2007-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/671416摘要：二次世界大戰後，有機合成工業發達，各種合成農藥大量使用，帶動農業的蓬勃發展；然卻也造成環境的嚴重破壞，物種滅絕，甚至嚴重影響人類健康，因而降低有機化學合成農藥的使用，提高產品安全性的需求日殷，使得生物農藥之發展愈顯迫切。 幾丁質是普遍存在昆蟲的外骨骼 (exoskeleton)之成分，也是地球上含量僅次於纖維素的胺基醣型式的多醣，開發利用潛力無窮；昆蟲除了外骨骼，腸道中的圍食膜亦含有幾丁質成分，圍食膜具有保護昆蟲腸道上皮絨毛細胞，避免直接受到食物磨擦及微生物接觸，因此圍食膜為昆蟲攝食後與食物直接接觸的構造，適合作為以幾丁質為標的的生物殺蟲劑標靶。圍食膜之形成與分解受幾丁質合成酵素(chitin synthase)及幾丁質&#37238;(chitinase)所調控。本計畫擬以幾丁質&#37238;為標的，選殖重要害蟲(如小菜蛾)腸道的幾丁質&#37238;基因，利用pHY300載體，建構於枯草桿菌中表現，藉由幾丁質&#37238;基因的過量表現，擾亂圍食膜形成，進而造成昆蟲發育受阻；我們過去研究亦已證實galectin-1蛋白(一種源自人類的蛋白質，具有與幾丁質結合之作用部位)，可與幾丁聚醣作用，並對小菜蛾具有毒性作用；此種以幾丁質(chitin)為標的的生物性殺蟲劑，具有下述之優點(1)幾丁質&#37238;為源自昆蟲本身，安全性高， (2) 幾丁質&#37238;為蛋白質，可分解，無環境殘留問題，(3)幾丁質為昆蟲共同具有之構造，適用性廣。長程目標則擬發展一種以幾丁質為作用標的的生物性殺蟲劑，並探討其作用機制，建立其基因轉殖植株，發展為生物殺蟲劑(生物農藥)之可行性。 <br> Abstract: The use of organic synthetic pesticide has made significant improvements in agricultural production. However, its effect on the environment and human health has also posed a serious problem. To counteract these problems an alternative approach to using chemical pesticides is currently being investigated. Chitin is one of the most abundant amino biopolymer found in nature and it has the potential to be utilised as an alternative source of organic pesticides. It makes up the structural elements of the exoskeletons in various insects and it is also found in the peritrophic membranes that line their midgut. It is the first tissue that comes into contact with ingested food. Chitin is not found in vertebrates and plants, and as such, its metabolism constitutes a potential target for selective bio-insecticidal use in controlling fungi-borne diseases and insect pests. Thus it is the aim of the current project to develop a chitin-targeted bioinsecticde. In order to develop this bioinsecticide, the chitinase gene will be cloned from important pests, such as Plutella xylostella to over expressed in E. coli and B. subtilis. The insecticidal activity of chintinase over-expressed in E.coli and B. subtilis will be further explored in Plutella xylostella etc.. There are at least three prominent features of the chitin-targeted bio-insecticide. Firstly, chitin-targeted bio-insecticide is not toxic to humans since chitin does not exist in human tissues. Secondly, it is a proteinaceous bio-insecticide that is bio-gradable in nature. Third and finally, it is a broad-spectrum bio-insecticide since its action is targeted at chitin, a component of all insects. The long-term goal of this proposal also aims to explore the potential of chitinase gene as a bio-insecticide in transgenic plants.幾丁質生物農藥圍食膜BioinsecticideChitinPeritrophic membrane