STRUCTURAL CHARACTERIZATION OF THE FLIGHT MUSCLE OF MANDUCA SEXTA

There are several properties of the flight muscle Manduca sexta that are interesting. In its physiological characteristics, like mammalian skeletal and cardiac striated muscle, it is a synchronous muscle. However, it is much more similar structurally to the more widely known asynchronous insect flight muscles of Drosophila and Lethocerus. The goal of the thesis is to study the structural characteristics and perform mechanical studies of dorsal and ventral muscle of Manduca flight muscle. In pursuit of this goal, a secondary purpose was to develop better storage conditions for skinned insect muscle which can maintain muscle structure and function. Maximum active force as a function of time in storage was compared for storing at 4℃ without glycerol and storing at -80℃ with 75% glycerol. The maximum force values were almost the same during days 0-4. However, the muscle stored at -80℃ with 75% glycerol gave higher active force in high calcium (pCa 4.5) solution over a longer time in storage than muscle stored at 4℃. Both ventral and dorsal muscles can deliver 40-50% of original active force for up to 21 days in storage. X-ray diffraction experiments were done to compare the response of chemically skinned Manduca flight muscle to temperature and to the induction of rigor. The lattice spacing (d10) decreased and intensity ratio I20/I10 increased when the temperature of the relaxing solution bathing the solution increased from 10℃ to 40℃. Lattice spacing (d10) decreased, but the I20/I10 intensity ratio increased slightly while concentration of dextran increased from 1% to 6%. Six percent dextran was insufficient to restore the in vivo lattice spacing.M.S. in Molecular Biochemistry and Biophysics, May 201