Developmental Biology 4.卵膜表面受体的激活决定胚胎AP轴的两个端点 torso突变体缺少原头区和尾区, localized release of ligand that activates torso receptor torso蛋白为酪氨酸激酶类受体。 未受精前, torso已均匀地分布 在卵的质膜上。但其腺体 torsolike vitelline membrane 定位在两端的卵外膜( vitelline ligand membrane)上,不能与 torso结合。 受精时, torsolike得以释放, perivitelline space torsolike与 torso结合, torso活化, receptor 启动信号传导。 Torsolike蛋白的存在量很低, 受精后其扩散距离有限。其突变体 类似 Torso突变体。 torso receptor activated at poles
Developmental Biology 4. 卵膜表面受体的激活决定胚胎AP轴的两个端点 torso突变体缺少原头区和尾区， torso蛋白为酪氨酸激酶类受体。 未受精前，torso已均匀地分布 在卵的质膜上。但其腺体torsolike 定位在两端的卵外膜(vitelline membrane)上，不能与torso结合。 受精时，torsolike得以释放， torsolike与torso结合, torso活化， 启动信号传导。 Torsolike蛋白的存在量很低， 受精后其扩散距离有限。其突变体 类似torso突变体
Developmental 5.卵膜中的母体蛋白决定胚胎D一V极性 Dorsal-cactus pathway P Fig 5.9 The mechanism of localization of dorsal protein to the nucleus. In unfertilized eggs, dorsal protein is present cytoplasm in the cytoplasm bound to the cactus protein, which prevents it entering nuclei. The signal delivered by Toll receptor activation is transmitted along an Nucleus intracellular signaling pathway involving other matemal gene products(e.g. those of tube and pelle), with the end result that cactus protein is degraded and so dorsal cactus no longer binds to dorsal protein, which can then enter the nucleus pelle OO tube Perivitelline ntral signal (spatzle fragment)
Developmental Biology 5. 卵膜中的母体蛋白决定胚胎D－V极性
Developmental Biology Dorsa蛋白的V-D浓度梯度的形成 Toll activated ventrally Cross-section of syncytial blastoderm nuclei telling protein in membrane 6ooσoo。 OOOOo cytoplasm D spatzle cytoplasm activation of Toll in ventral region by spatzle Toll receptor protein Fig 5.8 Toll protein activation result derived ligand(the spatzle fragment) in a gradient of intranuclear dorsal which is processed in the perivitelline protein along the dorso-ventral axis space after fertilization. The localized Before receptor activation, the dorsal activation of the Toll receptor results in protein (red ) is distributed throughout the the entry of dorsal protein into nearby peripheral band of cytoplasm. The Toll nuclei. The intranuclear concentration protein is a receptor that is only activated of dorsal protein is greatest in ventral in the ventral region, by a maternally nuclei, resulting in a ventral to dorsal gradient
Developmental Biology Dorsal蛋白的V－D浓度梯度的形成
Developmental Biology 6.卵发生过程中母体基因产物的合成及分布 follcle cell locle cell Germm Egg chamber AmuMIllLImI stem cells oocyte ZIZITTIINWA nurse cell yte Fig. 5. 10 Egg development in Drosophila Oocyte develop surrounded by follicle cells and the resulting structure buds off ment begins in a germarium. with stem cells at one end. One from the germarium as an egg chamber. Successively produced stem cell will divide four times to give 16 cells with cytoplasmic egg chambers are still attached to each other at the poles. The connections between each other. One of the cells that is oocyte grows as the nurse cells provide material through the connected to four others will become the oocyte. the others cytoplasmic bridges. The follicle cells play a key role in will become nurse cells. The nurse cells and oocyte become pattening the oocyte
Developmental Biology 6. 卵发生过程中母体基因产物的合成及分布
Developmental Biology 卵子发生过程中某些基因特异性表达 Fig. 5. 11 Drosophila oocyte develop- ment. A developing Drosophila oocyte (right)is shown attached to its 15 nurse cells (left) and surrounded by a monolayer of 700 follicle cells. The oocyte and follicle layer are cooperating at this time to define the future dorso-ventral axis of the egg and embryo, as indicated by the expression of a gene only in the follicle cells overlying the dorsal anterior region of the oocyte(blue staining). Photograph courtesy of A Spradling
Developmental Biology 卵子发生过程中某些基因特异性表达