Meeting Abstract

S6-1.5  Thursday, Jan. 5  Latitudinal variation in protein expression in the salt marsh mussel Geukensia demissa FIELDS, Peter A.*; COX, Kelly; KARCH, Kelly R.; Franklin & Marshall College; Franklin & Marshall College; Franklin & Marshall College peter.fields@fandm.edu

Individuals of a broadly distributed species often experience significantly different environmental conditions depending on location. For example, Geukensia demissa, the ribbed salt marsh mussel, occurs intertidally from the Gulf of St. Lawrence to the Yucatan Peninsula; within this range, northern populations are exposed to temperatures cold enough to freeze tissue, while southern populations can experience temperatures approaching the species’ upper lethal limit. We are interested in determining whether the species comprises a panmictic population demonstrating extreme eurythermality, or whether populations at different locations possess unique adaptations to cope with local conditions. We have collected G. demissa at nine locations from Maine to Mississippi and are using a proteomic approach to describe how protein expression varies across this species’ latitudinal range. We acclimated individuals of each group to common conditions (18°C, constant immersion) for four weeks, and exposed a subset of these to acute heat stress (40°C for 1 h, followed by 24 h recovery at 18°C). Gill proteins were separated using 2-D gel electrophoresis, and image analysis software was used to detect proteins that vary in abundance with latitude, acute heat stress, or both. The proteins varying most significantly are being identified via mass spectrometry in order to detect differences in the mechanisms by which mussels from different locations protect themselves from heat damage. To put our proteomic work into context, we also are creating an ITS-based molecular phylogeny of these groups. By combining phylogenetic information and proteomic data on responses to acute heat stress, we expect to better describe how species adapt to environmental conditions across broad latitudinal ranges.