Meeting Abstract
P2.98 Wednesday, Jan. 5 Skeletal muscle cardiolipins in the Eastern red spotted newt (Notophthalmus viridescens viridescens) ROBERSON, S.A.; CALCUTT, M.W.; BERNER, N.J.*; Sewanee: University of the South; Vanderbilt University; Sewanee: University of the South nberner@sewanee.edu
Eastern red spotted newts are active in winter. Our previous work shows that they acclimate enzyme activity, metabolic rate, and membrane phospholipid fatty acid (FA) composition in skeletal muscle seasonally. Cold-acclimated (8°C) newts have higher skeletal muscle cytochrome c oxidase (CCO) activity than warm-acclimated (26°C) newts. In addition, cold-acclimated newts have roughly half the mol% of 18:2 n-6 (linoleic) and twice the mol% of 20:4 n-6 (arachidonic acid) and 22:6 n-3 (docosahexaenoic acid) of warm-acclimated newts. Membrane FA composition can affect activity of membrane-bound proteins such as CCO through association with a specific phospholipid: cardiolipin (CL). All our previous work has been done on whole skeletal muscle tissue. This experiment was performed to test the hypothesis that the FA makeup of CL changes with season, as a step toward testing whether or not changes in CL may be responsible for seasonal changes in CCO activity. Newts were collected in winter and summer. Upon collection, newts were euthanized and frozen at -80°C under N2 gas until lipids were isolated. Lipid extraction from approximately 0.2 g skeletal muscle was performed using chloroform:methanol (2:1 v/v) with BHT. CL was purified from extracted lipids via HPLC on a silica column. Identification of FAs associated with CL was performed using LC-MS/MS. Data from 2 summer and 3 winter newts show different charge to mass ratios (m/z) for skeletal muscle CL in different seasons: summer = 1447.97 m/z versus winter = 1449.99 m/z. The MS/MS spectra indicate the following FA makeup of these CLs: summer (18:2)4-CL with minor amounts of (18:1)2(18:3)2-CL and winter (18:2)3(18:1)-CL only. We have not yet determined if such changes in CL result specifically in changes in CCO activity.
