GAL1 是一種半乳糖結合蛋白(Galectin)， 具有多重功 能， 包括細胞貼附、增生、分化之功能。GAL1 蛋白於細 胞質中合成後，分泌至細胞外，再與細胞膜上含β-galactosyl 之蛋白結合，而引發細胞內之訊號傳遞。GAL1 與膜蛋白結合的 motif 主要具有 Galβ1-4GlcNAc 結構，與幾丁質聚醣膜(β-1, 4 N-acetyl-D-glucosamine)結構類似；實驗室先前實驗已證實GAL1 可與幾丁質聚醣膜結合。幾丁質為甲殼類生物外骨骼及腸 道外基質(matrix)主要成份；本研究擬探討GAL1 蛋白與幾 丁質之作用基制， 及GAL1 蛋白對昆蟲脫皮之影響； 結果 顯示GAL1 蛋白與幾丁質聚醣膜之作用呈劑量相關， 以 GAL1 蛋白萃取液或純化之GAL1(200-1000µg/ml)餵食昆 蟲幼蟲，可以延遲果蠅幼蟲之發育時間；而小菜蛾幼蟲餵 食GAL1 蛋白後， 幾乎完全無法正常化蛹， 可能幼蟲脫皮 過程受到干擾所致， 然須進一步探討才能確認其作用機 制； 由本實驗之結果顯示GAL1 蛋白可以抑制昆蟲幼蟲正 常發育，具有發展作為生物殺蟲劑之潛力，值得深入探討 GAL1 蛋白作為生物農藥之可行性。 Galectin-1 (GAL1), a β-galactosyl binding lectins, has been shown to modulate cell adhesion, cell-matrix interaction, cell proliferation and some immune functions. GAL1 is an extracellular proteins act to cross-linking cell surface and substrate glycoconjugates. It is proposed that GAL1, having a single CRD domain recognized the structural motif Galβ1-4GlcNAc that is similar to that of chitosan membrane (β-1, 4 N-acetyl-D-glucosamine). In an earlier work, we have found that GAL1-coated chitosan membrane could support 3T3 cells proliferation. These studies further investigate 1) the interaction of GAL1 and chitosan in vitro; 2) the effect of GAL1 on insect larvae development. These results showed that GAL1 dose-dependently bind with chitosan in vitro. These results suggested that chitosan could be a nature ligand of GAL1. Furthermore, GAL1 was found to be toxic to some insects, such as the dipteran of Drosophila melanogaster and the lepidoptera of Plutella xylostella. The development of diamondback moth (P. xylostella) larvae were significantly disturbed when feeded with GAL1 extract and/or recombinant GAL1 proteins purified from GAL1 over-expressed E. coli. The development of D. melanogaster larvae were also significantly delayed when feeded with 200-1000µg/ml GAL1; These results indicate the recombiant GAL1 exhibites high insecticidal activity and may be a candidate for bio-insecticide. However, the mechanism of insecticidal toxicity of GAL1 still has to be elucidated
