Meeting Abstract
35.1 Friday, Jan. 4 Changes in protein expression in the dogfish shark rectal gland following natural feeding DOWD, W. W.*; WOOD, C. M.; KAJIMURA, M.; WALSH, P. J.; K�LTZ, D.; Univ. of California, Davis; McMaster University, Hamilton, Ontario, and Bamfield Marine Sciences Centre, British Columbia; McMaster University, Hamilton, Ontario, and Bamfield Marine Sciences Centre, British Columbia; Univ. of Ottawa; Univ. of California, Davis wwdowd@ucdavis.edu
The rectal gland is the principal salt-secreting organ in elasmobranchs, yet its functional response to normal physiological variation (e.g., due to feeding, stress) has only recently been examined. To complement studies on acid-base, digestive, and osmoregulatory physiology in response to natural feeding, we investigated protein-level responses in the rectal gland of spiny dogfish (Squalus acanthias) 6 hours, 20 hours, and 5 days (reference control) after a meal. Our objective was to identify proteins involved in regulation of osmoregulatory and metabolic processes in response to feeding. Proteins were separated by two-dimensional gel electrophoresis, and protein spots that were significantly up- or down-regulated >2 fold (i.e., increased more than 100% or decreased more than 50%) were detected using gel image analysis software. Of 684 proteins analyzed on 2D gels, 16 proteins changed significantly 6 hours after feeding vs. 5 day controls (5 decreased; 11 increased), and 12 proteins changed >2 fold 20 hrs after feeding vs. 5 day controls (2 decreased; 10 increased). Thirteen of these proteins were identified using mass spectrometry and classified into functional pathways using bioinformatics databases. Rectal gland proteins that were regulated following feeding fell into three main categories: cytoskeletal/muscular (e.g., tropomyosin alpha chain), energy metabolism (e.g., malate dehydrogenase), and nucleotide metabolism (nucleoside diphosphate kinase). Overall, our results suggest that maintaining the cellular supply of energy (for example, to fuel the costly Na+/K+-ATPase pump) is a key component of the rectal gland�s response to feeding.
