Meeting Abstract
P3.119 Wednesday, Jan. 6 Changes in protein expression in gill tissue of the ribbed marsh mussel Geukensia demissa in response to aerial exposure FIELDS, P.A.*; GAO, L.; WOLFGANG, A.; Franklin and Marshall College; Franklin and Marshall College; Pequea Valley High School peter.fields@fandm.edu
The ribbed mussel Geukensia demissa inhabits salt marshes along the eastern coast of North America from Florida to the Gulf of St. Lawrence. Geukensia often occurs above mean tidal height in its habitat, in part to avoid predation, and so can experience periods of emersion exceeding 12 h. To examine the effects of prolonged aerial exposure on protein expression in gill tissue of Geukensia, we acclimated mussels to continuous immersion at 15C for three weeks. We then exposed 6 individuals to moist 15C air for 3, 12 or 18 h. After 24 h recovery, immersed, proteins were extracted from gill tissue. We analyzed changes in protein expression among treatment groups via two-dimensional gel electrophoresis, separating proteins by mass and isoelectric point. The density of 981 protein spots on the 24 gels (4 treatments x 6 replicates) was quantified (Delta2D software), and changes in protein expression profiles among treatment groups were compared using hierarchical cluster analysis (HCL) and principal components analysis (PCA). We found clear differences in protein expression depending on the duration of emersion. Geukensia responds robustly after 3 h emersion (221 spots upregulated relative to control, 22%). Remarkably, there is little overlap in the proteins significantly upregulated after 3 h emersion (vs. control, t-test α=0.01) compared to 12 h (104 spots; 5 spots overlap) or 18 h (64 spots; 11 spots overlap). Furthermore, both HCL and PCA indicate that the protein expression profiles of the 18 h group cluster with the controls, and the 3 h and 12 h groups cluster together, suggesting that 18 h emersion may be stressful enough to inhibit new protein synthesis. Tandem mass spectrometry will be used to identify those proteins that are upregulated most strongly in each of the treatment groups.
