The Regulation of Cell Fate Gene Stalky in Dictyostelium.

• Main Author: 柯正豪
• Other Authors: Wen-Tsan Chang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/72465372932221566341

碩士 === 國立成功大學 === 生物化學研究所 === 88 === Amoebae of Dictyostelium discoideum feed and grow as independent cells in the soil, like many other eukaryotic microorganisms, but when the food supply is exhausted, they aggregate into groups and develop as a multicellular organism. In the mound stage, the cells develop into prestalk and prespore cells, and the prestalk cells sort to the tip, and the tip elongates to form a slug with a posterior zone composed of cells that will become spores and an anterior zone made up of cells that will give rise to the stalk. Dictyostelium indeed offer an ideal model for the study of fundamental strategies and mechanisms of cellular communication, the molecular mechanics of cell movement, cell differentiation, and morphogenesis. Using insertional mutagenesis isolated a stalky mutant in which cells destined to become spores end up as stalk cells. Stalky mutant aggregates and forms slugs in the normal manner, but when these culminate they produce very long structures made up entirely of stalk cells. The stalky gene is strongly expressed in the prespore region of aggregates but not in the anterior prestalk zone. In order to characterize the biochemical activity of STKA protein, we have identified two nuclear localization sequence (NLSs), KPSKKRKP and LRKKKRI. To identify the cis-acting elements in the stkA promoter, we cloned and sequenced the upstream regulating sequence of stkA gene. In situ staining of the pstkA (-3389)-lacZ transformants showed that temporal and spatial pattern of stkA expression are developmentally regulated and cell-type specific. In order to study how the morphogen affects the β-galactosidase expression pattern of the stkA promoter, we used cAMP and DIF as inducers, we found that the stkA promoter can be induced by cAMP, not DIF.