抄録
Many bivalve species are cultured widely around the world due to their commercial importance. As a result of the increases in areas and production associated with intensive culture, mass mortalities of bivalves caused by a wide variety of agents have become a serious problem. Various infectious diseases represented by protozoan and bacterial diseases have been threatening shellfish culture industries, and hence, many investigations have been made on the defense mechanisms, as well as diseases, in bivalves. The molluscan defense mechanism is comprised of the only innate immunity, which is also dependent on cellular components such as hemocytes possessing phagocytic and bactericidal activities and on humoral defense molecules such as lectin and lysozyme. In this review, we summarize cellular defense mechanisms in bivalve molluscs focusing on hemocytes: 1) morphology and classification, 2) functional profiles (phagocytosis, encapsulation, wound repair), 3) reactive oxygen species, 4) effects of natural and anthropogenic environmental factors, and 5) stress and signaling pathways.
