Monday, December 10, 2007 - 10:29 AM

Desiccation elicits synthesis of a distinct muscle protein pattern in the Antarctic midge, Belgica antarctica

Aiqing Li, li.586@osu.edu1, Giancarlo Lopez-Martinez, lopez-martinez.1@osu.edu1, Joshua B. Benoit, benoit.8@osu.edu1, Michael A. Elnitsky, elnitsma@muohio.edu2, Richard E. Lee, leere@muohio.edu2, and David L. Denlinger, denlinger.1@osu.edu1. (1) Ohio State University, Department of Entomology, 400 Aronoff laboratory, 318 West 12th Avenue, Columbus, OH, (2) Miami University, Department of Zoology, 212 Pearson Hall, Oxford, OH

Desiccation stress is well recognized as a major challenge for the Antarctic midge, Belgica antarcitca, but desiccation is also exploited by the midge as a strategy to enhance freeze tolerance. In this study, larvae of the midge were desiccated at 75% relative humidity (RH) for 12 h to obtain a body water loss of 32.2%. This midge can tolerate a loss of up to 70% of its body water. Proteins were extracted from the desiccated larvae and controls held at 100% RH, and fractionated into Tris–HCl soluable and urea-thiourea soluble fractions. Analysis of desiccation-responsive proteins was performed using 2-dimensional gel electrophoresis and nanoscale capillary LC/MS/MS. A total of 27 regulated proteins (13 Tris–HCl soluble and 14 urea-thiourea soluble) were identified: 18 were upregulated and 9 were downregulated upon desiccation. Twenty one of the proteins that were identified, including all of the urea-thiourea soluble proteins, were muscle proteins. These proteins had high identity to several different types of muscle proteins including 10 myosin heavy chains, myosin light chain, 3 tropomyosins, 6 actins and kettin. Several additional proteins were functionally involved with defense, protein fate, energy metabolism, and membrane transport. We conclude that the response to desiccation elicits the synthesis of a distinct pattern of muscle proteins that are likely to be involved in cytoskeleton rearrangements.

Species 1: Diptera Chironomidae Belgica antarctica (Antarctic midge)