外源凝集素──水产动物御敌的有力兵器

外源凝集素是非免疫起源的热敏蛋白质或糖蛋白，由于其多价构型及对持定细胞多糖具结合亲和力，它们选择凝集某些细胞（包括脊椎动物血球及一些病原微生物）和沉淀某些复杂碳水化合物；其凝集活动常被单糖所抑制，有的却需某些二糖、三糖或多糖。外源凝集素分离自广泛的低等和较高等的生物。一些地区水产养殖业受挫，因素较多，但对发病机理认识之缺乏和调动养殖对象本身防病积极性之不足，是其重要原因。外源凝集素可在诸如凝集外来细胞，调理作用等的防御活动中扮演识别因子，协助一些生理活性物发挥作用，参与吞噬、胞囊、凝固、止血及创伤修复等作用。在生物学、细胞学、生物化学、医学和食品科技上有广泛用途。迄今外源凝集素的许多性能并未全清，在自然界中的精细生理作用仍是个谜。本文论述外源凝集素的定义、性能及用途，以提请有关人士重视。

Lectins, a Powerful Defensive Weapon of Aquatic Animals

Lectins are heat-sensitive proteins of glycoproteins of non-immune origin. They can selectively agglutinate some cells including vertebrate erythrocytcy and pathogenetic microbes because of their polyvalent confisuration and binding affinity for specific cell surface polysaccharides.Lectins are isolated from a wide variety of biolosical resources such as seaweeds, sponges,molluscs, crustaceans, fish eggs, body fluids of invertebrates and lower vertebrates, etc.Huge scale intensive and semi-intensive aquaculture including marine culture has suffered setbscks in some placess. Although it is true, there are many causative factors for this, yet there are two Anpotunt aspects, i. e.lack of knowledge of disease mechanism and insufficient mobilization of the positive factors of the cultured species,that should not be neglected.Lectins and their agglutination activities act by recognizing and differentiation between self and non-self materials, guard against foreign invasion, repair wounds, assist in phagocytosis,encapulation, opsonisation, and so on. Besides, lectins are widely useful in biology, cytology,biochemistry, medicine, food science and technology. But their precise physiological role in nature is unknown.This article discusses definition, brief research history, properties and uses of lectins. It hoped that people, especially those aquaculturists, will pay more attention to the investigation and application of lectins.