Differential protein expression in Corbicula fluminea upon exposure to a Microcystis aeruginosa toxic strain

Changes in protein expression induced by a Microcystis aeruginosa toxic strain in the freshwater clam Corbicula fluminea were studied using a proteomic approach in an effort to identify new molecular biomarkers. Clams were fed with 1 x 10(6) cells mL(-1) of a M. aeruginosa toxic strain (IZANCYA 2), during 24 b. Cytosolic fractions of gills and digestive tract were analyzed by two-dimensional (2D) electrophoresis in 7 cm IPG strips (pH 4-7). On average, about 400 spots were resolved using Coomassie staining. Altered protein expression was quantitatively detected in 16-13 spots in gills and digestive tract, respectively. In 2D electrophoresis gel protein maps from gills, 10 of 16 spots were downregulated. In the digestive tract, the general tendency was an increase in the protein expression level after the exposure. The altered protein spots were excised and analyzed by MALDI-TOF-MS, with identification of 8 proteins in gills and 5 in the digestive tract. Most of the identified proteins are involved in cytoskeleton assembly. Metabolic proteins were also detected. These results are in agreement with predicted effects of PP1 and PP2A phosphatase inhibition as major effect of microcystins-related toxicity.