Changes in Branchipolynoe seepensis membranar subproteome from lucky strike hydrothermal vent field

Abstract

Lucky Strike hydrothermal vent field is the largest known vent in the Mid-Atlantic Ridge (MAR), characterized by fluids that reach temperatures of 330ºC at 1,700m deep and by high amounts of metals (e.g. Cd, Cu, Fe, Hg, Mn and Zn). The vent polychaete Branchipolynoe seepensis lives in the palleal cavity of the mussel dominant species Bathymodiolus azoricus, cleaning the gills surface from particles in excess. This scale-worm is found more frequently inside the host mussel compared to other scale-worms, probably related with local environmental characteristics. Polychaetes are a very good trace-metal bioindicators, accumulating metals directly related with local metal bioavailability. The aim of this study was to understand the changes in protein expression of the membranar subproteome of polychaetes B. seepensis in response to metal concentration characteristics of Lucky Strike vent sites. Mussels were collected from two sites from Lucky Strike Hydrothermal vent field, Montségur-MS and Eiffel Tower-ET, during BIOBaz mission in August 2013 and polychaetes separated from the mussels. Subcellular fractionation was performed by sequential centrifugation of polychaetes tissues and 2D-SDS-PAGE applied to the membranar subproteome. Metal concentrations were also determined in polychaetes cellular and subcellular fractions by ICP-OES. Protein expression signatures show significant differences in 471 protein spots for B. seepensis between the two vent sites, with 11 specific for Montségur and 382 specific for Eiffel Tower. Common proteins to both sites with the higher change in expression (2-fold or higher) were selected to be identified by MALDI-TOF. Metal concentrations in the cellular (insoluble) and subcellular (thermo labile and heat-stable compounds) fractions were higher in ET and MS, respectively. Data suggests that metal concentrations from both sites reflect the environmental fluctuations between the two microhabitats within the same vent field and are related with the changes found at the subproteome level.