regulating these changes.
