The comparative study of immunity between two scallop species Chlamys farreri and Argopecten irradians

Abstract

Zhikong scallop (Chlamys farreri) and Bay scallop (Argopecten irradians), two major aquaculture
molluscan species in China, are different in some important traits such as life cycle, growth
performance and temperature tolerance. In the present study, the malondialdehyde (MDA) content and four immune parameters including phagocytic activity, respiratory burst and activities of superoxide dismutase (SOD) and acid phosphatase (ACP) of scallops under heavy metal exposure and bacteria challenge were measured by flow-cytometric method and immunochemistry assays to compare the immunity of these two scallop species. In the non-treated scallops, the phagocytosis of hemocytes, MDA content, the activities of SOD and ACP in hepatopancreas of Bay scallops were all significantly higher than those of Zhikong scallops. After challenged with Vibrio anguillarum, the ROS level in hemocytes of Bay scallops was significantly lower than that of Zhikong scallops at 30 min, and the cumulative mortality of Bay scallop was also significantly lower than that of Zhikong scallop at 2nd-5th day. The exposure of Pb2+ with different concentration induced significantly higher phagocytic activity, ACP activities, SOD activities, MDA content in hepatopancreas and significantly stronger respiratory burst in hemocyte of Bay scallops compared with those of Zhikong scallops, while the hemocyte
mortalities in Bay scallops were significantly lower than that in Zhikong scallops. The results collectively indicated that Bay scallops had a higher level of immune potential than Zhikong scallops, suggesting its greater capacity for stress response and immune resistance against pathogens as well.