Poster: Temperature responses

Abs # 139: Measuring Respiration and Thermal Properties of Arabidopsis Fatty Acid Mutants

Presenter:	Hsiao, Yueh , hsiaoyj@wilkes.edu
Authors	Hsiao, Yueh  (A)   Lucent, Del  (A)   Mikhalkova, Deana  (A)   Nemani, Abhishek  (A)   Terzaghi, William  (A)
Affiliations:	(A): Wilkes University

Fatty acid composition is proposed to affect the fluidity and melting temperature of biological membranes. Membranes with differing fatty acid composition should therefore exhibit different thermal responses. We are testing these hypotheses with the A. thaliana mutants, Ssi2 (defective in fatty acid desaturation) and FAB1 (defective in fatty acid biosynthesis). Respiration at different temperatures was measured with an oxygen electrode attached to a temperature controlled water bath. Thermal properties were measured by differential scanning calorimetry. Ssi2 and FAB1 showed changes in activation energy at 12^oC and 14^oC, respectively, on an Arrhenius plot of respiration vs. T. The wild type, Columbia showed a change at 10^oC. Also, Columbia seedlings showed a temperature coefficient of 2.12 while FAB1 and Ssi2 showed temperature coefficients of 1.65 and 1.70, respectively. Ssi2 showed a greater heat of fusion and a higher melting point than wild-type seedlings upon analysis with a differential scanning calorimeter. We attribute these data to differences in fatty acid composition between the mutant and wild type seedlings.