Meeting Abstract
In order to generate sound, cetaceans (whales, dolphins, and porpoises) push air through their nasal passages and across their phonic lips. They are able to move the air necessary for phonation by contracting muscles that surround air sacs, which are associated with their nasal passages. While these muscles have been described anatomically, their contractile abilities remain unknown. In order to better understand the functional abilities of these muscles, the purpose of our study is to determine the myosin heavy chain protein composition in the left and right nasal musculature (anterior and posterior internus and externus and intermedius muscles), palatopharyngeal sphincter, and genioglossus complex of bottlenose dolphins (Tursiops truncatus) and harbor porpoises (Phocoena phocoena) using SDS-polyacrylamide gel electrophoresis. Myosin was extracted from the vocal/nasal muscle samples (~2.5 mg) of four dolphins and four porpoises, and aliquots of each myosin extract were electrophoresed at 275 V for 24-hours in 8% acrylamide, 30% (v/v) glycerol separating gels. Images of the silver stained gels were captured, and the staining densities of each myosin band in each sample were determined using ImageJ software. These values were converted into proportions of total myosin represented by each band in each sample and were used to calculate average proportions of each myosin isoform in the muscles of both species, which will allow us to compare the myosin expression patterns in these dolphin and porpoise muscles. Quantifying the myosin heavy chain protein expression in these vocal/nasal muscles will allow us to construct hypotheses about the contractile abilities of these muscles in cetaceans.
