形態態發生是指生物在胚胎發育過程中，已分化的上皮細胞藉由一連串的細胞形狀、細胞數目、及細胞極性的改變而形成各種立體結構的組織及器官，而目前對於調控形態發生的分子作用機制則仍不十分清楚。但與細胞形狀維持有關的細胞骨架及控制細胞極性的分子，應與形態發生有密切的關係。本實驗利用果蠅桿小體的形態發生來探討形態發生的分子機制。果蠅桿小體是位於眼睛內對光敏感的胞器，桿小體的發育開始於蛹週期早期，藉由感光細胞形狀的改變，而產生成熟果蠅桿小體的形態。由於感光細胞改變形狀時，細胞極性的建立扮演了重要的角色，因此本研究欲探討細胞極性基因，crumbs對於桿小體形態發生的影響。利用基因轉殖果蠅來誘發crumbs的過度表現以檢驗Crumbs對桿小體形態發生的作用，結果發現改變感光細胞的極性會擾亂桿小體的形態發生，並且導致感光細胞的死亡。此結果顯示，細胞極性對於桿小體的形態發生及感光細胞功能的維持，扮演了重要的角色。 Morphogenesis is a developmental process that brings differentiated cells together to form a three-dimensional tissue or organ by coordinating a series changes in cell shape, polarity, and cell number. Genetic regulation of morphogenesis remains unclear but cytoskeletal elements and cell polarity genes are thought to be important in this process. We have used a model, the rhabdomere morphogenesis in Drosophila that allows us to study the molecular regulation of morphogenesis. Rhabdomere is a photosensitive organelle that begins to form at the mid-pupal stage of eye development by turning its apical surface toward the center of ommatidium. However, the mechanism that mediates rhabdomere morphogenesis is unclear. Recent evidence showed that cell polarity genes play important roles in morphogenesis. Thus we are interested in examining if cell-polarity gene, crumbs plays any role in rhabdomere formation. Our results showed that ectopic expression of Crumbs protein in transgenic flies alter the polarity of photoreceptors. The consequence of altering cell polarity resulted in mislocalization of rhabdomere and cell death at photoreceptors. These results suggest that apical signals may play an important role in rhabdomere formation.
