Meeting Abstract
To maintain membrane function at low temperature, many ectotherms that live in temperate climates incorporate more polyunsaturated fatty acids (PUFAs) into their membranes in winter. The eastern newt (Notophthalmus viridescens) uses thermal acclimation to remain active throughout the year. Winter-acclimated newts swim faster at low temperature and have higher activities of metabolic enzymes in skeletal muscle compared to summer-acclimated newts. The muscle membranes of winter-acclimated newts also have higher PUFA contents compared to summer-acclimated newts, and northern populations have muscle membranes with higher PUFA contents than southern populations. However, it is not clear how seasonal membrane remodeling and differences in membrane composition between populations affects whole-animal performance. To determine if the remodeling of membranes affects thermal tolerance and the thermal dependence of swimming performance, we manipulated membrane composition independently of acclimation temperature. Newts were separated into four diet regimes: high saturated fatty acid (SFA), high monounsaturated fatty acid (MUFA), high omega-3 PUFA, and high omega-6 PUFA for 12 weeks. All newts were housed at 20˚C (12L:12D). Next, we measured the swimming speed of newts at a range of temperatures between 6-33.5˚C. We also measured the lower critical temperatures (CT min) and upper critical temperatures (CT max) of newts.
