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標題: | 果蠅新基因shrimp ball在胚胎發育背部密合過程所扮演的角色 Roles of a novel gene, shrimp ball, in the dorsal closure process during Drosophila embryogenesis |
作者: | Yu-Ping Yang 楊宇平 |
出版年 : | 2001 |
學位: | 碩士 |
摘要: | 在果蠅胚胎發育中,背部密合(dorsal closure)過程是胚胎體側的表皮細胞移動覆蓋裸露的內胚膜(amnioserosa),將內胚膜包起的過程。至少有三類的基因產物是胚胎背部密合所需要的,並且都表現在表皮細胞。第一類為結構性蛋白,影響細胞形狀。第二類與第三類為表現調節背部密合過程的蛋白質;第二類為Drosophila Jun-amino(N)-terminal kinase (DJNK)訊息分子,第三類為與Decapentaplegic(Dpp,果蠅TGFβ之同源基因),相關的訊息分子。 新發現的基因,shrimp ball(shpb),具有胚胎背部開洞的突變性狀。shpb表現為轉錄因數,具有包含BTB/POZ的高度保守的區域。在胚胎背部密合時期,shpb大量表現在內胚膜內;而shpb突變則造成DJNK訊息的標的基因,如dpp與puc,表現型態與程度的改變。由此觀察,shpb應位於目前已知DJNK訊息的最上游,並且正向調節目前未知的胚胎背部密合起始訊息。shpb所活化的起始訊息經過raw的抑制調節,使得下游的DJNK與Dpp訊息被侷限在前緣細胞(leading edge cell)內表現。並且根據基因本身的表現型態,shpb極有可能連結內胚膜發育與胚胎背部密合的過程。 由於shpb的突變也造成EGFR(Epidermal Growth Factor Receptor)訊息傳遞路徑的標的基因,fasciclin Ⅲ(fas Ⅲ),表現的改變,因此shpb也參與於EGFR訊息路徑,可能是造成突變胚胎腹部型態改變的原因。 During dorsal closure in Drosophila, cells of the lateral epidermis migrate over the amnioserosa to encase the embryo. At least three classes of characterized dorsal-opened group gene products, which function in the epidermis, are involved in the process. Class Ⅰ genes code for structural proteins. Class Ⅱ genes encode Drosophila Jun amino (N)-terminal kinase (DJNK) signaling molecule and Class Ⅲ genes encode Decapentaplegic (Dpp)-mediated signaling molecules. A newly discovered embryonic lethal gene, shrimp ball (shpb), encodes a transcription factor with highly conserved BTB/POZ domain. Severe dorsal closure defect was found in shpb mutants. shpb expresses mainly in amnioserosa, indicating its function in amnioserosa. shpb mutation caused lose of two DJNK target gene expression. Dorsal-opened phenotype caused by shpb can be rescued by ubiquitous expression of dpp and mutation of raw. raw mutation also converts the ventral denticles to naked cuticle in shpb mutants. From the observation, we postulate that shpb is acting at the upstream position of the DJNK signaling and positively regulates an unknown initial signal, which is responsible for activation of the dorsal process. shpb may also link the gap between function of dorsal closure and amnioserosa, where is suggested to be the site emitting dorsal closure signal. shpb is also postulated to act in the EGFR (Epidermal Growth Factor Receptor) signaling pathway. shpb mutation causes disappearance of EGFR-dependent Fasciclin Ⅲ (Fas Ⅲ) expression, indicating its positive role in EGFR signaling. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/75242 |
全文授權: | 未授權 |
顯示於系所單位: | 動物學研究所 |
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