Studies on the Dual Functions of Defense Molecules

肉蝇凝集素是一种半乳糖结合型凝集素，可在肉蝇幼虫血淋巴中诱导，对机体损伤作出反应。这种凝集素对于排除以下证据中的异物是必不可少的。将绵羊红细胞注射到肉蛾幼虫的腹腔中，随着时间的推移，红细胞被裂解并从血淋巴中消失。然而。当血细胞与抗人肉瘤凝集素抗体或半抗原糖半乳糖一起注射时，未检测到血细胞的清除。免疫前血清或非半抗原葡萄糖对血细胞裂解无影响。Northern杂交分析表明，该凝集素基因在个体发育过程中有两次表达：第一次是在胚胎期，第二次是在…阶段更多的是在蛹阶段。在蛹阶段合成的Sarcophaga凝集素被证明是形象盘发育所必需的。当腿或翼盘在含有蜕皮激素的情况下进行体外培养时，它们会分化为成体结构。当培养液中有抗Sarcophaga凝集素或半乳糖时，分化停止于溶解阶段，而前免疫血清或葡萄糖不干扰成像盘的分化。这表明Sarcophaga凝集素在成像盘的终末分化过程中是必不可少的。由于没有在培养基中添加Sarcophaga凝集素，因此它必须由想象的圆盘本身合成。免疫印迹实验表明，在溶血阶段，想象盘(包括翼盘和腿盘)合成了Sarcophaga凝集素。由此可见，Sarcophaga凝集素具有防御和发育的双重功能，很可能一个基因-一个蛋白质-一个功能的概念并不一定正确。生物系统似乎能够以两种方式(或多种方式)利用ASME蛋白来维持其动态平衡，这取决于环境条件。较少

Sarcophaga lectin is a galactose-binding lectin induced in the hemolymph of Sarcophaga peregrina (flesh fly) larvae in response to body injury. This lectin is essential for the elimination of foreign substance from the following evidence. When sheep red blood cells were injected into the abdominal cavity of Sarcophaga larvae, they were lysed and disappeared from the hemolymph withtime. However. when the blood cells were injected together with antibody against Sarcophaga lectin or hapten-sugar galactose, no elimination of the blood cells was detected. Premimune serum or non-hapten sugar glucose had no effect on the lysis of the blood cells. This indicates that Sarcophaga lectin is a defense molecule and participates in the elimination of foreign of substances invading through the damaged body wall.Northern blot analysis using cDNA for Sarcophaga lectin revealed that the gene for this lectin is expressed twice during ontogeny without any outside stimuli : First in the embryonic stage and … More then again in the pupal stage. Sarcophaga lectin synthesized at the pupal stage was shown to be necessary for the development of imaginal discs. When leg or wing discs were cultured in vitro in the presence of ecdysone, they differentiate into adult structures. When anti-Sarcophaga lectin or galactose was present in the culture medium, the differentiation stopped at the stage of apolysis, whereas preimmune serum or glucose did not interfere with the differentiation of imaginal discs. This indicates that Sarcophaga lectin is essential for the terminal differentiation of imaginal discs. Since no Sarcophaga lectin was added to the culture medium, it must be synthesized by the imaginal disc itself. Immunoblotting experiments showed that imaginal discs (both wing and leg discs) synthesize Sarcophaga lectin at the stage of apolysis. Therefor, it is clear that Sarcophaga lectin has dual functions in defense and development.It is likely that the concept of one gene-one protein-one function is not necessarily correct. Biological system seems to be able to use the asme protein in two ways (or in multiple ways) to maintain its homeostasis, depending upon environmental conditions. Less